Exam 1 Info - Lecture Notes Flashcards
(136 cards)
1
Q
with a single ventricle, there isn’t a good separation of … vs … blood
A
oxygenated; deoxygenated
2
Q
anatomy of heart alters according to …
A
metabolic demands
3
Q
four chambered hearts evolved independent in … and …
physiology … –> maintaining constant temp
A
birds; mammals; homoiotherms;
4
Q
…: form and function are intrinsically related to one another
e.g. teeth
A
principle of complementarity
5
Q
… found withino rgans
A
smooth muscle
6
Q
(maintenance of life)
maintain boundaries –> isolating internal enviro
…: many of the gradients used (concentration gradients which establish electrical signaling and ion transport, etc) necessitates these boundaries
A
signaling interface
7
Q
(maintenance of life) movement –> both internal and external
dictated by … system which moves body parts in coordination with … system
additional muscles include … and … which move liquids around internally (e.g. blood, food being digested, etc)
A
muscular; skeletal;
cardiac;
smooth;
8
Q
(maintenance of life) movement:
…: cellular movement –> performed by …; motility comparable to how single celled organisms move
A
contractility;
cilia
9
Q
(maintenance of life) responsiveness –> interacting with enviro
sense and respond to stimuli
nervous system integrates … input and stimulates a response (e.g. reflex)
… responses –> monitoring and adjusting internal states
A
environmental; endocrine
10
Q
(maintenance of life) …: breaking down food and absorbing nutrients
metabolism –> breakdown of nutrients to obtain … and …; catabolism + anabolism; fueled by …
A
digestion;
energy; structural ability; oxygenation
11
Q
(maintenance of life) excretion:
removal of waste
…: unused nitrogen accumulated from protein breakdown
…: from respiration
…: from digestive system -unabsorbed food
A
urea;
CO2;
feces
12
Q
(maintenance of life) reproduction:
…: level of reproduction is dependent on system
organismal level of repro
A
cellular division
13
Q
…: organs working together to perform some physiological task
A
organ systems
14
Q
(organ systems) integumentary: synthesizes …, houses cutaneous receptors and sweat and oil glands
acts as a significant … organ
important for physiological functions such as .., …, and …
A
vitamin D:
sensory;
gas exchange; water regulation; temp regulation
15
Q
(organ systems) skeletal:
protection and support, provides framework for muscles to cause movement
… homeostasis
A
calcium
16
Q
(organ systems) muscular:
manipulation of …, …, …, …, … (e.g. shivering)
A
environment; posture; locomotion; facial expression; heat production
17
Q
(organ systems) nervous: activates appropriate muscles and glands according to … signals and …
A
environmental; internal states
18
Q
(organ systems) endocrine:
… control
cardiovascular:
blood transport which enables transport of …, …, …, etc
A
hormonal;
gas; nutrients; waste
19
Q
(organ systems) lymphatic system/immune:
picks up fluid leaking from blood vessels and returns it to blood, houses … –> responds to .. present in body
A
white blood cells;
foreign substances
20
Q
(organ systems) respiratory:
supplies blood with adequate … and removes …
gas exchange occurs within air sacs in lungs –>…
A
oxygen; CO2;
alveoli
21
Q
(organ systems) digestive: breaks down food into absorbable units
urinary: primary function is to remove …
regulates …/.. as well as … and … regulation
reproductive: offspring production
A
nitrogen;
water retention; excretion; electrolyte; pH
22
Q
fundamental operational principle of physiology is … –> several factors for survival that necessitate a balance
nutrients, oxygen, water, normal body temps for homeothermic animals (bodily functions optimized for a certain temp - for people around … degrees C), appropriate atmospheric pressure
low pressures –> will begin bleeding from lungs due to …
A
homeostasis; 37; tissue compression
23
Q
…: chemicals for energy and cell building
carbs, proteins, fats, minerals and vitamins
A
nutrients
24
Q
oxygen: necessary to “…” foods with - … release from foods
A
burn; Energy
25
...: provides the environment necessary for chem rxns
water
26
normal body temp impacts rates of chemical rxns:
| ... --> level of change of biochemical processes if temp changes by ten degrees
Q 10
27
appropriate atmospheric pressure: adequate ... and ...
