CTB NTK for Final

Question 1

Inward currents promote ________. Outward currents promote _______.

Answer 1

Inward currents promote depolarization. Outward currents promote (re)polarization.

Question 2

3 structural elements of ion channels

Answer 2

permeation module, gate module, and sensor module

Question 3

muscle fiber surrounded by _____, fascicle surrounded by ______, whole muscle surrounded by ______.

Answer 3

fiber surrounded by endomysium, fascile by perimysium, muscle proper by epimysium

Question 4

CapZ

Answer 4

binds to the barbed end of actin

Question 5

Titin

Answer 5

large protein that creates an elastic connection between z discs

Question 6

Nebulin

Answer 6

prevents actin polymerization

Question 7

Dystrophin

Answer 7

stabilizes plasma membrane of skeletal muscle (mutated in muscular dystrophy)

Question 8

What are the T-tubule Ca channels?

Answer 8

Dihydropyridine receptors (DHPR), they are voltage dependent and connect to RYR “feet” proteins that span the SR-T space

Question 9

What protein spans the SR-T space and is responsible for Ca release from the SR?

Answer 9

Ryanodine receptor (RYR) “feet” proteins

Question 10

What pumps Ca++ back into the SR?

Answer 10

SERCA (2 Ca pumped per ATP)

Question 11

What are the 3 activation states of muscle?

Answer 11

Contracting (myosin walks along actin, requires ATP, activated by Ca), relaxation (proteins inhibit actomyosin interactions), and rigor (ATP depleted, no passive stretching)

Question 12

Tropomyosin

Answer 12

blocks actin-myosin binding during relaxation

Question 13

Troponin: TN-C, TN-I, and TN-T

Answer 13

TN-C binds Ca, TN-I inhibits actin-myosin interaction and TN-T binds tropomyosin.

Ca binds to TN-C –> conformational changes move tropomyosin out of myosin binding site and allow actomyosin binding

Question 14

Advantages and disadvantages of longer muscles?

Answer 14

Advantages: greater shortening ranges and shortening rates. Disadvantage: require more ATP

Question 15

Classifying muscle types

Answer 15

Type I: slow twitch (red) have smaller diameter, are fatigue resistant, have more myoglobin, and have lipid droplets.

Type IIa: moderately fast and red

Type IIb: fast twitch (white) have low mitochondria content and low oxidative enzyme content.

Question 16

What is dystrophin?

Answer 16

The protein that transmits force of muscle contraction to ECM (in membrane), w/ homology to spectrin. It’s mutated/deficient in muscular dystrophy.

Question 17

What are some symptoms of myesthenia gravis?

Answer 17

Weakness and fatigue in skeletal muscles, ptosis (droopy eyelids), diplopia (double vision), impaired speech, etc.

Question 18

What causes MG? How to treat MG?

Answer 18

Caused by a problem in the NMJ – MEPPs are smaller (even w/ same amount of ACh). Treated w/ acetylcholinesterase inhibitors like prostigmin and mestinon