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MCAT > BIOLOGY FINAL REVIEW > Flashcards

BIOLOGY FINAL REVIEW Flashcards

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1
Q

Cell theory

A

All living things are composed of cells

The cell is the basic functional unit of life

Cells arise only from preexisting cells

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2
Q

Peroxisomes

A

Peroxisomes contain hydrogen peroxide, they break down long chain fatty acids and participate in the synthesis of phospholipids

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3
Q

Microfilaments

A

Made of actin

Play a role in cytokinesis, form the cleavage furrow during mitosis

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4
Q

Microtubules

A

Made of hollow polymers of tubulin

Radiate throughout the cell, providing pathways for the motor proteins kinesin and dynein

Make cilia and flagella

Centrioles are found in the centrosome

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5
Q

cilia and flagella

A

cilia are for movement of materials along cell surface, flagella are for movement of the cell itself

share the same structure (9+2), only in eukaryotes

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6
Q

Centrioles

A

the organizing centers for microtubules

during mitosis, they migrate to opposite poles and organize the mitotic spindle, microtubules that attach to the chromosomes via kinetochores and pull apart the sister chromatids

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7
Q

Intermediate filaments

A

Diverse, includes keratin

Cell-cell adhesion or maintenance of overall cytoskeleton integrity, help anchor other organelles

varying protein identity

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8
Q

Epithelial tissue

A

protects against pathogen invasion

involved in absorption, secretion, sensation
tightly joined to each other and to the underlying basement membrane

constitute the parenchyma, functional parts of the organ

often polarized (facing lumen or interacts with underlying blood vessels, structural cells

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9
Q

Epithelial tissue classifications

A

Classified by layers and shape

simple has on layer of cells, stratified have multiple, pseudostratified only appears to have multiple

cuboidal are cube-shaped, columnar are long and thin, squamous are flat

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10
Q

Connective tissue

A

supports the body and provides a framework for the epithelial cells to carry out their function

constitute the stroma, support structure
bone, cartilage, tendons, ligaments, adipose tissue, blood

most produce and secrete materials to form the extracellular matrix (collagen, elastin)

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11
Q

Archaea

A

historically considered extremophiles, have ability to use alternative sources of energy

hypothesized to share an origin with eukaryotes, associate their DNA with histones like us

divide by binary fission

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12
Q

Bacteria

A

can be obligately aerobic, aerotolerant, etc

have a cell wall and phospholipid cell membrane that together are known as the envelope

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13
Q

Bacteria classifications

A 
spherical = cocci
rod-shaped = bacilli
spiral-shaped = spirilli
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14
Q

Bacteria Gram negative vs positive

A

gram positive absorbs the violet stain, have a thick layer of peptidoglycan, contains lipoteichoic acid
gram negative absorbs the pink-red safranin counterstain, have a thin layer of peptidoglycan, have an additional outer membrane containing lipopolysaccharides (that triggers immune response)

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15
Q

Bacteria flagella structure

A

Flagella are composed of a filament, basal body, and hook

filament is hollow, helical structure composed of flagellin

basal body anchors the flagellum to the cytoplasmic membrane and serves as the motor

hook connects the filament and the basal body

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16
Q

Prokaryotes in general (DNA, cell membrane, ribosome)

A

have a single circular molecule of DNA concentrated in the nucleoid region

DNA acquired from external sources may be carrier on circular plasmids
plasmids carrier DNA not necessary for survival

Cell membrane is used for ETC and generation of ATP
contain a 30S + 50S = 70S ribosome

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17
Q

Binary fission

A

Binary fission takes less energy and proceeds more rapidly

circular chromosome attaches to cell wall and replicates while the cell continues to grow in size, eventually two exist and the cell divides along the midline

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18
Q

Plasmid use prokaryotes

A

Plasmids may carry virulence factors from external sources that increase pathogenicity

a subset of plasmids called episomes can integrate into the genome of the bacterium

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19
Q

Transformation, conjugation, and transduction

A

transformation is the integration of foreign genetic material taken from the vicinity (usually from lysed bacteria)

conjugation is sexual reproduction using a conjugation bridge made from sex pili to transfer genetic information between a donor male (+) and a female (-)
conjugation allows for rapid acquisition of antibiotic resistance or virulence factors

transduction is transfer of genetic material using a vector, usually a virus

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20
Q

Transposons

A

Transposons are genetic elements capable of inserting and removing themselves from the genome

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21
Q

Prokaryotic life cycle

A

Lag phase- adapting
exponential (log) phase- adapted
stationary phase- reduction of resources
death- out of resources

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22
Q

Viruses

A

genetic information may be circular or linear, composed of either DNA or RNA, have a protein coat known as a capsid

lack ribosomes and must use host cell

enveloped viruses are easier to kill

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23
Q

bacteriophages

A

bacteriophages are viruses that target bacteria, simply inject their genetic material inside

have a tail sheath (syringe) and tail fibers (for recognition)

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24
Q

positive sense vs negative sense RNA

A

single-stranded RNA from viruses can be positive sense (directly translate genome) or negative sense(serves as template for complementary strand which then serves as template for synthesis)
negative sense must carry an RNA replicase

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25
Q

retrovirus type of virus

A

retrovirus are enveloped, single stranded
carry reverse transcriptase
can only be removed by killing the cell

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26
Q

virus infection mechanism and limitations

A

viruses can only infect certain cells, must bind to specific receptors

enveloped viruses fuse with plasma membrane (HIV)

sometimes mistaken as useful molecule and brought into cytoplasm

viral genome must be returned to its original form before packaging

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27
Q

how viral progeny leave cell

A

progeny can either be released through the initiation of cell death or simple lysing of cell after being filled with virions, or leave by fusing with the plasma membrane (extrusion)

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28
Q

lytic cycle or lysogenic cycle

A

lytic cycle has little regard for survival of host cell (virulent)

lysogenic cycle integrates into host genome and is replicated as the bacterium reproduces
can be converted to lytic cycle by environment

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29
Q

prions

A

infections proteins, trigger misfolding of other proteins

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30
Q

viroids

A

very short circular ssRNA, typically infects plants and silence genes

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31
Q

Cell cycle stages

A

Four stages: G1, S, G2, M
first three are interphase, where cell spends most of its time

G0 phase implies no preparation for division

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32
Q

G1 stage

A

G1- Presynthetic gap

creates organelles and protein, increase size
passage into S stage is governed by restriction point, must contain proper complement of DNA

p53 controls this

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33
Q

S stage

A

S- Synthesis of DNA

replicates its genetic material, will have two identical chromatids although chromosome number has not changed

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34
Q

G2 stage

A

G2- Postsynthetic gap
checks that there is enough cytoplasm and organelles (adequate size), DNA replication proceeded correctly

p53 controls this

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35
Q

M stage

A

M- Mitosis

Prophase, metaphase, anaphase, and telophase

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36
Q

Cyclins and cylin-dependent kinases

A

Cyclins and cyclin-dependent kinases are responsible for cell cycle. Can create complex which phosphorylates transcription factors that promote transcription of genes required for next stage

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37
Q

Mitosis-Prophase

A

condensation of the chromatin into chromosomes
centriole pairs separate and move towards opposite poles, located at centrosome

centrosome-
responsible for correct division of DNA
MTOC at centrosomes form spindle fibers, asters

