Neuromuscular Junction

Question 1

What gap junctions made of?

Answer 1

Connexon channels

Question 2

What type of synapses are gap junctions?

Answer 2

Electrical synapses

Question 3

Where are gap junctions (electrical synapses) present?

Answer 3

In cardiac and smooth muscle

Question 4

Where are chemical synapses present?

Answer 4

Skeletal muscle

Question 5

What are gap junctions?

Answer 5

Connections between adjacent cells that allow the flow of ions and electrical pulses

Question 6

What is a chemical synapse?

Answer 6

Calcium concentration gradient at axonal terminal end triggering exocytosis of neurotransmitters

Question 7

How can Ach have different affects on different receptors?

Answer 7

Metabotropic: Muscarinic receptors leads to hyperpolarization ( increased K+)
Ionotropic receptors: leads to membrane depolarization

Question 8

What is retrograde and anterograde movement?

Answer 8

Retrograde: movement from axon terminal to the soma
Anterograde: movement from soma towards axon terminal

Question 9

What does kinesis do?

Answer 9

Carries vesicles from soma to axon ending via ATP

Question 10

What does dynein do?

Answer 10

Carries recycled vesicles from axon to some via ATP

Question 11

What negative affect can dynein have?

Answer 11

It can carry viruses from to the neuron nucleus

Question 12

What does the neural musculojunction include?

Answer 12

The motor endplate + axonal ending

Question 13

What is the purpose of the post-junctional fold?

Answer 13

To increase the surface area of the sarcolemma

Question 14

What is the purpose of SNARE proteins?

Answer 14

To mediate transmitter vesicle docking, fusion and release of cytokines

Question 15

What do v-SNAREs do?

Answer 15

Involved in vesicle binding

Question 16

What do t-SNAREs do?

Answer 16

Synaptic membrane binding

Question 17

What are common v-SNAREs?

Answer 17

Synaptobrevin and Synaptotagmin

Question 18

What are common t-SNAREs?

Answer 18

Syntaxin and SNAP-25

Question 19

How does Botox B and Tetanus toxin work?

Answer 19

By cleaving synaptobrevin

Question 20

How does Botox A work?

Answer 20

By cleaving SNAP-25

Question 21

What is the purpose of synaptotagmin work?

Answer 21

Binds Ca2+ triggering the release of vesicles

Question 22

Where is synaptobrevin located?

Answer 22

In the vesicle membrane

Question 23

Where is syntaxin located?

Answer 23

In the pre-synaptic membrane

Question 24

Where is SNAP-25 located?

Answer 24

In the pre-synaptic membrane

Question 25

Where is synaptotagmin located?

Answer 25

In the vesicle membrane

Question 26

What does MEEPs stand for and what is it?

Answer 26

Miniature-endplate potentials; it is the amount of ACh released from one vesicle

Question 27

How much depolarization does one MEPP amount to?

Answer 27

.4 mV

Question 28

What is one quanta?

Answer 28

One MEEP/one vesicle release

Question 29

What do SNARE proteins use for energy?

Answer 29

GTP for fusion

ATP for release

Question 30

What occurs in Myasthenia Gravis?

Answer 30

Autoreactive antibodies bind to AChR blocking the binding of ACh

Question 31

What is collapse fusion?

Answer 31

When the vesicle becomes a part of the membrane

Question 32

What is the clinical significance of myasthenia gravis?

Answer 32

Causes asymmetrical ptosis

Question 33

What is Lambert-Eaton Syndrome?

Answer 33

Ca2+ channel autoimmune deficiency

Question 34

What occurs in LE syndrome?

Answer 34

Antibodies attack calcium channels resulting in a reduced number or channels which reduces the amount of neurotransmitter release