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OSSF EXAM 2: QUESTIONS WITH CORRECT ANSWERS
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OSSF EXAM 2: QUESTIONS WITH CORRECT ANSWERS
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OSSF EXAM 2: QUESTIONS WITH CORRECT ANSWERSWhat is conductance and what is its relationship with resistance? Right
Ans - measure how easily an ion moves through a membrane
inverse relationship with resistance
What parts of the eye are vascular? Right Ans - sclera, choroid, ciliary body,
iris
What are purkinje fibers? Right Ans - specialized cells of cardiac muscle
which coordinate contraction and conduct electrical signals
Tectospinal tract Right Ans - motor pathway originating in the tectum of
the midbrain
orientation towards auditory or visual stimuli
List the five motor pathways Right Ans - rubrospinal tract
vestibulospinal tracts
reticulospinal tracts
tectospinal tracts
corticospinal tracts
vomeronasal system Right Ans - detection of chemical stimuli such as
pheromones and relays info to accessory olfactory bulb
list the three sensory pathways Right Ans - medial leminscal
spinothalemic
spinocerebral
how does the membrane act as a capacitor? Right Ans - separates the
different changes in and out of the cell membrane?
hyperpolarization Right Ans - makes cell more negative
increasing potential energy
depolarization Right Ans - makes cell more positive
decreasing potential energy
,what drives ion movement across membrane? Right Ans - membrane
permiability
electrical and chemical gradients
why is the cell negatively charged at rest? Right Ans - large intracellular
anions
types of channels involved in membrane potential? Right Ans - ligand-
gated
mechanically-gated
voltage-gated
leak
is Na greater in or out of the cell at resting potential? Right Ans - out
is K greater in or out of the cell at resting potential? Right Ans - in
is Ca greater in or out of the cell at resting potential? Right Ans - out
is Cl greater in or out of the cell at resting potential? Right Ans - out
why does permeably impact membrane potential? Right Ans - will be
influenced by ion with highest permiability
what ions are most permeable to membrane at rest and why? Right Ans - K
because of the leak channels
slowly leak out of the cell increasing negativity
function of Na/K pump
energy requirements? Right Ans - ATPase pumps 3 Na out of the cell and 2
K ions in to hyperpolarize cell
most energy expensive function of the body (10-40% of ATP available)
what happens without the Na/K pump? Right Ans - ions concentrations
would reach equilibrium
too much Na would enter cell followed by water followed y lysis
easily excitable cells
graded potential
,what is amplitude dependent on? Right Ans - small shift in resting
membrane potential in either direction
amplitude is dependent on stimulus intensity
action potential
what is stimulus intensity correlated with? Right Ans - large, short
depolarization that is propagated for communication
AP frequency correlated with stimulus intensity
three phases of action potential initiation Right Ans - depolarization -
opens voltage-gated Na+ -> Na rushes in cell -> voltage-gated Na channels
close and voltage-gated K open before Na equilibrium is met
repolarization - K flows out of cell
hyperpolarization - voltage-gated K channels close and membrane potential
restored though K leak channels and Na/K pump
when does K favor electric gradient? Right Ans - resting membrane
potential
when does K favor concentration gradient? Right Ans - during
repolarizaton after and AP
absolute refractory perior Right Ans - immediately after initiation of action
potential when no other AP can be generated
depolarization and repolarization phases
relative refractory period Right Ans - when second action potential can be
generated with stronger stimulus
hyperpolarization phase
two gates on voltage Na channels
when are each of them closed Right Ans - extracellular activation gate
closed at rest
intracellular gate open at rest and will close when cell is not at resting
potential
AP response to larger stimulus Right Ans - amplitude will never change
frequency of AP will increase
, what phase of an action potential will differ across cell types most
significantly? Right Ans - repolarization phase
how are action potentials used in neurons, muscle cells, and endocrine cells?
Right Ans - neurons - chemical communication
muscle cells - contraction
endocrine cells - secretion
describe summation of potentials in neurons and how the firing of an action
potential is decided Right Ans - both excitatory and inhibitory potentials
travel to the Na voltage-gated channel rich axon hillock to be summed
if depolarization reaches threshold ap is initiated
describe the transmission of sound Right Ans - waves enter the tympanic
membrane and cause bones (osscles and stapes) to vibrate ->
pressure waves of the perilymph ->
oscillations of the vestibular membrane ->
endolymph pressure change ->
stereocilia bathed in endolymph deflection ->
electrical signal as K channels open and depolarize the hair cell ->
Ca influx causes glutamate release
voltage threshold has been met at the axon hillock and Na channels have
opened
where does the AP travel next? what structures reamplify the AP? Right
Ans - down the axon towards synapse and reamplified at unmyelinated nodes
of ranvier
how do nodes increase speed via saltatory conductance? Right Ans -
increased Na channels
voltage threshold has been met at the axon hillock and Na channels have
opened
what prevents the AP from moving backwards? Right Ans - K leave
axoplasm after depolarization to repolarize axolemma
how does myelin impact AP propagation? Right Ans - insulation decreases
capacitance and increases signal speed
prevents sticking to walls to axon
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