Physiology Final Exam Flashcards
(115 cards)
1
Q
what are the 4 basic cell/tissue types and their functions?
A
-muscle; skeletal, cardiac, and smooth: mechanical activity
-neurons/nervous: conduct electrical signals
-epithelial: secrete + absorption, protection
-connective: connect, anchor, support, ECM
2
Q
__________ is the state of balance between physiological variables
A
homeostasis
3
Q
a ___________ is when the increase or decrease of the variable being regulated brings about a response to move the variable in the opposite direction of the original change
A
negative feedback system
4
Q
a __________ accelerates a process to get an “explosive” system
A
positive feedback system
5
Q
in ___________, changes in variables are anticipated and prepared for to fine tune homeostatic response and minimize fluctuations in the regulated variable
A
feedforward regulation
6
Q
what are the 4 intracellular chemical messengers and their functions?
A
-hormone: target cells in 1 or more distance places in the body
-neurotransmitters: neuron or effector cell in close proximity to site of neurotransmitter release
-paracrine: target cells in close proximity to site of release of the paracrine substance
-autocrine: acts on the same cell that secreted the substance
7
Q
how does information flow in a neuron?
A
dendrite (receive info) -> cell body (genetic info for protein synthesis) -> axon hillock (propagate electrical signals) -> axon (carries ongoing signals to target cells) -> axon terminal (release neurotransmitters from axon)
8
Q
what are the 3 functional classes of neurons and where to they send info to?
A
afferent: from receptors into the CNS
efferent: out of CNS to effector cells (muscles, glands, neurons, etc.)
interneurons: integrators and signal changers within the CNS
9
Q
what are glial cells?
what are the 4 types?
A
surround the axon and dendrites of neurons and provide physical and metabolic support
nonneural
-oligodendrocytes: form myelin in CNS
-astrocytes: regulate composition of extracellular fluid in CNS by removing K+ and neurotransmitters
-microglia: macrophage-like immune function
-ependymal: line fluid filled cavities in brain and spinal cord and regulate flow of CSF
10
Q
separation of charges results in __________
A
electrical potential
11
Q
all body cells under resting conditions have potential difference across membranes so inside is __________ with respect to the outside
A
negative
12
Q
membrane potential a result of 2 factors:
A
(1) uneven distribution of Na+ and K+ across plasma membrane
(2) unequal permeabilities of membrane to Na+ and K+
13
Q
describe equilibrium potential and Nernst equation
A
2 fluxes become equal in magnitude but opposite in direction so there is no net movement of ions
the Nernst equation describes electrical potential needed to balance a given ion concentration gradient
14
Q
the GHK equation is used to calculate ___________ by considering membrane permeabilities of other ions
A
resting membrane potential
15
Q
what are leak channels?
A
constitutively open K+ channels
makes inside of cell negative
16
Q
at resting membrane potential, driving force for Na+ diffusion is __________ than K+
A
greater
17
Q
importance of the Na+/K+-ATPase pump?
A
maintains concentration gradients by creating a negative resting potential because 3 Na+ out and 2 K+ in every cycle
indirect contribution to membrane potential
18
Q
what is a graded potential?
A
small changes in membrane potential confined to small regions of the plasma membrane
no threshold or refractory period
19
Q
what is an action potential?
A
large alterations in membrane potential
generated rapidly, all-or-none
20
Q
what are the 3 gated ion channels and how do they effect each other?
A
ligand gated: open in response to binding of signaling molecules
mechanically gated: open in response to physical deformation of plasma membranes
-> both mediate graded potentials to initiate stimulus for action potentials
voltage gated: give membrane ability to undergo action potentials
21
Q
__________ are the myelin forming glial cells in the CNS
__________ are the myelin forming glial cells in the PNS
A
oligodendrocytes
Schwann cells
22
Q
what is the difference between an excitatory and inhibitory synapse?
