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Biology Flashcards

1
Q

Cell theory

A
  1. All living things are made of cells
  2. The cell is basic functional unit of life
  3. All cells arise from other cells
  4. Genetic information is carried in the form of deoxyribonucleic acid (DNA) and is passed from parent to daughter cell
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2
Q

Nucleus

A

Stores genetic information and is the site of transcription

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3
Q

Mitochondrion

A

Involved in ATP production and apoptosis

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4
Q

Lysosome

A

Contain hydrolytic enzymes that break down molecules ingested through endocytosis and cellular waste products
Can also be involved in apoptosis when its enzymes are released

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5
Q

Rough endoplasmic reticulum

A

Synthesizes proteins destined for secretion

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6
Q

Smooth endoplasmic reticulum

A

Involved in lipid synthesis and detoxification

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7
Q

Golgi apparatus

A

Packages, modifies and distributes cellular products

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8
Q

Peroxisome

A

Break down very long chain fatty acids, synthesize lipids and contribute to the pentose phosphate pathway
Dependent on hydrogen peroxide for function
Participate in phospholipid synthesis

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9
Q

Cytoskeletal elements

A

Microfilaments, microtubules, intermediate filaments, centrioles and flagella

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10
Q

Which proteins make up microfilaments?

A

Actin

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11
Q

Which proteins make up microtubules?

A

Tubulin

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12
Q

Which proteins make up intermediate filaments?

A

Keratin, design, vimentin and lamins (depending on cell type)

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13
Q

Centrioles

A

Consist of nine triplets of microtubules around a hollow center
Found in centrosomes
Involved in microtubule organization in the mitotic spindle

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14
Q

Components of flagella

A

Consist of nine doublets of microtubules on the outside and two microtubules on the inside

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15
Q

What do fibroblasts produce?

A

Collagen

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16
Q

Are fibroblasts epithelial cells or connective tissue?

A

Connective tissue

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17
Q

Endothelial cells

A

Line blood vessels

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18
Q

Are endothelial cells epithelial cells or connective tissue?

A

Epithelial cells

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19
Q

Alpha-cells

A

Produce glucagon in the pancreas

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20
Q

Are alpha-cells epithelial cells or connective tissue?

A

Epithelial cells

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21
Q

Osteoblasts

A

Produce osteoid

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22
Q

Osteoid

A

The material that hardens into bone

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23
Q

Are osteoblasts epithelial cells or connective tissue?

