exam 1 musculoskeletal physiology

Question 1

skeletal muscle

Answer 1

striated, tubular and multinucleate
voluntary
attached to skeleton

Question 2

smooth muscle

Answer 2

non striated, spindle shaped, uninucleate
involuntary
covers walls of internal organs

Question 3

cardiac muscle

Answer 3

striated, branched and uninucleated
involuntary
covers heart wall

Question 4

isotonic

Answer 4

load is constant, muscle shortens

Question 5

isometric

Answer 5

load is increasing, muscle doesn’t shorten

Question 6

muscle fiber characteristics

Answer 6

very long and multinucleate, surrounded by sarcolemma

Question 7

fascicle is made of what

Answer 7

made of muscle fibers

Question 8

muscle is made of

Answer 8

fascicles

Question 9

myofibrils are made of what and what do they do

Answer 9

thin and thin filaments, surrounded by sarcoplasmic reticulum
these make up the muscle fibers

Question 10

thick filament

Answer 10

myosin

Question 11

thin filament

Answer 11

actin

Question 12

types of troponin

Answer 12

T, I, C

Question 13

T troponin

Answer 13

tropomyosin

Question 14

I troponin

Answer 14

inhibits actin binding

Question 15

C troponin

Answer 15

binds calcium

Question 16

dystrophin function

Answer 16

holds sarcomeres together

Question 17

sarcolemma surrounds what?

Answer 17

muscle fibers

Question 18

what initiates contraction?

Answer 18

high intracellular calcium

Question 19

what causes relaxation?

Answer 19

low intracellular calcium

Question 20

where does contractile intracellular calcium come from?

Answer 20

sarcoplasmic reticulum

Question 21

what protein sequesters calcium into the SR?

Answer 21

SERCA

Question 22

what regulates calcium release from the SR?

Answer 22

RyR (ryanadine receptor)

Question 23

what does calsequestrin do?

Answer 23

binds calcium in the SR

Question 24

what is a dihydropuridine receptor?

Answer 24

it is a voltage gated calcium receptor on T tubules that activates RyR receptors

Question 25

ATP binds myosin to cause what?

Answer 25

released state

Question 26

ATP hydrolysis causes

Answer 26

myosin head to move to a cocked position

Question 27

calcium presence during the cocked state causes what?

Answer 27

binding of myosin to actin

Question 28

Pi is released and causes what?

Answer 28

strong cross bridge state and power stroke

Question 29

what happens after the power stroke?

Answer 29

ADP is released, and actin and myosin are bound until ATP binds

Question 30

what happens when calcium binds troponin C?

Answer 30

tropomyosin (troponin T) moves to reveal the myosin binding site on actin

Question 31

what causes tetanus?

Answer 31

large intracellular store of Ca++ due to repeated stimulation

Question 32

slow twitch muscle characteristics

Answer 32

red, do oxidative metabolism with high mitochondria and low glycogen

Question 33

Fast twitch type IIa muscle fiber characteristics

Answer 33

red, do oxidative metabolism with very high mitochondria and have abundant glycogen

Question 34

Fast twitch type IIx/b muscle fiber characteristics

Answer 34

fatiguable, white, glycolytic metabolism, fewer mitochondria and high glycogen

Question 35

what is frequency summation?

Answer 35

increased force within a single fiber by summing multiple twitches

Question 36

what is a motor unit

Answer 36

motor neuron and the muscle fibers that it innervates

Question 37

innervation ratio

Answer 37

myofibrils: neuron fast twitch: 1 neuron innervates many fibers slow twitch: 1 neuron innervates less fibers

Question 38

what is CICR

Answer 38

calcium induced calcium release, utilized by cardiac muscles because DHP is not linked to RyR

Question 39

cardiac action potentials driven by

Answer 39

Ca++ or Na+

Question 40

relative speed of each muscle

Answer 40

skeletal > smooth > cardiac

Question 41

what does the IP3 receptor do

Answer 41

mediated calcium release from the endoplasmic reticulum

Question 42

what does calcium calmodulin do?

Answer 42

activates MLCK to phosphorylate MLC, causes cross bridge cycling in cardiac and smooth muscle

Question 43

neuron AP causes release of

Answer 43

acetylcholine

Question 44

Ach receptor in muscle

Answer 44

nicotinic

Question 45

muscle APs cause depolarization of?

Answer 45

sarcolemma and T tubules, opens voltage gated Na+ channels

Question 46

what causes muscle contraction

Answer 46

increase in calcium

Question 47

what initiates fusion of the vesicle with the membrane?

Answer 47

calcium

Question 48

myasthenia gravis, cause and presentation

Answer 48

destruction of nicotinic receptors: droopy eyes, generalizes muscle weakness

Question 49

Lambert eaton cause and presentation

Answer 49

destruction of voltage gated calcium channels on the presynaptic side, gets better throughout the day