A
excitatory: depolarizes and brings the membrane potential in the postsynaptic cell closer to threshold
inhibitory: driven farther from threshold (hyper polarize) or stabilize at resting potential
23
Q
compare electrical vs chemical synapses
A
electrical: plasma membranes of presynaptic and postsynaptic cells are joined by gap junctions to allow current to directly flow through connecting channels
chemical: axon of the presynaptic neurons end in axon terminals that hold synaptic vesicles that contain neurotransmitter molecules, permit integration of multiple signals
24
Q
6 steps of neurotransmitter release
A
(1) action potential reaches terminal
(2) voltage gated Ca2+ channel opens
(3) Ca2+ enters axon terminal
(4) neurotransmitter released and diffuse into cleft
(5) neurotransmitter binds to post synaptic receptors
(6) neurotransmitter removed from synaptic cleft
25
compare EPSPs and IPSPs
EPSPs: net movement of positive ions into postsynaptic cell causing slight depolarization and bring membrane potential closer to threshold
IPSPs: potential change in postsynaptic neuron a byperpolarizng graded potential
- affect Cl- and K+ only
26
membrane potential of a __________ cell is affected by both excitatory and inhibitory inputs
postsynaptic
27
compare presynaptic inhibition vs facilitation
inhibition: decrease amount of neurotransmitter released
facilitation: increase amount of neurotransmitter released
28
what are the components of the CNS and PNS?
CNS:
brain
spinal cord
PNS:
afferent division (somatic sensory, visceral sensory, special sensory)
efferent division (somatic motor, autonomic motor - sympathetic, parasympathetic, enteric)
29
compare the afferent and efferent of PNS
afferent: info from sensory receptors to CNS
- long part of axon outside CNS and part in PNS
efferent: signals out of CNS to muscles, glands, and tissues
- somatic and autonomic
30
compare somatic vs autonomic nervous systems
both in PNS and efferent
somatic:
- single neuron between CNS and skeletal muscles cells
- innovates skeletal muscle cells
- lead only to muscle cell excitation
autonomic:
- 2 neuron chain connected by synapse between CNS and effector organ
- innervates smooth and cardiac muscle, glands, GI neurons, but not skeletal
- excitatory and inhibitory
31
compare sympathetic vs parasympathetic neurons
sympathetic:
- from thoracic and lumbar regions of spinal cord
- ganglia lie close to spinal cord to form 2 chains on each side of cord - sympathetic trunk
parasympathetic:
- from brainstem and sacral portion of spinal cord
- ganglia lie within or close to organs postganglionic neurons innervate
32
3 protective elements of the brain
meninges: thick dura mater next to bone, arachnoid mater in the middle, and thin pia mater next to nervous tissue
cerebrospinal fluid: between arachnoid and pia
blood brain barrier: controls substances that enter extracellular fluid of the brain and rates at which they enter
33
5 types of sensory receptors and what they detect
- mechanoreceptors: pressure, stretch, touch, blood pressure, tension
- thermoreceptors: cold or warmth
- photoreceptors: light wavelengths
- chemoreceptors: binding of particular chemicals to receptor membrane
- nociceptors: pain
34
transduction of a given stimulus leads to a graded potential in receptor membrane called the ___________
receptor potential
35
compare slowly vs rapidly adapting receptors
slowly: maintain persistent or slowly decaying receptor potential during a constant stimulus, initiating an action potential in afferent neurons for duration of stimulus
rapidly: generate receptor potential and action potentials at onset of stimulus but quickly stop responding
36
define coding, sensory unit, and receptive field
coding: conversion of stimulus energy to a signal that conveys relevant sensory information to CNS
sensory unit: a single afferent neuron with all receptor endings
receptive field: area of body that leads to activity in a particular afferent neuron when stimulated
37
stimulus modality primarily coded for by __________
type of receptors activated
38
__________ along afferent neurons and ___________ are 2 ways in which stimulus intensity is coded
frequency of 2 action potentials
recruitment of sensory units
39
what is lateral inhibition?