breathing; gas exchange
28
homeostasis occurs through control systems:
first need a sensor which communicates with a ... (entity that compares baseline to present state- difference between two values is ...)
dynamic equilbrium achieved via a ... --> effector moves factor in opposite direction that stimulus has done
... process
nervous and endocrine systems play primary roles
controller; error signal; negative feedback loop; continuous;
29
homeostatic control of variables necessitates a receptor control sensor and effector:
.. is the sensor
... which determines set point
effector
receptor;
| control center
30
cell can signal to itself that has occurred via changes in
electrical potentials
31
long-distance communication and action potentials or a way that a cell can signal to itself is initiation of a ... that occurs when ovum is fertilized by sperm:
... are the primary means of signaling
calcium wave; chemical signals
32
chemical signals can be generated for the same cell or for others:
signals are manufactured and stored in ... which exit via exocytosis
substantial for chemical signals to only be recognized by cells that you need to receive that signal
vesicles
33
one of the most basic methods of intercellular communication -- ... between those cells
physical connection
34
gap junctions: specialized type of protein (...):
thousands of these where the two cells meet
creates one continuous ... between the cells
chemical signals will travel to other cell as fast as diffusion will allow --> essentially ...
coordinated ... occurs due to gap junctions
connexins;
cytoplasm;
instantaneous; beating of heart
35
contact-dependent signaling:
a protein on one cell that fits with a protein on the other cell --> these are ... (...)
CAMs signal that the two cells ... with one another
CAMs; cell adhesion molecules;
| made contact
36
contact-dependent signaling: .... cells have contact dependent signals --> keeps them anchored to one another
substantial for maintaining tissues in the location where those tissues are supposed to be --> when they're found somewhere else, they will die via ...
skin; programmed cell death
37
...: chemical agent produced and exits via exocytosis, which then binds on a receptor on that one cell's surface receptor
...: signaling to the local enviro --> just in the immediate neighborhood (e.g. infections and ... - interfere with viable replication)
autocrine; paracrine; interferons
38
long-distance signaling: ... (hormonal)
long distance intercellular communication can occur through ... --> electrical signal will travel down length of neuronal axon
neurons don't communicate with one another via ... signals
endocrine; neurons; electrical
39
```
long-distance communication:
no electrical signals travel between cells, the action potential merely stimulates the release of ...
... --> special class of neurotransmitter that acts as hormone
```
neurotransmitters;
| neurohormones
40
chemicals that bind to receptors = ligand
X ligand is ... for Y receptor --> means that this is a specific relationship, wherein the ligand only binds to one receptor
cognate
41
cytokines:
produced by any cell that has a ... --> means that RBC's can't signal that something's occurring
stress and inflammation change cytokine expression - ... cytokines are activated in these situations
nucleus;
| pro-inflammatory
42
for water-soluble only ligands, they are ... and must have ... which generate a signaling cascade
lipophobic; surface receptors
43
lipophilic signal molecules --> inaccurate, if they were simply lipophilic they would never be able to go anywhere
should say .../...
because these can diffuse across membrane they don't need ..,. instead have receptors in ... or ... - these receptors don't activate a signaling cascade
amphiphilic; amphipathic;
| surface receptors; cytosol; nucleus;
44
lipophilic signal molecules:
... can occur when ligand binds to receptors
these receptors tend to be ...
lipophilic ligands are "..." -- quickly activate ...: they bind to one receptor and immediately go to nucleus and start making mRNA
dimerization;
transcription factors;
fast track to the nucleus;
transcription
45
lipophilic signal molecules:
tend to be ligands like ...
