Neuromuscular Physiology I

Question 1

Skeletal tissue - histology

Answer 1

• long, cylindrical fibre
• striated
• multinucleated

Question 2

Cardiac tissue - histology

Answer 2

• short, branched
• striated
• single nucleus

Question 3

Smooth tissue - histology

Answer 3

• short, spindle shaped
• not striated
• single nuclues

Question 4

Skeletal tissue - function

Answer 4

• voluntary movement
• produces heat
• protect organs

Question 5

Cardiac tissue - function

Answer 5

contracts to pump blood

Question 6

Smooth tissue - function

Answer 6

• involuntary movement
• move food
• involuntary respiration
• secretions
• blood in arteries

Question 7

Muscle layers

Answer 7

muscle -> fascicles -> muscle fibres -> myofibrils

Question 8

4 steps of the myogenic pathway

Answer 8

1. MITOSIS of additional satellite cells
2. MYOTUBE formation
3. TRANSLOCATION of myotube across sarcolemma
4. FUSION of myotube withe existing myofibril

Question 9

Thick filament contractile properties

Answer 9

• 6-subunit myosin protein
• 2 MHCs
• 2 MLCs

Question 10

Thin filament contractile properties

Answer 10

• 2 twisted strings of spherical actin molecules
• tropomyosin on actin
• Troponin

Question 11

Tropomyosin role

Answer 11

blocks binding site

Question 12

Troponin role

Answer 12

moves tropomyosin out of the way to allow binding

Question 13

3 sub-class of troponin

Answer 13

• troponin C
• Troponin I
• Troponin T

Question 14

Troponin C role

Answer 14

calcium binding site

Question 15

Troponin I role

Answer 15

Inhibitory

Question 16

Troponin T role

Answer 16

binds troponin I to tropomyosin

Question 17

How is myosin activated before binding to myosin?

Answer 17

ATP hydrolysis

Question 18

Desmin

Answer 18

connects z-disk of sarcomeres from 2 myofibrils

Question 19

Nebulin

Answer 19

bond actin, non elastic

Question 20

Titin

Answer 20

connects m-line to z-disk. acts as molecular spring

Question 21

a-actin

Answer 21

forms z-disk

Question 22

what are the 4 main proteins in the cytoskeleton

Answer 22

1. Desmin
2. Nebulin
3. Titin
4. a-actin

Question 23

white matter vs grey matter

Answer 23

White matter in the brain is myelinated, whereas grey is unmyelinated

Question 24

Resting membrane potential value

Answer 24

-70mV

Question 25

How does a muscle action potential happen?

Answer 25

transmission of nerve impulses by NT across synaptic cleft to post-synaptic motor end plate (nicotinic receptors). opens voltage gated Na+ channels and depolarizes the plasma membrane

Question 26

What is the motor unit

Answer 26

the alpha motor neuron and muscles it innervates

Question 27

Motor unit ratio for fine movement

Answer 27

Low motor unit ratio; 1:1

Question 28

Motor unit ratio for gross movement

Answer 28

high motor unit ratio; 100:1

Question 29

What does the max force of a muscle directly relate to?

Answer 29

its cross-sectional area; independent of size

Question 30

What % of fibers are ‘slow twitch’?

Answer 30

45-55%