Physio released exam (titled "PhysioIMG_10##")

consider a non-charged, permeable solute, "x". Which of the following statements would be correct at equilibrium?

a. the net flex of X across the membrane would be zero

b. the individual fluxes of X across the membrane in both directions would be zero

c. the concentration of X inside the cell would be equal to the concentration outside the cell

d. A and C

e. B and C

d. A and C

Compartments A and B are separated by a membrane that is permeable to K+ but not to Na+ or Cl-. At time zero, a solution of KCl is poured into compartment A and pure H2O is poured into compartment B. At equilibrium...

a. the concentration of K+ in A will be lower than it was at time zero

b. the diffusion of K+ from A to B will equal to diffusion of K+ from B to A

c. there will be a potential difference across the membrane, with side A negative relative to side B

d. B and C

e. A B and C

e. A B and C

compared to extracellular fluid, the inside of a typical excitable cell has

a. a greater concentration of protein

b. a lower concentration of K+

c. a greater concentration of Na+

d. a large negative resting membrane potential

e. two of the above are true

e. two of the above are true (a and d)

Ion channels in cell membranes

a. may open in response to a change in potential difference across the membrane

b. are non-specific (i.e. every channel can allow passage of any ionic species)

c. may open in response to binding a ligand

d. A and C

e. B and C

d. A and C

The channels through which ions flow during the rapid rising phase of the action potential and are involved in a positive feedback cycle are

voltage-regulated Na+ channels

the equilibrium potential for an ionic species is..

a. the concentration gradient that allows an ion to flow into a cell

b. the membrane potential that would need to exist to exactly balance the concentration gradient for that ion across the plasma membrane

c. the membrane potential that would exist if the permeability of the ion increased to infinity

d. the concentration gradient at the peak of the action potential

b (b was in red which means the correct answer but c was highlighted so i'm not really sure the correct answer, when i looked it up it seems that b is correct)

the resting membrane potential of a typical excitable cell would move toward 0 volts (i.e. depolarize) most directly because of which of the following? Assume normal intracellular and extracellular fluid compositions and normal resting permeabilities initially.

a. a decrease in the permeability of K+

b. a decrease in the permeability of Na+

c. a decrease in the extracellular concentration of Na+

d. a decrease in the extracellular concentration of K+

e. all of the above would be equally effective

a. a decrease in the permeability of K+

the increased rate of action potential conduction (propagation) in an axon surrounded by Schwann cells, compared to an axon with the same diameter but without myelin, is due to:

a. there is a greater amount of Na+ passing everywhere through the membrane

b. K+ ions are concentrated only at the nodes in myelin sheath

c. ionic currents do not pass through the membrane at every site along the axon

d. a greater resistance of cytoplasm within the axon

e. an increase in K+ permeability during the repolarization phase of the action potential

C

a suprathreshold (i.e. greater than threshold) stimulus is required, and is effective, to elicit an action potential during the

a. latent period

b. absolute refractory period

c. relative refractive period

d. none of the above

c. relative refractive period

the stimulus strength-duration curve of a neuron..

a. relates the magnitude of a stimulus to the duration of an isotonic contraction

b. relates the magnitude of a stimulus to its required duration for effective stimulation

c. relates the duration of a stimulus to the strength of an isometric concentration

d. relates the magnitude of an isometric twitch to the duration of the same twitch

e. none of the above

B

for a cation with two charges (i.e. divalent) that is present in the extracellular fluid at a concentration that is ten times greater than its concentration inside a cell, its equilibrium potential will be approximately...

a.+29 mV

b. +116 mV

c. 0 mV

d. -58mV

e. -116 mV

A. +29 mV

which of the following is most directly responsible for the unidirectional characteristic of the propagation of an action potential along an axon?

