Kaplan Flashcards
1
Q
Allantois
A
The embryonic membrane that contains the growing embryo’s waste products
2
Q
Alleles
A
Genes coding for alternative forms of a given trait
3
Q
Amino Acid-Derivative Hormones
A
Hormones that are synthesized by modifying amino acids
- Act via secondary messengers
4
Q
Aldosterone
A
Steroid hormone produced in the adrenal cortex that is responsible for reabsorption of sodium and water and excretion of potassium and hydrogen ions
5
Q
Adrenal Medulla
A
Synthesizes and releases epinephrine and norepinephrine, which stimulate an increase in the metabolic rate and blood glucose levels
6
Q
Adrenal Cortex
A
Synthesizes and releases corticosteroids
7
Q
Acrosome
A
Large vesicle at the head of a sperm cell containing enzymes that degrade the ovum cell membrane to allow fertilization
8
Q
Afferent Neurons
A
Neurons that carry information to the central nervous system from the periphery
- AKA sensory neurons
9
Q
Adrenocorticotropic Hormone (ACTH)
A
Synthesized and released by the anterior pituitary
- Stimulates adrenal cortex
- Regulated by CRF
10
Q
Action Potential
A
Sharp change in the membrane potential of neurons or muscle cells caused by a change in the selective permeability to Na+ and K+ using voltage-gated ion channels
- All or nothing events
11
Q
Seminiferous Tubules
A
Located in the testes, the seminiferous tubules are the site of sperm production
12
Q
Semilunar Valves
A
Valves (aortic and pulmonary) that prevent the backflow of blood from the arteries in the ventricles
13
Q
Semen
A
The fluid discharges during ejaculation
- Consists of sperm cells and seminal fluid
14
Q
Secondary Repsonse
A
Subsequent infections by pathogens that trigger a more immediate response from the memory cells produced during the primary immune response
15
Q
Second Messenger
A
A small molecule that transduces a hormonal signal from the exterior of the cell to the interior. Usually released when a peptide hormone binds to its receptor
- cAMP is example
16
Q
Schwann Cells
A
Cells that produce myelin in the peripheral nervous system
17
Q
Sarcoplasmic Reticulum
A
A modified form of endoplasmic reticulum; stores calcium that is used to trigger contraction when muscle is stimulated
18
Q
Sarcomere
A
The structural unit of striated muscle
- Composed of thin (mostly actin) and thick (mostly myosin) filaments
19
Q
Saltatory Conduction
A
A means by which action potentials jump from node to node along an axon
20
Q
Ribonucleic Acid (RNA)
A
A nucleic acid found in both the nucleus and cytoplasm and most closely linked with transcription and translation
21
Q
Translocation
A
A form of chromosomal rearrangement in which a portion of one chromosome swaps with a portion of a nonhomologous chromosome
22
Q
Transverse Tubules (T-Tubules)
A
A system of tubules that provides channels for ion flow throughout skeletal and cardiac muscle fibers to facilitate the propagation of an action potential
23
Q
Tricuspid Valve
A
A valve between the right atria and the right ventricle
- Consists of 3 cusps and prevents backflow of blood from the right ventricle to the right atrium
24
Q
Threshold Voltage
A
The minimal voltage that must be reached in order for an action potential to be fired at the axon hillock
25
Thyroid Hormones
Synthesized and released by the thyroid gland
- Triiodothyronine (T3) and thyroxine (T4)
- Stimulate cellular respiration as well as protein and fatty acid synthesis and degradation
26
Testosterone
Hormone secreted by the interstitial cells of the testes
- Responsible for embryonic sexual differentiation, male sexual development, and the maintenance of masculine secondary sexual characteristics
27
Totipotent
Stem cells that have the ability to become any cell within any system of the body
28
Thyroid-Stimulating Hormone (TSH)
Synthesized and released by the anterior pituitary
- Stimulates the thyroid gland to absorb iodine and to synthesize and secrete thyroid hormones
- Regulated by thyroid releasing hormone (TRH), which is released by the hypothalamus
29
Tetrad
Collectively, the 4 chromatids involved when a pair of homologous chromosomes synapse during prophase I of meiosis
30
Thermoregulation
Maintenance of a constant internal body temperature
31
Endometrium
The mucosal lining of the uterus where the embryo implants
- Progesterone is necessary for the maintenance during pregnancy
32
Endoderm
The innermost of the 3 primary germ layers
