Chapter 7 and 8 - Electrical excitability and action potentials & Synaptic transmission and NMJ (2019) - Evals #5 by Keim Flashcards Preview

PHYSIOLOGY - 1st Year 1st Sem Comprehensive Exam > Chapter 7 and 8 - Electrical excitability and action potentials & Synaptic transmission and NMJ (2019) - Evals #5 by Keim > Flashcards

Flashcards in Chapter 7 and 8 - Electrical excitability and action potentials & Synaptic transmission and NMJ (2019) - Evals #5 by Keim Deck (24)
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1

In myelinated peripheral nerves, the myelin sheath is interrupted at regular intervals forming short uncovered areas. What are these areas called?

Nodes of Ranvier

2

What is TRUE regarding “use dependent” action of local anesthetics ?

Inhibition of Na+ current progresses in a time-dependent manner with increasing repetitive stimulation or firing of action potentials.

3

Which NMJ structure is targeted by tetanus toxin?

Synatobrevin

4

Which channel is activated to produce excitatory end plate current or called end plate potential (EPP) in the muscle membrane.

ACh receptor channel

5

Which part of Nav and Cav subunits are homologous to a single subunit of a voltage gated potassium channel?

Domains 1-4 of alpha subunit

6

What channel often give rise to a more sustained depolarizing current which is the basis for the long-lived action potentials in cardiac cells and smooth muscle cells?

Ca2+ channel

7

S stimulates A, what events will take place in the presynaptic terminal of the cell

Axonal membrane will be depolarized and action potential is generated

8

A patient was given a tubocurarine inhibitor. Which channel in the NMJ is the target of the drug?

Acetylcholine receptor channel

9

Sequence of simple action potential?

1. stimulation of action potential
2. depolarizing stimulus makes it more positive than the threshold
3. slower repolarization (negative going) phase
4. negative resting membrane potential

10

Replacing or destruction of acetylcholine which has the most important effect?

Destruction of Ach by AChE

11

An organic cation applied to an axon that Prevents the outward current of K+ and reveals Na+ inward?

Tetraethylammonium

12

True about graded response potential?

Hyperpolarization is always ineffective

13

Also known as Anomalous Rectifier which conducts more K in inward direction?

Kir K+ channels

14

Mr. Balboa is a famous boxer. After his bout he cannot raise his arms and his speech is slurred. What probability increases that it is not LEMS?

Mr. Balboa is not exposed to cold

15

As the graded response spreads, its magnitude decays exponentially with distance from the site of stimulation because of passive loss of electrical current to the medium. This decay is called?

Electrotonic conduction

16

The part of action potential that lies above 0 mv

Overshoot

17

True or False:

As the graded response spreads, its magnitude decays exponentially with distance from the site of stimulation.
TRUE

True

18

What is the nature of relationship between strength and duration of stimulus to evoke action potential?

Inversely proportional

19

10 y.o px had a punctured wound at right sole. Px had muscle spasms at right leg. Px was diagnosed with tetanus. The toxin blocks the fusion of synaptic vesicle (or cleaves) at what SNARE protein?

Vesicular SNARE Synaptobrevin (v-SNARE)

20

Increase Ca and Mg in presynaptic terminals have effect on quantal release of Acetylcholine and EPP?
A. Increase Ca2+, Increase Mg2+
B. Increase Ca2, Normal Mg2+
C. Decrease Ca2+, Decrease Mg2+
D. Decrease Ca2+, Normal Mg2+

B. Increase Ca2, Normal Mg2+

21

Which of the ff is responsible for the continuous depolarizing of nerve and skeletal cells?
a. Conotoxin
b. Tetrodotoxin
c. Tubocurarine
d. Nicotine

d. Nicotine

22

Which of the following locations has the least number of Na+ channels?
A. Nodes of ranvier
B. Unmyelinated portion
C. Myelinated portion
D. None of the choices

C. Myelinated portion

23

Which vesicular protein acts as calcium sensor thus favors fusion of the vesicles with the presynaptic membrane?
A. Synaptotagmin
B. Synaptobrevin
C. SNAP-25
D. Syntaxin A

A. Synaptotagmin

24

Steps in metabotropic receptor?

1. Muscarinic ACh receptor activation
2. Release of alpha-GTP + Beta-gamma from the heterotrimeric G protein
3. Activation of inward rectifier K+ channel by Beta-gamma
4. Membrane Hyperpolarization
5. Decrease in heart rate

p 208 Fig 8-3