A

Connective tissue

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24
Q

Chondroblasts

A

Produce cartilage

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25
Are condroblasts epithelial cells or connective tissue?
Connective tissue
26
Where do archaea live?
Live in harsh environments | Use alternative sources of energy
27
Shapes of bacteria
Cocci, bacilli and spirilli
28
Cocci
Bacteria that is spherical
29
Bacilli
Bacteria that is rod-shaped
30
Spirilli
Bacteria that is spiral-shaped
31
Obligate aerobe
Can survive when oxygen is present Can carry out aerobic metabolism when oxygen is present Cannot survive when oxygen is absent Cannot carry out anaerobic metabolism when oxygen is absent
32
Facultative anaerobe
Can survive when oxygen is present Can carry out aerobic metabolism when oxygen is present Can survive when oxygen is absent Can carry out anaerobic metabolism when oxygen is absent
33
Obligate anaerobe
Cannot survive when oxygen is present Cannot carry out aerobic metabolism when oxygen is present Can survive when oxygen is absent Can carry out anaerobic metabolism when oxygen is absent
34
Aerotolerant anaerobe
Can survive when oxygen is present Cannot carry out aerobic metabolism when oxygen is present Can survive when oxygen is absent Can carry out anaerobic metabolism when oxygen is absent
35
Can obligate aerobe survive with oxygen?
Yes
36
Can obligate aerobe carry out aerobic metabolism when oxygen is present?
Yes
37
Can obligate aerobe survive without oxygen?
No
38
Can obligate aerobes carry out anaerobic metabolism when oxygen is absent?
No
39
Can facultative anaerobe survive with oxygen?
Yes
40
Can facultative anaerobe carry out aerobic metabolism when oxygen is present?
Yes
41
Can facultative anaerobe survive without oxygen?
Yes
42
Can facultative anaerobe carry out anaerobic metabolism when oxygen is absent?
Yes
43
Can obligate anaerobe survive with oxygen?
No
44
Can obligate anaerobe carry out aerobic metabolism when oxygen is present?
No
45
Can obligate anaerobe survive without oxygen?
Yes
46
Can obligate anaerobe carry out anaerobic metabolism when oxygen is absent?
Yes
47
Can aerotolerant anaerobe survive with oxygen?
Yes
48
Can aerotolerant anaerobe carry out aerobic metabolism when oxygen is present?
No
49
Can aerotolerant anaerobe survive without oxygen?
Yes
50
Can aerotolerant anaerobe carry out anaerobic metabolism when oxygen is absent?
Yes
51
Gram-positive bacteria
Have a thick layer of peptidoglycan and lipoteichoic acid | Contain no outer membrane
52
Gram-negative bacteria
Have a thin layer of peptidoglycan | Have an outer membrane containing lipopolysaccharides and phospholipids
53
Eukaryotic flagella
Contain microtubules composed of tubulin, organized in a 9+2 arrangement
54
Bacterial flagella
Made of flagellin and consist of a filament, a basal body and a hook
55
Mechanisms of bacterial genetic recombination
Transformation, conjugation and transduction
56
Transformation
The acquisition of genetic material from the environment that can be integrated into the bacterial genome
57
Conjugation
The transfer of genetic information from one bacterium to another across a conjugation bridge
58
Transduction
The transfer of genetic material from one bacterium to another using a bacteriophage as a vector
59
What can be transferred across a conjugation bridge?
A plasmid can be transferred from F+ cells to F- cells Or A portion of the genome can be transferred from Hfr cell to a recipient
60
Four phases of bacterial growth curve
Lag phase, exponential phase, stationary phase and death phase
61
Lag phase
Bacteria gets used to environment; little growth during this time
62
Exponential (log) phase
Bacteria use available resources to multiply at an exponential rate
63
Stationary phase
Bacterial multiplication ceases as resources are used up
64
Death phase
Bacteria die as resources become insufficient to support the colony
65
Why are viruses considered obligate intracellular parasites?
Because they do not contain organelles such as ribosomes; therefore, in order to reproduce and synthesize proteins, they must infect cells and hijack their cellular machinery
66
The pathway of retroviral nucleic acids from infection of a host cell to release of viral progeny
Nucleic acid enters as single-stranded RNA --> RNA undergoes reverse transcription (using reverse transcriptase) to form double-stranded DNA --> DNA can enter the host genome and replicate with the host cell --> DNA is transcribed to mRNA --> mRNA can be used to make structural proteins --> mRNA doubles as the viral genome for new virions --> virions are assembled from the structural proteins and mRNA genome --> virions can be released to infect other cells
67
Lytic cycle
Bacteriophages replicate in the host cell in extremely high numbers until the host cell lyses and releases the virions
68
Lysogenic cycle
Bacteriophage genome enters the host genome and replicates with the host cell as a provirus. At some point (after exposure to a particular stimulus), the provirus leaves the host genome and can be used to synthesize new virions
69
How do prions cause disease
They cause disease by triggering a change in the conformation of a protein from an alpha-helix to a beta-pleated sheet. This change reduces solubility of the protein and makes it highly resistant to degradation
70
Why are viruses not considered living things?
They are acellular, cannot reproduce without the assistance of a host cell, and many contain RNA as their genetic material
71
Nucleolus
A subsection of the nucleus in which ribosomal RNA (rRNA) is synthesized
72
Microfilaments
Composed of actin Provide structural protection for the cell Can cause muscle contraction through interactions with myosin Help form the cleavage furrow during cytokinesis in mitosis
73
Microtubules
Composed of tubulin Create pathways for motor proteins like kinesis and dynein to carry vesicles Contribute to the structure of cilia and flagella, where they are organized into nine pairs of microtubules in a ring with two microtubules at the center (9+2 structure)
74
Intermediate filaments
Involved in cell-cell adhesion or maintenance of the integrity of the cytoskeleton Help anchor organelles
75
Epithelial tissues
Cover the body and line its cavities, protecting against pathogen invasion and desiccation Form parenchyma Polarized (one side facing the lumen and the other facing the outside)
76
Parenchyma
The functional parts of the organ
77
Classifications of epithelia
Simple epithelia, stratified epithelia and pseudostratified epithelia
78
Simple epithelia
Have one layer
79
Stratified epithelia
Have many layers
80
Pseudostratified epithelia
Appear to have multiple layers because of differences in cell heights, but actually have one layer
81
Epithelia shapes
Cuboidal cells, columnar cells, squamous cells
82
Connective tissue function
Support and provide a framework for epithelial cells | Form the stroma by secreting materials to form an extracellular matrix
83
Stroma
Support structure
84
Examples of connective tissues
Bone, cartilage, tendons, ligaments, adipose tissue and blood
85
How to classify bacteria?
Gram staining bacteria with crystal violet stain, followed by a counterstain with safranin. Gram-positive bacteria turn purple. Gram-negative bacteria turn pink-red.
86
Chemotaxis
Moving in response to chemical stimuli
87
How do prokaryotes carry out the electron transport chain?
Using the cell membrane
88
Prokaryotic ribosomes
30S and 50 S
89
Eukaryotic ribosomes
40S and 60S
90
Binary fission
The prokaryote's chromosome replicated while the cell grows in size, until the cell wall begins to grow inward along the midline of the cell and divides it into two identical daughter cells
91
Plasmids
Carry extrachromosomal material | Contain antibiotic resistance genes
92
Virulence factors
Antibiotic resistance genes
93
Episomes
Plasmids that can integrate into the genome
94
Transpons
Genetic elements that can insert into or remove themselves from the genome
95
Capsid
A protein coat in a virus
96
Bacteriophages
Viruses that target bacteria Contain a tail sheath, which injects the genetic material into a bacterium Contain a tail fiber, which allows the bacteriophage to attach to the host cell
97
Positive sense viruses
Single-stranded RNA can be translated by the host cell
98
Negative sense viruses
A complementary strand to the single-stranded RNA must be synthesized using RNA replicase, which can then be translated
99
Retroviruses
Contain a single-stranded RNA genome, to which a complementary DNA is made using reverse transcriptase The DNA strand can then be integrated into the genome
100
Viroids
Plant pathogens that are small circles of complementary RNA that can turn off genes, resulting in metabolic and structural derangements of the cell and, potentially, cell death
101
Can a virus have single-stranded DNA?
Yes
102
Can a virus have double-stranded DNA?
Yes | Must use the cell's RNA polymerase machinery in the nucleus to make its own mRNA
103
Can a virus have single-stranded RNA?
Yes
104
Can a virus have double-stranded RNA?
Yes
105
How are archaea similar to bacteria?
They are single-celled organisms that lack a nucleus or membrane-bound organelles, contain a single circular chromosome, divide by binary fission or budding
106
How are archaea similar to eukaryotic cells?
They start translation with methionine, contain similar RNA polymerases and associate their DNA with histones
107
What kind of genetic information can viruses have?
Either single-stranded or double-stranded DNA or RNA
108
Cell cycle stages
G0, G1, S, G2, M
109
G0 stage
The cell performs its normal functions and it is not planning to divide
110
G1 stage (presynthetic gap)
Cell grows and performs its normal functions. DNA is examined and repaired Cells create organelles for energy and protein production, while also increasing their size Has the restriction point
111
S stage (synthesis)
Replication of DNA and sister chromatids are held together at the centromeres
112
G2 stage (post synthetic gap)
Cell continues to grow and replicates organelles in preparation for mitosis. Cell continues to perform its normal function
113
M stage
Mitosis
114
Mitotic phases
Prophase, metaphase, anaphase, telophase and cytokinesis
115
Prophase
Nuclear membrane disappears, chromosomes become tightly coiled, centrioles move to opposite poles of the cell and begin to form the spindle apparatus and spindle fibers attach at the kinetochore of each chromosome
116
Metaphase
Centrioles align chromosomes along the midline of the cell (metaphase plate) using spindle fibers
117
Anaphase
Spindle fibers pull sister chromatids apart so there's a set of chromosomes on either pole of the cell
118
Telophase and cytokinesis
Organelles separate moving to either pole of the cell, cell membrane splits the cell in half with each half having its own genetic material and organelles, nuclear membrane re-forms in each identical daughter cell, chromosomes loosen up and the spindle apparatus breaks down
119
What is the ploidy of the daughter cells produced from meiosis I?
Two haploid daughter cells
120
What is the ploidy of the daughter cells produced from meiosis II?
Four haploid daughter cells
121
Homologous chromosomes
XX Four copies of the same chromosome Related chromosomes of opposite parental origin
122
Sister chromatids
| | or X Two copies of the same chromosome Identical copies of the came DNA that are held together at the centromere
123
Meiosis I phases
Prophase I, metaphase I, anaphase I and telophase I
124
Prophase I
Nuclear membrane disappears, chromosomes become tightly coiled, centrioles move to opposite poles of the cell and begin to form the spindle apparatus and spindle fibers attach at the kinetochore of each chromosome Homologous chromosomes come together as tetrads during synapsis; crossing over
125
Metaphase I
Centrioles align homologous chromosomes along opposite sides the midline of the cell (metaphase plate) using spindle fibers
126
Anaphase I
Spindle fibers pull homologous chromosomes apart so there's a set of chromosomes on either pole of the cell Contromeres do not break
127
Telophase I
Organelles separate moving to either pole of the cell, cell membrane splits the cell in half with each half having its own genetic material and organelles, nuclear membrane re-forms in each haploid daughter cell, chromosomes may or may not loosen up and the spindle apparatus dissolves
128
Interstitial cells of Leydig
Secrete testosterone and other male sex hormones (androgens)
129
Sertoli cells
Nourish sperm during their development
130
During which phase of meiosis is a primary oocyte arrested?
Prophase I
131
During which phase of meiosis is a secondary oocyte arrested?
Metaphase II
132
Acrosome
Contains enzymes that are capable of penetrating the corona radiata and zone pellucid of the ovum, permitting fertilization to occur
133
Which organelle forms the acrosome?
Golgi apparatus
134
Phases of the menstrual cycle
Follicular phase, ovulation, luteal phase and menses
135
Features of the follicular phase
Egg develops, endometrial lining becomes vascularized and glandularized GnRH secretion stimulates FSH and LH secretion, which promotes follicle development --> Estrogen is released, stimulating vascularization and glandularization of the decidua
136
Features of ovulation
Egg is released from follicle into peritoneal cavity Stimulated by sudden surge in LH
137
Features of the luteal phase
Corpus luteum produces progesterone to maintain the endometrium LH promotes the ruptured follicle to become the corpus luteum, which secretes progesterone, which maintains the uterine lining --> High estrogen and progesterone levels cause negative feedback on GnRH, FSH and LH
138
Features of menses
Shedding of endometrial lining Estrogen and progesterone levels drop --> endometrial lining is sloughed off --> the block on GnRH production is removed
139
FSH levels in the follicular phase
High
140
FSH levels in ovulation
High
141
FSH levels in the luteal phase
Low
142
FSH levels in menses
Low
143
LH levels in the follicular phase
No changes
144
LH levels in ovulation
Super high (LH spike)
145
LH levels in the luteal phase
No changes
146
LH levels in menses
Low
147
Estrogen levels in the follicular phase
Low, then high
148
Estrogen levels in ovulation
High
149
Estrogen levels in the luteal phase
High
150
Estrogen levels in menses
Low
151
Progesterone levels in the follicular phase
Low
152
Progesterone levels in ovulation
Low
153
Progesterone levels in the luteal phase
High
154
Progesterone levels in menses
Low
155
Androgens
Male sex hormones
156
Diploid (2n) cells
Have two copies of each chromosome
157
Haploid (n) cells
Have one copy of each chromosome
158
Interphase
G1, S and G2 phases | DNA is uncoils in the form of chromatin
159
Restriction point
Present in G1 DNA is checked for quality Must be passed for the cell to move into the S stage
160
p53
Plays a role in the two major checkpoints of the cell cycle G1 to S and G2 to M
161
Cyclins
Bind to cyclin-dependent kinases (CDK), phosphorylating and activating transcription factors for the next stage of the cell cycle
162
Cancer
Occurs when cell cycle control becomes deranged, allowing damaged cells to undergo mitosis without regard to quality or quantity of the new cells produced Cancerous cells may begin to produce factors that allow them to escape their site and invade or metastasize elsewhere
163
Tetrad
Four chromatids of homologous chromosomes
164
Which stage of meiosis represents Mendel's second law (the law of independent assortment)?
Prophase I
165
Which stage of meiosis represents Mendel's first law (the law of segregation)?
Anaphase I
166
Is meiosis II more similar to meiosis I or mitosis?
Mitosis, except the daughter cells are haploid
167
X chromosome
Carries a sizable amount of genetic information
168
Mutations of X-linked genes
Cause sex-linked disorders
169
Hemizygous
Males because they have unpaired X chromosomes
170
Who most often expresses sex-linked disorders?
Males because they are hemizygous for the X chromosome
171
Who is most often a carrier to sex-linked disorders?
Women because they have two copies of the X chromosome
172
Y chromosome
Carries little genetic information | Contains the SRY (sex-determining region Y) gene
173
SRY (sex-determining region Y) gene
Present on Y chromosome | Causes gonads to differentiate into testes
174
Where does sperm develop?
Seminiferous tubules in the testes
175
How are sperm nourished?
By sertoli cells
176
What secrets testosterone and androgens in the testes?
Interstitial cells of Leydig
177
Epididymis
Stores sperm and gives it mobility
178
Ejaculation pathway
Vas deferens --> ejaculatory duct --> urethra --> penis
179
Seminal vesicles
Contribute fructose to nourish sperm and produce alkaline fluid
180
Prostate gland
Produces alkaline fluid
181
Bulbourethral glands
Produce clear viscous fluid that cleans out any remnants of urine and lubricates the urethra during sexual arousal
182
Semen
Sperm + seminal fluid
183
Spermatogenesis
Four haploid sperm are produced from a spermatogonium
184
Primary spermatocytes
Germ cells after S phase
185
Secondary spermatocytes
Germ cells after meiosis I
186
Spermatids
Germ cells after meiosis II
187
Spermatozoa
Germ cells after maturation
188
Sperm parts
Head, midpiece and flagellum
189
Sperm head
Contains genetic material and is covered with an acrosome
190
Sperm midpiece
Generates ATP from fructose and contains many mitochondria
191
Sperm flagellum
Promotes sperm mobility
192
Where are ova (eggs) produced?
Follicles in the ovaries
193
Where does an egg get ovulated each month?
Peritoneal sac and then it gets drawn into the Fallopian tube (oviduct)
194
Where is sperm deposited during intercourse?
Vaginal canal
195
Vulva