direct ...
hormones; transcriptional activation
46
all androgens are ... based -- these rapidly diffuse into cells (tend to be ...)
cholesterol; lipophilic
47
the receptors for water-soluble ligands tend to cross the entire ... --> they are activated via ... that occur upon binding
cell membrane; conformational shifts
48
ways to initiate signaling in water-soluble ligands:
ligand activates receptor which then activates amplifying enzymes which stimulates release of thousands of signaling molecules -- ...
common families of amplifying enzymes: .., ..,. ...
signaling cascade;
| adenylyl cyclase; guanylyl cyclase; phospholipase C
49
ways to initiate signaling in water-soluble ligands:
second messengers activated by amplifying enzymes activate ... - stick a phosphate group onto something else because phosphates are negatively charged, which will stimulate conformational change on the molecule that it was added so that can either .../... that molecule
same kinase can activate a lot of molecules and deactivate a lot of molecules
protein kinases; activate; inactivate;
50
ways to initiate signaling in water-soluble ligands:
sometimes second messenger cascades stimulate ... -- proteins that are calcium sensitive will instantly bind to ... and undergo conformational change
calcium release; free calcium
51
for a signaling cascade, if there's a series of enzymes, those enzymes will be stuck to the ... in that ... such that activation will occur efficiently
cytoskeleton; specific order
52
g-protein coupled receptor signaling:
G-proteins are proteins that bind to ...
there are ... and ... G proteins
.... for the G-protein receptors
GTP;
monomeric; trimeric;
7-transmembrane domains
53
g-protein coupled receptor signaling:
... 7-transmembrane G-protein coupled receptors
when G-proteins is activated, one part of the G protein "splits off" of the rest of the protein and will then bind to. ... -- the amplifying enzyme in this cascade
adenylyl cyclase activates ... (converts ... to ...) which will then bind to and activate ...
serpentine;
adenylyl cascade;
cAMP: ATP; cAMP;
protein kinase A
54
g-protein coupled receptor signaling:
protein kinase A phosphorylates other proteins to continue propagating the signal and lead to the adequate response
adenylyl cyclase will remain activated for a long time due to the fact that cAMP is ... in the cytosol (this is bc it's very effective at activating kinases and so cell does not want cAMP to remain activated if its unnecessary)
degraded rapidly;
55
phospholipase C system is also activated by GPCRs:
... works on phospholipids
in general .... cleave lipids
PL-C is what is activated by the G protein instead of adenylyl cyclase
phospholipsae;
| lipases
56
phospholipase C system is also activated by GPCRs:
PL-C embedded in ... of plasma membrane --> no lipids will be in cytoplasm
PL-C cleaves the lipid into ... and ... --> diacylglycerol has ... and thus remains in the plasma membrane; Bc IP3 has three phosphae groups it ...
inner leaflet;
inositol triphosphate; diacylglycerol;
two fatty acid chains; diffuses into cytoplasm
57
DAG activates ... which again phosphorylates other molecules to yield a cellular response
IP3 will bind to proteins on the ER and initiate .., which also propagates the signal
protein kinase C;
| calcium release;
58
GPCRs an be adjacent to ion channels in the membrane which have ... interior, and ... ball that can open or close it. this is held to the transmembrane domain by a chain of ...
hollow; globular; amino acids
59
GPCRs:
ion channels have a specific ... that only allow specific ions to travel through them
changes in ... will then allow for ion movement
... receptor acts in this way -- neurotransmitter found in muscle
... of the cell will change according to ion movement
diameter;
membrane permeability;
acetylcholine;
voltage
60
calcium is substantial in ... --> binds to proteins that regulate the state of muscle contraction --> one of these proteins is ..., which allows the muscle to contract - essentially alters to the ... of muscle
muscle contraction;
| troponin; length
61
proteins that control exocytosis are in ... family of proteins- these are calcium-sensitive proteins
"squish" neurotransmitter in ... into plasma membrane
SNARE; vesicle
62
... is substantial in calcium signaling
calmodulin
63
... is activated by nitric oxide. G cyclase does the same thing as ..., but activates ... instead
guanylyl cyclase;
| A cyclase; cGMP
64
nitric oxide acts as a ... in brain
also substantial in endothelial cells - NO causes ..
