Neuromuscular junction

Question 1

what is the somatic motor division

Answer 1

neuron that originates from CNS and projects its axon to the target tissue - skeletal muscle

Question 2

the synapse of the somatic motor neuron on a muscle fiber is called what

Answer 2

neuromuscular junction

Question 3

what do motor neurons stimulate

Answer 3

skeletal muscles

Question 4

what makes up the motor unit

Answer 4

one motor neuron axon and its branches to multiple muscle fibers

Question 5

physical elements of NMJ

Answer 5

-presynaptic axon terminal (filled with synaptic vesicles and mitochondria)
-synaptic cleft
-postsynaptic membrane

Question 6

what neurotransmitters are contained in vesicles in the pre synaptic terminal

Answer 6

acetylcholine

Question 7

what kind of receptors are on the post synaptic terminal of NMJ

Answer 7

nicotinic ACh receptors

Question 8

what are the key players in NMJ events

Answer 8

acetylcholine
nicotinic ACh receptor
acetylcholinesterase

Question 9

what occurs at the end plate potential

Answer 9

sodium ions enter the muscle fiber when acetylcholine gated channels open causes the electron potential inside the fiber at the local area to increase

Question 10

what is the resting membrane potential in skeletal muscle fibers

Answer 10

-80 to -90mV

Question 11

how long is the duration of an action potential

Answer 11

1-5 milliseconds

Question 12

why must the current penetrate deep into the myofibrils

Answer 12

because the fibers are so large that the action potentials cause almost no current deep in the fiber

Question 13

how is the transmission of the action potential reached deep in the muscle fiber

Answer 13

along T- tubules

Question 14

voltage gated changes sensed by dihydropyridine receptors are linked to release of what

Answer 14

calcium

Question 15

calcium release channels are also called what

Answer 15

ryanodine receptor channels

Question 16

what binds calcium

Answer 16

calsequestrin

Question 17

calcium binds to what in the cross bridge formation

Answer 17

troponin

Question 18

steps in initiating muscle contraction

Answer 18

1. Ach released binding to receptors
2. action potential reaches T tubule
3. sarcoplasmic reticulum releases Ca
4. active site exposure - cross bridge formation
5. contraction begins

Question 19

steps in muscle relaxation

Answer 19

1. Ach broken down by AChE
2. sarcoplasmic reticulum recaptures Ca
3. active sites covered, no cross bridge interaction
4. contraction ends
5. passive relaxation occurs - back to normal resting length

Question 20

botulinum toxin

Answer 20

caused by toxin clostridium botulin (causes botulsim)

Question 21

when botulinum toxin is consumed what happens

Answer 21

prevents muscles from responding to nerve impulses

Question 22

what does botulinum toxin block the release of

Answer 22

ACh

Question 23

botulinum toxin for migraines

Answer 23

injected around pain fibers where the nerve and muscle meet (around affected area of headache)
prevents headaches before they start

Question 24

how long does one treatment of botox last for headaches

Answer 24

10-12 weeks

Question 25

what are the risks of botox for headaches

Answer 25

toxin accidentally spreading into the body

Question 26

what are the side effects of botox

Answer 26

trouble speaking or swallowing, difficulty breathing, muscle weakness

Question 27

Myasthenia gravis

Answer 27

autoimmune condition

Question 28

what does the body produce antibodies against in myasthenia gravis

Answer 28

motor end plate Ach receptors

Question 29

what are symptoms are myasthenia gravis

Answer 29

extreme msucle weakness

Question 30

is myasthenia gravis inherited

Answer 30

no

Question 31

what is the cure for myasthenia gravis

Answer 31

none

Question 32

what is the antagonist that blocks the actions of Ach at the receptor channel

Answer 32

curare

Question 33

what does curare bind to

Answer 33

Ach receptors

Question 34

how does curare affect ion permeability

Answer 34

doesn’t alter ion permeability
it is NOT inactivated by AChE

Question 35

what are organophosphates

Answer 35

group of chemicals that modify the NMJ

Question 36

what do organophosphates do

Answer 36

irreversibly inhibit AChE