External female anatomy
196
Oogenesis
One haploid ovum and a variable number of polar bodies are formed from an oogonium
197
Primary oocyte
Present at birth and arrested in prophase I
198
Secondary oocyte
Only one is present after every ovulation and arrested in metaphase II until either menses or fertilization
199
When does an oocyte complete meiosis II?
When it is fertilized
200
Zona pellucida
Surround the oocyte | Acellular mixture of glycoproteins that protect the oocyte and contain the compounds necessary for sperm binding
201
Corona radiata
Surround the oocyte | A layer of cells that adhered to the oocyte during ovulation
202
What releases gonadotropin-releasing hormone (GnRH)?
Hypothalamus
203
Gonadotropin-releasing hormone (GnRH)
Causes the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
204
Follicle-stimulating hormone (FSH) in males
Stimulates Sertoli cells | Trigger spermatogenesis
205
Luteinizing hormone (LH) in males
Cause the interstitial cells to produce testosterone
206
Testosterone
Responsible for the maintenance and development of the male reproductive system and male secondary sex characteristics (facial and axillary hair, deepening of the voice and changes in growth patterns)
207
Follicle-stimulating hormone (FSH) in females
Stimulates ovarian follicles | Stimulate the production of estrogen and progesterone
208
Luteinizing hormone (LH) in females
Causes ovulation | Stimulate the production of estrogen and progesterone
209
Why does the sudden surge in LH occur?
Estrogen stops having negative feedback effects at a certain threshold and begins to have positive feedback effects
210
What causes negative feedback on GnRH, LH and FSH levels?
High levels of estrogen and progesterone
211
What happens if fertilization occurs?
The blastula produces human chorionic gonadotropin (hCG) which, as an LH analog, can maintain the corpus luteum
212
What happens near the end of the first trimester?
hCG levels drop as the placenta takes over progesterone production
213
Menopause
Occurs when the ovaries stop producing estrogen and progesterone (ages 45 and 55) Menstruation stops FSH and LH levels rise
214
Sperm development
Spermatogonium --> primary spermatocyte --> secondary spermatocyte --> spermatid --> spermatozoan
215
Vas deferens
Tube connecting the epididymis to the ejaculatory duct
216
Cowper's glands
Produce a fluid to clear traces of urine in the urethra
217
What is the last point in the meiotic cycle in which the cell has a diploid number of chromosomes?
Telophase I
218
Determinate cleavage
Cell division that results in cells having definitive lineages; that is, at least one daughter cell is already programmed to differentiate into a particular cell type
219
Indeterminate cleavage
Cell division that results in cells that can differentiate into any cell type (or a whole organism)
220
Stages of development from zygote to gastrula
Zygote --> 2-cell embryo --> 4-cell embryo --> 8-cell embryo --> 16-cell embryo --> morula --> blastula (blastocyst) --> gastrula
221
During which stage of development does implantation occur?
Blastula (blastocyst)
222
Primary Germ Layers
Ectoderm, mesoderm, endoderm
223
Ectoderm
Nervous system, integumentary system, eyes and ears
224
Mesoderm
Musculoskeletal system, circulatory system, excretory system, endocrine system, reproductive system, digestive system, respiratory system
225
Endoderm
Epithelial linings of organs, liver, pancreas, thyroid, bladder, distal tracts of the excretory and reproductive systems
226
Induction
The process by which nearby cells influence the differentiation of adjacent cells
227
What tissues do neural crest cells develop into?
PNS and skin
228
Why is induction important?
It insures the proper spatial location and orientation of cells that share function or have complementary functions
229
Determination
The commitment of a cell to a particular lineage
230
Differentiation
The actual changes that occur in order for the cell to assume the structure and function of the determined cell type
231
Types of potency
Totipotency, pluripotency and multipotency
232
Types of cell-cell communication
Autocrine, paracrine, juxtacrine and endocrine
233
Apoptosis
Programmed cell death
234
Necrosis
Cell death due to injury
235
Totipotent cell lineages
Any cell type in the developing embryo (primary germ layers) or in extra-embryonic tissues (amnion, chorion, placenta)
236
Pluripotent cell lineages
Any cell type in the developing embryo (primary germ layers)
237
Multipotent cell lineages
Any cell type within a particular lineage (hematopoietic stem cells)
238
Autocrine
The signal acts on the same cell that secreted it
239
Paracrine
The signal acts on local cells
240
Juxtacrine
The signal acts on an adjacent cell through direct receptor stimulation
241
Endocrine
The signal travels via the bloodstream to act at distant sites
242
What does apoptosis result in?
Contained blebs of the dead cell that can be picked up and digested by other cells
243
What does necrosis result in?
Spilling of cytoplasmic contents
244
What is the oxygenation status of the blood in the umbilical arteries?
Deoxygenated
245
What is the oxygenation status of blood in the umbilical vein
Oxygenated
246
Three fetal shunts
Foramen ovale, ductus arteriosus, ductus venosus
247
What vessels or heart chambers does the foramen ovale connect?
Right atrium to left atrium
248
What vessels or heart chambers does the ductus arteriosus connect?
Pulmonary artery to aorta
249
What vessels or heart chambers does the ductus venosus connect?
Umbilical vein to inferior vena cava
250
Which organ does the foramen ovale bypass?
Lungs
251
Which organ does the ductus arteriosus bypass?
Lungs
252
Which organ does the ductus venosus bypass?
Liver
253
Key developmental features of the first trimester
Organogenesis
254
Key developmental features of the second trimester
Growth, movement, face develops, digits elongate
255
Key developmental features of the third trimester
Growth, brain development, transfer of antibodies to the fetus
256
Organogenesis in the first trimester
Heart, eyes, gonads, limbs, liver and brain
257
First phase of birth
Cervix thins and the amniotic sac ruptures
258
Second phase of birth
Urine contractions and birth of the fetus
259
What coordinates uterine contractions?
Prostaglandins and oxytocin
260
Third stage of birth
Placenta and umbilical cord expulsion
261
Fertilization
The joining of a sperm and an ovum
262
Where does fertilization occur?
In the ampulla of the fallopian tube
263
How does the sperm fertilize the egg (i.e. the cortical reaction)?
It uses ayrosomal enzymes to penetrate to corona radiata and zona pellucida --> Once it contacts the oocyte's plasma membrane, the sperm establishes the acrosomal apparatus and injects its pronucleus --> When the first sperm penetrates, it causes the release of calcium ions, which prevents additional sperm from fertilizing the egg and increases the metabolic rate of the resulting diploid zygote
264
Fraternal (dizygotic) twins
Result from the fertilization of two eggs by two different sperm
265
Identical (monozygotic) twins
Result from the splitting of a zygote in two
266
Cleavage
The early divisions of cells in the embryo | These mitotic divisions result in a larger number of smaller cells, as the overall volume does not change
267
Why does a zygote become an embryo after the first cleavage?
Because it is no longer unicellular
268
Morula
A solid mass of cells seen in early development
269
Blastula (blastocyst)
Has a fluid-filled center called a blastocoel and has two different cell types, including trophoblasts and the inner cell mass
270
Blastocoel
Fluid inside the center of a blastula
271
Types of cells in a blastula
Trophoblasts and inner cell mass
272
Trophoblasts
Become placental structures
273
Inner cell mass
Become the developing organism
274
Where does a blastula implant?
In the endometrial lining
275
What happens after the blastula implants?
It forms the placenta
276
Chorion
Penetrate the endometrium and create the interface between maternal and fetal blood using chorionic villi
277
How is the embryo supported before the placenta forms?
Yolk sac
278
Allantois
Involved in early fluid exchange between the embryo and the yolk sac
279
Amnion
Lies inside the the chorion and produces amniotic fluid
280
How is the developing organism connected to the placenta?
Via the umbilical cord
281
Gastrulation
The archenteron is formed with a blastopore at the end. As the archenteron grows through the blastocoel, it contacts the opposite side, establishing three primary germ layers (ectoderm, endoderm and mesoderm)
282
Neurulation
The development of the nervous system
283
When does neurulation occur?
After the formation of the three germ layers
284
How does neurulation occur?
The notochord induces a group of overlying ectodermal cells to form neural folds surrounding a neural groove --> the neural folds fuse to form the neural tube, which becomes the CNS --> the tip of each neural fold contains neural crest cells
285
What does the neural tube become?
CNS
286
Teratogens
Substances that interfere with development, causing defects or even death of the developing embryo
287
How does diabetes in pregnant women affect the fetus?
Increase fetal size and cause hypoglycemia after birth
288
How does folic acid deficiency in pregnant women affect the fetus?
Neural tube defects
289
How is determination accomplished?
Uneven segregation of cellular material during mitosis | Using morphogens
290
Morphogens
Promote development down a specific cell line
291
How can a cell respond to a morphogen?
It must have competency
292
How is differentiation accomplished?
Via selective transcription to take on characteristics appropriate to its cell line
293
Stem cells
Cells that are capable of developing into various cell types
294
Totipotent cells
Able to differentiate into all cell types, including the three germ layers and placental structures
295
Pluripotent cells
Able to differentiate into all three germ layers and their derivatives
296
Multipotent cells
Able to differentiate only to a specific subset of cell types
297
Inducer
Releases factors to promote the differentiation of a competent responder
298
Growth factors
Peptides that promote differentiation and mitosis in certain tissues
299
Reciprocal induction
When two tissues both induce further differentiation in each other
300
How does signaling occur?
Via gradients
301
Do cells migrate to arrive at their anatomically correct location?
Yes
302
When is apoptosis useful?
Sculpting anatomical structures (e.g. removing webbing between digits)
303
Regenerative capacity
The ability of an organism to regrow certain parts of the body
304
Does the liver have high or low regenerative capacity?
High
305
Does the heart have high or low regenerative capacity?
Low
306
Does the kidneys have high or low regenerative capacity?
High
307
Senescence
The result of multiple molecular and metabolic processes; most notably, the shortening of telomeres during cell division
308
Where does nutrient, gas and waste exchange occur in the fetus?
At the placenta
309
How are oxygen and carbon dioxide exchanged between the mother and fetus?
Passively through changes in concentration gradient
310
Fetal hemoglobin (HbF)
Has a higher affinity for oxygen than adult hemoglobin (primarily HbA), which also assists in the transfer (and retention) of oxygen into the fetal circulatory system
311
Placental barrier
Serves as the immune protect against many pathogens Transfers antibodies from mother to fetus Secretes estrogen, progesterone and human chorionic gonadotropin (hCG)
312
Notochord
Forms from the mesoderm and causes neurulation
313
Can a fetus produce immunoglobulins?
No, because they are immunologically naive
314
Can fetal hemoglobin cross the placenta?
No, because it's too large
315
Is fetal hemoglobin the same size as adult hemoglobin?
No, it's larger
316
When do somatic cells stop dividing?
When the telomeres become too short to effectively protect genomic material
317
Telomerase
An enzyme that allows for synthesis of telomeres to counteract telomere shortening during mitosis
318
Why are embryonic stem cells controversial?
Because they require destruction of an embryo to harvest
319
How can one increase the level of potency of adult stem cells?
Treatment with various transcription factors
320
Would using one's own stem cells remove the risk or rejection when the cells are introduced into an individual?
Yes
321
Can adult stem cells be pluripotent?
Rarely so, unless pluripotency has been induced by strategic use of transcription factors
322
Incomplete regeneration
Newly formed tissues are not identical in structure or function to the tissues that have been injured or lost (e.g. scars)
323
What is the last structure to become fully functional in a fetus?
The lungs
324
Axon
Transmits electrical signals (action potentials) from the soma to the synaptic knob
325
Axon hillock
Integrates excitatory and inhibitory signals from the dendrites and fires an action potential if the excitatory signals are strong enough to reach threshold
326
Dendrite
Receive incoming information signals and carry them to the soma
327
Myelin sheath
Acts as insulation around the axon and speeds conduction Prevents signal loss Prevents the dissipation of the neural impulse and crossing of neural impulses from adjacent neurons
328
Soma
The cell body of a neuron, contains the nucleus, ER and ribosomes
329
Synaptic bouton (nerve terminal)
Lies at the end of the axon and releases neurotransmitters
330
The collection of cell bodies in the CNS
Nucleus
331
The collection of cell bodies in the PNS
Ganglion
332
Astrocyte
Nourish neurons and form the blood-brain barrier
333
Ependymal cell
Produce cerebrospinal fluid
334
Microglia
Phagocytic cells that ingest and breakdown waste products and pathogens in CNS
335
Oligodendrocyte
Produce myelin and the CNS
336
Schwann cell
Produce myelin the PNS
337
When does an axon hillock fire an action potential?
When the excitatory signals are strong enough to reach threshold
338
Which part of the neuron fires an action potential?
The axon hillock
339
Which part of the neuron releases neurotransmitters?
The synaptic bouton
340
What produces myelin in the CNS?
Oligodendrocytes
341
What produces myelin in the PNS?
Schwann cells
342
How is the resting membrane potential maintained?
Sodium/potassium ATPase and selective permeability of ions
343
What is the approximate voltage of the resting membrane potential?
-70 mV
344
Temporal summation
The integration of multiple signals close to each other in time
345
Spatial summation
The integration of multiple signals close to each other in space
346
During the action potential, which ion channel opens first?
Sodium ion channels
347
How are sodium ion channels regulated?
Inactivation, the opening of potassium ion channels, at +35 mV
348
What effect does the opening of the sodium ion channel have on the polarization of the cell?
It depolarizes the cell
349
During the action potential, which ion channel opens second?
Potassium ion channels
350
How are potassium ion channels regulated?
Closing at low potentials (slightly below -70 mV)
351
What effect does the opening of the potassium ion channel have on the polarization of the cell?
Repolarization of the cell and eventually hyper-polarization
352
Absolute refractory period
It does not matter how much or how strong the stimuli are, no further action potential will be initiated
353
Relative refractory period
Occurs during the hyper polarization phase | If strong enough stimulus is present, another action potential will be fired
354
What ion is primarily responsible for the fusion of neurotransmitter-containing vesicles with nerve terminal membrane?
Calcium
355
What are the three main methods by which a neurotransmitter's action can be stopped?
Enzymatic degradation, reuptake and diffusion
356
When do sodium ion channels open?
At -50 mV
357
How can the inactivation of sodium ion channels be reversed?
By repolarizing the cell
358
When do potassium ion channels open?
At +35 mV
359
Central Nervous System (CNS)
Brain and spinal cord
360
Peripheral Nervous System (PNS)
Afferent and efferent neurons
361
Afferent neurons
Carry sensory information from the periphery to the CNS
362
Efferent neurons
Carry information from the CNS to the periphery to initiate an action
363
Somatic nervous system
Voluntary
364
Autonomic nervous system
Involuntary
365
Sympathetic nervous system
Fight or flight response Increased heart rate, bronchial dilation, redistribution of blood to locomotor muscles, dilation of pupils, slowing of digestive and urinary function
366
Parasympathetic nervous system
Rest and digest response Slowed heart rate, bronchial constriction, redistribution of blood to the gut, promotion of exocrine secretions, constriction of pupils, promotion of peristalsis and urinary function
367
Monosynaptic reflex
A sensory (afferent, presynaptic) neuron fires directly onto a motor (efferent, postsynaptic) neuron
368
Polysynaptic reflex
A sensory (afferent, presynaptic) neuron may fire directly onto a motor neuron (efferent, postsynaptic) neuron, but interneurons are used as well. The interneurons fire onto other motor neurons.
369
Neurons
Highly specialized cells responsible for the conduction of impulses
370
Do neurons communicate through electrical or chemical forms?
Both
371
How does electrical communication among neurons work?
Via ion exchange and the generation of membrane potentials down the length of the axon
372
How does chemical communication among neurons work?
Via neurotransmitter release from the presynaptic cell and the binding of these neurotransmitters to the postsynaptic cell
373
Nodes of Ranvier
Exposed areas of myelinated axons that permit saltatory conduction