information from afferent neurons with receptors at edge of stimulus is strongly inhibited compared to information from afferent neurons at the center
40
6 factors that affect perception
- sensory receptor mechanisms and processing info along efferent pathways
- emotions, personality, experience
- lack of suitable receptors
- damaged neural networks
- drugs
- mental illness
41
4 modalities for somatic sensation and the receptors for them
touch and pressure: mechanoreceptors
posture and movement: muscle-spindle stretch receptors and Golgi tendon organs
temperature: thermoreceptors
pain and itch: nociceptors
42
compare referred pain and hyperalgesia
referred pain: sensation of pain experienced at site other than injured or diseased tissue
hyperalgesia: increased sensitivity to pain stimulus
43
what is analgesia?
selective suppression of pain without effects on consciousness or other sensations
44
specific pathways for somatic senses cross from the side of the body where __________ to the other side in the spinal cord or brainstem
receptor is located
45
compare the anterolateral pathway and the dorsal column pathway
anterolateral: ascending, makes its first synapse between sensory receptor neuron and second neuron located in gray matter of the spinal cord
dorsal column: sensory neurons do not cross over or synapse immediately, instead ascend on same side of cord and make its first synapse in the brainstem
46
what is accommodation?
what is the problem with someone who can't see distant and near?
accommodation: shape of lense is altered by contraction and relaxation of ciliary muscle
viewing distant: eyeball too long or refraction too great
viewing near: eye too short for lens, images focused behind the retina
47
compare hyperopia to myopia
myopia: unable to see distant objects (nearsighted)
hyperopia: poor near sight, can be seen if accommodation reflex increases the curvature of the lens (farsighted)
48
2 types of photoreceptors
rods and cones
49
compare rods and cones
rods: disc membranes are intracellular
- extremely sensitive and respond to very low levels of illumination
cones: light sensitive discs formed from in-foldings of the surface plasma membrane
- only respond to bright light
50
all rods and cones face __________ and light must travel through ___________ before reaching photoreceptors
the back of the retina
all retinal cells
51
ON vs OFF pathways
52
compare dark vs light adaptation
dark: bright into dark light
- "temporary blindness"
- rhodopsin cannot respond fully again until restored to resting state by enzymatic reassociation of retina with opsin, which takes several minutes
light: dark to bright light
- rhodopsin activated as retinal dissociates
- cones operating
53
___________ whose axons form the optic nerve are the afferent neurons in the visual system
ganglion cells
54
sound waves are caused by vibrations of molecules and have the properties of __________ and __________
frequency and pitch
55
what is the pathway of a sound wave?
external auditory ear canal -> tympanic membrane -> middle ear -> inner ear -> malleus, incus, stapes -> oval window
56
what are the semicircular canals?
when the head moves, semicircular canals and attached body of hair cells move with it
the direction of head movement determines the direction stereo cilia are bent and which hair cells are stimulated
57
all receptors in vestibular system are _____receptors
mechano
58
what are the 5 taste submodalities and what is detected to produce it?
sweet: glucose
sour: acid
salty: sodium
bitter: G protein mediated
unami: glutamate and amino acids
59
the olfactory system is unique in that its neurons do not synapse in the thalamus but instead _____________
project directly to olfactory cortex and limbic system
60
a contraction is the generation of __________, not just muscle shortening
tension
61
what is a motor unit?
a motor neuron and the muscle fibers it innervates
located in one muscle but are distributed throughout
contract when an action potential occurs in a motor neuron
62
9 steps that occur at the neuromuscular junction
1) motor neuron action potential
2) Ca2+ enters voltage-gated channels
3) acetylcholine release
4) acetylcholine binding opens ion channels
5) Na+ entry
6) local current between depolarized end plate and adjacent muscle plasma membrane
7) muscle fiber action potential initiation
8) propagated action potential in muscle plasma membrane
9) acetylcholine degradation
63
6 steps of excitation-contraction coupling?