... in endothelial cells - nitrogen group from arginine is cleaved off which forms NO and citrulline --> increases ... to muscles under stress
neurotransmitter;
vasodilation;
nitric oxide synthase; blood flow
65
carbon monoxide is potent signaling molecule:
in low concs.
potent ..
vasodilator
66
phospholipase A2 is present in skin and is responsible for ... cleavage --> activates ... and ...
arachidonic acid; COX 1 and 2
67
phospholipase A2:
activates proteins that are ... and thus cause pain by ... on neurons
NSAIDs counter this - relieve pain by reducing ...
"real" pain killers are ... because it travels to the brain and acts there
vasoconstrictors; pinching;
swelling;
opioids
68
... is the ligand that is supposed to be there
agonist
69
antagonist blocks the receptor's activity - blocks receptor's ...
active site
70
... is what causes the specific action not the ligand
e.g. epinephrine can bind to ... adrenergic receptor and can cause constriction of vessel, whereas with ... adrenergic receptor, the vessel will dilate
asthma inhalers work this way by having chemicals that bind specifically to .... receptor
receptor;
| alpha; beta; beta 2 adrenergic receptor
71
... increases amount of receptors in an attempt to maintain homeostatic level of signaling. ... can also occur
upregulation; downregulation
72
downregulation occurs when there is a constant signal that isn't supposed to be a constant signal --> intended to ... neurons towards ... - this is why drug tolerance occurs
for opiates, downregulation and upregulation occurs extremely quickly- thus, ... usually occurs after individual goes clean for a short amount of time and then take the same amount they used to take before going clean
desensitize; constant signaling; overdosing;
73
... is protein that allows for endocytosis
clathrin
74
nervous system: organ system designed to think
get information in form of ... info
must decide what to do with that sensory info --> some kind of ... system is necessary
if sensory system warrants a response, a ... system is necessary
sensory;
integration;
motor;
75
two major categories for nervous system: ... and ...
| peripheral carries info to ...
central; peripheral; CNS
76
PNS: afferent + efferent neurons;
...: give info about state of organs they innervate (e.g. skin, skeletal muscles, joints)
...: sense neurons in gut- convey impulses from digestive system
.. neurons carry info to initate response
somatic afferent fibers;
visceral afferent fibers;
motor
77
PNS:
.../voluntary NS
.../involuntary NS --> ... (digestive system), smooth and cardiac muscle, ... glands; still control over some of these muscles to some degree - but very limited; autonomic is divided into ... and ...
somatic;
| autonomic; viscera; endocrine; sympathetic; parasympathetic
78
... included in CNS (technically part of brain
eyes
79
parasympathetic "rules most of existence" - system designed to ..., helps promote ... functions during periods of rest
maintaining ...
..., ..., ..., etc.
responsible for ... and ...
```
conserve energy;
house-keeping;
homeostasis;
vagal tone; breathing; heartbeat;
rest; digest
```
80
sympathetic: responses to important needs
mobilizes body when ... is necessary
... or ...
speeds up fibers that innervate ... of heart
action;
fight or flight;
pacemakers
81
sympathetic:
four Fs: ..., ..., ..., ...