374
Synapse
Consist to the nerve terminal of the presynaptic neuron, the membrane of the postsynaptic cell, and the space between the two
375
Synaptic cleft
The space between two neurons
376
What are individual axons bundled into?
Nerves or tracts
377
Can a single nerve carry multiple types of information?
Yes, including sensory, motor or both
378
Can a single tract carry multiple types of information?
No
379
Ganglia
Cell bodies of neurons of the same type within a nerve cluster in the PNS
380
Nuclei
Cell bodies of the individual neurons within a tract cluster in the CNS
381
Neuroglia (Glial cells)
Other cells within the nervous system in addition to neurons
382
Blood-brain barrier
Controls the transmission of solutes from the bloodstream into nervous tissue
383
Where are ependymal cells?
They line the ventricles of the brain
384
Cerebrospinal fluid
Physically supports the brain and serves as a shock absorber
385
Sodium/Potassium ATPase
Pumps three sodium ions out of the cell for every two potassium ions pumped in
386
Excitatory signals
Cause a neuron to depolarize
387
Inhibitory signals
Cause a neuron to hyperpolarize
388
How are signals propagated down the axon?
Through an action potential
389
Why does an impulse propagate down the length of the axon?
Because the influx of sodium in one segment of the axon brings the subsequent segment of the axon to threshold. The fact that the preceding segment of the axon is in its refractory period means that the action potential can only travel in one direction
390
Where are neurotransmitters released from a neuron?
At the nerve terminal into the synapse
391
What happens when the action potential arrives at the nerve terminal?
Voltage-gated calcium channels open
392
Do calcium ions flow into or out of the neuron when the voltage-gated calcium channels open?
Into the neuron
393
What happens when the voltage-gated calcium channels open?
Vesicles filled with neurotransmitter fuse with the presynaptic membrane, resulting in the exocytosis of neurotransmitter into the synaptic cleft, which then bind to their receptors on the postsynaptic cell
394
How to stop the propagation of a signal?
Neurotransmitters must be cleared from the postsynaptic cleft through: enzymatic breakdown of the neurotransmitters, reabsorption of the neurotransmitter by the presynaptic cell through reuptake channels, the neurotransmitter can diffuse out the of the synaptic cleft
395
What is the white matter in the CNS made of?
Myelinated axons
396
What is the grey matter in the CNS made of?
Unmyelinated cell bodies and dendrites
397
In the brain, is the white matter deeper than the grey matter?
Yes
398
In the spinal cord, is the white matter deeper than the grey matter?
No
399
Reflex arcs
Use the ability of interneurons in the spinal cord to relay information to the source of a stimulus while simultaneously routing it to the brain
400
Action potential
All or nothing response
401
Where do sensory neurons enter the spinal cord?
On the dorsal side
402
Where do motor neurons exit the spinal cord?
On the ventral side
403
Neurotransmitter released by pre-ganglionic neurons
Acetylcholine
404
Is acetylcholine released by the parasympathetic or the sympathetic pre-ganglionic neurons?
Both
405
What does a sympathetic post-ganglionic neuron release?
Epinephrine or norepinephrine
406
What does a parasympathetic post-ganglionic neuron release?
Acetylcholine
407
What color does gram-positive bacteria turn into after staining?
Purple
408
What color does gram-negative bacteria turn into after staining?
Pink-red
409
What does the tail sheath on a bacteriophage do?
Injects the genetic material into a bacterium
410
What does the tail fiber on a bacteriophage do?
Allows the bacteriophage to attach to the host cell
411
What is the chemical precursor for a peptide hormone?
Amino acids (polypeptides)
412
What is the chemical precursor for a steroid hormone?
Cholesterol
413
Where is the receptor fir a peptide hormone?
On the cell membrane
414
Where is the receptor fir a steroid hormone?
Inside the cell
415
What is the mechanism of action for a peptide hormone?
Stimulates a receptor (usually a G protein-coupled receptor), affecting levels of second messengers (commonly cAMP) Initiates a signal cascade
416
What is the mechanism of action for a steroid hormone?
Binds to a receptor, induces conformational change and regulates transcription at the level of the DNA
417
What is the method of travel in the bloodstream for a peptide hormone?
Dissolves and travels freely
418
What is the method of travel in the bloodstream for a steroid hormone?
Binds to a carrier protein
419
How fast do the effects of a peptide hormone onset?
Very quickly
420
How fast do the effects of a steroid hormone onset?
Very slowly
421
What is the duration of action for a peptide hormone?
Short-lived
422
What is the duration of action for a steroid hormone?
Long-lived
423
How are amino acid-derivative hormones synthesized?
Amino acid-derivative hormones are made by modifying amino acids, such as the addition of iodine to tyrosine (in thyroid hormone production)
424
Direct hormone
Secreted into the bloodstream and travel to a target tissue where they have direct effects
425
Tropic hormone
Cause secretion of another hormone that then travels to the target tissue to cause an effect
426
Hypothalamus hormones
Gonadotropin-releasing hormone (GnRH), corticotropin-releasing factor (CRF), thyroid-releasing hormone (TRH), dopamine and growth hormone-releasing hormone (GHRH)
427
Gonadotropin-releasing hormone (GnRH)
Releases follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary
428
Corticotropin-releasing factor (CRF)
Releases adrenocorticotropic hormone (ACTH) from the anterior pituitary
429
Thyroid-releasing hormone (TRH)
Releases thyroid stimulating hormone (TSH) from the anterior pituitary
430
Dopamine (Prolactin-inhibiting factor, PIF)
A decrease in dopamine promotes prolactin secretion by the anterior pituitary
431
Growth hormone-releasing hormone (GHRH)
Releases growth hormone (GH) from the anterior pituitary
432
What is the target organ of gonadotropin-releasing hormone (GnRH)?
Ovaries or testes
433
What is the target organ of corticotropin-releasing factor (CRF)?
Adrenal cortex
434
What is the target organ of thyroid-releasing hormone (TRH)?
Thyroid gland
435
What is the target organ of dopamine?
Breast tissue
436
What is the target organ of growth hormone-releasing hormone (GHRH)?
Muscles and bones
437
What are the hormones released by the target organ of gonadotropin-releasing hormone (GnRH)?
Estrogen and progesterone or testosterone
438
What are the hormones released by the target organ of corticotropin-releasing factor (CRF)?
Glucocorticoids (cortisol and cortisone)
439
What are the hormones released by the target organ of thyroid-releasing hormone (TRH)?
Triiodothyronine (T3) and thyroxine (T4)
440
Which two hormones are primarily involved in calcium homeostasis?
Calcitonin and parathyroid hormone
441
Which endocrine tissue synthesizes catecholamines?
The adrenal medulla
442
What are the two main catecholamines it produces?
Epinephrine and norepinephrine
443
Which two pancreatic hormones are the major drivers of glucose homeostasis?
Insulin and glucagon
444
Where does insulin come from?
Beta cells in the pancreas
445
Where does glucagon come from?
Alpha cells in the pancreas
446
What effect does insulin have on blood glucose?
Lowers it by stimulating glucose uptake by cells and anabolic processes like glycogen, fat and protein synthesis
447
What effect does glucagon have on blood glucose?
Increases it by stimulating protein and fat degradation, glycogenolysis and gluconeogenesis
448
Which three hormones are primarily involved in water homeostasis?
Antidiuretic hormone (ADH or vasopressin), aldosterone and atrial natriuretic peptide (ANP)
449
What releases calcitonin?
Parafollicular (C-) cells of the thyroid
450
Calcitonin
Decreases blood calcium concentration by promoting calcium excretion in the kidneys, decreasing calcium absorption in the gut and promoting calcium storage in bones
451
What releases parathyroid hormone?
Parathyroid glands
452
Parathyroid hormone (PTH)
Increases blood calcium concentration by decreasing calcium excretion by the kidneys and increasing bone resorption Activates vitamin D Promotes resorption of phosphate from bone Reduces phosphate reabsorption in the kidney
453
What releases antidiuretic hormone (ADH or vasopressin)?
The hypothalamus via posterior pituitary
454
Antidiuretic hormone (ADH or vasopressin)
Increases blood volume and decreases blood osmolarity | By increasing reabsorption of water in the collecting duct of the nephron
455
What releases aldosterone?
Adrenal cortex
456
Aldosterone
Increases blood volume with no effect on blood osmolarity by promoting sodium reabsorption in the distal convoluted tubule and collecting duct, thus increasing water reabsorption Increases potassium and hydrogen ion excretion Regulated by renin-angiotensin-aldosterone system
457
What releases atrial natriuretic peptide (ANP)?
The heart
458
Atrial natriuretic peptide (ANP)
Decreases blood volume with no effect on blood osmolarity by promoting excretion of salt and water in the kidneys in response to stretching to the atria (high blood volume)
459
Are peptide hormones polar or non-polar?
Polar
460
Can peptide hormone pass through the cell membrane?
No, because they are polar
461
Are steroid hormones polar or non-polar?
Non-polar
462
Can steroid hormones pass through the cell membrane?
Yes, because they are non-polar
463
How do steroid hormones function?
They bind to and promote a conformational change of intracellular or intranuclear receptors; the hormone-receptor complex binds to DNA, affecting the transcription of a particular gene
464
Amino acid-derivative hormones
Modified amino acids | Share some features with peptide hormones and some features with steroid hormones
465
Examples of amino acid-derivative hormones
Epinephrine, norepinephrine, triiodothyronine and thyroxine
466
Do direct hormones affect endocrine or non-endocrine tissues?
Non-endocrine
467
Do tropic hormones affect endocrine or non-endocrine tissues?
Endocrine
468
What is the bridge between the nervous and endocrine systems?
The hypothalamus
469
Negative feedback
The final hormone (or product) of a pathway inhibits hormones (or enzymes) earlier in the pathway, maintaining homeostasis
470
How does the hypothalamus stimulate the anterior pituitary gland?
Through paracrine release of hormones into the hypophyseal portal system, which directly connects the two organs
471
Anterior pituitary hormones
Follicle-stimulating hormone (FSH), luteinizing hormone (LH), adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), prolactin, endorphins and growth hormones
472
Tropic hormones released by the anterior pituitary
FSH, LH, ACTH and TSH
473
Direct hormones released by the anterior pituitary
Prolactin, endorphins and growth hormones
474
Posterior pituitary
Releases two hormones produced in the hypothalamus: Antidiuretic hormone (ADH or vasopressin) and oxytocin
475
What triggers ADH release?
Low blood volume or increased blood osmolarity
476
Oxytocin
Secreted during childbirth and promotes uterine contractions Promotes milk ejection Involved in bonding behavior Has a positive feedback loop
477
Hormones produced by the thyroid
Triiodothyronine (T3), thyroxine (T4) and calcitonin
478
Hormones released by follicular cells
T3 and T4
479
Triiodothyronine (3) and thyroxine (T4)
Contain iodine Increase metabolic rate Alter utilization of glucose and fatty acids
480
Vitamin D
Necessary for calcium and phosphate absorption from the gut
481
Adrenal cortex hormones
Cortisol, cortisone, aldosterone, androgens (like testosterone) and estrogen
482
Glucocorticoids released by the adrenal cortex
Cortisol and cortisone
483
Mineralocorticoids released by the adrenal cortex
Aldosterone
484
Cortical sex hormones released by the adrenal cortex
Androgens (like testosterone) and estrogen
485
Cortisol and cortisone
``` Increase blood glucose concentration Reduce protein synthesis Inhibit the immune system Participate in the stress response Stimulated by ACTH ```
486
How is aldosterone regulated?
By the renin-angiotensin-aldosterone system
487
Adrenal medulla hormones
Epinephrine and norepinephrine
488
Epinephrine and norepinephrine
Involved in fight-or-flight response, promote glycogenolysis, increase the basal metabolic rate, increase heart rate, dilate the bronchi and alter blood flow
489
Hormones produced by the pancreas
Glucagon, insulin and somatostatin
490
What produces somatostatin?
Delta-cells of the pancreas
491
Somatostatin
Inhibits insulin and glucagon secretion
492
Pineal gland
Releases melatonin
493
Melatonin
Helps regulate circadian rhythms
494
Hormones produced by the stomach
Secretin, gastrin and cholecystokinin
495
Hormones produced by the kidneys
Erythropoietin
496
Erythropoietin
Stimulate bone marrow to produce erythrocytes in response to low oxygen levels in the blood
497
Hormones secretes by the thymus
Thymosin
498
Thymosin
Important for proper T-cell development and differentiation
499
What releases corticoids?
The adrenal cortex
500
What happens if there is overproduction of growth hormone in children?
Gigantism
501
What happens if there is overproduction of growth hormone in adults?
Acromegaly
502
Acromegaly
Enlargement of the small bones in the extremities and of certain facial bones, such as the jaw
503
What happens if there is a deficiency of growth hormone in children?
Dwarfism
504
Causes of hypothyroidism
Inflammation of the thyroid | Iodine deficiency
505
What happens if a newborn has hypothyroidism?
Cretinism
506
Cretinism
Poor neurological and physical development, including mental retardation, short stature and coarse facial features
507
Goiter
Swelling of the thyroid
508
Causes of hyperthyroidism
Goiter
509
Is oxytocin a peptide or steroid hormone?
Peptide
510
What stimulates somatostatin secretion?
High blood glucose or high blood amino acid levels
511
Is somatostatin inhibitory or excitatory?
Inhibitory
512
What stimulates renin production?
Low blood pressure causes the juxtaglomerular cells of the kidney to produce renin
513
Renin
An enzyme that converts the plasma protein angiotensinogen to angiotensin I
514
Where does angiotensin I convert into angiotensin II?
In the lungs via angiotensin-converting enzymes
515
Angiotensin II
Stimulates the adrenal cortex to secrete aldosterone
516
Is vasopressin a peptide or steroid hormone?
Peptide
517
Respiratory pathway
Nares --> nasal cavity --> pharynx --> larynx --> trachea --> bronchi --> bronchioles --> alveoli
518
Which muscles are involved in inhalation?
Diaphragm and external intercostal muscles
519
Muscles involved in exhalation?
Passive: recoil of diaphragm and external intercostal muscles Active: internal intercostal muscles and abdomen
520
What is the purpose of surfactant?
Reduces surface tension at the air-liquid interface in the alveoli to prevent their collapse
521
What is the mathematical relationship between vital capacity (VC), inspiratory reserve volume (IRV), expiratory reserve volume (ERV) and tidal volume (TV)?
VC = IRV + ERV + TV
522
If blood levels of CO2 become too low, how does the brain alter the respiratory rate to maintain homeostasis?
Decrease breathing rate
523
What are some of the mechanisms used in the respiratory system to prevent infection?
Immune mechanisms in the respiratory system include vibrissae in the nares, lysosome in the mucous membranes, the mucociliary escalator, macrophages in the lungs, mucosal IgA antibodies and mast cells
524
What is the chemical equation for the bicarbonate buffer system?
CO2 (g) + H2O (l) H2CO3 (aq) H+ (aq) +HCO- (aq)
525
Respiratory failure refers to inadequate ventilation to provide oxygen to the tissues. How would the pH change in respiratory failure?
In respiratory failure, ventilation slows, and less carbon dioxide is blown off. As this occurs, the buffer equation shifts to the right, and more hydrogen ions are generated. This results in a lower pH of the blood.
526
Where does the air inhaled get warmed and humidified?
Nares
527
Vibrissae
Nasal hairs
528
Where does the air inhaled get filtered?
Nasal hairs (vibrissae), mucous membranes and mucocilliary escalator
529
Alveoli
Small sacs that interface with the pulmonary capillaries, allowing gases to diffuse across a one-cell-thick membrane
530
Where is surfactant?
In the alveoli
531
Pleurae
Cover the lungs and line the chest wall
532
Visceral pleura
Lies adjacent to the lung itself
533
Parietal pleura
Lines the chest wall
534
Intrapleural space
Lies between the visceral and partial pleurae and contains a thin later of fluid, which lubricates the two pleural surfaces
535
Diaphragm
A think skeletal muscle that helps to create the pressure differential required for breathing
536
Is inhalation an active or passive process?
Active
537
Inhalation (negative-pressure breathing)
The diaphragm and external intercostal muscles expand the thoracic cavity --> volume of the intrapleural space increases --> pressure of the intrapleural space decreases --> lungs expand --> lung pressure is dropped --> air from the environment enters
538
Is exhalation an active or passive process?
It can be either
539
Passive exhalation
Relaxation of the muscles of inspiration (diaphragm and external intercostal muscles) --> elastic recoil of the lungs --> chest cavity decreases in volume --> pressure differentials seen during inhalation are reversed
540
Active exhalation
Internal intercostal muscles and abdominal muscles are used to forcibly decrease the volume of the thoracic cavity --> air is pushed out
541
Spirometer
Measures lung capacities and volumes
542
Total lung capacity (TLC)