- Gives rise to the linings of the digestive and respiratory tracts and to parts of the liver, pancreas, thyroid, and bladder
33
Ectoderm
The outermost of the 3 primary germ layers
- Gives rise to the skin, nervous system, lens of the eye, and inner ear
34
Efferent Neurons
Neurons that carry information from the central nervous system to other parts of the body
- Motor neurons
35
Endocrine Glands
Glands that synthesize and secrete hormones into the circulatory system
36
Diploid
Cells with 2 copies of each chromosome, usually one from the mother and one from the father
- Eukaryotic somatic cells
37
Direct Hormones
Hormones that travel to a target tissue to cause an action without another hormone acting as an intermediary
38
Diastole
The stage of the cardiac cycle in which the heart muscle relaxes and collects blood into its chambers
39
Disruptive Selection
Type of natural selection where both phenotypic extremes are favored over the average phenotype
40
Disjunction
The separation of homologous chromosomes during anaphase I of meiosis
41
Enteric Nervous System
A collection of millions of neurons within the gastrointestinal system that governs the function of the GI tract
- Functions independently of the brain and spinal cord
42
Endothelial Cells
Cells that line blood vessels
- Produce and release chemicals that aid in vasodilation and vasoconstriction
43
Endorphins
Synthesized and released by the anterior pituitary
- Inhibit perception of pain
44
Amnion
Innermost extraembryonic membrane
- Produces amniotic fluid in which the growing fetus is suspended
45
Genetic Map
Created by analyzing recombination frequencies of linked genes
- Shows the distance between 2 genes or the order of several genes on a chromosomes
46
Genotype
Genetic makeup of an individual
47
Gene
Unit of DNA that encodes a specific protein or RNA molecule
48
Gastrulation
Process by which a single-layered blastula becomes a three-layered gastrula
49
Genetic Drift
Changes in the composition of the gene pool by chance
50
Gastric Glands
Located in the stomach
- Secrete HCl and various enzymes when stimulated by gastrin
51
Homozygous
Organisms that contain 2 identical alleles of the same gene on homologous chromosomes
52
Immunoglobin
Produced in response to a specific foreign substance that recognizes and binds to that antigen and triggers an immune response
- Synonymous with antibody
53
Hypodermis
Layer of loose connective tissue below the dermis that binds the dermis to the body
54
Hyperventilation
An increase in the rate of respiration or tidal volume
- Lack of oxygen or decrease in pH promotes
55
Induction
Influence of a group of cells on the development of other cells
56
Indeterminate Cleavage
Cell division in embryogenesis that results in each cell maintaining its totipotency
57
Incomplete Dominance
Describes a situation in which an organism heterozygous for a trait will have a phenotype that is intermediate between both homozygous phenotypes
58
Inferior Vena Cava
Large vein that returns deoxygenated blood from the lower body to the right atrium of the heart
59
Inner Cell Mass
Group of cells in a blastocyst that develop into the embryo
60
Innate Immunity
Nonspecific immunity provided by structures and cells
61
Humoral Immunity
The synthesis of specific antibodies by activated B-cells in response to an antigen
62
Heterozygous
Organisms that contain 2 different alleles for the same gene on homologous chromosomes
63
Glucagon
Increases blood glucose concentrations by promoting gluconeogenesis and the conversion of glycogen to glucose in the liver
- Produced and secreted by the α-cells of pancreas
64
Homologous Chromosomes
Chromosomes in a diploid cell that contain alleles for the same traits at corresponding loci
65
Growth Hormone (GH)
Stimulates bone and muscle growth as well as glucose conservation
- Synthesized and released by anterior pituitary
- Inhibited by somatostatin and stimulated by growth hormone releasing hormone
66
Glomerulus
Network of capillaries within Bowman's capsule that serves as the site of filtration
67
Golgi Apparatus
An organelle that plays a role in the packaging and secretion of proteins and other molecules produced intracellularly
68
Glucocorticoids
Raise blood glucose levels while decreasing protein synthesis
- Synthesized and released by the adrenal cortex
69
Haploid
Cells with only one copy of each chromosome
- Germ cells
70
Hemoglobin
Protein found in erythrocytes made up of 4 polypeptide chains, each containing a heme group
