Hf1 - Stauber Nmj

Front 1

What is a motor unit composed of?

Back 1

single axon, which then results in many muscle fibers contracting

Front 2

What is the difference between Weakness and Fatigue

Back 2

Weakness is the loss of strength while fatigue is a time dependent weakness.

Example: You can have 20% muscle weakness constantly. You can have no muscle weakness, but do heavy lifting and become fatigued and unable to perform maximally

Front 3

Non-eye Type I muscle (color, speed, mode)

Back 3

white, fast, glycolytic

Front 4

Non-eye Type II Muscle (color, speed, mode)

Back 4

red, slow, oxidative

Front 5

CMAP

Back 5

recorded muscle potential that is a result of multiple motor units being stimulated resulting in increased force

Front 6

What is the structure of the Neuromuscular Junction (3 structures)?

Back 6

Presynaptic terminal, axon, and synapse. There is also a postsynaptic terminal

Front 7

What does graded potential mean? Give some examples.

Back 7

A graded potential is one that is time and concentration dependent. For example an EPP and pacemaking Sinoatrial Node are graded

Front 8

What is a EPP (endpoint potential)?

Back 8

An endpoint potential is a nonpropagated membrane depolarization

Front 9

What is a MEPP?

Back 9

Miniature Endpoint potential. This depolarization occurs by chance and releases some Ach

Front 10

What are the properties of the neuromuscular junction

Back 10

unidirectional, sensitive to drugs, signal delay, EPP, and amplification

Front 11

What are the prejunctional events in the NMJ?

Back 11

synthesis of ACh, packaging, vesicle supply and Ach release.

Front 12

The Ach receptor binds how many ACh?

Back 12

2

Front 13

What happens to the choline in the synaptic cleft?

Back 13

It gets recycled by transfer back into the presynaptic cleft. This can be inhibited by hemicholinium

Front 14

What is the Na+Choline co-transport system?

Back 14

This is what is used to reuptake choline into the presynaptic cleft.

Front 15

How do we calculated the number of vesicles released from a NMJ?

Back 15

N = Qr x p
Qr is the quantums released
p is the probability of release

Front 16

What triggers the release of Ach into the NMJ?

Back 16

Voltage-gated channels of the (L-type, lazy) allow Ca2+ to enter the nerve terminal

Ca2+ then triggers exocytosis of ACH

Front 17

What are the two steps in the exocytosis of ACh into the NMJ?

Back 17

First the vesicle docks with a docking protein and then releases its contents upon fusing

Front 18

How is calcium removed from the presynaptic terminal?

Back 18

This is done by a process of a Na+-Ca2+ exchanger, it is a slow process

Front 19

What are the events in a synaptic cleft?

Back 19

Diffusion of ACh, Binding of Ach to receptors (2 Ach/receptor), inactivation of ACh

Front 20

What are the post-junctional events in NMJ?

Back 20

Ion permeability change, the Na+/K+ channel which allows for EPP and muscle action

Front 21

What is post-tetanic facilitation (PTF) as it relates to the NMJ?

Back 21

A small amount of excess calcium accumulates in teh terminal, which makes a greater number of vesicles fuse, releasing more ACh and an amplified response.

However eventually too much stimuli will deplete Ach which will lead to failure to produce an AP

Front 22

What can hinder ACh synthesis?

Back 22

Cyanide, Choline deficiency, Hemicholinium

Front 23

How can ACh transmission fail?

Back 23

decrease EC Ca2+, Increase EC Mg2+, Botulinium Toxin, and Microtubular distrupting drugs

Front 24

What is the difference between curare and alpha bungarotoxin?

Back 24

Well they are both ACh receptor blockers.
Curare is a competitive inhibitor (reversible) while alpha bungarotoxin is irreversible

Front 25

What two compounds can lead to persistant depolarization of the post-synaptic membrane and what does this mean?

Back 25

Succinylcholine (reversible)
Decamethonium

This means that the membrane has been depolarized for so long that no further AP are created

Front 26

What is the effect of marginal NMJ have on CMAP?

Back 26

we see that there is a decremental response and that the post-tetanic potential worsens

Front 27

What are two drugs/compounds that alter ACh destruction and what do they do?

Back 27

Edrophonium (tensilon) is a reversible competitor that blocks AChE. It is useful in treating Myasthenia Gravis

DFP - diisofluorophosphate is irreversible and leads to systemic NMJ failure and paralysis (ACh remains in the NMJ... overstimulation)