1) action potential propagated along muscle cell membrane and into T-tubules
2) Ca2+ released from terminal cisternae
3) Ca2+ binding to troponin removes blocking action of tropomyosin
4) cross-bridge binds, rotates, and generate force
5) Ca2+ transported back into sarcoplasmic reticulum
6) Ca2+ removal from troponin restores tropomyosin blocking action
64
what is the sliding filament mechanism?
force generation produces shortening of skeletal muscle fiber and the overlapping thick and thin filaments in each sarcomere move past each other, propelled by movements of cross-bridge
65
4 steps of the cross-bridge cycle
1) cross-bridge binds to actin
2) cross-bridge moves
3) ATP binds to myosin, causing cross-bridge to detach
4) hydrolysis of ATP energizes cross-bridge
66
4 functions of ATP in skeletal muscle
1) hydrolysis of ATP by Na+/K+-ATPase in plasma membrane maintains Na+ and K+ gradients
2) hydrolysis of ATP by Ca2+-ATPase in sarcoplasmic reticulum provides the energy for active transport of calcium ions reticulum
3) hydrolysis of ATP by myosin-ATPase energizes cross-bridges, providing energy for force generation
4) binding of ATP to myosin dissociates cross-bridges bound to actin, allowing the bridges to repeat their cycle of activity
67
compare isometric vs isotonic contractions
isometric: muscle develops tension but does not shorten; when muscle supports a load in a constant position or attempts to move another load that is greater than the tension
isotonic: muscle changes length while load on muscle remains constant
- 2 types:
- concentric: tension exceeds load and shortening occurs
- eccentric: unsupported loads is greater than the tension generated by cross-bridges
68
3 types of skeletal muscle fibers
slow-oxidative: combine low myosin-ATPase activity with high oxidative capacity
fast-oxidative-glycolytic: combine high myosin-ATP activity with high oxidative capacity and intermediate glycolytic capacity
fast-glycolytic: combine high myosin-ATPase activity with high glycolytic capacity
69
a whole muscle is made up of a combination of different types of muscle fibers organized into __________
motor units
70
tension can be developed in a whole muscle depends upon 2 factors:
(1) tension developed by each individual fiber
(2) number of active fibers
71
what are muscle antagonists?
groups of muscles that produce oppositely directed movement at a joint
72
compare and contrast structure of smooth and skeletal muscle
smooth: not striated
not under direct voluntary control
smaller cells
smaller concentration of thick myosin containing filaments and thin actin containing filaments
skeletal:
striated
under voluntary control
larger cells
larger concentration of thick myosin containing filaments and thin actin containing filaments
both:
use cross-bridge movements between actin and myosin to generate force
calcium ions generate force
contain thick myosin containing filaments and thin actin containing filaments
73
cross-bridge activation in smooth muscle (5 steps)
(1) Ca2+ binds to calmodulin, a Ca2+-binding protein that is present in the systole of all cells and whose structure is related to troponin
(2) Na2+-calmodulin complex binds to another systolic protein, myosin-light chain kinase, thereby activating enzyme
(3) active myosin, light-chain kinase then uses ATP to phosphorylate myosin light chain in globular head of myosin
(4) phosphorylation of myosin drives cross-bridge away from thick filament backbone, allowing it to bind to actin
(5) cross-bridges go through repeated cycles of force generation as long as myosin light chains are phosphorylated
74
2 sources of Ca2+ to initiate contraction in smooth muscle
(1) sarcoplasmic reticulum
(2) extracellular Ca2+ entering cell through plasma membrane Ca2+ channels
75
what is the latch state?
in smooth muscle when stimulation is persistent and cytosolic Ca2+ concentration remains elevated, the rate of ATP hydrolysis by the cross-bridge decline even though isometric tension is maintained
76
what is the pacemaker potential?