- Responsible for transporting oxygen from the alveoli to the tissues
71
Starling Forces
Balance between hydrostatic and oncotic pressures on both sides of a membrane
- Essential for maintaining proper fluid volumes and solute concentrations
72
Stabilizing Selection
Type of natural selection where the average phenotype is favored while those outside the norm are eliminated
73
Spongy Bone
Lighter and less dense than compact bone
- Interconnecting lattice of bony spicules (trabeculae)
74
Spermatozoa
Mature sperm specialized for transporting the genetic info from the male to the ovum
75
Somatostatin
Inhibits release of glucagon and insulin
- Produced and secreted by δ - cells in pancreas
76
Synaptic Terminals
Ends of axons that form one side of the synaptic cleft
- Vesicles of neurotransmitters stored here
77
Synapse
Space between the axon terminal of one neuron and the dendrite of another neuron where neurotransmitters are released
78
Surfactant
Liquid substance produced by the lung that reduces surface tension in the alveoli
- Prevents lung collapse and decreases effort needed to inhale
79
Superior Vena Cava
Large vein that returns deoxygenated blood from the upper body to the right atrium of the heart
80
Steroid Hormones
Nonpolar hormones that cross the cell membrane and act by binding intracellular receptors
81
Hepatic Portal Vein
Carries nutrients absorbed in the small intestine to the liver
82
Corpus Luteum
Tissue that forms from the collapsed ovarian follicle
- Produces and secretes progesterone and estrogen
83
Frameshift Mutation
Mutation in which a number of nucleotides are either deleted or inserted
- Shift in DNA reading frame
84
Ganglia
Group of neuronal cell bodies in the peripheral nervous system
- Sensory or autonomic
85
Exocrine Glands
Glands that synthesize and secrete substances through ducts
86
Episomes
Plasmids that have the ability to integrate into the host genome
87
Erythrocytes
Oxygen-carrying component of blood
- Red blood cells (RBC's)
88
Estrogen
Stimulates the development of the female reproductive tract and secondary sexual characteristics and is partly responsible for the LH spike that causes ovulation
- Synthesized and released by the ovaries, ovarian follicles, corpus luteum, and placenta
89
Conjugation
Form of sexual reproduction used by bacteria
- genetic material is exchanged through a pilus
90
Corona Radiata
Outer layer of cells surrounding the oocyte
- Derived from follicular cells
91
Facultative Anaerobe
Organism that makes ATP by aerobic respiration if oxygen is present, but that can switch to fermentation for sufficient ATP when oxygen is not available
92
Expressivity
Refers to the variability in phenotypes that can occur with a given genotype
93
Follicle - Stimulating Hormone (FSH)
Stimulates maturation of ovarian follicles in females and maturation of the seminiferous tubules and sperm production in males
- synthesized and released by the anterior pituitary
- Regulated by estrogen and GnRH
94
Foramen Ovale
Shunt that connects the right atrium to the left atrium in order to bypass the fetal lung
95
Follicle
Multilayered sac of cells that protects and nourishes the developing ovum
96
Determinate Cleavage
Division of cells during embryogenesis in which each cell specializes early in development
97
Depolarization
Process that occurs when the voltage-gated Na+ channels open, allowing Na+ to rush into the cell
98
Dendrite
Extension of the neuron that transmits impulses toward the cell body
99
Descending Limb of the Loop of Henle
Portion of the nephron permeable only to water
- Filtrate becomes more concentrated as it travels through this portion
100
Dermis
Layer of skin beneath the epidermis that is subdivided into the papillary layer and the reticular layer
- Contains sweat glands, sense organs, blood vessels, hair follicle bulbs
- Derived from mesoderm
101
Crossing Over
Exchange of genetic material between homologous chromosomes that occurs during prophase I of meiosis I
102
Diaphysis
Cylindrical shaft of a long bone
- Filled with bone marrow for the production of blood cells
103
Ductus Venosus
Shunt that connects the umbilical vein to the inferior vena cava in order to bypass the fetal liver
104
Archenteron
Central cavity in the gastrula stage of embryological development
- Lined by endoderm
- Gives rise to adult digestive tract
105
Arteries
Vessels that carry blood away from the heart
- Muscular