a. local currents

b. the all or none characteristic of the action potential

c. the refractory period

d. the relative permeabilities in the resting state

e. schwann cells that make myelin

c. the refractory period

transmitter release from a motoneuron terminal is associated with each of the following EXCEPT:

a. fusion of vesicles with the presynaptic membrane

b. outward passive diffusion of Na+ ions from the presynaptic terminal

c. an action potential having invaded the presynaptic terminal earlier

d. subsequent generation of an endplate potential

e. the inward flow of Ca2+ ions into the presynaptic terminal having occured

B

what is the event that causes depolarization of the motor endplate, following the binding of acetylcholine to its receptor at the neuromuscular junction

the influx of Na+ ions through chemically-regulated channels

botulinum toxin..

a. binds to acetylcholine receptors, causing flaccid paralysis

b. binds to acetylcholinesterase, causing spastic paralysis

c. blocks release of acetylcholine from motor neuron terminals, causing flaccid paralysis

d. two of the above

C

during isometric contraction in skeletal muscle,

a. sarcomere length does not change

b. the I bands shorten about 50% and the A bands stay the same

c. the thick and thin filaments slide past each other about 50%

d. the H-zone disappears

e. b and c are correct

A. sarcomere length does not change

which of the following would occur during lengthening of resting muscle, if it was stretched by an external force?

a. increase in A band width

B. increase in I band width

c. Increase in H zone width

d. two of the above

e. none of the above

D. two of the above ( b and c)

Ca2+ ions are released from which of the following in skeletal muscle to initiate contraction?

a. transverse tubules

b. troponin C

c. lateral sacs of the sarcoplasmic reticulum

d. the sarcoma

e. presynaptic vesicles

c. lateral sacs of the sarcoplasmic reticulum

loss of which of the following would most likely destabilize the position of the A-bands of skeletal muscle?

a. nebulin

b. titin

c. troponin T

d. actin

e. tropomyosin

b. titin

the latent period would be expected to be longest in ..

a. an isometric contraction in which a small amount of force is generated

b. an isometric contraction in which a large amount of force is generated

c. an isotonic contraction in which a small load is moved

d. an isotonic contraction in which a large load is moved

D. an isotonic contraction in which a large load is moved

the decrease in the amount of tension generated in skeletal muscle at sarcomere lengths greater than the plateau region of the force/ length relationship is due to a decrease in:

a. the number of cross-bridges that form following activation

b. thin filament length

c. the I band length

d. the H band length

e. both b and C

a. the number of cross-bridges that form following activation

the immediate effect of ATP binding to an attached cross-bridge is:

a. the power stroke, during which filaments slide past each other

b. the return stroke, i.e. myosin undergoes one of two conformational changes

c. hydrolysis of ATP to ADP and Pi

d. detachment of myosin to actin

e. force generation

D. detachment of myosin from actin

slow muscle fibers in limb muscles, compared to fast muscle fibers...

a. tend to be larger in diameter

b. contract more rapidly

c. fatigue more slowly

d. contain the same protein isoforms

e. none of the above are correct

c. fatigue more slowly

cardiac muscle cannot undergo a tetanic contraction due to..

a. a long refractory period

b. action potential passing through gap junctions very slowly

c. a net loss of Ca 2+ only during phase 4 of the action potential in ventricular cells

d. a net loss of Na2+

a long refractory period

on average, the amount of Ca2+ sequestered by sarcoplasmic reticulum during a single cardiac contraction -relaxation cycle is equal to

a. the amount of ca2+ that triggers release from the sarcoplasmic reticulum

b. the amount of ca2+ that is pumped out of the cell by the Ca2+-ATPase in the sarcolemme

c.the amount of ca2+ released from the sarcoplasmic reticulum

c.the amount of ca2+ released from the sarcoplasmic reticulum

which of the following is a FALSE statement

a. single-unit muscle cells are often activated by stretch

b. single-unit smooth muscle cells are usually active spontaneously

c. single-unit smooth muscle cells are usually activated independently

d. gap junctions are rarely present in multi-unit smooth muscles

e. none of the above are false statements

c. single-unit smooth muscle cells are usually activated independently

smooth muscle contraction is mediated by the phosphorylation of _______, which occurs as a result of a chain of biochemical events including the binding of calcium ions to _________

a. ADP, calmodulin

b. calmodulin, myosin

c. actin, troponin

d. myosin, troponin

e. myosin, calmodulin

e. myosin, calmodulin

surgical removal of which part of the temporalis muscle would most directly lead to the greatest reduction in ability to undergo rapid, powerful contractions

a. anterior

b. middle

c. posterior

d. all of the above would have an identical effect

e. none of the above- the temporalis muscle is uniformly and exclusively composed of slow fibers

c. posterior

which of the following is/ are not part(s) of a muscle spindle?