following depolarization, the membrane begins to depolarize so a series of action potentials occurs, producing a rhythmic state of contractile activity
77
___________ muscle can be excited or inhibited by neural activity and __________ muscle can only be excited
smooth
skeletal
78
compare single vs multiunit smooth muscle
single:
-undergo synchronous activity, both electrical and mechanical-whole muscle tissue responds to stimulation as a single unit
-in intestinal tract, uterus, and small blood vessels
multi:
-no or few gap junctions
-each cell responds independently and tissue behaves as multiple units
-in large airways to lungs, large arteries, hair in skin
79
10 steps of excitation-contraction coupling
(1) membrane depolarized by Na+ entry as an action potential begins
(2) depolarization opens L-type Ca2+ channels in T-tubules
(3) small amount of "trigger" Ca2+ enters cytosol, contributing to cell depolarization
(4) trigger Ca2+ binds to and opens ryanodine receptor Ca2+ channels in the sarcoplasmic reticulum membrane
(5) Ca2+ flows into cytosol, increasing Ca2+ concentration
(6) binding of Ca2+ to troponin exposes cross-bridge binding sites on thin filaments
(7) cross-bridge cycling causes force generation and sliding of thick and thin filaments
(8) Ca2+-ATPase pumps return Ca2+ to sarcoplasmic reticulum
(9) Ca2+-ATPase pumps and Na+/Ca2+ exchangers remove Ca2+ from cell
(10) the membrane is repolarized when K+ exes to end action potential
80
the strength of a contraction can be varied by __________ or __________
neurotransmitters
hormones
81
what are L-type Ca2+ channels?
causes depolarization during cardiac muscle cell action potentials due to the influx of Ca2+ through voltage-gated channels
82
interneurons receive sensory information from (3):
(1) same muscle that is controlled by motor neuron
(2) other nearby muscles
(3) neurons in the tendons, joints, and skin
83
all muscle spindle stretch receptors provide sensory information about the overall __________ and rate of ___________
length of the muscle
length change
84
what is alpha-gamma coactivation?
prevents loss of information about muscle length during rapid shortening contractions
85
what is the monosynaptic stretch reflex?
afferent nerve fibers in stretched muscle synapse directly on motor neurons to that muscle without any interneurons
86
compare reciprocal innervation and synergistic muscle activation
reciprocal innveration:
- divergence of neuronal pathways to influence both agonist and antagonist muscles of a particular movement
- simultaneously contracted to stiffen a limb joint
- branches of afferent nerve endings from stretch receptors end on inhibitory interneurons
synergistic muscle activation:
- muscles whose contractions assist the intended motion
87
___________ provide sensory information about the tension being generated by a muscle
Golgi tendon organs
88
withdrawal reflex
89
function of the basal nuclei
form a link in the looping of parallel circuits in which activity of motor system is transmitted from a specific region of sensorimotor cortex to basal nuclei, to thalamus, and back to cortical area
90
define muscle tone and hypertonia and hypotonia
muscle tone: when skeletal muscle is relaxed there is a slight and uniform resistance when stretched by an external force
-hypertonia: abnormally high muscle tone
-hypotonia: abnormally low muscle tone
91
postural reflex
92
3 chemical classes of hormones
amines
peptides and proteins
steroids
93
the amino acid _________ is the precursor to all amine hormones
tyrosine
94
___________ is precursor to all steroid hormones
cholesterol
95
__________ is the predominant steroid secreted by the testes and is converted to the other hormones in target cells
testosterone
96
only a _________ hormone is able to diffuse out of the capillaries and exert effects on target cells
free
97
contraction of a hormone in the blood is determined by __________ and rate of __________
hormone synthesis/secretion
hormone removal/metabolism
98
compare up and down regulation
up: an increase in the number of hormones receptors in a cell
down: a decrease in receptor number
99
what is a tropic hormone
stimulates secretion of another hormone and growth of stimulated gland
100
what does tropic and trophic mean?