The maximum volume of air in the lungs when one inhales completely
543
Residual volume (RV)
The minimum volume of air in the lungs when one exhales completely
544
Vital capacity (VC)
The difference between the minimum and maximum volume of air in the lungs
545
Tidal volume (TV)
The volume of air inhaled or exhaled in a normal breath
546
Expiratory reserve volume (ERV)
The volume of additional air that can be forcibly exhaled after a normal exhalation
547
Inspiratory reserve volume (IRV)
The volume of additional air that can be forcibly inhaled after a normal inhalation
548
Ventilation center
Regulated ventilation | A collection of neurons in the medulla oblongata
549
Chemoreceptors
Respond to carbon dioxide concentrations, increasing the respiratory rate when there are high concentrations of carbon dioxide in the blood
550
Hypercarbia
High carbon dioxide concentrations in the blood
551
Hypercapnia
High carbon dioxide concentrations in the blood
552
How does the ventilation center respond to low oxygen concentrations in the blood?
Increasing breathing rate
553
Hypoxemia
Low oxygen concentrations in the blood
554
How can ventilation be consciously controlled?
With the cerebrum (although the medulla oblongata will override the cerebrum during extended periods of hypo- or hyperventilation)
555
How do lungs perform gas exchange with the blood?
Simple diffusion across concentration gradients
556
Pulmonary arteries
Carry deoxygenated blood with high carbon dioxide concentration to the lungs
557
Pulmonary veins
Carry oxygenated blood with low carbon dioxide concentration away from the lungs
558
How do lungs participated in thermoregulation?
The large surface area of interaction between the alveoli and capillaries allows the respiratory system to assist in thermoregulation through vasodilation and vasoconstriction of capillary beds
559
How do lysozyme in the nasal cavity and saliva protect the respiratory system?
Attack peptidoglycan cell walls of gram-positive bacteria
560
How do macrophages protect the respiratory system?
They engulf and digest pathogens and signal to the rest of the immune system that there is an invader
561
What are mucosal surfaces covered with?
IgA antibodies
562
How do mast cells protect the respiratory system?
They have antibodies on their surface that, when triggered, can promote the release of inflammatory chemicals Involved in allergic reactions
563
How is the respiratory system involved in pH control?
Through the bicarbonate buffer system
564
How does the respiratory system control pH when blood pH decreases?
Respiration rate increases to compensate by blowing off carbon dioxide. This causes a left shift in the buffer equation, reducing hydrogen ion concentration.
565
How does the respiratory system control pH when blood pH increases?
Respiration rate decreases to compensate by trapping carbon dioxide. This causes a right shift in the buffer equation, increasing hydrogen ion concentration.
566
Total lung capacity (TLC)
= VC (vital capacity) + RV (residual volume)
567
What can introducing fluid or air to the intrapleural space do?
Collapse the lung
568
Epiglottis
Covers the glottis during swelling to ensure that no food enters the trachea
569
Are the trachea and bronchi lined by ciliated epithelial cells?
Yes
570
Where are the vocal cords?
Larynx
571
What happens if the lungs become stiff?
Inspiratory reserve volume decreases
572
Hyperventilation
Decreases blood carbon dioxide concentration
573
Positive end-expiratory pressure
Providing a higher pressure than normal at the end of expiration, forcing extra air into the alveoli to prevent alveolar collapse
574
Heart chambers
Right atrium, right ventricle, left atrium, left ventricle
575
Which valve prevents back flow to the right atrium?
Tricuspid valve (between right atrium and right ventricle)
576
Which valve prevents back flow to the right ventricle?
Pulmonary valve (between right ventricle and pulmonary artery)
577
Which valve prevents back flow to the left atrium?
Mitral (bicuspid valve) (between left atrium and left ventricle)
578
Which valve prevents back flow to the left ventricle?
Aortic valve (between left ventricle and aortic artery)
579
Structures in the conduction system of the heart
Sinoatrial node (SA node) --> atrioventricular node (AV node) --> bundle of His (AV bundle) and its branches --> Purkinje fibers
580
In which direction do arteries carry blood?
Away from the heart
581
In which direction do capillaries carry blood?
From arterioles to venules
582
In which direction do veins carry blood?
Towards the heart
583
Are arteries thick or thin?
Thick
584
Are capillaries thick or thin?
Very thin (one cell layer)
585
Are veins thick or thin?
Thin
586
Do arteries have smooth muscles?
Yes (a lot)
587
Do capillaries have smooth muscles?
No
588
Do veins have smooth muscles?
Yes (a little)
589
Do arteries have valves?
No
590
Do capillaries have valves?
No
591
Do veins have valves?
Yes
592
Why does the right side of the heart contain less cardiac muscle than the left side?
The right side of the heart pumps blood into a lower-resistance circuit and must do so at lower pressure; therefore, it requires less muscle. The left side of the heart pumps blood into a higher-resistance circuit at higher pressures; therefore, it requires more muscle. The left side of the heart contains more muscle than the right side because the systemic circulation has a much higher resistance and pressure.
593
If all autonomic input to the heart were cut, what would happen?
The heart would continue beating at the intrinsic rate of the pacemaker (SA node). The individual would be unable to change his or her heart rate via the sympathetic or parasympathetic nervous system, but the heart would not stop beating.
594
Components of plasma
Nutrients, salts, respiratory gases, hormones and blood proteins (clotting proteins, immunoglobulin, etc.)
595
Hematocrit
The percentage of a blood sample occupied by red blood cells
596
Hematocrit units
Percentage points
597
Which types of leukocytes are involved in the specific immune response?
Lymphocytes
598
Where do platelets come from?
Megakaryocytes in the bone marrow
599
Which cell types in blood contain a nucleus?
Leukocytes (including neutrophils, eosinophils, basophils, monocytes/macrophages and lymphocytes)
600
Which cell types in blood do not contain a nucleus?
Erythrocytes and platelets
601
Platelets
Cellular fragments or shards
602
In bacterial sepsis (overwhelming bloodstream infection), a number of capillary beds throughout the body open simultaneously. What effect would this have on the blood pressure? Besides the risk of infection, why might sepsis be dangerous for the heart?
Opening up more capillary beds (which are in parallel) will decrease the overall resistance of the circuit. The cardiac output will therefore increase in an attempt to maintain constant blood pressure. This is a risk to the heart because the increased demand on the heart can eventually tire it, leading to a heart attack or a precipitous drop in blood pressure.
603
What is the chemical equation for the bicarbonate buffer system?
CO2 (g) + H2O (l) H2CO3 (aq) H+ (aq) + HCO3- (aq)
604
What enzyme catalyzes the bicarbonate buffer system?
The combining of carb on dioxide and water is catalyzed by carbonic anhydrase
605
Where should you look on the oxyhemoglobin dissociation curve to determine the amount of oxygen that has been delivered to tissues?
The amount of oxygen deliver can be seen as a drop in the y-value (percent hemoglobin saturation) on an oxyhemoglobin dissociation curve. E.g. if the blood is 100% saturated while in the lungs (at 100 mmHg O2) and only 80% saturated while in the tissues (40 mmHg O2), then 20% of the oxygen has been released to tissues.
606
What can cause a right shift of the oxyhemoglobin dissociation curve?
Increased CO2 Increased [H+] (i.e. decreased pH) Increased temperature Increased 2,3-BPG
607
What can cause a left shift of the oxyhemoglobin dissociation curve?
Decreased CO2 Decreased [H+] (i.e. increased pH) Decreased temperature Decreased 2,3-BPG
608
Exposure of which subendothelial compounds start the coagulation cascade?
Collagen and tissue factor
609
Which protein helps stabilize the clot formed by the coagulation cascade?
Fibrin
610
Cardiac output (CO)
= HR x SV = heart rate x stroke volume
611
Ohm's law applied to circulation
delta P = CO x TPR
612
Cardiovascular system
Consists of a muscular four-chambered heart, blood vessels and blood
613
What kind of muscle composes the heart?
Cardiac muscle
614
What kind of circulation is supported by the heart?
Pulmonary circulation and systemic circulation
615
Atrioventricular valves
Separate the atria from the ventricles Tricuspid (right heart) Mitral (bicuspid) (left heart)
616
Where is the tricuspid valve?
Between the right atrium and the right ventricle
617
Where is the mitral (bicuspid) valve?
Between the left atrium and the left ventricle
618
How are the ventricles separated from the vasculature?
Semilunar valves Pulmonary (right heart) Aortic (left heart)
619
Where is the pulmonary valve?
Between the right ventricle and the pulmonary artery
620
Where is the aortic valve?
Between the left ventricle and the aortic artery
621
Pathway of blood
Right atrium --(tricuspid valve)--> right ventricle --(pulmonary valve)--> pulmonary artery --> lungs --> pulmonary veins --> left atrium --(mitral valve)--> left ventricle --(aortic valve)--> aorta --> arteries --> arterioles --> capillaries --> venules --> veins --> venae cavae --> right atrium
622
Systole
The period during ventricular contraction when the AV valves are closed
623
Diastole
The heart is relaxed and the semilunar valves are closed
624
Arteries
Thick, highly muscular structures with an elastic quality
625
Why is it important for arteries to have an elastic quality?
For recoil and propelling blood forward within the system
626
Arterioles
Small muscular arteries that control flow into the capillary beds Have the ability to contract and dilate in order to affect blood pressure
627
Capillaries
Have walls that are one cell thick | They are the sites of gas and solute exchange
628
Why is it important for capillaries to have one-cell thick walls?
It makes them narrow enough that red blood cells can travel through them in single-file lines
629
Veins
Inelastic, thin-walled structures that transport blood to the heart They are able to stretch, but they cannot recoil Have valves
630
Why is it important for veins to be able to stretch?
To accommodate large volumes of blood
631
Since veins are able to stretch but cannot recoil, how are veins compressed?
By the surrounding skeletal muscles
632
Why is it important for veins to have valves?
To maintain one-way flow in the system
633
Venules
Small veins
634
Portal system
Blood passes through two capillary beds in series
635
Hepatic portal system
Blood travels from the gut capillary beds to the liver capillary bed via the hepatic portal vein
636
Hypophyseal portal system
Blood travels form the hypothalamus to the anterior pituitary
637
Renal portal system
Blood travels form the glomerulus to the vasa recta through an efferent arteriole
638
Erythrocytes (red blood cells)
Lack mitochondria, a nucleus and organelles
639
Why is it that erythrocytes lack mitochondria, a nucleus and organelles?
To make room for hemoglobin
640
Hemoglobin
A protein that carries oxygen
641
Leukocytes (white blood cells)
Partake in the immune system
642
Where are leukocytes (WBCs) formed?
In the bone marrow
643
Types of leukocytes
Granular leukocytes and agranulocytes
644
Granular leukocytes
Act in nonspecific immunity Neutrophils, eosinophils, basophils
645
Agranulocytes
Act in specific immunity Lymphocytes and monocytes
646
Thrombocytes (platelets)
Cell gradients from megakaryocytic that are required for coagulation
647
Blood antigens
A, B, O, Rh factor (D)
648
What is the relationship between I^A (A), I^B (B) and i (O)?
I^A (A) and I^B (B) are codominant | I (O) is recessive
649
Does an individual have ABO antibodies for ABO allele he or she has or does not have?
Does not have
650
Is positive Rh factor a dominant or recessive trait?
Dominant
651
What kind of antibodies would an Rh-negative individual create?
Anti-Rh antibodies, but only after exposure to Rh-positive blood
652
Blood pressure
The force per unit area that is exerted on the walls of blood vessels by blood Divided into systolic and diastolic components It must be high enough to overcome the resistance created by arterioles and capillaries, but low enough to avoid damaging the vasculature and surrounding structures
653
How is blood pressure measured?
With a sphygmomanometer
654
How is blood pressure maintained?
By baroreceptor and chemoreceptor reflexes
655
Hormones released when blood pressure is low
Aldosterone and antidiuretic hormone (ADH or vasopressin)
656
Hormones released when blood osmolarity is high
ADH (antidiuretic hormone or vasopressin)
657
Hormones released when blood pressure is high
Atrial natriuretic peptide (ANP)
658
Where does gas and solute exchange occur?
At the capillaries
659
What does gas and solute exchange rely on?
Concentration gradients to facilitate diffusion across the capillary walls
660
Are capillaries leaky?
Yes, which aids in transport of gases and solutes
661
Starling forces
Consist of hydrostatic pressure and osmotic (oncotic) pressure
662
Hydrostatic pressure
The pressure of the fluid within the blood vessel Forces fluid out at the arteriolar end of a capillary bed
663
Osmotic pressure
The sucking pressure drawing water towards solutes
664
Oncotic pressure
Osmotic pressure due to proteins Draws fluid back into the capsular bed at the venue end
665
Does hemoglobin exhibit cooperative binding?
Yes
666
Is there a high or low partial pressure of oxygen in the lungs?
High
667
Why is it important for the lungs to have high partial pressure of oxygen?
To promote the loading of oxygen onto hemoglobin
668
Is there a high or low partial pressure of oxygen in the tissues?
Low
669
Why is it important for the tissues to have low partial pressure of oxygen?
To promote the unloading of oxygen
670
Why is it important for hemoglobin to exhibit cooperative binging?
With each successive oxygen bound to hemoglobin, the affinity of the other subunits to oxygen increases. With each successive oxygen release from hemoglobin, the affinity of the other subunits to oxygen decreases.
671
How is carbon dioxide carried in the blood?
In the form of carbonic acid or bicarbonate and hydrogen ions
672
Why does carbon dioxide travel in the blood in the form of carbonic acid or bicarbonate and hydrogen ions?
Carbon dioxide is non polar and not particularly soluble, while bicarbonate, hydrogen ions and carbonic acid are polar and highly soluble
673
What does a right shift in the oxyhemoglobin dissociation curve mean?
Decreased affinity for oxygen
674
What does a left shift in the oxyhemoglobin dissociation curve mean?
Increased affinity for oxygen
675
Where can a left shift in the oxyhemoglobin dissociated curve be seen?
The lungs and in fetal hemoglobin
676
Coagulation
Results from an activation cascade Endothelial lining of a blood vessel is damaged --> collagen and tissue factor underlying the endothelial cells are exposed --> Coagulation cascade is activated --> Blood clot forms over the damaged area
677
What is fibrin activated by?
Thrombin
678
How can clots be broken down?
By plasmin
679
Are erythrocytes aerobic or anaerobic?
Anaerobic
680
Where are erythrocytes phagocytized?
In the spleen and liver
681
Where are erythrocytes produced?
In the red bone marrow
682
How long do erythrocytes circulated in the blood?
For 120 days
683
What is the correct sequence of a cardiac impulse?
SA node --> atria --> AV node --> bundle of His --> Purkinje fibers --> ventricles
684
How does the osmotic pressure relate to the hydrostatic pressure at the venous end of a capillary bed?
It is greater than the hydrostatic pressure
685
How does the osmotic (oncotic) pressure change in a capillary end from the arterial end to the venous end?
It doesn't
686
How does the hydrostatic pressure change in a capillary end from the arterial end to the venous end?
It decreases from the arterial end to the venous end
687
Do proteins normally cross the capillary wall?
No
688
How is pressure in the aorta related to pressure in the superior vena cava?
It is always higher than the pressure in the superior vena cava
689
Due to kidney disease, a person is losing albumin into the urine. What effect is this likely to have within the capillaries?
Decreased oncotic pressure
690
What generates osmotic (oncotic) pressure?
Plasma proteins
691
The world record for the longest-held breath is 22 minutes and 0 seconds. If a sample were taken from this individual during the last minute of breath-holding, which of the following might be observed?
Decreased pH Holding one's breath for a prolonged period would result in a drop of oxygenation and an increase in pCO2. The increased carbon dioxide would associate with water to form carbonic acid, which would dissociate into a proton and bicarbonate anion. Further, the low oxygen saturation would eventually lead to anaerobic metabolism in some tissues, causing an increase in lactic acid. These would all lead to a decreased pH
692
A person has a heart attack that primarily affects the wall between the two ventricles. Which portion of the electrical conduction system is most likely affected?
Bundle of His
693
Which vascular structure creates the most resistance to blood flow?
Arterioles
694
Which vascular structure creates the greatest drop in blood pressure?
Arterioles
695
Innate (nonspecific) immunity
Consists of defenses that are always active against pathogens, but that are not capable of targeting specific invaders and cannot maintain immunologic memory
