Week Three Day 2

Question 1

These channels are voltage gated and are the primary reason for threshold to be reached and an action potential to be generated.

Answer 1

321 Pre-Reading: Na+ channels, this leads to the Hodgkin’s cycle and threshold being reached, causing the all or nothing action potential.

Question 2

During the rapid upswing of an action potential these channels open quickly and are responsible for the depolarization effect:
A: Voltage gated Na+ channels
B: Voltage gated Ca2+ channels
C: Voltage gated Cl- channels
D: Voltage gated K+ channels

Answer 2

321 PPT (7 but also throughout): A

Question 3

During the rapid downswing of an action potential these channels are open and are responsible for the rapid repolarization effect:
A: Voltage gated Na+ channels
B: Voltage gated Ca2+ channels
C: Voltage gated Cl- channels
D: Voltage gated K+ channels

Answer 3

321 PPT (7 but also throughout): D

Question 4

Select all that apply:
During the upswing of the action potential these channels are open:
A: Voltage gated Na+ channels
B: Voltage gated Ca2+ channels
C: Voltage gated Cl- channels
D: Voltage gated K+ channels

Answer 4

321 PPT (9): A and D
The K+ channels open less quickly and stay open longer, this is why depolarization occurs. (and refractory period)

Question 5

True or False: Na+ channels transition from inactive to closed more quickly when the membrane potential is repolarizing or repolarized?

Answer 5

321 PPT (12): True

Question 6

True or False: Na+ channels can transition from the inactive to open state, this is what causes relative refractory.

Answer 6

321 PPT (12): False: this is the reason absolute refractory period exists.

Question 7

How does the brain distinguish between slight and severe pain?
A. Slight pain causes smaller action potentials than severe pain.
B. Slight pain causes fewer action potentials to be generated than severe pain.

Answer 7

321 Pre-Reading (1): B; Action potentials are all or nothing events. Size is not seen, only frequency.

Question 8

Why are cells not capable of turning off an action potential once threshold is reached?

Answer 8

321 Pre-Reading (6):
The threshold for action potential generation occurs when a depolarizing stimulus opens a sufficient number of Na+ channels such that the net current flowing into the cell is inward (i.e. the inward current through Na+ channels exceeds the outward current through K+ and Cl- channels). At this critical voltage, the depolarization produced by the initial stimulus begins to be amplified through the positive feedback of the Hodgkin cycle. The inward current produced causes more Na+ channels to open, more inward current, more depolarization, … . Once the cell enters this positive feedback cycle, there is no turning back until all available Na+ channels have opened and the membrane potential approaches the Na+ equilibrium potential. This sequence of events is what underlies the discrete nature of the action potential.

Question 9

How would sympathetic stimulation effect the heart? Parasympathetic?

Answer 9

322-324 HFF Nervous system drawing station (8):
Sym: Increase rate
Para: Decrease rate

Question 10

How would sympathetic stimulation effect the lungs? Parasympathetic?

Answer 10

322-324 HFF Nervous system drawing station (8):
Sym: Relax muscles (dilate airway)
Para:

Question 11

How would sympathetic stimulation effect the GI? Parasympathetic?

Answer 11

322-324 HFF Nervous system drawing station (8):
Sym: Decrease motility
Para: Increase motility

Question 12

How would sympathetic stimulation effect the bladder? Parasympathetic?

Answer 12

322-324 HFF Nervous system drawing station (8):
Sym: Contract sphincter
Para: Contract detrusor and relax sphincter

Question 13

How would sympathetic stimulation effect the blood vessels? Parasympathetic?

Answer 13

322-324 HFF Nervous system drawing station (8):
Sym: Relax (dilate) heart and skeletal
Contract (constrict) smooth muscle and skin
Para: Little action

Question 14

How would sympathetic stimulation effect the sweat glands? Parasympathetic?

Answer 14

322-324 HFF Nervous system drawing station (8):
Sym: Increase sweat production
Para: NOTHING

Question 15

True or False: Preganglionic parasympathetic neurons are longer than their postganglionic counter parts?

Answer 15

322 Pre-Reading (16): True

Question 16

True or False: Preganglionic sympathetic neurons are longer than their postganglionic counter parts?

Answer 16

322 Pre-Reading(16): False

Question 17

Which vertebrae have lateral horns? (be specific)

Answer 17

322 Pre-Reading:
T1-L2: Sympathetic
S2-S4: Para-sympathetic (also cranial)

Question 18

Which type of autonomic neurons release Ach?

Answer 18

322 Pre-Reading(16): All except post ganglionic sympathetic neurons.

Question 19

True or False: Post-ganglionic sympathetic neurons are located near or within their target?

Answer 19

322 Pre-Reading(16): False, they are located within sympathetic ganglion in sympathetic chains.

Question 20

What is the vertebral level at which the spinal cord normally ends in an adult?

Answer 20

324 IRAT Q5: L1/L2

Question 21

What is the highest level at which it is considered safe to perform a lumbar puncture in an adult? At the disc between vertebral levels

Answer 21

324 IRAT Q4: L3/L4