- Do not have valves
106
Appendicular Skeleton
Bones of the pelvis, pectoral girdles, and the limbs
107
Antidiuretic Hormone (ADH)
Acts on the collecting duct to increase water reabsorption
- peptide hormone
- AKA vasopressin
- Produced by hypothalamus and stored in posterior pituitary gland
108
Antigen
Substance that is bound by an antibody, causing an immune reaction
109
Anterior Pituitary
Synthesizes and releases many vital hormones
- FSH, LH, TSH, ACTH, prolactin, endorphins, and growth hormone (FLAT PEG)
- Under hormonal control of hypothalamus
110
Filtrate
Material that passes from the blood vessels into Bowman's space
111
Ascending Limb of the Loop of Henle
Portion of the nephron not permeable to water
- Filtrate concentration is decreased
112
Inversion
Form of chromosomal rearrangement in which a portion of a chromosome breaks off and rejoins the same chromosome in the reverse position
113
Vagus Nerve
Provides parasympathetic signaling to the thoracic and abdominal cavities
- Cranial nerve
114
Umbilical Cord
Connects vasculature of the fetus to the placenta
115
Intrinsic Factor
Protein secreted by parietal cells of the stomach that is necessary for vitamin B12 absorption
116
Intrapleural Space
Space between the visceral and parietal pleura that cover the lungs
117
Tropic Hormones
Hormones that travel to a target tissue and cause the release of another hormones
118
Test Cross
Cross between an organism of an undetermined genotype and another that is homozygous recessive for the trait of interest
119
Intestinal Glands
Contains brush-border enzymes such as maltase, sucrase, and lactase to digest disaccharides
120
Systole
Stage of the cardiac cycle in which the heart muscle contracts and pumps blood
121
Zona Pellucida
Inner layer of glycoproteins surrounding the oocyte
- Secreted by follicular cells and the oocyte itself
- Penetration by a sperm cell forces the secondary oocyte to undergo meiosis II
122
Epiglottis
Flap of cartilage that covers the glottis when swallowing food in order to prevent food particles from entering the larynx
123
White Fibers
Fast-twitch muscle fibers
- Primarily anaerobic and fatigue easily
124
Epidermis
Outermost layer of skin, which is composed of sublayers
- Stratum basalis, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
- Protective barrier against microbial attack
- Derived from the ectoderm
125
Villi
Fingerlike projections that extend out of the small intestine in order to increase surface area for maximal absorption
126
Enteropeptidase
Digestive enzyme secreted by cells in the duodenum
- Converts trypsinogen to trypsin
127
Ventricles
Muscular lower chambers of the heart
- Right pumps deoxygenated blood to the lungs
- Left pumps oxygenated blood throughout body
128
Large Intestine
Absorbs salts, water, and some vitamins
- Consists of cecum, colon, and rectum
129
Veins
Vessels that carry blood toward heart
- Thin-walled and have valves
130
Leukocytes
Component involved in cell defense and immunity
- White blood cells
- Neutrophils, basophils, eosinophils, lymphocytes, monocytes
131
Somatic Nervous System
Division of peripheral nervous system that is responsible for voluntary movement
132
Somatic Cells
All cells excluding the germ cells
133
Small Intestine
Section of the digestive tract that can be subdivided into 3 section: duodenum, jejunum, and ileum
- Digestion and absorption
134
Smooth Muscle
Nonstriated muscle responsible for involuntary action
- Controlled by autonomic
135
Sodium - Potassium Pump
Protein that hydrolyzes one ATP to transport 3 Na+ out of the cell for every 2 K+ it transports into the cell
136
Skeletal Muscle
Type of muscle responsible for voluntary movement, consisting of multinucleated, striated muscle fibers
137
Sister Chromatids
Relationship between the strands of DNA after replication
- 2 identical chromatids held together at centromere
- Mitotic spindle pulls apart
138
Rh Factor
Surface protein expressed on red blood cells that can induce an immune response
139
Signaling Cascade
Series of events, starting with the binding of a peptide hormone to a surface receptor
- Results in a change in cellular behavior
140
Reverse Transcriptase
Enzyme in retroviruses that uses RNA strands as templates for synthesizing cDNA molecules
141
Adaptive Immunity
Highly specific form of immunity that develops in response to exposure to pathogens
- Humoral and cytotoxic
142
Collecting Duct