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38
Q

Mitosis-Metaphase

A

centriole pairs are now at opposite ends

chromosomes align at metaphase plate

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39
Q

Mitosis-Anaphase

A

centromeres split so that each chromatid has its own distinct centromere
sister chromatids separate and are pulled toward opposite poles

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40
Q

Mitosis-Telophase

A

reverse of prophase

spindle apparatus disappears
nuclear membrane reforms
nucleoli reappear, chromosomes uncoil

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41
Q

Mitosis-Cytokinesis

A

separation of cytoplasm and organelles

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42
Q

Meiosis 1 general concept and term

A

homologous chromosomes separated, generating haploid cells, known as reductional division

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43
Q

Meiosis 1 difference from mitosis - prophase

A

homologous chromosomes come together and intertwine in a process called synapsis
each synaptic pair is referred to as a tetrad
crossing over occurs if chromosomes break at point of contact (chiasma)

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44
Q

Meiosis 1 difference from mitosis - metaphase

A

tetrads align at plate, homologous chromosomes are held up with one spindle fiber (in meiosis there are two for each pair of sister chromatids)

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45
Q

Meiosis 1 difference from mitosis - anaphase

A

homologous pairs separate and are pulled to opposite poles

first law of segregation, either chromosome can end up in either daughter cell

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46
Q

Meiosis 1 difference from mitosis - telophase

A

each chromosome still consists of two sister chromatids, the cells are now haploid

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47
Q

Meiosis 2 general concept and term

A

similar to mitosis, separation of sister chromatids, equational division

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48
Q

X chromosome

A

X chromosome contains more genetic information

males only have one allowing for sex-linked disorders

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49
Q

Y chromosome

A

contains very little information

contains SRY (sex-determing region Y) which codes for the initiation of testis development. In absence all zygotes will be female

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50
Q

testicles

seminiferous tubulus and interstitial cells of Leydig

A

seminiferous tubules
sperm are produced, nourished by sertoli cells

interstitial cells of Leydig
testosterone is secreted

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51
Q

epididymis

A

sperm develop, flagella gain motility

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52
Q

seminal vesicles, prostate gland, and bulbourethral gland

A

create seminal fluid

seminal vesicles contribute fructose

prostate gland gives mild alkaline properties to protect against female reproductive acidity

bulbourethral (prostate) gland produces a cleaning and lubricating fluid

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53
Q

spermatogenesis order

A

Diploid Spermatogonia -> Diploid Primary spermatocytes -(meiotic division)-> Haploid secondary spermatocytes -> haploid spermatids -> mature spermatozoa

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54
Q

sperm anatomy

A

head (genetic material),
midpiece (mitochondria)
acrosome cap (penetrating ovum, made from Golgi Apparatus)

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55
Q

ovaries

A

produce estrogen and progesterone

located in pelvic cavity, consists of thousands of follicles

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56
Q

follicles

A

follicles are multilayered sacs that contain and nourish the eggs

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57
Q

oogenesis order and timing

A

By birth, all oogonia are considered primary oocytes, arrested in prophase 1.
One primary oocyte per month will complete meiosis I, producing a secondary oocyte and a polar body.
The secondary oocyte remains in metaphase II unless fertilization occurs.

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58
Q

zona pellucida

A

Oocytes are surrounded by zona pellucida

protects the oocyte and contains compounds for sperm cell binding

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59
Q

corona radiata

A

corona radiata surrounds the zona pellucida

Meiosis II is triggered when both layers are penetrated

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60
Q

hypothalamus start of puberty

A

At the start of puberty, hypothalamus releases GnRH which triggers the anterior pituitary gland to synthesize and release FSH and LH

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61
Q

FSH and LH general males

A

FSH stimulates Sertoli cells, sperm maturation

LH causes the interstitial cells of Leydig to produce testosterone
testosterone exerts negative feedback on hypothalamus, anterior pituitary

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62
Q

FSH and LH general females

A

Estrogens are secreted in response to FSH

Progesterone is secreted by the corpus luteum in response to LH

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63
Q

Menstrual cycle general definition and stages

A

The process of the endometrial lining growing and shedding in response to estrogen and progesterone levels
Follicular phase, ovulation, luteal phase, menstruation/pregnancy

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64
Q

Follicular phase

A

begins when the menstrual flow begins from previous cycle
GnRH increases due to decreased estrogen and progesterone, causes increased FSH and LH
these two hormones develop follicles, which begin to produce estrogen
in response to estrogen, gnRH, LH, and FSH concentrations level off.
in response to estrogen, regrowth of the endometrial lining occurs

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65
Q

Ovulation

A

in response to estrogen reaching a threshold, gnRh, LH, and FSH levels spike
the LH surge induces ovulation, the release of the ovum from the ovary into peritoneal cavity

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66
Q

Luteal Phase

A

after ovulation, the ruptured follicle forms the corpus luteum
the corpus luteum secretes progesterone
high levels of progesterone cause negative feedback on GnRH, FSH, and LH

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67
Q

Menstruation

A

if implantation does not occur, the corpus luteum loses its stimulation from LH, progesterone levels decline, and the uterine lining is sloughed off

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68
Q

Pregnancy (menstrual cycle)

A

if fertilization has occurred, the zygote develops into a blastocyst that implants in the uterine lining and secretes hCG (an analog of LH)

hCG maintains the corpus luteum, which secretes estrogen and progesterone during first trimester, keeping uterine lining in place

in second trimester hCG levels decline, the placenta can secrete enough progesterone and estrogen by itself

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69
Q

Menopause

A

ovaries become less sensitive to FSH and LH, resulting in ovarian atrophy. Menstruation stops. Blood levels of FSH and LH increase as negative feedback is removed

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70
Q

Fertilization steps

A

a secondary oocyte is ovulated on day 14, where it travels into the fallopian tube and can be fertilized up to 24 hrs after ovulation

first sperm to come into direct contact with the secondary oocyte creates the acrosomal apparatus

after penetration of sperm through cell membrane, the cortical reaction (release of calcium ions) occurs

as the zygote moves to the uterus for implantation, it undergoes rapid mitotic cell divisions. The first cleavage officially creates an embryo

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71
Q

Corticol reaction (fertilization)

A

release of calcium ions that depolarizes the cell membrane of the oocyte which prevents multiple fertilization and increases the metabolic rate of the zygote

Membrane is now called the fertilization membrane

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72
Q

Indeterminate cleavage vs determinate cleavage

A

Indeterminate cleavage results in cells that can still develop into complete organisms
determinate cleavage results in cells that are committed to differentiating

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73
Q

Blastulation of embryo

A

several divisions after the embryos first division, it becomes a solid mass of cells known as a morula

the morula forms the blastula

the blastula burrows into the endometrium

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74
Q

Blastulation- blastocoel

A

the blastula’s inner cavity is called a blastocoel

contains the trophoblast (surrounds the blastocoel and gives rise to chorion which becomes placenta, serves as an interface between the maternal blood supply and the embryo)

also contains the inner cell mass (protrudes into the blastocoel and gives rise to the organism itself)

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75
Q

Blastulation- development and connection of the placenta

A

trophoblasts form chorionic villi, which develop into placenta

the embryo is connected to the placenta by the umbilical cord
two arteries, one vein. vein is oxygenated

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76
Q

Blastulation- support of embryo

A

until the placenta is functional, the embryo is supported by yolk sac

The allantois is involved in early fluid exchange between the embryo and the yolk sac. Surrounded by the amnion membrane, which serves as a shock absorber. Chorion also forms an outer membrane around the amnion