696
Adaptive (specific) immunity
Response targets a specific pathogen and maintains immunologic memory of the infection to mount a faster response during subsequent infections
697
Site of B-cell development
Bone marrow
698
Site of T-cell development
Bone marrow
699
Site of B-cell maturation
Bone marrow (but are activated in the spleen or lymph nodes)
700
Site of T-cell maturation
Thymus
701
Major functions of B-cells
Produce antibodies
702
Major functions of T-cells
Coordinate immune system and directly kill infected cells
703
Are B-cells specific or nonspecific?
Specific
704
Are T-cells specific or nonspecific?
Specific
705
Are B-cells humoral or cell-mediated?
Humoral
706
Are T-cells humoral or cell-mediated?
Cell-mediated
707
Which cells are considered granulocytes?
Neutrophils, eosinophils, basophils and mast cells
708
Which cells are considered agranulocytes?
Lymphocytes (B-cells and T-cells) and macrophages (monocytes)
709
Is innate immune faster or slowed than adaptive immunity?
Faster
710
Site of B-cell activation
Spleen or lymph nodes
711
What is the immunologic function of skin?
Physical barrier | Secretion of antimicrobial enzymes
712
What is the immunologic function of defensins?
Antibacterial enzymes on the skin
713
What is the immunologic function of lysozyme?
Antimicrobial | Present in tears and saliva
714
What is the immunologic function of mucus?
Present on mucous membranes | Traps incoming pathogens (in the respiratory system, cilia propel the mucus upward so it can be swallowed or expelled)
715
What is the immunologic function of stomach acid?
Antimicrobial
716
What is the immunologic function of normal gastrointestinal flora?
Provides competition, making it hard for pathogenic bacteria to grow in the gut
717
What is the immunologic function of complement?
A set of proteins in the blood that can create holes in bacteria
718
Which cells are professional antigen-presenting cells?
Macrophages, dendritic cells in the skin, some B-cells and certain activated epithelial cells
719
MHC-I
Found in all nucleated cells and presents proteins created within the cell (endogenous antigens); this can allow for detection of cells infected with intracellular pathogens (especially viruses)
720
MHC-II
Only found in antigen-presenting cells and presents proteins that result from the digestion of extracellular pathogens that have been brought in by endocytosis (exogenous antigens)
721
What activates natural killer cells?
Cells that do not present MHC (such as virally infected cells and cancer cells)
722
What activates neutrophils?
Bacteria, especially those that have been opsonized (tagged with an antibody on their surface)
723
What activates eosinophils?
Invasive parasites and allergens
724
What activates basophils?
Allergens
725
What activates mast cells?
Allergens
726
Where are defensins?
On the skin
727
Where are lysozymes?
In tears and saliva
728
Where are mucosa?
On mucous membranes
729
Where are complements?
In the blood
730
Where is MHC-I?
On all nucleated cells
731
Where is MHC-II?
On antigen-presenting cells
732
Opsonization
Mark a pathogen for destruction by phagocytic cells
733
Plasma cell
Form from B-cells exposed to antigen and produce antibodies
734
Memory B-cell
Form from B-cells exposed to antigen and lie in wait for a second exposure to a I=given antigen to be able to mount a rapid, robust response
735
Helper T-cell (CD4+ cells)
Coordinate the immune system through lumphokines and respond to antigen bound to MHC-II
736
Cytotoxic T-cell (CD8+ cells)
Directly kill virally infected cells and response to antigen bound to MHC-I
737
Suppressor (regulatory) T-cell
Quell the immune response after a pathogen has been cleared and promote self-tolerance
738
Memory T-cell
Lie in wait until a second exposure to a pathogen to be able to mount a rapid, robust response
739
What are the three main effects circulating antibodies can have on a pathogen?
Opsonization, causing angulation of the pathogen in insoluble complexes that can be taken up by phagocytic cells, or neutralize the pathogen by preventing its ability to invade tissues
740
How do antibodies become specific for a given antigen?
B-cells originally mature in the bone marrow and have some specificity at that point; however, antibodies that can respond to a given antigen undergo hypermutation, or rapid mutation of their antigen-binding sites. Only those B-cells that have the highest affinity for the antigen survive and proliferate, increasing the specificity for the antigen over time.
741
Positive selection
Occurs when T-cells in the thymus that are able to respond to antigen presented on MHC are allowed to survive (those that do not respond undergo apoptosis)
742
Negative selection
Occurs when T-cells that respond to self-antigens undergo apoptosis before leaving the thymus
743
Which cells account for the fact that the secondary response to a pathogen is much more rapid and robust than the primary response?
Memory cells
744
Active immunity
The stimulation of the immune system (activation of B-cells) to produce antibodies against a pathogen
745
Passive immunity
The transfer of antibodies to prevent infection, without stimulation of the plasma cells that produce these antibodies
746
Filariasis is the name for an infection with a certain group of parasites, most notable Wuchereria bancrofti. This parasite resides in lymph nodes and causes blockage of flow. If an individual had W. bancrofti infection in the lymph nodes of his or her thigh, what would likely happen?
Fluid would be unable to return from the lower leg, and edema would result. This infection leads to elephantiasis, severe swelling of the limb with thickening of the skin.
747
What structure is primarily responsible for returning material from lymphatic circulation to the cardiovascular system?
The thoracic duct carries lymphatic fluid into the left subclavian vein
748
The immune system divisions
Innate immunity | Adaptive immunity
749
Where do immune cells come from?
Bone marrow
750
Where are immune responses mounted?
Spleen and lymph nodes
751
Gut-associated lymphoid tissue (GALT)
Tonsils and adenoids
752
Nonspecific (innate) noncellular defenses
Skin, defensins, mucous, lysozyme, stomach acid, colonization of the gut (i.e. flora), complement, interferons
753
Interferons
Given off by virally infected cells and help prevent viral replication and dispersion to nearby cells
754
Nonspecific (innate) cellular defenses
Macrophages, MHC-I, MHC-II, dendritic cells, natural killer cells, granulocytes (neutrophils, eosinophils, basophils, and mast cells)
755
Macrophages
Ingest bathoses and present them on major histocompatibility complex (MHC) Secrete cytokines
756
Dendritic cells
Antigen presenting cells in the skin
757
Where are dendritic cells?
In the skin
758
Natural killer cells
Attack cells not presenting MHC molecules, including virally infection cells and cancer cells
759
Neutrophils
Ingest bacteria, particularly opsonized bacteria | Can follow bacteria using chemotaxis
760
How do neutrophils follow bacteria?
Chemotaxis
761
Eosinophils
Usual in allergic reactions and invasive parasitic infections Releases histamine, causing an inflammatory response
762
Basophils
Used in allergic reactions
763
Mast cells
Used in allergic reactions | Found in the skin
764
Where are mast cells?
In the skin
765
Humoral identity
Centered on antibody production by plasma cells, which are activated by B-cells
766
How are plasma cells activated?
By B-cells
767
Antibodies
Target a particular antigen Contain two heavy chains and two light chains Have a constant region and variable region The tip of the variable region is the antigen-binding region
768
What happens when an antibody is activated?
The antigen-binding region undergoes hypermutation to improve the specificity of the antibody produced Cells may be given signals to switch isotopes of antibody (IgM, IgD, IgG, IgE, IgA)
769
What do cell-surface antibodies do?
Activate immune cells or mediate allergic reactions
770
Humoral immunity activation
Antibodies bind to antigens --> hypermutation in the antigen-binding region occurs --> antibody-antigen complex response (opsonization, aggulation or neutralization) --> immune response activated or allergic reaction activated --> Memory B-cells wait for second exposure in order to become more rapid
771
Cell-mediated (cytotoxic) immunity
Centered on the functions of T-cells T-cells undergo maturation in thymus through positive selection and negative selection --> the peptide hormone thyroxine promotes T-cell development --> helper T-cells respond to antigen on MHC-II and coordinate the rest of the immune response, secreting lymphokines to activate various arms of immune defense --> Th1 cells secrete interferon gamma, which acerbates macrophages --> Th2 cells activate B-cells, primarily in parasitic infections --> cytotoxic T-cells (Tc, CTL, CD8+) respond to antigen on MHC-I and kill virally infected cells --> suppressor (regulatory) T-cells (Treg) tone down the immune response after an infection and promote self-tolerance
772
Autoimmune conditions
A self-antigen is recognized as foreign, and the immune system attacks normal cells
773
Allergic reactions
Nonthreatening exposures incite an inflammatory response
774
What form of immunity is immunization?
Active immunity
775
Lymphatic system
A circulatory system that consists of one-way vessels with intermittent lymph nodes Equalizes fluid distribution, transports fats and fat-soluble compounds in chylomicrons and provides sites for mounting immune responses
776
How does the lymphatic system connect to the cardiovascular system?
Thoracic duct in the posterior chest
777
In DiGeorge syndrome, the thymus can be completely absent. The absence of the thymus would leave an individual unable to mount specific defenses against which of the following types of pathogens?
Viruses T-lymphocytes, which mature in the thymus, are the only specific defense against intracellular pathogens.
778
Where are most self-reactive T-cells eliminated?
Thymus
779
What is the response of the immune system to down regulation of MHC molecules on somatic cells?
Natural killer cells induce apoptosis of affected cells Healthy cells exhibit MHC-I molecules. Natural killer cells monitor the expression of MHC molecules on the forces of cells. Viral infection and cancer often cause a reduction in the expression of MHC-I molecules on the cell surface. Natural killer cells detect this lack of MHC and induce apoptosis in the affected cells
780
What happens when CD8+ T-cells are activated?
Cytotoxic chemicals are secreted
781
Lymphoma is cancer of the cells of the lymphoid lineage. These cells often reside within lymph nodes. What type of cell is not likely to cause a lymphoma?
Any cell that is not in the B-cell or T-cell lineages
782
Clonal selection
When the adaptive immune system encounters an antigen, only the cells with receptors (antibodies or T-cell receptors) specific to that antigen are activated
783
Which cell type is a phagocyte that attacks bacterial pathogens in the bloodstream?
Neutrophils Dendritic cells also have a similar function, but they exist in the skin, not the bloodstream
784
What type of immunity is likely to be affected by removal of the spleen?
Humoral immunity because it's where B-cells mature and proliferate
785
Mechanical digestion
Physically breaks food into smaller pieces | e.g. chewing
786
Chemical digestion
Involves hydrolysis of bonds and breakdown of food into smaller biomolecules
787
Path of food through the body
Oral cavity (mouth) --> pharynx --> esophagus --> stomach --> small intestine --> large intestine --> rectum --> anus
788
What effect does the parasympathetic nervous system have on the digestive system?
Increases secretion from all of the glands of the digestive system and promotes peristalsis
789
What effect does the sympathetic nervous system have on the digestive system?
Decreases secretion from all of the glands of the digestive system and slows peristalsis
790
What two main enzymes are found in the saliva?
Salivary amylase (ptyalin) and lipase
791
What does the mucous cell secrete?
Mucus (rich in bicarbonate)
792
What does the chief cell secrete?
Pepsinogen
793
What does the parietal cell secrete?
HCl and intrinsic factor
794
What does the G-cell secrete?
Gastrin
795
What does the mucous cell do?
``` Protects lining of stomach Increases pH (bicarbonate) ```
796
What does the chief cell do?
Digests proteins once activated by H+
797
What does the parietal cell do?
HCl: decreases pH, kills microbes, denatures proteins, some chemical digestion Intrinsic factor: absorption of vitamin B12
798
What does the G-cell do?
Increases HCl production | Increases gastric motility
799
Is sucrase an enzyme or a hormone?
Enzyme
800
Is secretin an enzyme or a hormone?
Hormone
801
Is Dipeptidase an enzyme or a hormone?
Enzyme
802
Is cholecystokinin an enzyme or a hormone?
Hormone
803
Is enteropeptidase an enzyme or a hormone?
Enzyme
804
What does sucrase do?
Brush-border enzyme | Breaks down sucrose (a disaccharide) into monosaccharides (glucose and fructose)
805
What does secretin do?
Increases pancreatic secretions into the digestive tract, especially bicarbonate Reduces HCl secretion Decreases motility
806
What does dipeptidase do?
Brush-border enzyme | Breaks down dipeptides into free amino acids
807
What does cholecystokinin do?
Recruits secretions from gallbladder and pancreas | Promotes satiety
808
What does enteropeptidase do?
Activates trypsinogen and procarboxypeptidases, which initiates an activation cascade
809
How do bile and pancreatic lipase work together to digest fats?
Bile accomplishes mechanical digestion of fats, emulsifying them and increasing their surface area. Pancreatic lipase accomplishes chemical digestion of fats, breaking their ester bonds.
810
Salivary amylase (ptyalin)
Digests starch into smaller sugars (maltose and dextrin)
811
Lipase
Digests fats
812
Which pancreatic enzyme(s) can digest carbohydrates?
Pancreatic amylase
813
Which pancreatic enzyme(s) can digest proteins?
Trypsin, chymotrypsin, carboxypeptidases A and B
814
Which pancreatic enzyme(s) can digest fats?
Pancreatic lipase
815
What are the main components of bile?
Bile salts (amphipathic molecules derived from cholesterol that emulsify fats), piglets (especially bilirubin from the breakdown of hemoglobin) and cholesterol
816
Where is bile synthesized?
Liver
817
Where is bile stored?
gallbladder
818
Where does bile carry out its digestive function?
Duodenum
819
Functions of the liver
``` Process nutrients (through glycogenesis and glycogenolysis, storage and mobilization of fats and gluconeogenesis) Produces urea Detoxifies chemicals Activates or inactivates medications Produces bile Synthesizes albumin and clotting factor ```
820
The accessory organs of digestion originate from which primary germ layer?
Endoderm
821
Bile salts
Amphipathic molecules derived from cholesterol that emulsify fats
822
How does the liver process nutrients?
Glycogenesis Glycohenolysis Storage and mobilization of fats Gluconeogenesis
823
What are the two circulatory vessels in a villus?
Capillaries and lacteals
824
What are the four fat-soluble vitamins?
Vitamins A, D, E, K
825
What are the three sections of the small intestine?
Duodenum, jejunum and ileum
826
What are the three sections of the large intestine?
Cecum, colon and rectum
827
Vibrio cholera causes a severe infection in the intestines, leading to massive volumes of watery diarrhea - up to 20 liters per day. Given these symptoms, Dows cholera likely impose the small intestine or the large intestine?
While the large intestine's main function is to absorb water, the small intestine actually absorbed a much larger volume of water. This, massive volumes of watery diarrhea are more likely to arise from infections in the small intestine than the large intestine.
828
What do the capillaries in a villus absorb?
Water-soluble nutrients | e.g. monosaccharides, amino acids, small fatty acids, water-soluble vitamins and water
829
What do the lacteals in a villus absorb?
Fat-soluble nutrients | e.g. fats, cholesterol and dat-soluble vitamins
830
Intracellular digestion
Involves the oxidation of glucose and fatty acids to make energy
831
Extracellular digestion
Occurs in the lumen of the alimentary canal
832
Accessory organs of digestion
Salivary glands, pancreas, liver and gallbladder
833
Enteric nervous system
In the wall of the alimentary canal and controls peristalsis | Its activity is unregulated by the parasympathetic nervous system and down regulated by the sympathetic nervous system
834
Hormones that regulate feeding behavior
Antidiuretic hormone (ADH or vasopressin), aldosterone, glucagon, ghrelin, leptin and cholecystokinin
835
How does antidiuretic hormone (ADH or vasopressin) regulate feeding behavior?
Promotes thirst
836
How does aldosterone regulate feeding behavior?
Promotes thirst
837
How does glucagon regulate feeding behavior?
Promotes hunger
838
How does ghrelin regulate feeding behavior?
Promotes hunger
839
How does leptin regulate feeding behavior?
Promotes satiety
840
How does cholecystokinin regulate feeding behavior?
Promotes satiety
841
Digestion in the oral cavity
Mastication starts the mechanical digestion of food Salivary amylase and lipase start the chemical digestion food Food is formed into a bolus and swallowed
842
Pharynx
Connects the moth and posterior nasal cavity to the esophagus
843
Esophagus
Propels food to the stomach using peristalsis
844
How does food enter the stomach?
Through the lower esophageal (cardiac) sphincter)
845
Parts of the stomach
Fundus, body, antrum and pulorus
846
Stomach
Has a lesser and greater curvature and is thrown into folds called rugae