tropic: stimulates secretion of another hormone and growth of stimulated gland
trophic: specifically referring to growth-promoting actions
101
define primary and secondary hypo- and hyper- secretion of hormones
primary hypo: secreting too little hormone the gland is not functioning properly
secondary hypo: endocrine gland receiving too little stimulation by its tropic hormone
primary hyper: gland secreting too much of the hormone on its own
secondary hyper: excessive stimulation of gland by its tropic hormone
102
define hypo- and hyper-responsiveness
hypo: decreased responsiveness of target cells to hormone
hyper: increased responsiveness of target cells to hormone
103
2 posterior pituitary hormones
oxytocin and vasopressin
104
__________ hormones are first in a 3-hormone sequence to bring about desired response
hypophysiotropic
105
compare T4 and T3
T4:
- 4 iodines
- converted to T3 in target tissues by enzymes
T3:
- 3 iodines
- major thyroid hormone
106
__________ thyroid hormone concentrations exhibit negative feedback control on hypothalamus and anterior pituitary gland
plasma
107
__________ hormone receptors are found in nuclei of most cells of body
thyroid
108
what is hypothyroidism?
plasma concentrations of thyroid hormone below normal
109
describe the process of fertilization
The spermatozoon and ovum combine their haploid nuclei to create a diploid zygote.
Once a male ejaculates, the spermatozoa increase motility and fertilize the ovum.
A second oocyte is released from the ovary and moves along the uterine tube, and the spermatozoa passes through the corona radiata to reach the cell membrane of the oocyte. The spermatozoa release an enzyme, hyaluronidase, that allows it to enter the oocyte.
The oocyte goes through meiosis while the spermatozoon creates chromosomes to combine with the maternal chromosomes.
110
why are so many sperm needed for successful fertilization?
The male needs to ejaculate around 300 million spermatozoa because most of them do not survive the journey through the vagina and to the uterus, only about 100 of them do, and only a single ovum is released from an ovary during ovulation.
Therefore, more sperm needs to be released to increase the chances of fertilization since only one egg is produced.
111
how are the 3 germ layers formed?
Within a few days of implantation, cells begin the process of gastrulation where the cells of the epiblast move to the primitive streak, where invagination occurs.
Cells are sent into the region between the epiblast and the hypoblast.
The epiblast forms the ectoderm, the hypoblast forms of the endoderm, and the cells that proliferate between those 2 layers forms the mesoderm.
112
describe the structure of a blastocyst
A solid ball of cells, the morula, enters the uterus and changes into a blastocyst, which is a hollow ball of cells with a cavity called the blastocoele.
There are cells outside, trophoblasts, and the cells inside form the inner cell mass
113
what are the functions of the 4 extraembryonic membranes?
The yolk sac at first has a large role in providing the embryo nourishment but this later decreases when the amnion begins to form. The amnion provides protection by lining the amniotic cavity and envelops the embryo in amniotic fluid.
The allantois forms part of the urinary bladder and contributes to the body stalk which is the protective tissue between the embryo and the chorion.
The chorion encases the embryo and extend villi and blood vessels to eventually establish the structure and development of the placenta.
114
how does a fetal obtain nutrients and gases from the maternal blood
A fetus obtains nutrients and gases from the maternal blood through the placenta.
The placenta is connected to the fetus via the body stalk, which combines with the yolk stalk to form the umbilical cord.
The umbilical cord has 2 arteries that transport deoxygenated blood to the placenta and a single vein that returns oxygenated blood to the embryo.
115
from what structures do the 4 major tissue groups arise?
The ectoderm forms the nervous system, skin, hair, and nails, which contributes to the rise of nervous tissue and epithelial tissue.
The mesoderm forms the skeletal and muscular systems, which contributes to the rise of muscular tissue and most connective tissues. The endoderm forms the linings of the respiratory and digestive systems, where epithelial tissues can also arise from.