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77
Q

Gastrulation definition

A

Once the cell is implanted it can begin the generation of three distinct cell layers

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78
Q

archenteron

A

the membrane invaginates into the blastocoel, forming the archenteron, which later becomes the gut. The opening, called the blastopore, becomes the anus in deuterostomes

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79
Q

Ectoderm

A

Ectoderm- “attracto derm”

epidermis, hair, nails, epithelia of nose, mouth, eye, nervous system

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80
Q

Mesoderm

A

Mesoderm- “means oderm”

musculoskeletal and circulatory system, excretory system, gonads, muscular and connective tissue layers, kidneys

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81
Q

Endoderm

A

Endoderm- “internal derm”

digestive and respiratory tracts, pancreas, thyroid, bladder, liver

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82
Q

Differentiation control

A

selective transcription controls differentiation

is mediated by chemical substances called inducers
responder cells must be competent to be induced

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83
Q

Neurulation

A

Once the three germ layers are formed, the notochord forms from the mesoderm

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84
Q

Formation of notochord

A

notochord induces ectoderm cells to slide inward, forming neural folds, which surround a neural groove and eventually fuse into a neural tube
neural crest cells at the tip of each fold form the peripheral nervous system

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85
Q

Teratogens

A

Teratogens are substances that interfere with development

Folic acid deficiency results in spina bifida

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86
Q

determination
specification
differentiation

order and description

A

Specification (cell is designated as a certain type) -> Determination (cell differentiation is designated) -> Differentiation

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87
Q

Potency and types of potent cells

A

Potency describes ability to differentiation

Totipotent can differentiate into any type
Pluripotent can differentiate into all but placenta
Multipotent can differentiate into all from a particular group

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88
Q

Autocrine signals
Paracrine signals
Juxtacrine signals
Endocrine signals

definitions

A

Autocrine signals - same cell
Paracrine signals - local area
Juxtacrine signals - no diffusion, directly stimulating adjacent cell
Endocrine signals - travel through blood

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89
Q

growth factors definition

A

peptides that promote differentiation

types of inducers

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90
Q

Reciprocal development definition

A

development of one induces development of the other

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91
Q

How does apoptosis occur?

A

the cell undergoes changes in morphology and divides into apoptotic blebs
apoptotic blebs become apoptotic bodies, which are digested by other cells

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92
Q

placental barrier and placenta in fetal circulation

A

Placental barrier serves for immunity, placenta serves nutrient, gas, and waste exchange functions

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93
Q

oxygenation in fetal circulation

A

Oxygenation occurs at placenta
Umbilical arteries carry blood away from fetus like all arteries
deoxygenated
Umbilical veins carry blood towards the fetus
oxygenated, from placenta

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94
Q

foramen ovale

A

connects the right atrium to the left atrium, bypassing right ventricle

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95
Q

ductus arteriosus

A

shunts leftover blood from the pulmonary artery to the aorta

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96
Q

ductus venosus

A

shunts blood returning from the placenta via the umbilical vein directly into the inferior vena cava, bypassing the liver

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97
Q

First trimester

A

heart begins to beat, cartilaginous skeleton begins to harden into bone, by 8 weeks most of organs have formed, the brain is fairly developed, and the embryo becomes known as the fetus

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98
Q

Second trimester

A

fetus undergoes tremendous growth, takes on a human appearance

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99
Q

Third trimester

A

rapid growth, antibodies are transferred to fetus at highest rate, eventually growth rate slows in ninth month

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100
Q

Birth

A

coordinated by prostaglandins and oxytocin

water breaking is the amniotic sac rupturing

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101
Q

myelin purpose and production

A

prevents signal loss or crossing of signals

produced by oligodendrocytes (CNS) or Schwann cells (PNS)

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102
Q

tracts (nervous system)

A

only one type of information

cell bodies of neurons in the same tract are grouped into nuclei

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103
Q

Glial cells- Astrocytes

A

nourish neurons and form the blood-brain barrier

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104
Q

Glial cells- ependymal cells

A

produce cerebrospinal fluid

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105
Q

Glial cells- microglia

A

phagocytic cells for the CNS

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106
Q

Glial cells- oligodendrocytes and Schwann cells

A

Oligodendrocytes (CNS) and Schwann cells (PNS) produce myelin

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107
Q

Action potential

A

Na+ influx open in response to reaching the threshold, causing depolarization
positive potential triggers Na+ channels to inactivate and K+ channels to open, causing repolarization
hyperpolarization occurs as K+ overshoots
Na+/K+ ATPase acts to restore resting potential and sodium potassium gradients

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108
Q

Neurotransmitters release

A

when action potential reaches the nerve terminal, Ca+ channels open, triggering fusion of the membrane-bound vesicles and exocytosis of the neurotransmitters

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109
Q

Neurotransmitters breakdown

A 
Three main mechanisms for breakdown
enzymatic reactions (ex: acetylcholinesterase)
reuptake carriers (ex: serotonin, dopamine, norepinephrine)
simple diffusion
110
Q

White matter

A

axons encased in myelin sheaths

located deep in the brain but shallow in the spinal cord

111
Q

Grey matter

A

unmyelinated cell bodies and dendrites

shallow in the brain but deep in the spinal cord

112
Q

Spinal cord order

A

Cervical, thoracic, lumbar, sacral (top to bottom)

113
Q

Somatic vs autonomic nervous system nerve setup

A

in autonomic system, peripheral component contains two neurons
in somatic nervous system motor neuron goes directly from spinal cord to muscle

114
Q

Autonomic nervous system branches and general mechanism

A

ANS consists of sympathetic and parasympathetic

Parasympathetic uses acetylcholine, vagus nerve is responsible for much of it

Sympathetic nervous system uses acetylcholine in preganglionic neurons, norepinephrine in postganglionic neurons

115
Q

Reflexes, two types

A

bypassing the brain and use interneurons

monosynaptic
single synapse between sensory and motor neuron
knee-jerk reflex

polysynaptic
at least one interneuron between sensory and motor neurons
withdrawal reflex

116
Q

Peptide hormones

A

made from AAs, derived from larger precursor polypeptides
charged, so cannot pass through plasma membrane and must use secondary messenger system
generally water soluble, do not require carriers

117
Q

Steroid hormones

A

derived from cholesterol, so nonpolar
can easily cross cell membrane
not water soluble, must use carriers

118
Q

which hormones are peptide which are steroid

A

Peptide- FSH, LH, ACTH, TSH, Prolactin, Endorphins, GH, ADH, Oxytocin, Calcitonin, PTH, Glucagon, Insulin, Somatostatin, Melatonin, Erythropoietin, ANP, Thymosin

Steroid- cortisol/cortisone, aldosterone, testosterone, estrogen, progesterone
-(end in one or ol or en)

119
Q

tyrosine derived hormones; types and binding location

A

epinephrine, norepinephrine
bind to G protein-coupled receptors

triiodothyronine, thyroxine
bind intracellularly

120
Q

Hypothalamus

A

bridge between nervous and endocrine systems
sleep-wake cycles, blood osmolarity, appetite and satiety
regulated by negative feedback
interacts with anterior pituitary through hypophyseal portal system
interacts with posterior pituitary directly

121
Q

hypophyseal portal system hormone relationships (hypothalamus -> anterior pituitary)

hints:
GnRH
GHRH
TRH
CRF
A

Gonadotropin-releasing hormone (GnRH) ->
Follicle-stimulating hormone (FSH), Luteinizing hormone (LH)