847
Secretory cells lining the stomach
Mucous cells, chief cells, partial cells and G-cells
848
Pepsinogen
Secreted by chief cells in the stomach | A protease activated by the acidic environment of the stomach
849
Gastrin
Secreted by G-cells in the stomach | A peptide hormone that increases HCl secretion and gastric motility
850
Chyme
Food particles that have undergone mechanical and chemical digestion in the stomach
851
How does food pass into the duodenum?
Through the pyloric sphincter
852
Duodenum
The first part of the small instance | Primarily involved in chemical digestion
853
Disaccharidases
Brush-border enzymes that break down maltose, iso-maltose, lactose, and sucrase into monosaccharides
854
Peptidases
Brush-border enzymes
855
Types of peptidases
Aminopeptidase and dipeptidase
856
Acinar cells
In the pancreas | Produce pancreatic juices that contain bicarbonate, pancreatic amylase, pancreatic peptidases and pancreatic lipase
857
Pancreatic peptidases
Trypsinogen, chymotrypsinogen, carboxypeptidases A and B
858
Bile
Emulsifies fats, making them soluble and creasing their surface area
859
Gallbladder
Stores and concentrates bile
860
Jejunum
In the small intestine | Primarily involved in absorption
861
Ileum
In the small intestine | Primarily involved in absorption
862
What is the small intestine lined with?
Villi
863
What are the villi of the small intestine covered with?
Microvilli
864
Microvilli
Cover the villi of the small intestine to increase their surface are available for absorption
865
Lacteal
A vessel of the lymphatic system
866
Large intestine
Absorbs water and salts, forming semisolid feces
867
Cecum
An out pocketing that accepts fluid from the small intestine through the iléocaecal valve The site of attachment of the appendix
868
Colon divisions
Ascending, transverse, descending and sigmoid portions
869
Rectum
Stores feces
870
Anus
Excretes feces
871
What do gut bacteria produce?
Vitamin K and biotin (vitamin B7)
872
Biotin
Vitamin B7
873
Do G-cells produce HCl?
No, they produce gastrin
874
What produces HCl in the stomach?
Parietal cells
875
Do chief cells produce pepsinogen?
Yes
876
Do parietal cells produce alkaline mucus?
No, they they produce HCl and intrinsic factors
877
What produces alkaline mucus in the stomach?
Mucous cells
878
Do mucous cells produce intrinsic factor?
No, they produce alkaline mucus
879
What produces intrinsic factor in the stomach?
Parietal cells
880
In an experiment, enteropeptidase secretion was blocked. As a direct realist, levels of all of the following active enzymes would likely be affected except: a. Trypsin b. Aminopeptidase c. Chymotrypsin d. Carboxypeptidase A
Aminopeptidase Aminopeptidase is a brush-border peptidase secreted by the cells lining the duodenum; it does not require enteropeptidase for activation. Both trypsinogen and procarboxypeptidases A and B are activated by enteropeptidase. Once activated, trypsin can activate chymotrupsinogen; if trypsinogen cannot be activated, then chymotrypsinogen will not be activated either.
881
Does trypsin hydrolyze specific peptide bonds?
Yes
882
Does lactase hydrolyze lactose to glucose and galactose?
Yes
883
Does pancreatic amylase hydrolyze starch to maltose?
Yes
884
Does lipase emulsify fats?
No, it is involved in the digestion of fats chemically in the duodenum, allowing them to be brought into duodenal cells and packaged into chylomicrons
885
What emulsifies fats in the intestines?
Bile
886
Where are proteins digested?
In the stomach and small intestines
887
Stomach digestion of proteins
Pepsin (secreted as pepsinogen) hydrolyzes specific peptide bonds
888
Small intestines digestion of proteins
Trypsin (secreted as trypsinogen), chymotrypsin (secreted as chymotrypsinogen), carboxypepdases A and B (secreted as procarboxypeptidases A and B), amino peptidase and dipeptidases hydrolyze specific parts of the peptide
889
Is sucrase secreted by the salivary glands?
No, it is a brush-border enzyme found on duodenal cells
890
Is carboxypeptidase secreted by the pancreas?
Yes
891
Is trypsin secreted by the pancreas?
Yes
892
Is lactase secreted by the duodenum?
Yes
893
A two-week-old male infant is bright to the ER. His mother reports that he has been unable to keep any milk down; shortly after he nurses, he has sudden projectile vomiting. During exam, an olive-shaped mass can be felt in his upper abdomen. It is determined that there is a constriction in the digestive system that prevents food from reaching the small instant from the stomach. Which structure is most likely the site of the problem?
Pyloric sphincter
894
Many medications have anticholinergic side effects, which block the activity of parasympathetic neurons throughout the body. Older individuals may be on many such medications simultaneously, exacerbating the side effects. Which of the following would not be expected in an individual taking medications with anticholinergic activity? a. Dry mouth b. Diarrhea c. Slow gastric emptying d. Decreased gastric acid production
Diarrhea
895
Enzymes in the stomach function in which pH range?
Acidic pH
896
Enzymes in the duodenum function in which pH range?
Neutral-slightly alkaline pH
897
Cholangiocarcinoma: a cancer of the bile ducts that can ultimately lead to full occlusion of the duct lumen Can it lead to elevated levels of bilirubin in the blood?
Yes
898
Autoimmune hemolytic anemia: a disease in which the RBCs are attacked by antibodies and are lysed Can it lead to elevated levels of bilirubin in the blood?
Yes
899
Ménétrier's disease: rugae thicken and overlying glands lose secretory ability Can it lead to elevated levels of bilirubin in the blood?
No
900
Acetaminophen (Tylenol) overdose: the accumulation go toxic metabolites can cause rapid liver failure Can it lead to elevated levels of bilirubin in the blood?
Yes
901
Elevated bilirubin
Implies a blockage to bile flow, increased production of bilirubin (from massive hemoglobin release), or an inability of the liver to produce bile
902
Rugae
Folds in the stomach wall
903
What is the primary site of chylomicrons absorption?
Lacteals in small intestines
904
What is the primary site of amino acid absorption?
Capillary beds in small intestines
905
What is the primary site of vitamins A and E absorption?
Lacteals in small intestines
906
What is the primary site of cholesterol absorption?
Lacteals in small intestines
907
Starch is hydrolyzed into maltose by enzymes from:
Salivary glands and pancreas
908
Does vitamin D (cholecalciferol) drain to the liver before arriving at the right side of the heart?
No
909
Does threonine (an amino acid) drain to the liver before arriving at the right side of the heart?
Yes
910
Does fructose (a monosaccharide) drain to the liver before arriving at the right side of the heart?
Yes
911
Does vitamin B5 (pantothenic acid) drain to the liver before arriving at the right side of the heart?
Yes
912
Where do capillary beds in the small intestines lead to?
They come together, forming the portal vein, which drains to the liver
913
Where do lacteals in the small intestines lead to?
They come together, forming the thoracic duct, which drains directly into the left subclavian vein
914
Structures in the excretory pathway
Bowman's space --> proximal convoluted tubule --> descending limb of the loop of Henle --> ascending limb of the loop of Henle --> distal convoluted tubule --> collecting duct --> renal pelvis --> ureter --> bladder --> urethra
915
Vessels in the renal vascular pathway
Renal artery --> afferent arteriole --> glomerulus --> efferent arteriole --> vasa recta --> renal vein
916
What arm of the nervous system is responsible for contraction of the detrusor muscle?
The parasympathetic system
917
What are the three processes by which solutes are exchanged between the filtrate and the blood?
Filtration, secretion and reabsorption
918
Bowman's capsule
The site of filtration, through which water, ions, amino acids, vitamins, and glucose pass (essentially everything besides cells and proteins)
919
Proximal convoluted tubule (PCT)
Controls solute identity, reabsorbing vitamins, salt, water, amino acids and glucose, while secreting potassium and hydrogen ions, ammonia and urea
920
Descending limb of the loop of Henle
Water reabsorption using the medullary concentration gradient Permeable to water, but not salt
921
Ascending limb of the loop of Henle
Salt reabsorption and allowing dilution go the urine in the diluting segment (passive and active reabsorption) Permeable to salt, but not water
922
Distal convoluted tubule (DCT)
Reabsorbing salts while secreting potassium and hydrogen ions, ammonia and urea Responsive to aldosterone only
923
Collecting duct
Urine concentration Its variable permeability allows water to be reabsorbed based on the needs of the body Responsive to aldosterone and antidiuretic hormone
924
Filtration
The movement of solutes from blood into filtrate at Bowman's capsule The direction and rate of filtration is determined by Starling forces, which account for the hydrostatic and oncotic pressure differentials between the glomerulus and Bowman's space
925
Secretion
The movement of solutes from blood into filtrate anywhere besides Bowman's capsule
926
Reabsorption
The movement of solutes from filtrate into blood
927
What is the predominant cell type in the epidermis?
Keratinocytes
928
What are the layers of the epidermis, from superficial to deep?
``` Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale ```
929
What are the layers of the dermis, from superficial to deep?
Papillary layer | Reticular layer
930
What are some mechanisms the body uses to cool itself?
Sweating | Vasodilation
931
What are some mechanisms the body uses to retain heat?
Shivering Vasoconstriction Piloerection Insulation provided by fat
932
Excretory system
Regulation of blood pressure Blood osmolarity Acid-base balance Removal of nitrogenous wastes
933
Kidney
Produces urine
934
Pathway of urine
Leaves the kidney --> renal pelvis --> ureter --> bladder --> urethra
935
Parts go the kidney
Cortex, medulla, hilum
936
Kidney hilum
Contains a renal artery, renal vein and ureter
937
Does the kidney contain a portal system (two capillary beds in series)?
Yes
938
Blood flow in the renal portal system
Renal artery --> afferent arterioles --> glomeruli in Bowman's capsule (the first capillary bed) --< efferent arteriole --> vasa recta --> nephron (second capillary bed) --> renal vein
939
Detrusor muscle
The bladder muscular lining | Is under parasympathetic control
940
Bladder sphincters
Internal urethral sphincter and external urethral sphincter
941
Internal urethral sphincter
Consists of smooth muscle and is under involuntary (parasympathetic) control
942
External urethral sphincter
Consists of skeletal muscle and is under voluntary control
943
Countercurrent multiplier system
Created by the flows in the vasa recta and nephron being in opposite directions Allows for maximal reabsorption of water
944
Where is the diluting segment in the ascending limb of the loop of Henle?
In the outer medulla, because salt is actively reabsorbed in this site. The solution is, therefore, hypotonic compared to the blood.
945
How does the kidney function when blood pressure (and volume) are low?
Aldosterone (steroid hormone regulated by the renin-angiotensin-aldosterone system) increases sodium reabsorption in the distal convoluted tubule and collecting duct, there by increasing water reabsorption. This results in an increased blood volume (and pressure), but no change in blood osmolarity. Antidiuretic hormone (ADH or vasopressin :: a peptide hormone synthesized by the hypothalamus and released by the posterior pituitary :: stimulated by low blood volume and high blood osmolarity) increases the permeability of the collecting duct to water, increasing water reabsorption. This results in an increased blood volume (and pressure) and a decreased blood osmolarity.
946
How can the kidney regulate pH?
By selective reabsorption or secretion of bicarbonate or hydrogen ions
947
Skin
Acts as a barrier, protecting from the elements and invasion by pathogens Thermoregulation (maintenance of a constant internal temperature) Prevention of dehydration and salt loss from the body
948
Skin layers
Hypodermis (subcutaneous layer), dermis and epidermis
949
Stratum basale
Contains temp cells that proliferate to form keratinocytes
950
Keratinocytes
Their nuclei are lost in the status granulosum and many thin layers form in the stratum corneum
951
Melanocytes
Produce melanin
952
Melanin
Protects the skin from DNA damage caused by ultraviolet radiation Passed to the keratinocytes
953
Langerhans cells
Special macrophages that serve as antigen-presenting cells in the skin
954
Where are the sensory cells in the skin located?
In the dermis
955
Sensory cells in the dermis
Merkel cells (deep pressure and texture), free nerve endings (pain), Meissner's corpuscles (light touch), Ruffini endings (stretch) and Pacinian corpuscles (deep pressure and vibration)
956
Merkel cells detect:
Deep pressure and texture
957
Meissner's corpuscles detect:
Light tough
958
Free nerve endings in the dermis detect:
Pain
959
Ruffini endings detect:
Stretch
960
Pacinian corpuscles detect:
Deep pressure and vibration
961
What are sweat glands intreated by?
Postganglionic cholinergic sympathetic neurons
962
Piloerection
Arrector pili muscles contract, causing hairs to stand on end, trapping a layer of warmed air around the skin
963
Where in the nephron is sodium actively transported?
Proximal convoluted tubule, distal convoluted tubule and the thick ascending loop of Henle
964
Which region of the kidney has the lowest solute concentration under normal physiological circumstances?
The cortex
965
In the nephron, amino acids enter the casa recta via the process of:
Reabsorption
966
On a very cold day, a man waits for over an hour at the bus stop. Which structure helps his body set and maintain a normal temperature?
The hypothalamus
967
Glucose reabsorption in the nephron occurs in the:
Proximal convoluted tubule
968
Under normal physiological circumstances, the primary function of the nephron is to create urine that is hypertonic, hypotonic or isotonic to the blood?
Hypertonic
969
Diabetic nephropathy is commonly detected by finding protein in the urine of a patient. In such a disease, where is the likely defect in the nephron?
The glomerulus
970
A laceration cuts down into a layer of loose connective tissue in the skin. Which layer of the skin is this?
Papillary layer
971
Papillary layer
In the dermis | Predominantly loose connective tissue
972
Stratum corneum
In the epidermis | Contains dead keratinocytes
973
Stratum lucidum
In the epidermis | Contains dead keratinocytes
974
Reticular layer
In the dermis | Predominantly dense connective tissue
975
When the pH of the blood is high, which substance is likely to be excreted in larger quantities in the urine?
Bicarbonate ions
976
In which layer of the skin can the stem cells of keratinocytes be found?
Stratum basale
977
Sarin is a potent organophosphate that can be used in chemical warfare. As an inhibitor of acetylcholinesterase, sarin causes excessive buildup of acetylcholine in all synapses where it is the neurotransmitter. Is urination likely to increase or decrease? Is sweating likely to increase or decrease?
Urination is likely to increase and sweating is likely to increase An excess of acetylcholine will lead to activation of all parasympathetic neurons, pre-ganglionic sympathetic neurons, and the post-ganglionic sympathetic neurons that interval sweat gland. Because the parasympathetic nervous system causes contractions of the bladder, one would expect increased urination. The increased activation of swat glands would lead to increased sweating as well.
978
Which type(s) of muscles is(are) striated?
Skeletal and cardiac
979
Which type(s) of muscles is(are) always uninucleated?
Smooth
980
Which type(s) of muscles is(are) always polynucleated?
Skeletal
981
Which type(s) of muscles is(are) voluntary?
Skeletal
982
Which type(s) of muscles is(are) innervated by the autonomic nervous system?
Smooth and cardiac
983
Which type(s) of muscles is(are) exhibiting myogenic activity?
Smooth and cardiac
984
Which zone or band in the sarcomere does not change its length during muscle contraction?
A-band :: it is the enter length of the myosin filament. Filaments do not change length, but rather slide over each other.
985
What are the events that initiate muscle contraction?
Release of acetylcholine from motor neuron --> activation of acetylcholine receptors in sarcolemma --> depolarization of sarcolemma --> spreading of signal using T-tubules --> release of calcium from sarcoplasmic reticulum (SR) --> binding of calcium to troponin --> conformational shift of tropomyosin --> exposure of myosin-binding sites --> myosin binds to actin
986
What role does the binding of ATP to the myosin head play in the cross bridge cycle?
It allows the myosin filament to disconnect from actin
987
What role does the dissociated of ADP and inorganic phosphate from the myosin head play in the cross bridge cycle?
It causes the powerstroke
988
Tetanus (the physiological phenomenon, not the disease)
The summation of multiple simple twitches that occur too quickly for the muscle to relax, leading to a stronger and more prolonged contraction of the muscle
989
Compact bone
Dense Used for strength Forms most of the outer layers of a bone
990
Spongy (cancellous) bone
Has many spaces between bony spicules called trabeculae The sire of marrow production Found in the interior core of the bone Helps distribute forces or pressures on the bone
991
Structural parts of a bone
Diaphysis --> metaphyses --> epiphyses (which have epiphyseal [growth] plates)