a. nuclear bag intrafusal fiber

b. extrafusal fiber

c. Ia afferent fiber

d. IIa afferent fiber

e. two of the above

b. extrafusal fiber

a decrease in muscle length would likely cause a decrease in action potential frequency in which of the following

a. afferent fibers having primary endings

b. afferent fibers having secondary endings

c. beta motoneurons

d. gamma motoneurons

e. two of the above

e. two of the above

which of the following would most likely occur during bruxing, following a completely relaxed state in which the teeth are in full occlusion

a. increase in action potential frequency in Golgi tendon organs in jaw closure

b. increase in muscle spindle activity in jaw openers

c. decrease in muscle spindle activity in jaw openers

d. decrease in action potential frequency in Golgi tendon organs in jaw openers

e. all of the above

a. increase in action potential frequency in Golgi tendon organs in jaw closure

which of the following contributes to maintaining muscle spindle sensitivity

a. inhibition of gamma motor neurons during muscle shortening

b. decrease in afferent activity during muscle lengthening

c. increase in action potential frequency in gamma motor neurons after muscle shortening

d. increase in afferent activity during muscle shortening

e. none of the above

c. increase in action potential frequency in gamma motor neurons after muscle shortening

a pattern generator for mastication probably resides within the

a. cerebral cortex

b. brainstem

c. cerebral cortex and cerebellar cortex

d. cerebellar cortex

e. area postrema of the medulla

b. brainstem

the cell bodies of motoneurons, that innervate jaw-closing muscles, are located primarily in which of the following?

a. trigeminal mesencephalic nucleus

b. facial motor nucleus

c. hypoglossal motor nucleus

d. trigeminal motor nucleus

e. none of the above

d. trigeminal motor nucleus

during the preparatory phase of swallowing

a. the food bolus is formed

b. the lip of the tongue presses against incisors or anterior hard palate

c. the tongue rises against buccal teeth (premolars, molars)

d. glossopharyngeal sphincter forms

e. all of the above

e. all of the above

the jaw-opening reflex

a. involves a path between stimulus and response that has more than one synapse

b. is initiated primarily by activation of Golgi tendon organs in jaw opening muscles

c. is initiated primarily by activation of Golgi tendon organs in jaw closing muscles

d. includes the mesencephalic nucleus that has a prominent role in this reflex

e. none of the above is true

a. involves a path between stimulus and response that has more than one synapse

37. concerning suckling in infants

a. only jaw closing muscles have a prominent role

b. is virtually identical to adult sucking with respect to involvement of specific muscles

c. lowering of mandible alone in sufficient for espression of milk

d. begins to develop in utero

e. none of the above

d. begins to develop in utero

which of the following muscles is least likely to be utilized during swallowing before tooth eruption

a. tongue

b. buccinators

c. masseter

d. orbicularis oris

e. none of the above- i.e. all of these are essential

c. masseter

which of following is true statement concerning the control of swallowing

a. the pharyngeal phase can be under voluntary control

b. dorsal interneurons in the brain stem are involved in the initiation and programming of swallowing

c. ventral interneurons directly stimulate muscles (i.e. they are motor neurons) involved in swallowing

d. the esophageal phase can be under voluntary control

e. all of the above are true

b. dorsal interneurons in the brain stem are involved in the initiation and programming of swallowing

which of the following is/ are characteristic of expulsion during vomiting

a. upper esophageal sphincter relaxes

b. intrathoracic pressure increases

c. intra-abdominal pressure increases

d. antrum if stomach relaxes

e. all are characteristics of expulsion

e. all are characteristics of expulsion