Growth hormone-releasing hormone (GHRH) -> 
Growth hormone (GH)

Thyroid-releasing hormone (TRH) ->
Thyroid-stimulating hormone (TSH)

Corticotropin-releasing factor (CRF) -> 
Adrenocorticotropic hormone (ACTH)
122
Q

Anterior pituitary tropic hormones

A

Follicle-stimulating hormone and Luteinizing hormones act on the gonads
Adrenocorticotropic hormone acts on the adrenal cortex
Thyroid stimulating hormone acts on the thyroid

123
Q

Anterior pituitary direct hormones

A

Prolactin stimulates milk production during pregnancy in response to elevated estrogen and progesterone
dopamine from the hypothalamus decreases its secretion

Growth hormone promotes the growth of bone and muscle
-prevents glucose uptake in certain tissue and stimulates the breakdown of fatty acids

Endorphins decrease pain

124
Q

Posterior pituitary hormones

A

Antidiuretic hormone -response to low blood volume, works on the the collecting duct to increase water reabsorption from filtrate

Oxytocin- bonding, coordinated contraction of smooth muscle (breasts when lactating, uterus)
unique for its positive feedback look

125
Q

Thyroid hormones

A

controlled by thyroid-stimulating hormone

T3 and T4

  • mediate basal metabolic rate, higher amounts lead to increased cellular respiration
  • high levels decrease the amount of TSH (anterior pituitary) and TRH (hypothalamus)
  • made from iodine

calcitonin

  • produced from C-cells (parafollicular cells)
  • decreases plasma calcium levels
126
Q

Calcitonin mechanism (kidneys, gut, bone)

A

increasing calcium excretion from the kidneys
decreasing calcium absorption from the gut
increasing storage of calcium in the bone

127
Q

Parathyroid glands hormones

A

four small glands on posterior surface of thyroid

Parathyroid hormone (PTH)

  • antagonistic to calcitonin, increases plasma calcium levels
  • activates vitamin D, required for the absorption of calcium and phosphate in the gut
128
Q

Adrenal CORTEX hormones

A

Corticosteroids: Glucocorticoids and Mineralocorticoids, cortical sex hormones

Glucocorticoids increase plasma glucose levels in response to stress
-cortisol and cortisone

Mineralocorticoids regulate salt and water homeostasis, particularly on kidneys
-aldosterone increases sodium reabsorption in the distal convoluted tubule and collecting duct, water follows

Cortical sex hormones

  • Androgens and estrogens
  • females are much more sensitive, in males testicles make most androgens
129
Q

Aldosterone release pathway

A

decreased blood pressure -> juxtaglomerular cells of the kidney secrete renin -> renin cleaves angiotensinogen to angiotensin I -> converted to angiotensin II by angiotensinconverting enzyme (ACE) -> angiotensin II stimulates release of aldosterone

130
Q

Glucocorticoids release pathway

A

under control of adrenocorticotropic hormone (ACTH) from anterior pituitary in response to corticotropin-releasing factor (CRF) from the hypothalamus

131
Q

Adrenal MEDULLA hormones

A

Catecholamines
sympathetic hormones epinephrine and norepinephrine

glycogenolysis in liver and muscle
increase basal metabolic rate
increase heart rate, dilate the bronchi, shunt blood flow to sympathetic systems, vasodilation and vasoconstriction to appropriate system

132
Q

Pancreas (endocrine)

A

islets of langerhans contain alpha, beta, and delta cells

alpha secretes glucagon
-times of fasting, triggers glycogenolysis, gluconeogenesis, -degradation of protein and fat

beta secretes insulin

  • antagonistic to glucagon, store glucose as glycogen
  • in excess causes hypoglycemia, not enough is diabetes

delta secretes somatostatin

  • inhibitor of both insulin and glucagon
  • in response to high blood glucose and AA concentrations
  • produced by hypothalamus
133
Q

Types of diabetes

A

type I is autoimmune destruction of beta cells
type II is resistance to insulin

in both excess water excretion due to the water being more osmotically active

134
Q

Gonads endocrine function

A

testes secreted testosterone in response to LH and FSH

ovaries secrete estrogen and progesterone in response to LH and FSH

135
Q

Pineal gland endocrine function

A

melatonin

circadian rhythm

136
Q

kidneys endocrine function

A

kidneys produce erythropoietin

stimulates bone marrow to increase production of RBCs

137
Q

heart endocrine function

A

heart release atrial natriuretic peptide
help regulates salt and water balance, excretion of sodium increases urine volume
antagonistic to aldosterone

138
Q

thymus endocrine function

A

thymus releases thymosin

important for T-cell development

139
Q

Lungs

A

two mainstem bronchi separate air flow
membranes known as pleurae surround each lung, surface adjacent to lung is known as the visceral pleura and the outer part is the parietal pleura

140
Q

Inhalation and exhalation mechanisms

A

inhalation- external intercostal muscles and diaphragm expand the thoracic cavity to decrease pressure in lungs
exhalation- passive process unless using the internal intercostal muscles during active tasks

141
Q 
Lung volumes
TLC
RV
VC
TV
ERV
IRV
A

TLC- total lung capacity, maximum volume in lungs
RV- residual volume, volume remaining after a full exhale
VC- vital capacity, total lung capacity minus residual volume
TV- tidal volume, normal breaths worth of air
ERV- additional air that can be exhaled after a normal exhalation
IRV- additional air that can be inhaled after a normal inhalation

142
Q

breathing regulation

A

primarily regulated by the ventilation center in the medulla oblongata

  • contains chemoreceptors that respond to carbon dioxide concentration
  • more CO2 = more respiration
143
Q

Gas exchange lungs to circulatory system

A

pulmonary arteries originate from right ventricle, go to lungs, deoxygenated
pulmonary veins returns to the left atrium of the heart, oxygenated

144
Q

immune function respiratory system

A

nasal cavity has small hairs, lysozyme (attacks peptidoglycan walls of gram positive bacteria)

cilia on internal airways propel mucus up the respiratory tract
-mucociliary escalator

lungs contain macrophages and mast cells (have preformed antibodies)

145
Q

Bicarbonate buffer system and regulation of blood pH

A

CO2 (g) + H2O (l) H2CO3 (aq) H+ (aq) + HCO3- (aq)
more CO2 = more H+

blood ph is normally between 7.35 and 7.45

higher respiratory rate = more CO2 loss
kidneys work slower to modulate secretion and reabsorption of acid and base

146
Q

Heart anatomy

A

Right side accepts deoxygenated blood and moves it to the lungs by way of pulmonary arteries (pulmonary circulation)
Left side accepts oxygenated blood and forces out through the body (systemic circulation)

147
Q

Electrical conduction in heart

A

Sinoatrial node (SA) -> atrioventricular node (AV) -> bundle of His -> Purkinje fibers

As the depolarization wave spreads from SA node, it causes the two atria to contract simultaneously

atrial systole (contraction) results in an increase in atrial pressure that forces more blood into ventricles 
-called the atrial kick

once the signal reaches the AV node, it is delayed to allow the ventricles to fill, then travels down bundle of His

Purkinje fibers distribute the electrical signal through the ventricular muscle
-muscle cells are connected by intercalated discs which contain many gap junctions

148
Q

Systole/Diastole

A

During systole, ventricular contraction and closure of the AV valves occurs and blood is pumped out of ventricles
-higher pressure due to contraction