Portion of the nephron permeable to water and ions
- Filtrate is concentrated
- Degree of water reabsorption is controlled by ADH
143
Compact Bone
Much more dense than spongy bone
- Consists of Haversian systems (osteons)
144
Codominance
An organism heterozygous for a trait will have a phenotype that expresses both alleles in full
- Both alleles are dominant
145
Chyme
Combination of partially digested food and acid that forms in the stomach
146
Chromatin
Chromosomes in their uncoiled state
147
Cholecystokinin (CCK)
Stimulates the release of bile and pancreatic enzymes into the small intestine; promotes satiety
- Secreted by the duodenum in response to the presence of chyme
148
Chorion
Outermost extraembryonic membrane
- Contributes to the formation of the placenta
149
Centrosome
Portion of the cells containing the centrioles
150
Chemical Digestion
Enzymatic breakdown of large molecules into smaller molecules
151
Catecholamines
Norepinephrine, epinephrine, and dopamine
- Also hormones produced by the adrenal medulla that play a significant role in the sympathetic nervous system
152
Carbonic Anhydrase
Enzyme that catalyzes the conversion of carbonic acid to carbon dioxide and water as well as the formation of carbonic acid from carbon dioxide and water
- Important in the bicarbonate buffer system
153
Axial Skeleton
The skull, vertebral column, rib cage, and hyoid bone
154
Atrioventricular Valves
Valves located between the atria and the ventricles
- Tricuspid and mitral
155
Cartilage
Firm, elastic, translucent connective tissue consisting of collagenous fibers embedded in chondrin
- Produced by cells called chondrocytes
- Principal component of embryonic skeletons and can harden and calcify into bone (ossify)
156
Cell Theory
Foundational belief in modern biology that all living things are composed of cells, the cell is the basic functional unit of life, that all cells arise from preexisting cells, and that DNA is the genetic material
157
Atria
2 thin-walled upper chambers of the heart
- Right receives deoxygenated blood from the vena cava
- Left receives oxygenated blood from the pulmonary veins
158
Zygote
Fertilized egg
159
Cell - mediated (cytotoxic) Immunity
Branch of the immune system in which intracellular pathogens are eliminated by killing their host cells
-T- cells are the primary mediators
160
Central Nervous System
Consists of the brain and the spinal cord
161
Cardiac Muscle
Type of muscle found within the heart; may contain one or two nuclei
- Involuntary
- Striated
- Able to depolarize independent of the nervous system
162
Calcitonin
Decreases plasma Ca2+ concentration
- Synthesized and released by the thyroid gland
163
Capillaries
Blood vessels composed of a single layer of endothelial cells, facilitating exchange of gases, nutrients, and waste products between the blood and interstitial fluid
164
Blood buffer system
Relies primarily on the carbonic acid buffer system
- Release of carbon dioxide causes increased formation of water and an increase in pH
- Increased retention of HCO3-causes the pH to rise as well
165
Blood Antigens
Proteins or sugars found on the erythrocyte cell surface
- 3 antigens used to differentiate blood groups are A, B, and Rh
166
Blastulation
The process by which a morula develops into a blastula with a fluid filled cavity called a blastocoel
167
Bile
An alkaline fluid synthesized in the liver, stored in the gallbladder, and released into the duodenum
- Aids in the emulsification, digestion, and absorption of fats
168
Binary Fission
Method of asexual reproduction by which prokaryotes divide
- Circular DNA molecule replicates and then moves to the edge of the cell; cell divides into two daughter cells of equal size
169
Bacteriophages
Viruses that can only infect bacteria
170
Axon Hillock
Portion of the neuron that connects the cell body to the axon
171
Monosynaptic Reflex
Reflex pathway that has only one synapse between the sensory and the motor neuron
172
Monozygotic Twins
Result when a zygote splits into 2 embryos
- Identical twins
173
Morula
Solid ball of cells that develops from the zygote through cleavage
174
Multipotent
Stem cells that can differentiate into multiple cell types within a particular group
175
Myelin Sheath
Insulating structure that surrounds axons
176
Mitochondria
The site of aerobic respiration that provides the cell with a majority of its energy in the form of ATP
177
Mitosis
