Muscles 2

Question 1

brain regions involved in voluntary movement

Answer 1

primary motor cortex (premotor cortex, basal ganglia, thalamus, midbrain, cerebellum)

Question 2

corticospinal tract

Answer 2

descending tract (ventral and interior lateral white matter)

Question 3

upper motor neuron

Answer 3

brain to spinal cord

Question 4

alpha (lower) motor neuron

Answer 4

spinal cord to muscle

Question 5

motor unit

Answer 5

a single motor neuron and all the muscle fibres it innervates

Question 6

neuromuscular junction

Answer 6

area where motor neuron makes synaptic contact with the muscle fibre

Question 7

All muscle fibers respond….

Answer 7

simultaneously

Question 8

ALS

Answer 8

amyotrophic lateral sclerosis; upper and lower motor neurones degenerate leading to weakness from disuse (of muscles)

Question 9

three components of neuromuscular junction

Answer 9

• presynaptic motor neuron filled with synaptic vesicles
• synaptic cleft
• post synaptic membrane of skeletal muscle fibre

Question 10

motor end plate

Answer 10

region of sarcolemma at the neuromuscular junction

Question 11

Theres usually ____________ that cover the neuromuscular junction

Answer 11

schwann cells

Question 12

junctional folds

Answer 12

increase surface area to fit in as many nicotinic ACh receptors as possible

Question 13

motor neuron vesicles contain…

Answer 13

acetylcholine

Question 14

muscle sarcolemma contains…

Answer 14

nicotinic acetylcholine receptors

Question 15

nicotinic acetylcholine receptors are….

Answer 15

monovalent cation channels

Question 16

opening of Each receptors require…

Answer 16

two ACh molecules

Question 17

Na+ entry through nACh receptors….

Answer 17

generates an excitatory end-plate potential and initiates an action potential

Question 18

Once AP’s stop firing in the alpha motor neuron, acetylcholine in the synaptic cleft must be,,,,

Answer 18

removed and diffuse away or be broken down

Question 19

What does ACh break down into?

Answer 19

acetate and choline

Question 20

what breaks down ACh?

Answer 20

acetylcholinesterase

Question 21

what makes acetylcholine?

Answer 21

choline (recycled) and acetyl CoA

Question 22

where is acetyl CoA produced?

Answer 22

from mitochondria

Question 23

choline acetyltransferase

Answer 23

produce acetyl CoA in mitochondria

Question 24

myasthenia gravis

Answer 24

disorder of neuromuscular transmission; body produces antibodies that bind to ACh receptors; causes degeneration of postjunctional folds

Question 25

sarcoplasmic reticulum

Answer 25

specialized calcium storage organelles organized within t-tubules

Question 26

t-tubules

Answer 26

how sarcolemma penetrates into muscle fibre

Question 27

excitation-contraction coupling

Answer 27

process by which electrical excitation of surface membrane triggers an increase of [Ca2+] in muscle

Question 28

rise in [Ca2+] intracellularly

Answer 28

triggers contraction in all muscle types

Question 29

How can Ca2+ enter the sarcoplasm?

Answer 29

• from extracellular space via voltage gated channels

- released from storage reservoir of sarcoplasmic reticulum

Question 30

T-tubulespenetrate the muscle fibre and surround myofibrils at which points in each sarcomere?

Answer 30

at the A and I band junctions

Question 31

cisternae

Answer 31

specialized end regions of sarcoplasmic reticulum

Question 32

triad

Answer 32

t-tubules with two cisternae