992
Which part of the bone contributes most to linear growth?
Epiphyses :: it has the growth plates that contribute to linear growth
993
What chemical forms most of the inorganic component of bone?
Hydroxyapatite crystals
994
Osteoblast
Build bone
995
Osteoclast
Chew bone (break it down)
996
Chondrocyte
Form cartilage
997
What liquid provides the lubrication for movable joints?
Synovial fluid
998
What tissue produces synovial fluid
Synovium
999
Synovial fluid
Lubricates movable joints
1000
Types of muscles
Skeletal, smooth and cardiac
1001
Skeletal muscles
Involved in support and movement involved in propulsion of blood in the venous system Involved in thermoregulation Appear striated Are under voluntary (somatic) control Are polynucleated Can be divided into red (slow-twitch) fibers and white (fast-twitch) fibers
1002
Red (slow-twitch) fibers
Carry out oxidative phosphorylation
1003
White (fast-twitch) fibers)
Rely on anaerobic metabolism
1004
Smooth muscles
In the respiratory, reproductive, cardiovascular and digestive systems Appear non-striated Are under involuntary (autonomic) control Are uninucleated Can display myogenic activity
1005
Myogenic activity
Contraction without neural input
1006
Cardiac muscles
Comprise the contractile tissue of the heart Appear striated Are under involuntary (autonomic) control Are uninucleated (sometimes binucleated) Can display myogenic activity Cells are connected with intercalated disks that contain gap junctions
1007
Sarcomere
The basic contracile unit of striated muscle
1008
What are sarcomeres made of?
Thick (myosin) and thin (actin) filaments
1009
Where is troponin found on the sarcomere?
Thin (actin) filament
1010
Where is tropomyosin found on the sarcomere?
Thin (actin) filamentThin (actin) filament
1011
What does troponin do?
Regulates the actin-myosin interactions
1012
What does tropomyosin do?
Regulates the actin-myosin interactions
1013
Divisions of the sarcomere
Z-lines, M-line, I-band, H-zone, and A-band
1014
Z-lines
The boundaries of the sarcomere
1015
M-line
Located in the middle of the sarcomere
1016
I-band
Contains only thin filaments
1017
H-zone
Contains on thick filaments
1018
A-band
Contains all the thick filaments | The only part of the sarcomere that maintains a constant size during contraction
1019
Myofibrils
Sarcomeres attached end-to-end
1020
Myocyte (muscle cell or muscle fiber)
Contains many myofibrils
1021
Sarcoplasmic reticulum
Surrounds myofibrils | A calcium-containing modified ER
1022
Sarcolemma
The cell membrane of a myocyte
1023
T-tubules
Connected to the sarcolemma and oriented perpendicularly to myofibrils, allowing the incoming signal to reach all parts of the muscle
1024
Where does muscle contraction begin?
At the neuromuscular junction
1025
Neuromuscular junction
Where the motor neuron releases acetylcholine, which binds to receptors on the sarcolemma, causing depolarization
1026
What happens when the sarcolemma is depolarized?
The depolarization spreads down the sarcolemma to the T-tubules, triggering the release of calcium ions
1027
What happens when calcium ions are released?
Calcium bins to troponin, causing a shift in tropomyosin and exposure of the myosin-binding sites on the actin thin filament
1028
When does the shortening of the sarcomere occur?
When myosin heads bind to the exposed sites on actin, forming cross bridges and pulling the actin filament alone the thick filament, resulting in contraction :: the sliding filament model
1029
When does the muscle relax?
When acetylcholine is degraded by acetylcholinesterase, terminating the signal and allowing calcium to be Brough back into the SR. ATP binds to the myosin head, allowing it to release from actin
1030
Simple twitch
Muscle cells exhibiting an all-or-nothing response
1031
Frequency summation
Addition of multiple simple twitches before the muscle has an opportunity to fully relax
1032
How do muscle cells reduce oxygen debt?
Muscle cells have additional energy reserves
1033
Why is it important for muscles cells to reduce oxygen debt?
To forestall fatigue
1034
Oxygen debt
The difference between the amount of oxygen needed and the amount of oxygen present
1035
Creatine phosphate
Transfer a phosphate group to ADP, forming ATP
1036
Myoglobin
Heme-containing protein that is a muscular oxygen reserve
1037
Endoskeleton
Internal skeleton
1038
Exoskeleton
External skeleton
1039
Divisions of human skeletal system
Axial and appendicular skeletons
1040
Axial skeleton
Consists of structures in the midline | e.g. skull, vertebral column, ribcage and hyoid bone
1041
Appendicular skeleton
Consists of the bones of the limbs and the pectoral grille and the pelvis
1042
Which embryonic layer gives rise to bones?
Mesoderm
1043
Types of bones
Compact and spongy (cancellous)
1044
Periosteum
A layer of connective tissue that surrounds bone Serves as a site of attachment of bone to muscle Cells of the periosteum may differentiate into osteoblasts
1045
How are bones attached to muscles?
Tendons
1046
How are bones attached to each other?
Ligaments
1047
Bone matrix
Has organic components, like collagen, glycoproteins and other peptides Has inorganic components, like hydroxyapatite
1048
Bone organization
Bones are organized into concentric rings called lamellae around a central Harversian or Volkmann's canal. This structural unit is called an osteon, or Haversian system Between lamellar rings are lacunae, where osteocytes reside, which are connected with canaliculi to allow for n'eurent and waste transfer
1049
What is the role of parathyroid hormone in bone building/breakdown?
It increases resorption of bone, increasing calcium and phosphate concentrations in the blood
1050
What is the role of vitamin D in bone building/breakdown?
Increases resorption of bone, leading to increased turnover and, subsequently, the production of stronger bones
1051
What is the role of calcitonin in bone building/breakdown?
Increases bone formation, decreasing calcium concentration in the blood
1052
Cartilage
A firm, elastic material secreted by chondrocytes Found in areas that require more flexibility or cushioning Avascular Not innervated
1053
Chondrocytes
Secrete cartilage
1054
Chondrin
Cartilage matrix
1055
How do bones form in fetal life?
From cartilage through endochondral ossification
1056
Where do the bones in the skull form from?
Undifferentiated tissue (mesenchyme) in intramembranous ossification
1057
Joint classifications
Immovable or movable
1058
Immovable joints
Fused together to form sutures or similar fibrous joints
1059
Movable joints
Strengthened by ligaments and contain a synovial capsule
1060
Articular cartilage
Coats each bone in the joint | Aids in movement and provides cushioning
1061
Antagonistic pairs
Muscles that serve opposite functions :: when one muscle contracts, the other lengthens
1062
An X-ray of the right femur in a child shows that it is shorter than the opposite femur, and below the average length for a child of this age. Which region of the bone is most likely to have caused this abnormality?
Epiphysis
1063
When the knee moves back and forth during walking, what prevents the surfaces of the leg bones from rubbing against each other?
Articular cartilage
1064
Yellow bone marrow
Contains predominantly adipose tissue
1065
To facilitate the process of birth, an infant's head is somewhat flexible. This flexibility is given in part by the two fontanelles, which are soft spots of connective tissue in the infant's skull. With time, the fontanelles will close through a process known as:
Intramembranous ossification
1066
A young woman presents to the ER with a broken hip. She denies any recent history of trauma to the joint. Blood tests reveal a calcium concentration of 11.5 mg/dL (normal: 8.4 -- 10.2). Which tissue is likely responsible for these findings?
Parathyroid
1067
What does it mean for an allele to be dominant?
Requires only one copy for expression
1068
What does it mean for an allele to be recessive?
Requires two copies for expression
1069
What does it mean for a genotype to be homozygous?
Both alleles are recessive or both alleles are dominant
1070
What does it mean for a genotype to be heterozygous?
One allele is recessive and the other is dominant
1071
What does it mean for a genotype to be hemizygous?
There is only one allele for a given gene
1072
Complete dominance
Occurs when a gene has only one dominant and one recessive allele
1073
Codominance
Occurs when a gene has more than one dominant allele and two different dominant allele can be expressed simultaneously
1074
Incomplete dominance
Occurs when a gene has no dominant allele and heterozygotes have phenotypes that are intermediate between homozygotes
1075
Penetrance
The portion of the population that expresses a phenotype, given a particular genotype
1076
Expressivity
The differences in expression (severity, location, etc.) of a phenotype across affected members of a population
1077
Which phase of meiosis most closely correlates to Mendel's first law?
Anaphase I
1078
Which phase of meiosis most closely correlates to Mendel's second law?
Prophase I
1079
Types of point mutations
Silent Missense Nonsense
1080
Silent mutation
Change in the nucleotide at the wobble position | No change in the amino acid produced
1081
Missense mutation
Change one nucleotide to another that results in change from one amino acid to another
1082
Nonsense mutation
Change one nucleotide to another that results in change from one amino acid to a stop codon Shortened protein
1083
Types of frameshift mutation
Insertion | Deletion
1084
Types of chromosomal mutations
``` Deletion Duplication Inversion Insertion Translocation ```
1085
Duplication mutation
Occur when a segment of DNA is copied multiple times in the genome
1086
Inversion mutation
Occur when a segment of DNA is reversed in the genome
1087
Translocation mutation
Occur when a segment of DNA is from one chromosome is swapped with a segment of DNA from another chromosome
1088
Why would genetic leakage in animals be rare prior to the last century?
It requires the formation of a hybrid organism that can then mate with members of one or the other parent species. While hybrids existed historically (especially mules), fertile hybrids were certainly rare before a more modern understanding of genetics (and a commercial, financial or academic impetus to create these organisms).
1089
Why is genetic drift more common in small populations?
It occurs due to chance, so its effects will be more pronounced with a smaller sample size.
1090
The founder effect
Occurs when a small group is reproductively isolated from the larger population, allowing certain alleles to take on a higher prevalence in the group than the rest of the population
1091
All five criteria of the Hardy-Weinberg principle are required to imply what characteristic of the study population?
The study population is not undergoing evolution; thus, the allele frequencies will remain stable over time
1092
Natural selection
Certain traits that arise from chance are more favorable for reproductive success in a given environment, and that that those traits will be passed on to future generations
1093
Modern synthesis model (Neo-Darwinism)
Selection is for specific alleles, which are passed to future generations through formation of gametes, and that these favorable traits arise from mutations
1094
Inclusive fitness
Reproductive success of an organism is not only due to the number of offspring it creates, but also the ability to care for young (that can then care for other); it explains changes not only at the individual level, but based on the survival of the species (and that individual's alleles within the species, including in other related individuals).
1095
Punctuated equilibrium
For some species, little evolution occurs for a long period, which is interrupted by rapid bursts of evolutionary change
1096
Patterns of selection
Stabilizing Directional Disruptive
1097
Change in population phenotype does the stabilizing pattern of selection bring?
Loss of extremes, maintenance of phenotype in a small window
1098
Change in population phenotype does the directional pattern of selection bring?
Movement towards one extreme or the other
1099
Change in population phenotype does the disruptive pattern of selection bring?
Movement towards both extremes with loss of the norm | Speciation may occur
1100
Patterns of evolution
Divergent Parallel Convergent
1101
What is the outcome of a divergent pattern of evolution?
Two species with a common ancestor become less similar because of different evolutionary pressures
1102
What is the outcome of a parallel pattern of evolution?
Two species with a common ancestor remain similar because of similar evolutionary pressures
1103
What is the outcome of a convergent pattern of evolution?
Two species with no recent common ancestor become more similar because of similar evolutionary pressures
1104
Species
The largest group of organisms capable of breeding to form fertile offspring Reproductively isolated from each other by pre- or post-zygotic mechanisms
1105
Hardy-Weinberg equations
p + q = 1 | p^2 + 2pq + q^2 = 1
1106
Alleles
Alternative forms of a gene
1107
Genotype
The combination of alleles one has at a given genetic locus
1108
Phenotype
The observable manifestation of a genotype
1109
Mendel's first law of segregation
States that an organism has two alleles for each gene, which segregate during meiosis, resulting in gametes carrying only one allele for a trait
1110
Mendel's second law of independent assortment
The inheritance of one allele does not influence the probability of inheriting a given allele for a different trait
1111
Griffith experiment
Demonstrated the transforming principle, converting non-virulent bacteria into virulent bacteria by exposure to heat-killed virulent bacteria
1112
Avery-MacLeod-McCarty experiment
Demonstrated that DNA is the genetic material because degradation of DNA led to a cessation of bacterial transformation
1113
Hershey-Chase experiment
Confirmed that DNA is the genetic material because only radio labeled DNA could be found in bacteriophage-infected bacteria
1114
Gene pool
Composed of all the alleles in a given population
1115
Mutations
Changes in DNA sequence
1116
Deletion mutation
Occurs when a large segment of DNA is lost
1117
Insertion mutation
Occurs when a segment of DNA is moved from one chromosome to another
1118
Bottleneck effect
Suddenly isolates a small population
1119
Outcomes of the bottleneck effect
Founder effect and inbreeding
1120
Punnet squares
Visually represent the crossing of gametes from parents to show relative genotypic and phenotypic frequencies
1121
Monohybrid cross
Accounts for one gene
1122
Dihybrid cross
Accounts for two genes
1123
Sex-linked cross
Sex chromosomes are usually used to indicate sec as well as genotype
1124
Recombination frequency
The likelihood of two alleles being separated during crossing over in meiosis
1125
Genetic maps
Can be made using recombination frequency as the scale in centimorgans
1126
Hardy-Weinberg principle
States that if a population meets certain criteria (aimed at a lack of evolution), then the allele frequencies will remain constant (Hardy-Weinberg equilibrium)
1127
Adaptive radiation
The rapid emergence of multiple species from a common ancestor, each of which occupies its own ecological niche
1128
Molecular clock model
The degree of difference in the genome between two species is related to the amount of time since the two species broke off from a common ancestor
1129
If a test cross on a species reveals the appearance of a recessive phenotype in the offspring, what must be true of the phenotypically dominant parent?
It must be genotypically heterozygous
1130
In a species of plant, a homozygous red flower (RR) is crossed with a homozygous yellow flower (rr). If the G1 generation is self-crossed and the F2 generation has a phenotypic ratio of red:orange:yellow of 1:2:1, which characteristic accounts for these results?
Incomplete dominance
1131
The five criteria of the Hardy-Weinberg principle
1. The population is very large 2. There are no mutations that affect the gene pool 3. Mating between individuals in the population is random 4. There is no migration of individuals into or out of the population 5. The genes in the population are all equally successful at reproduction
1132
As the climate became colder during the Ice Age, a particular species of mammal evolved a thicker layer of fur. What kind of selection occurred in this population?
Directional selection
1133
At what point are two populations descended from the same ancestral stock considered to be separate species?
When they can no longer produce viable, fertile offspring
1134
Darwin's main argument in his theory of evolution
Natural selection is the driving force for evolution There is a struggle for survival among organisms Those individuals with fitter variations will survive and reproduce
1135
Did Darwin consider the role of genetic mutation and recombination?
No because they were unknown at the time
1136
A child is born with a number of unusual phenotypic features and genetic testing is performed. The child is determined to have partial trisomy 21, with three copies of some segments of DNA from chromosome 21, and partial monosomy 4, with only one copy of some segments of DNA from chromosome 4. Which mutation could have occurred in one of the parental gametes during development to explain both findings?
Translocation (It's not an insertion mutation, because an insertion mutation only explains what happened in 21, but not what happened in 4. It's not a deletion mutation, because a delegation mutation on explains what happened in 4, but not what happened in 21)

MCAT (7 decks)

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