During diastole, the ventricles are relaxed, the semilunar valves are closed, and blood from the atria fills the ventricles
-lower pressure due to relaxation

149
Q

Cardiac output and calculation

A

Cardiac output is the total blood volume pumped by a ventricle in a minute

CO = HR x SV (volume per stroke)

150
Q

Veins, capillaries, arteries similarities and differences

A

Both veins and arteries have endothelial cells and smooth muscle

arteries have much more smooth muscle and are elastic, maintaining high pressure

capillaries are a single endothelial cell layer thick to allow for diffusion

veins are thinner than arteries, they are able to stretch to accommodate larger volume of blood (75% of blood is in the veins)

151
Q

how veins deal with low pressure

A

larger veins contain valves due to low pressure
failure leads to varicose veins, where blood pools

most veins are surrounded by skeletal muscle which forces blood against gravity

152
Q

Circulation pathway

A

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 -> vena cava -> right atrium

153
Q

hepatic portal system

A

blood leaving capillary beds in the walls of the gut passes through the hepatic portal vein before reaching the capillary beds in the liver

154
Q

hypophyseal portal system

A

blood leaving capillary beds in the hypothalamus travels to a capillary bed in the anterior pituitary

155
Q

renal portal system

A

blood leaving the glomerulus travels through an efferent arteriole before surrounding the nephron in a capillary network called the vasa recta

156
Q

Blood composition

A

plasma + erythrocytes, leukocytes, and platelets

red blood cells rely entirely on glycolysis for ATP

hematocrit is a measure of how much of the blood sample consists of red blood cells

157
Q

Leukocytes

A

white blood cells comprising less than 1 percent of blood

158
Q

Granular leukocytes vs Agranulocytes

A

Granular leukocytes

  • contain cytoplasmic granules which contain a variety of compounds that are toxic to invading microbes
  • neutrophils, eosinophils, basophils
  • involved in inflammatory reactions, allergies, pus formation, and destruction of bacteria and parasites

Agranulocytes

lymphocytes

  • specific immune response
  • B-cells mature in bone marrow, responsible for antibody generation
  • T-cells mature in thymus, responsible for killing virally infected cells and activating other immune cells

monocytes
-become macrophages

Both come from hematopoietic stem cells

159
Q

Thrombocytes

A

platelets

cell fragments released from cells in the bone marrow known as megakaryocytes
assist in blood clotting

160
Q

erythroblastosis fetalis

A

if a mother has an Rh+ child, any subsequent pregnancy will present a problem because the mother has anti Rh+ antibodies

in the first pregnancy the mother will not produce antibodies until the child is born

161
Q

Blood pressure, resistance calculation

A

ratio of systolic (contraction) to diastolic (relaxation)

resistance in blood vessels can be calculated same as any pipe
Resistance = 8L(viscosity)/ (pi)r^4

regulated using baroreceptors and chemoreceptors

162
Q

Bohr effect

A

increased CO2 results in right shift in bicarbonate buffer equation, resulting in H+ increase, these protons bind to hemoglobin and reduce affinity for oxygen (release their oxygen load)

163
Q

what causes left shift of hemoglobin binding curve

A

Fetal hemoglobin, carbon monoxide, INCREASED pH

less oxygen unloading

164
Q

what causes right shift of hemoglobin binding curve

A

Carbon dioxide, 2,3-BPG, Temperature, exercise

more oxygen unloading

165
Q

Fluid balance control mechanisms (pressure definitions); at capillaries

A

Fluid balance is controlled by the opposing hydrostatic and osmotic pressure

hydrostatic pressure is the pressure of the blood against the vessel walls

osmotic pressure is the sucking of solutes as they attempt to draw water into the bloodstream
mostly due to plasma proteins, thus called oncotic pressure

at arteriole end of capillary bed, hydrostatic pressure is much larger and water leaves; at venule end of capillary bed, hydrostatic pressure is lower and water enters back into circulation

166
Q

Coagulation

A

when the endothelium is damaged, it exposes tissue factor. platelets sense this and release their contents and aggregate. Coagulation factors sense tissue factor and issue an activation cascade

activation cascade: prothrombin -> thrombin by thromboplastin. fibrinogen -> fibrin by thrombin

clot is broken down by plasmin, which is generated from plasminogen

167
Q

Innate immunity definition

A

Innate immunity is always active against infection but lacks the ability to target specific invaders, also known as non-specific immunity

168
Q

Noncellular defenses of innate immunity

A
  • antibacterial enzymes called defensins found on the skin, sweat
  • mucous membranes produce lysozyme

GI Tract

Complement system

Interferons

169
Q

role of GI tract innate immunity

A

GI Tract

  • acid
  • bacteria in gut compete potential invaders
170
Q

role of complement system innate immunity

A

complement system

  • number of proteins in the blood that act as nonspecific defense, activated through a classical pathway (binding of antibody to pathogen) or alternative pathway (does not require antibodies)
  • punches holes in cell walls of bacteria
171
Q

role of interferons innate immunity

A

interferons

  • proteins that prevent viral replication and dispersion
  • cause nearby cells to decrease production of both viral and cellular proteins, also decreases the permeability these cells
  • upregulate MHC I and class II molecules
172
Q

Cellular defenses of innate immunity

A

Macrophages

Natural Killer cells

Granulocytes

173
Q

role of macrophages innate immunity

A

a type of agranulocyte

activate when a bacterial invader enters a tissue

first phagocytizes the invader, then digests the invader using enzymes, then presents to other cells using MHC

release cytokines, which stimulate inflammation and recruit additional immune cells

Macrophages and dendritic cells also have pattern recognition receptors such as toll-like receptors which recognize the category of the invader and allows for production of appropriate cytokines

174
Q

role of MHC I and II, types of antigen presenting cells

A

MHC binds to an antigen and carries it to the cell surface, where it can be recognized by the adaptive immune system

MHC I is present in all nucleated cells of the self
endogenous pathway

MHC II is displayed by antigen-presenting cells like macrophages in response to invaders
exogenous pathway

antigen-presenting cells include macrophages, dendritic cells, some B-cells, certain activated epithelial cells

175
Q

role of natural killer cells innate immunity

A

detect downregulation of MHC and induce apoptosis in these virally infected cells

therefore help with cancer

176
Q

role of granulocytes innate immunity

A

neutrophils are phagocytic, follow bacteria using chemotaxis, also detect bacteria once they have been opsonized (marked for death with antibody from B-cells)

eosinophils are primarily involved in allergic reactions and parasitic infections, release histamine (inflammatory response)
inflammation is particularly useful against extracellular pathogens

basophils are involved in allergic responses, least populous
mast cells are closely related but have smaller granules

177
Q

adaptive immunity definition

A

Adaptive or specific immunity is slower but can target specific pathogens and remember them

split into humoral immunity (B-cells) and cell-mediated/cytotoxic immunity (T-cells)

178
Q

Humoral immunity

A

May take up to a week to become fully effective
Antibodies are produced by B cells

Naive B cells wait in the lymph for their particular antigen. Upon exposure proliferate into plasma and memory B-cells

179
Q

Possible antibody responses

A

Opsonization- attract other leukocytes to phagocytize

Agglutination- antibodies cause pathogens to clump together

Neutralization- block the ability of a pathogen to invade tissue

180
Q

general structure of antibody, matching mechanism

A

disulfide linkages and noncovalent interactions hold the heavy and light chains together
B-cells undergo hypermutation at the antigen-binding region, trying to find the best match for the antigen