strong sensory stimuli
fighting; fleeing; feeding; f*** (mating)
82
neurons are not overwhelming majority of nervous tissue - most nervous tissue is composed of ... cells instead (neuroglia-glial cells):
different glial cells for CNS and PNS -->... differences between tissues in CNS and PNS
supporting; functional
83
(glial cells) astrocytes- CNS:
look like exploding cells --> highly branched
most abundant cell type in CNS
cling to ... and help keep them alive
during development, as brain is forming, neurons migrate from ... of brain to ... by following astrocytes that function as ... --> astrocytes act as path that neurons follow
neurons;
| interior of brain; cortex; scaffolds;
84
(glial cells) astrocytes:
control chemical enviro - sleep to give astrocytes time to mop up ... (esp ... ones, e.g. glutamate which is toxic in high levels)
astrocytes participate in ... modulate neuronal firing and directly participate in info processing
excessive neurotransmitters; excitatory; info processing;
85
(glial cells) astrocytes:
control what moves in and out of brain via ...
astrocyte feet - wrap around blood vessels in brain and secrete chemicals to communicate with capillary cells to facilitate ... --> capillaries make ... with astrocyte such that not much material can leak out of the capillaries
capillaries;
cell-cell contact;
tight junctions;
86
astrocyte feet:
... - astrocyte feet wrapping around capillaries (..., not astrocytes, are blood brain barrier; astrocytes are merely responsible for maintaining this)
areas in brain where capillaries are more ... than others (e.g. hypothalamus) - sampling fluid leaking out of capillaries to see if there's anything in blood that shouldn't be there
blood-brain barrier; capillaries;
| leaky;
87
(glial cells) astrocytes:
blood brain barrier so tight that ... cannot enter brain - typically white blood cells can secrete chemicals that break ... but this doesn't happen in blood-brain barrier
immune cells; cell-cell communication
88
(glial cells) microglia:
brain, spinal cord and eyes are ... - no immune cells
tiny cells that "mop up" when things go awry in CNS
... dead/dying neurons to prevent damage to neighboring neurons
because they're smaller, they can move around more easily
immune privileged;
| phagocytize;
89
(glial cells) ependymal cells:
there are ... spaces filled with ... -- ependymal cells line those areas, which are called ...
only lining ... of ventricles
... --> keep CSF flowing throughout ventricles
hollow; CSF;
ventricles;
surface;
ciliated
90
(glial cells) oligodendrocytes:
cells responsible for insulating axons of neurons in the CNS --> most axons have insulation
these cells manufacture ..., a type of fat, wraps around segments of different axons and coats them with myelin --> reduces amount of ... as action potential travels down neuronal axons
myelin; leakage of current;
91
(glial cells) oligodendrocytes:
without myelin, speed of signal transmission can be ... slower than it is with myelin --> myelin speeds up computational process speeds
one oligodendrocyte myelinates multiple segments of ... - differs from PNS
300x;
| multiple axons;
92
(glial cells) oligodendrocytes:
myelin in CNS is different than myelin in PNS --> in PNS cells that myelinate would ... and help facilitate ... of axon in a cut axon by acting like ... --> this does not occur in CNS which is why strokes/ spinal cord damage is extremely devastating
remain in the same place; regeneration; guideposts;
93
(glial cells) oligodendrocytes:
proteins on outside of CNS myelin that cause ... to collapse --> these proteins are ... compounds
e.g. "no go" protein
these aren't present in cells of PNS
growth cones; inhibitory;
94
(glial cells) satellite and schwann cells - PNS
...: wrap around neuronal cell bodies and sustain them
... - myelinating cells of PNS --> major diff between schwann and oligodendrocyte's methods of myelinating: one schwann cell only myelinates ... of a single axon
in between myelin segments, ... - in CNS as well
satellite;
| schwann; one single piece; nodes of Ranvier;
95
neurons:
born with way more than are necessary
neurons that don't undergo any connections undergo ...
...: neuron can never divide to make two neurons
apoptosis;
| terminally differentiated
96
neurons:
high metabolic rate:
...% of calories consumed daily are dedicated exclusively to maintaining body temps
of the rest, ..% of those left over go to maintaining brain
70; 80
97
neurons:
brain can only run on ... --> about a day's worth of glucose stored in ...
very low electricity running through brain
glucose; liver
98
cell body (perikaryon/soma) - where everything is manufactured in neuron; where ... and ... is located
extensive golgi to synthesize ...