Cell division or nuclear division in somatic cells that results in the daughter nucleus receiving a full complement of the organism's genome
178
Mitral Valve
Valve located between the left atrium and the left ventricle
179
Mode
Most frequently occurring value in a set of observations
180
Monohybrid Cross
Cross between 2 organisms where only one trait is being studied
181
Respiratory Rate
Breaths per minute
- Raising can decrease amount of CO2 in blood ---> increasing pH
- Lowering can increase CO2 in blood ---> lower pH
182
Resting Potential
Charge difference across the cell membrane of a neuron or a muscle cell while at rest
183
Repolarization
Process that occurs when the voltage-gated Na+ channels close and voltage-gated K+ channels open during an action potential, allowing K+ to rush out of the cell and repolarize it
184
Pluripotent
Stem cells that can become other cells within the same primary germ layer
185
Plasma
Liquid portion of blood
- Aqueous mixture of nutrients, salts, respiratory gases, hormones, and blood proteins
186
Platelets
Cell fragments involved in the clotting process
- From megakaryocytes in bone marrow
187
Peroxisome
Organelle that contains hydrogen peroxide and participates in the breakdown of very ling chain fatty acids
188
Phenotype
Physical manifestation of an individual's genotype
189
Placenta
Organ formed by the uterus and the extraembryonic membranes of the fetus
- Exchange between fetal circulation and maternal circulation
190
Peristalsis
Involuntary muscular contractions that push food down the digestive tract
191
Interstitial Cells
Secrete testosterone and other androgens
- Located in testes
- AKA Leydig cells
192
Epiphyseal Plate
Portion of the bone where growth occurs
- Located in epiphysis
193
Epiphysis
Dilated ends of long bones in the appendicular skeleton
194
Liver
Essential organ of the human body responsible for the production of bile, detoxification of ingested substances, production of urea, and the processing and modification of nutrients for storage
- Also produces albumin and clotting factors
195
Dominant
Describes an allele that requires only one copy to be expressed
196
Dizygotic Twins
Results when 2 ova are fertilized by 2 different sperm
- Fraternal twins
197
Directional Selection
Type of natural selection where one extreme phenotype is favored over the average phenotype and other extreme phenotypes
198
Insulin
Decreases blood glucose concentrations by facilitating the uptake of glucose by muscle and adipose cells and the conversion of glucose to glycogen in muscle and liver cells
- Produced and secreted by β - cells
199
Interphase
Phase of the cell cycle in which cell division does not take place
- G1, S, G2 phases
200
Ductus Arteriosus
Shunt that connects the pulmonary artery to the aorta in order to bypass the fetal lung
201
Mendel's Law of Segregation
Mendel's postulation that there are alternate versions of genes that account for genetic variation
202
Mesoderm
Primary germ layer that lies between the ectoderm and the endoderm
- Gives rise to the musculoskeletal system, circulatory system, excretory system, gonads, connective tissue, and portions of the digestive and respiratory organs
203
Negative Pressure Breathing
The contraction of the diaphragm and the intercostal muscles increases the volume of the thoracic cavity, reducing the pressure in the intrapleural space
- Creates a vacuum that causes the lungs to suck in air
204
Mendel's Law of Independent Assortment
The alleles of different genes sort independently from one another during meiosis
205
Mechanical Digestion
Breakdown of food particles into smaller particles through such activities as biting, chewing, and churning
206
Median
The simplest division of a set of values; middle value that divides the values into the upper and lower half
207
Meiosis
Two phase cell division in germ cells that results in the formation of up to 4 haploid cells from one diploid cell
208
Lysosome
Membrane-bound vesicle that contain hydrolytic enzymes used for intracellular digestion
209
Lytic Cycle
Phase in viral replication in which the host cell is lysed and releases new virions
210
Mean
The average, calculated as the sum of observed values divided by the number of observed values
211
Pathway of the Electrical Impulse in the Heart
SA node ---> AV node ---> bundle of His ---> Purkinje fibers
212
Pathway of Respiratory Tract
Nasal or oral cavity ---> pharynx ---> larynx ---> trachea ---> bronchi ---> bronchioles ---> alveoli