181
Q

clonal selection in antibodies

A

only those that can bind the antigen with high affinity survive and replicated

182
Q

Secondary response of humoral immunity

A

Upon exposure B-cells proliferate into plasma and memory B-cells
plasma cells produce large amounts of antibodies

memory B-cells wait in the lymph node for reexposure to the same antigen

primary response takes a week or so
secondary response is more rapid, from the memory B-cells

183
Q

Cell mediated/cytotoxic immunity cell types roles

helper, cytotoxic, regulatory, memory

A

Helper T-cells

  • CD4+, secrete lymphokines that recruit other immune cells and increase their activity
  • Th1 release interferon gamma which activates macrophages
  • Th2 activate B-cells

-MHC II cells (bacterial, fungal, parasitic infections)

Cytotoxic (killer) T-cells
CD8+, directly kill virally infected cells
MHC I cells (viruses, intracellular infection)

Suppressor (regulatory) T-cells
CD4+, Foxp3, tone down the immune response, turn off self-reactive lymphocytes

Memory T-cells
wait until next exposure to same antigen

184
Q

T cells (clonal) selection

A

T-cells undergo both positive and negative selection in the thymus

positive selection- allows only the cells that can respond to the presentation of antigen on MHC
negative selection- causes apoptosis in cells that react to the self

maturation is facilitated by thymosin from the thymus

185
Q

Production immune system

bone marrow, spleen, thymus, lymph nodes, digestive system

A

Bone marrow produces all of the leukocytes

Spleen stores and activates B-cells

T-cells mature in the thymus

lymph nodes provide a place for immune cells to communicate and mount an attack, B-cells can be activated

Digestive system has gut-associated lymphoid tissue (GALT)
-tonsils, adenoids, peyer’s patches in the small intestine, lymphoid aggregates in the appendix

186
Q

Self and autoimmunity

A

Self-antigens signal to immune cells that the body is foreign and should not be attacked. Autoimmunity occurs when these fail

187
Q

Active vs passive immunity

A

Active immunity occurs when the immune system is stimulated to produce antibodies against a specific pathogen

Passive immunity results from the transfer of antibodies to an individual

188
Q

Lymphatic system

A

B-cells proliferate and develop within the lymphatic system in collections called germinal centers

Vessels carry lymph and join to form a thoracic duct in the posterior chest, which delivers the fluid into the left subclavian vein near the heart

Lymph nodes provide a space for the cells of the immune system to be exposed to possible pathogens

transports fats from the digestive system into the bloodstream using lacteals (small lymphatic vessels)

189
Q

Digestive system pathway

A

Oral cavity-> Pharynx -> Esophagus -> Stomach -> Small intestine -> Large intestine -> rectum

190
Q

Enteric nervous system

A

Enteric Nervous system is a collection of neurons that trigger peristalsis (rhythmic contractions)

191
Q

ADH, Aldosterone, glycogen, gherkin, leptin, cholecystokinin role in drive

A

ADH and aldosterone trigger the sensation of thirst, Glucagon and ghrelin stimulate feelings of hunger. Leptin and cholecystokinin stimulate satiety

192
Q

Oral cavity digestion

A

Chemical digestion begins with enzymes from salivary glands

like all digestive tract glands, innervated by the parasympathetic NS
salivary amylase, lipase

193
Q

Parts of pharynx

A

Nasopharynx (behind nasal cavity)
Oropharynx (back of the mouth)
Laryngopharynx (above the vocal cords)

194
Q

Stomach- divisions and associated glands

A

can be divided into four main anatomical divisions
fundus and body (gastric glands) (top)

antrum and pylorus (pyloric glands) (bottom)

195
Q

gastric glands (mucous, chief, parietal)

A

respond to signals from the vagus nerve

mucous cells
-produce the bicarbonate-rich mucus that protects the muscular wall from the harshly acidic environment

chief cells
-secrete pepsinogen, activated by acidity

parietal cells
-secrete HCl (H+), intrinsic factor (proper vit B12 absorption)
chief and parietal cells together produce gastric juice

196
Q

pyloric glands

A

contain G-cells, secrete gastrin

-gastrin induces the parietal cells to secrete more HCl and signals the stomach to contract

197
Q

Duodenum

A

first part of small intestine, responsible for the majority of chemical digestion
food enters through the pyloric sphincter
brush-border enzymes break down dimers and trimers of biomolecules into absorbable monomers

198
Q

Duodenum secretions

A

disaccharidases, which digest disaccharides

Enteropeptidase activates trypsinogen to trypsin

Secretin causes pancreatic enzymes to be released into the duodenum, reduces HCl secretion from parietal cells

enterogastrone, slows motility through digestive tract

Cholecystokinin stimulates the release of bile and pancreatic juices and promotes satiety

199
Q

Bile salts

A

bile salts are derived from cholesterol, facilitate the chemical digestion of lipids

  • have hydrophobic and hydrophilic regions, serve as bridge between aqueous and lipid environments
  • like soap, emulsify fats and cholesterol into micelles
200
Q

Pancreas functions digestive system

A

accessory organ with exocrine and endocrine functions

endocrine
insulin, glucagon, somatostatin (all for blood sugar)

exocrine
bulk of the pancreas is made of acinar cells that produce pancreatic juices

amylase, peptidases, lipases
-transferred to the duodenum via a duct system

enteropeptidase is the master switch for other zymogens

201
Q

Liver

A

bile production

synthesizes certain proteins necessary for proper body function
-albumin (plasma oncotic pressure), clotting factors

receives all blood draining from the abdominal portion of the digestive tract through the hepatic portal vein

this blood is processed by the liver before draining into the inferior vena cava

  • includes taking up excess sugar to create glycogen or storing fats as triacylglycerols, or the reverse of those processes
  • detoxifies endogenous and exogenous compounds
202
Q

bile pathway and bilirubin

A

bile ducts connect the liver with both the gallbladder and the small intestine

bile produced in the liver travels down these bile ducts where it may be stored in the gallbladder or secreted into the duodenum

major pigment of bile is bilirubin, a byproduct of the breakdown of hemoglobin

203
Q

Gallbladder

A

located beneath the liver, stores and concentrates bile
upon release of CCK, contracts and pushes bile out into the biliary tree

common site of cholesterol or bilirubin stone formation

204
Q

Jejunum and Ileum (digested/absorbed compounds and mechanism)

A

while the duodenum is primarily responsible for digestion, the jejunum and ileum are involved in the absorption of nutrients

simple sugars are absorbed by secondary active transport and facilitated diffusion into the epithelial cells lining the small intestine

blood passing by the epithelial cells creates a concentration gradient allowing the simple carbohydrates and amino acids to diffuse into the capillaries
-short chain fatty acids follow the same process

triglycerides and esterified cholesterol molecules are packaged into chylomicrons, and enter the lymphatic circulation through lacteals (small vessels that form the beginning of the lymphatic system)
-these lacteals converge and enter the venous circulation at the thoracic duct

Vitamins are absorbed by the small intestine

  • fat soluble vitamins (ADEK) dissolve directly into chylomicrons
  • water soluble vitamins are taken up across the endothelial cells of the small intestine, passing directly into the plasma

Water is absorbed by the small intestine

  • the fluid of the chyme must be reabsorbed through osmosis
  • water passes transcellularly (across cells) and paracellulary (between cells) to reach the blood
205
Q