...
...: where action potentials are generated from
clusters of somas = ... in CNS, ... in PNS
```
ER; golgi;
neurotransmitters;
neurofilaments;
axon hillock;
nuclei; ganglia
```
99
processes of neurons: dendrites and axons
...: transmit sensory info into neurons
...: motor info away
bundles of processes: ... in CNS, ... in PNS
dendrites;
axons;
tracts; nerves
100
dendrites:
receive info
in CNS, neurons synapsing on dendrites --> large array of dendrites surround neurons - ...
...
dendritic arbor;
| graded potential
101
```
axon:
one axon comes from ...
... - branch from neuron
typically ... per neuron
branches at end of axon which synapse onto something
...: synapse onto muscle tissue
```
axon hillock;
axon collateral;
one axon;
neuromuscular junction;
102
axon:
... docked on axon terminals
carry action potentials away from neuron
... - take bundles of "stuff" and by anterograde transport, transport these stuff to ... --> different types of motor protein facilitate ... transport - from axon terminal to cell body
if neurons relied just on ... alone, it would take way too long
vesicles;
| motor protein; neuronal terminals; retrograde transport; diffusion;
103
myelin sheaths:
as schwann cells are wrapping around, nucleus forms peripheral bulge called ...
schwann cells wrap neurons by starting on outside and wrapping towards inside - highly inefficient
neurilemma
104
.../.. --> rare, but can be seen over short distances in PNS
no ... in CNS
unmyelinated axons; semi-myelinated
| neurilemma
105
multipolar neurons: extensive .., one main axon that comes directly from axon hillock
most neurons are these
dendritic arbor
106
unipolar neuron takes info and sends it to ...
don't have ...
have ... on one end that generate action potential
CNS;
axon hillock
sensory receptors
107
...: bypass signal being sent to CNS and relay info directly back to a motor neuron
responsible for ... - much faster rxn
interneurons
108
neurons have ability to change internal states faster than any other cell type –...
o respond to changes in environment and send a signal as a response to wherever axons extend to --> action potential/nerve impulses
irritability
109
neurons change their internal composition of charges from the... to ...to generate these action potentials
outside of plasma membrane; inside of plasma membrane
110
potential difference: ... outside of cell versus inside of cell
number of charges
111
current is not necessarily equivalent to the ...
movement of ... ions rushing into the cell - actually very low current
cells are very low voltage systems
potential;
| sodium
112
higher levels of resistance can correspond to higher levels of ... - tend to be inefficient
resistor is ... for neuron
heat;
| plasma membrane
113
insulators are ... in neurons -no ion channels where this is present, but even if they were there, they'd be blocked by it
myelin
114
conductor for neuron is the ... -- good conductors, only physical impediment of ions through them is how ... they can actually move
ion channels; fast
115
leakage channels are ... regardless of neuron's state
always open
116
interior of the neuron is negative --> relative value, not absolute
more ... outside of the neuron than inside - ... in interior, which is why interior is deemed negative
deficit keeps voltage gated channels shut
positive charges; positive charge deficit
117
when ligand gated channels open to allow Na+ inside the cell, ... accumulate and stimulate the opening of the ..., because the gate has "arms" that contain ...