213
Penetrance
Percentage of people in a population with a certain genotype who express the associated phenotype
214
Pepsin
Cleaves peptide bonds, starting the digestion of proteins into individual amino acids
- Secreted as pepsinogen by the chief cells of the stomach
215
Refractory Period
Short period of time immediately following an action potential in which neurons or muscle cells are unresponsive to a stimulus
216
Pancreas
Exocrine functions: secrete pancreatic amylase, trypsinogen, chymotrypsinogen, procarboxypeptidases A and B, and pancreatic lipase into the small intestine
Endocrine functions: Secretion of insulin and glucagon
217
Parathyroid Hormone (PTH)
Increases blood Ca2+ concentration by increasing Ca2+ reabsorption in the kidneys and by stimulating calcium release from bone
- Synthesized and released by the parathyroid gland
218
Recombination Frequency
The likelihood of 2 genes on the same chromosome being separated onto 2 different chromosomes during crossing over
219
Recessive
Describes an allele that requires 2 copies to be expressed
220
Progesterone
Stimulates the development and maintenance of the endometrial walls for implantation of the embryo
- Synthesized and released by the ovaries, corpus luteum, and placenta
221
Osteoblasts
Cells in the bone tissue that secrete the organic constituents of the bone matric
222
Osteoclasts
Cells in the bone matric that are involved in bone degradation
223
Osteons
Structural unit of a compact bone that consists of a central canal surrounded by a number of concentric rings of bony matric called lamellae
224
Neural Crest Cells
Cells at the tip of the neural fold
225
Nephron
Functional unit of the kidney
226
Peptide Hormones
Polar hormones incapable of permeating the cell membrane that bind to the surface receptors and act through secondary messengers
227
Peripheral Nervous System
Neurons that are not a part of the central nervous system
- somatic and autonomic
228
Luteinizing Hormone (LH)
Stimulates ovulation and the formation of the corpus luteum
- Synthesized and released by anterior pituitary
- Regulated by estrogen, progesterone, and GnRH
229
Lymph Nodes
Swellings along the lymph vessels where lymph is filtered by leukocytes to remove antigens
230
Lymphatic System
System of vessels and lymph nodes that collect interstitial fluids and return them to the circulatory system, thereby maintaining fluid balance
231
Primary Spermatocytes
Diploid cells that undergo meiosis I to form 2 haploid secondary spermatocytes
232
Polar Body
Small, short-lived haploid cell created during oogenesis that receives very little cytoplasm, organelles, or nutrients
233
Posterior Pituitary
Stores and releases hormones synthesized by the hypothalamus
- Oxytocin and ADH
234
Primary Response
Initial response to a specific antigen
- T and B cells are activated
- Specific antibodies and memory cells for antigen produced
235
Red Fibers
Slow twitch muscle fibers
- Primarily aerobic
236
Pyloric Sphincter
Valve between the stomach and the small intestine that regulates the flow of chyme into the duodenum
237
Pyloric Glands
Glands located in the walls of the stomach that secrete the hormone gastrin to increase gastric acid production
238
Lysogenic Cycle
Phase of viral replication in which the DNA of the bacteriophage becomes integrated in the host's genome and replicates as the bacteria replicates
239
Proximal Convoluted Tubule
Portion of the nephron where glucose, amino acids, and other important organic molecules are reabsorbed
- Cortex of kidney
240
Prolactin
Stimulates milk production and secretion in female mammary glands
- Synthesized and released by anterior pituitary
241
Point Mutation
Mutation in which one nucleotide base is substituted by another
242
Portal Systems
Circulatory routes in which blood travels through 2 capillary beds before returning to the heart
243
Neurotransmitters
Chemical messengers released from synaptic terminals of a neuron that can bind to and stimulate a postsynaptic cell
244
Nodes of Ranvier
Gaps between segments of myelin sheath where action potentials can take place, allowing for saltatory conduction
245
Nondisjunction
Failure of homologous chromosomes or sister chromatids to separate properly during meiosis I or meiosis II
246
Obligate Intracellular Organisms
Organisms that require a host cell to express their genes and reproduce
247
Osmoregulation
Maintenance of water and solute concentrations