Large intestine

A

primarily involved in water absorption

Cecum

  • an outpocketing that accepts fluid exiting the small intestine through the ileocecal valve
  • where the appendix attaches

Colon

  • ascending, transverse, descending, sigmoid
  • mainly functions to absorb water and salts
  • concentrates the remaining material to form feces

Rectum

  • storage site for feces
  • many bacteria (produce vitamin K)
206
Q

kidneys anatomy

cortex, medulla, renal hilum

A

cortex (outer) and medulla (inner)

renal hilum is a deep slit in the center of its medial surface

renal artery, renal vein, and renal ureter enter and exit through hilum

207
Q

Kidney portal system

A

renal artery branches out, passes through the medulla, and enters the cortex as afferent arterioles

  • glomeruli are derived from these afferent arterioles
  • -Bowman’s capsule surrounds the glomerulus, and leads to a long tubule

after passing through a glomerulus, the efferent arterioles form a second capillary bed
-known as the vasa recta, surrounds the loop of Henle

208
Q

Bladder anatomy

A

has a muscular lining known as the detrusor muscle
has an internal and external urethral sphincter
-micturition reflex causes internal to relax

209
Q

filtration by kidney

A

20% of the blood that passes through the glomerulus enters Bowman’s space. This blood is now known as filtrate. This fluid movement is government by starling forces

  • Starling forces are the pressure differentials between hydrostatic and oncotic pressure. The hydrostatic pressure in the glomerulus is higher than Bowman’s space, so the fluid moves into the nephron
  • Pathogens can cause derangements of this flow
  • Filtrate is similar to blood but without cells or proteins
210
Q

secretion by kidney

A

the nephrons can secrete (take out of circulation) salts, acids, bases, and urea directly into the tubule through either active or passive transport
-the quantity and identity of secreted substances depends on the needs of the body

211
Q

reabsorption by kidney

A

some compounds that are filtered or secreted may be taken back up via reabsorption

  • glucose, AA, vitamins are always reabsorbed
  • antidiuretic hormone and aldosterone can alter the quantity of water reabsorbed to maintain blood pressure
212
Q

nephron summarized function and anatomy

A

the kidney keeps what the body needs and lose what it doesn’t, and concentrates the urine to conserve water

proximal convoluted tubule, loop of Henley, distal convoluted tubule, collecting duct

213
Q

Proximal convoluted tubule

A

in this region, amino acids, glucose, water-soluble vitamins, and the majority of salts are reabsorbed along with water

secretion of waste products, including hydrogen ions, potassium ions, ammonia, and urea also occurs here

214
Q

loop of henle (descending)

A

descending limb is permeable only to water, increasing concentration with more depth into the medulla favors the outflow of water, which is reabsorbed by the vasa recta

215
Q

countercurrent multiplier system

A

together the vasa recta and nephron create a countercurrent multiplier system

opposite flows, the filtrate is constantly being exposed to hypertonic blood

maximum reabsorption of water

216
Q

loop of henle (ascending)

A

the ascending limb is permeable to salts and is impermeable to water, therefore maximizes salt reabsorption by taking advantage of of decreasing medullary osmolarity (opposite of descending limb)

diluting segment can produce urine that is more dilute than blood
-important during overhydration

217
Q

distal convoluted tubule

A

responds to aldosterone, which promotes sodium reabsorption; water follows

site of waste product secretion like the proximal convoluted tubule

218
Q

collecting duct

A

responsive to both aldosterone and ADH

almost always reabsorbs water, to varying degrees

anything that is not reabsorbed from the tubule by the end of the collecting duct will be excreted

219
Q

blood pressure regulation role of excretory system

A

Aldosterone is a steroid hormone that is secreted by the adrenal cortex in response to decreased blood pressure
in response to renin, ACE; as discussed earlier
distal convoluted tubule and collecting duct to reabsorb sodium

Antidiuretic hormone (ADH) is a peptide hormone synthesized by the hypothalamus and released by the posterior pituitary
directly alters the permeability of the collecting duct
220
Q

osmoregulation role of excretory system

A

kidneys control by modulating the reabsorption of water and by filtering and secreting dissolved particles

221
Q

acid-base balance role of excretory system

A

kidneys are able to selectively increase or decrease the secretion or reabsorption of hydrogen ions and bicarbonate

slower than respiratory response but highly effective

222
Q

epidermis layers, shallowest to deepest

A

(Come Lets Get Sun Burned)

stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale
223
Q

stratum corneum

A

contains several dozen layers of flattened keratinocytes, forming a barrier that prevents invasions by pathogens and that helps to prevent loss of fluids and salt

224
Q

stratum lucidum

A

only present in thick, hairless skin; nearly transparent

sole of the foot or the palms

225
Q

stratum granulosum

A

the keratinocytes die and lose their nuclei

226
Q

stratum spinosum

A

where keratinocytes become connected to each other, also the site of Langerhans cells
-These are the macrophages, capable of presenting antigens to T-cells

227
Q

stratum basale

A

contains stem cells and is responsible for proliferation of keratinocytes that produce keratin
melanocytes produce melanin here, which is transferred to the keratinocytes
-skin color is caused by varying levels of activity of the melanocytes

228
Q

dermis layers, shallowest to deepest and purpose

A

papillary layer
loose connective tissue

reticular layer
sweat glands, blood vessels, hair follicles

most sensory receptors are also located here

229
Q

Merkel cells
Meissner’s corpuscles
Ruffini endings
Pacinian corpuscles

A 
Merkel cells (deep pressure and texture)
Meissner’s corpuscles (light touch)
Ruffini endings (stretch)
Pacinian corpuscles (deep pressure and vibration)
230
Q

hypodermis

A

layer of connective tissue that connects the skin to the rest of the body
contains insulating fat and fibrous tissue

231
Q

Thermoregulation role of skin

A

sweating controlled by the autonomic nervous system
arrector pili muscles contract, causing piloerection
brown fat in infants has a much less efficient electron transport chain, causing more heat loss

232
Q

Skeletal muscle

A

voluntary movement, striated due to sarcomeres, multinucleated

consists of red fibers and white fibers

233
Q

Red fibers and white fibers

A

red fibers

  • slow twitch
  • high myoglobin and mitochondria to carry out oxidative phosphorylation

white fibers

  • fast twitch
  • low myoglobin and mitochondria
234
Q

Smooth muscle unique characteristics

A

uninucleated

contain actin and myosin, but the fibers are not as well-organized so striations cannot be seen

can sustain contractions
-tonus

can contract without nervous system input in myogenic activity
-in response to stretch or other stimuli

235
Q

Cardiac muscle

A

uninucleated
appears striated
cardiac muscle cells are connected by intercalated discs, which contain many gap junctions

236
Q

Sarcomere definition and makeup

A

basic contractile unit of skeletal muscle
made of thick and thin filaments
-thick are made of myosin
-thin filaments are made of actin, troponin and tropomyosin
-titin anchors the actin and myosin filaments together

237
Q

Myofibrils

A

Sarcomeres are attached end-to-end to form myofibrils

myofibrils are covered with sarcoplasmic reticulum that contains a high concentration of Ca2+ ions

238
Q

Myocyte, sarcolemma

A

a myocyte is made from many myofibrils arranged in parallel, also called muscle fiber

the cell membrane of a myocyte is known are the sarcolemma
-capable of propagating an action potential and can distribute the action potential to all sarcomeres in a muscle using a system of transverse tubules (T-tubules) orientated perpendicularly to the myofibrils

