skeletal muscle physiology

Question 1

what is true of the neuromuscular junction of skeletal muscle
a. nicotine Ach is realsed
b. the motor end plate serves as the post synaptic density
c. the end plate potential can only be excited
d. all of the above

Answer 1

d

Question 2

what is not true of the excitation of a skeletal muscle contraction?
a. EPP is depolarized by Na+ rushing into the cell
b. the DEP receptor is electrically activated and allows Ca to exit the cell
c. DHP is mechanical and electrically connected
d. Ca is stored in the sarcoplasmic reticulum

Answer 2

d

Question 3

when DHP is activated what occurs (in order)
a. mechanically activated ryanodine is released
b. tropinin changes shape moves tropomyosin off of actin binding site
c. Ca is released from sarcoplasmic reticulum
d. Na depolarization switches DHP receptor on

Answer 3

d, a, c, b

Question 4

at an end plate potential there will always be an ___ ___

Answer 4

action potential

Question 5

______ takes a phosphate off of ATP and hooks it onto myosin head

Answer 5

ATPase

Question 6

what is true of cross bridge cycling?
a. charged myosin head attaches to actin binding site to begin power stroke
b. myosin then gets pulled closer to the midline and sarcomere shortens
c. The cross bridge cycling will continue with or without ATP
d. tropomyosin must be shifted over actin to continue cross bridge cycling

Answer 6

a

Question 7

relaxation of the somatic neuron stimulation involves stopping release and activation of what two things

Answer 7

DHP and ryodine

Question 8

______ removes Ca from cytoplasm and puts it back in storage

Answer 8

Ca ATPase

Question 9

which of these doesn’t play a direct role in relaxation
1. Ca ATPase
2. troponin & tropmyosin
3. elastic & connective tissue
4. Sodium

Answer 9

Sodium

Question 10

a myofiber twitch is

Answer 10

1 alpha motor neuron AP, 1 myofibril AP

Question 11

excitation to beginning of a contraction

Answer 11

latent period

Question 12

occurs when you don’t have complete relaxation between twitches

Answer 12

summation

Question 13

complete or fused tetanus means there is no relaxation of myofibrils; true or false?

Answer 13

true

Question 14

small motor units have what characteristics

Answer 14

small alpha motor neuron and small diameter myofibers

Question 15

larger motor units will be recruited first to execute a movement; true or false

Answer 15

false

Question 16

what is it called when you activated motor units are alternated to reduce fatigue

Answer 16

asynchronous recruitment

Question 17

which of these is true of phosphocreatine
a. creatine phosphate makes ATP
b. at rest: phosphocreatine + ADP –> creatine + ATP
c. is short term lasts 10-15 seconds
d. all of the above

Answer 17

c

Question 18

what happens to creatine phosphate after it is used

Answer 18

released into blood stream (2 isozymes can be used to detect heart attack based off what type of creatine is in blood.)

Question 19

what are two ways to make ATP

Answer 19

anaerobic respiration and aerobic respiration

Question 20

what is true of anaerobic respiration?
a. it is faster than aerobic but has a short duration of less than a minute
b. is limited to using glycogen and glucagon sources for energy
c. has an ATP yeild of 2
d. all of the above

Answer 20

d

Question 21

what is not true of aerobic respiration
a. glucose breaks all the way down to CO2 which is then exhaled
b. yeild 30-32 ATP
c. is for long endurance exercises
d. glucagon anf glycogen provide most of the ATP and energy

Answer 21

d.
fatty acids give the most energy

Question 22

fatigue that is characterized by no innervation of lower motor neuron or issues with mechanics of cross bridge cycling

Answer 22

peripheral fatigue

Question 23

with continued myofiber use what is lost to the interstitial fluid which effects the ability to repolarize (results in fatigue)

Answer 23

K+

Question 24

which of these are factors of fatigue?
a. lack of calcium to bind to troponin
b. high levels of ADP + Pi in cytoplasm may inhibit release of ADP from myosin heads
c. equilibrium within cell and cytoplasm
d. dehydration & low blood sugar
e. all of the above

Answer 24

e

Question 25

what removes lactic acid and sends it to the liver to be filtered and released to the blood stream to be coverted into glucose

Answer 25

cori cycle

Question 26

what is not true of fast twitch fibers
a. high ATPase fibers
b. crossbridge cycling 2-3x faster than slow twitch
c. low CaATPase activity
d. all of the above

Answer 26

c

Question 27

what fibers have high myoglobin, blood supply and mitochondria (small diameter)

Answer 27

oxidative fibers

Question 28

do anaerobic respiration have large diameter, less myoglobin and mitochondria

Answer 28

glycolytic fibers

Question 29

which is not a characteristic of a slow twitch or slow oxidative fiber (type I)
a. slow contraction
b. fatigue quickly
c. small in diameter
d. can’t build much force

Answer 29

b

Question 30

which is a characteristic of a fast twitch or fast oxidative glycolytic fiber (type IIa ) ?
a. fast contraction
b. resist fatigue longest
c. built a lot of force
d. smallest in diameter

Answer 30

a

Question 31

fastest contraction, fatigue quickly, and build a lot of force; these are characteristics of what muscle fiber?

Answer 31

fast twitch glycolytic (type 2b)

Question 32

what disease kills alpha motor neuron and results in flaccid paralysis

Answer 32

polio

Question 33

disease characterized by lack of dystophin and degradation of muscle cells

Answer 33

muscular dystrophy

Question 33

autoimmune disease, antagonistic antibodies mimic Ach; results in decreased sensitivity to Ach

Answer 33

myasthenia gravis