When the Na+ accumulates, ... stimulates movement of the ion channel's "arms" to open the gate
positive charges;
| voltage-gated Na+ channels; positive charge; +-+ repulsion
118
... or ... activate voltage gated channels
ligand gated ion channels; mechanically gated channels
119
sodium-potassium pump --> ensures that there is enough ... that can leave and enough .... that can enter
... being pumped out and ... being pumped in
once the K+ is pumped in, they immediately leak out
k+; Na+;
| 3 Na+; 2 K+
120
if we only had K+ leak channels, the cell's interior would be at ... mV, but presence of Na+ leak channels balance this slightly and maintains potential at around -70 mV
-90
121
graded potentials; moving only a couple ions into interior, resting membrane potential can reset very rapidly
use is to cause ... -- generally created on dendrites and on somas
most synapses are ... (axon sitting on dendrite), but there's also ... and ...
action potentials
| axodendritic; axosomatic; axoaxonic
122
when one neuron dumps neurotransmitters on dendrite of postsynaptic neuron, a ... generally results
graded potential
123
... of graded potential that decides whether or not an action potential is generated
summation
124
hyperpolarization vs depolarization is difference between ... and ... neurotransmitters: excitatory sends ... signal in dendrites of neurons -- binds and open channels that move ... charge in cell
inhibitory does the opposite: injects ... into cell
excitatory; inhibitory; depolarization
| positive; negative
125
graded potentials are short lived because they are small and spread out in all directions, because they are located at a .. spot in a dendrite
current flows in ... but once the channel is closed, no more positive charge will be injected into interior of cell -- graded potential doesn't sustain it bc it is a little pulse; current is not sustained and so it diffuses very quickly
random; all directions;
126
action potential doesn't decrease in ... from one point to another in the axon, unlike the graded potentials
doesn't dissipate
mangitude
127
-55 mV is the threshold for an action potential --> must be reached for action potential to actually occur
accumulated enough ... charges in interior of neurons such that na+ has accumulated in axon hillock to open the ... --> results in rush of Na+ down its conc gradient, bringing membrane potential to ...
voltage gated ion channels for Na+ close and K+ voltage gated ion channels open to allow for ..
... --> K+ voltage gated ion channels remain opening for slightly too long to cause hyperpolarization
```
positive;
voltage-gated ion channels;
+30 mV
repolarization;
undershoot
```
128
at rest the gated Na+ and K+ channels are ..
closed
129
change in voltage that results in action potential is related to the fact that gated sodium and potassium channels function in diff ways:
Na+ voltage gated channels are ... channels --> as soon as threshold is hit, they fly open - ... --> stay open for very short time. when they close, the voltage gated K+ channels open
K+ voltage gated ion channels respond to ... as well, but there's a pause -... channels
fast; instantaneous;
| threshold voltage; slow
130
Na+ voltage gated channels have two gates:
activated gates: ... at rest, opens when threshold is hit
inactivation gate - ... at rest, snaps shut at .. mV
the two gates open and close at diff times to ensure that fast opening and closing of Na+ gates doesn't last too long
having the activation and inactivation gates takes less time than it would if the Na+ channel only had one gate
closed;
| open; +30
131
K+ channels only have one gate- part of the reason why they're slow channels
activation gate takes a while to close which is what allows for ... - stay open bc they don't have ...
contributes to ... period
hyperpolarization; inactivation gate;
| absolute refractory
132
generating potential at axon hillock means that the action potential can travel in one direction - ...
down the axon
133
action potential continues from one node of Ranvier to another
faster a neuron fires = ... stimulus
more intense
134
for another action potential to be fired, ... has to be restored
... must be reset --> time for this to occur is the ...
if this wasn't here neuron would be depolarized the entire time and nothing would happen, because there would be no recognition of ... of stimulus, because the neurons would just remain depolarized and would keep firing based on the very first signal
resting membrane potential;
sodium channels; absolute refractory period;
absolute refractory period;
frequency;
135
absolute refractory period:
about ... from the time threshold is generated; incapable of firing another action potential during this time;
most K+ channels still open during this period --> ... is still occurring, causing ..., which ensures that if a train of signals is occurring they're of sufficient energy to stimulate another action potential
1ms; repolarization; undershoot;
136
conductance velocities:
signal doesn't leak due to ..., which means that action potentials occur extremely
quickly --> ... + distribution of ... only at ... allows for these high conductance speeds
myelin; insulator; voltage gated channels; nodes