239
Q

Regions of a sarcomere (Z,M,I,H,A)

A

Z-line defines the boundaries of each sarcomere

M-line runs down the center of the sarcomere

I-band is only thin filaments

H-zone is only thick filaments

A-band is entire thick filament, including part of thin filament

240
Q

muscle contraction pathway

A

contraction starts at the neuromuscular junction, where the nervous system communicates with muscles via motor neurons

the signal travels down until it reaches the nerve terminal, where acetylcholine is released into the synapse

acetylcholine binds to receptors on the sarcolemma, causing depolarizations

depolarization triggers an action potential, which spreads down the sarcolemma to the T-tubules

The action potential travels down the t-tubules into the muscle tissues to the sarcoplasmic reticulum

Ca2+ is released from the sarcoplasmic reticulum

The calcium ions bind to a regulatory subunit in troponin, triggering a change in the conformation of tropomyosin, to which troponin is bound

This exposes the myosin-binding site on the actin filament
the free globular heads of the myosin form an actin-myosin bridge

myosin carrying hydrolyzed ATP is able to bind with the myosin-binding site

The release of the inorganic phosphate and ADP in rapid succession provides the energy for the power stroke and results in sliding of the actin filament over the myosin filament

ATP binds to the myosin head, releasing it from actin

This ATP is hydrolyzed to ADP and P which recocks the myosin head so that it is in position to initiate another cross-bridge cycle

acetylcholine is degraded in the synapse by acetylcholinesterase
-allows the sarcolemma to repolarize

241
Q

Simple twitch

A

all-or-nothing response of a single muscle fiber to a brief stimulus

242
Q

Tetanus

A

Tetanus is the result of too frequent summations that the muscle is unable to relax at all

243
Q

Creatine phosphate

A

Creatine phosphate is created by transferring a phosphate group from ATP to creatine during times of rest
ATP + creatine creatine phosphate + ADP

244
Q

Oxygen debt and muscle fatigue of skeletal muscle

A

Fast-twitch muscle fibers have fewer mitochondria and rely on glycolysis and fermentation to make ATP under most circumstances

High concentrations of oxygen are required for muscle cells, especially slow-twitch (red)
-eventually even red muscle fibers must switch to anaerobic metabolism and produce lactic acid, at which point the muscle begins to fatigue

245
Q

Skeletal system axial and appendicular

A

Axial skeleton consists of the skull, vertebral column, ribcage, and hyoid bone (in anterior neck, used for swallowing)

Appendicular skeleton consists of the bones of the limbs, pectoral girdle, and pelvis

246
Q

Compact bone

A

makes up the diaphysis

strength comes from bony matrix which contains hydroxyapatite (calcium, phosphate) crystals

Composed of osteons/haversian systems

247
Q

Osteons

A

cylindrical structures that contain concentric circles of bony matrix called lamellae surrounding a central microscopic channel, which contains blood vessels, nerve fibers, and lymph vessels

longitudinal channels are known as Haversian canals
transverse channels are known as Volkmann’s canals

between the lamellar rings are lacunae, which house mature bone cells known as osteocytes and are interconnected by canaliculi that allow for nutrient and waste exchange

248
Q

peristeum

A

a fibrous sheath that surrounds the long bone to protect it as well as serve as a site for muscle attachment

249
Q

Spongy/Cancellous bone

A

found at the core of vertebral bones and at the epiphysis

composed of trabeculae instead of osteons, which contain red bone marrow

250
Q

Diaphysis, Metaphyses, epiphyses locations

A

Diaphyses (length) swells at the end to form metaphases, the epiphyses are on both ends

251
Q

Bone remodeling

A

Osteoblasts build bone
-Calcitonin

Osteoclasts resorb bone

  • polynucleated resident macrophages of bone
  • Parathyroid hormone
  • Vitamin D
  • -encourages the growth of new, stronger bone
252
Q

Cartilage

A

consists of a firm but elastic matrix called chondrin that is secreted by cells called chondrocytes
avascular and not innervated
most are the bones in the body are produced by endochondral ossification from cartilage

253
Q

Immovable joints

A

bones that are fused together to form sutures

-those of the skull

254
Q

Movable joints

A

strengthened by ligaments, connect bones to one another

consist of a synovial capsule, which encloses the joint cavity

  • a layer of soft tissue called the synovium secretes synovial fluid, which lubricates the movement of structures
  • the articular cartilage coats the articular surfaces of the bone so as to restrict the impact to the lubricated joint cartilage
255
Q

Muscle attachment to bone

A

The end of muscle with a larger attachment to bone is called the origin
The end with the smaller attachment to bone is called the insertion

256
Q

Types of muscle movement (flexor, extensor, abductor, adductor)

A 
Flexor muscle
decreases angle (biceps)
Extensor muscle
increases angle (triceps)

abductor
moves a part of the body away from the midline (deltoid)

adductor
moves a part of the body toward the midline (pectoralis major)

257
Q

Codominance vs incomplete dominance

A

Codominance
more than one dominant allele; AB blood typing

Incomplete dominance
heterozygote is intermediate between the two homozygous genotypes

258
Q

Penetrance vs expressivity

A

Penetrance is the proportion of individuals who express the phenotype; population level

Expressivity is the variance of phenotype; individual level

259
Q

Mendelian laws

A

First law of segregation
two alleles segregate during anaphase I of meiosis, resulting in gametes that carry only one allele for any inherited trait

Second law of independent assortment
two sister chromatids separate independently during prophase I of meiosis

260
Q

Frederick Griffith

A

exposed mice to strains of virulent bacteria under different conditions
when both dead virulent and live nonvirulent bacteria were injected into the mouse, the mouse died

261
Q

Avery, Macleod, McCarty

A

separated the subcellular components of the bacteria into different extracts
When the DNA was degraded but not the protein, the mice lived, and vice versa

262
Q

Hershey and Chase

A

radiolabeled DNA and protein on bacteriophages

no radiolabeled protein entered the cells, but radiolabeled DNA did

263
Q

Genetic leakage

A

the flow of genes between species

-hybrid species

264
Q

Genetic drift

A

changes in the composition of the gene pool due to random chance
more pronounced in small populations

265
Q

Test cross

A

used to determine an unknown genotype by crossing it with a homozygous recessive

266
Q

Gene mapping:

chiasma, recombination frequency, map unit

A

The further apart two genes are, the more likely a point of crossing, called a chiasma will occur between them
-this likelihood is called a recombination frequency

  • -roughly proportional to the distance between the genes
  • -in a genetic map, one map unit or centimorgan corresponds to a 1 percent chance of recombination occurring between two genes
267
Q

Five criteria for Hardy Weinberg

A

population is very large (no genetic drift)
no mutations
no sexual selection
no migration
all genes are equally successful at being reproduced

268
Q

Modern synthesis theory and differential reproduction

A

Neo-darwinism

adds knowledge of genetic inheritance and changes in the gene pool to Darwin’s original theory

When mutation or recombination results in a chance that is favorable to the organism’s reproductive success, that change is more likely to pass on to the next generation; the opposite is also true
-differential reproduction

269
Q

Inclusive fitness

A

an organism can be evolutionary successful by being altruistic in his group

270
Q

Punctuated equilibrium

A

changes in some species occur in rapid bursts

MCAT (10 decks)

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