muscle physiology 4

Question 1

what are the 2 ways force can be increased?

Answer 1

1. Increase number of motor units being activated
2. Increase rate of contractions per second

Question 2

at a low frequency is there tetanus?

Answer 2

NO, only twitches

Question 3

what are things you need to contract a muscle rapidly?

Answer 3

1. Rapid release of Ca+ (Larger SR = faster release)
2. ATP hydrolysis needs a very active ATPase isoform
3. Fast product release step (fast myosin isoform)

Question 4

how many ATP are used in a contraction sequence? when is each used?

Answer 4

2!

1. Provides energy for crossbridge movement
2. ATP binding to myosin breaks myosin-actin bond

Question 5

When maximal response is obtained with the maximal recruitment, how can you increase the force even further?

Answer 5

Increase the frequency of nerve stimulation to the motor units and have the muscles go into wave summation and tetany

Question 6

________ contraction happen when tehre is enough force to overcome inertia and muscle shortens as it contracts (bicep curls, leg curls, etc)

Answer 6

Concentric

Question 7

_________ contractions occur when you are decelerating an object or body part and lowering a load gently

Answer 7

Eccentric

Question 8

_______ contraction happens when contraction velocity remains constant but force can vary

Answer 8

Isokinetic/isovelocity

Question 9

Higher energy level = higher VO2 threshold = _______ O2 debt created

Answer 9

higher

Question 10

O2 debt can be up to ___x basal consumption

Answer 10

O2 debt can be up to 6x basal consumption

Question 11

½ O2 debt is repaid in ____, the rest can take hours

Answer 11

30s

Question 12

Sprinters use mainly ________ ATP generation… why?

Answer 12

anaerobic respiration
because the inability of O2 to reach the leg muscles and activate aerobic enzymes

Question 13

Long distance runners use more _____ (carbohydrates or fat? why?

Answer 13

fat! because Beta-oxidation of fatty acids yields way more ATP

Question 14

what are the 2 types of fatigue?

Answer 14

muscle, central/physiological

Question 15

most muscular activities involve __________ mechanisms

Answer 15

feed forward

Question 16

________ is a fatigue state in which Ca+ does not readily re-enter SR

Answer 16

Contracture

Question 17

_________ is associated with muscle fatigue and are mostly caused by metabolic changes

Answer 17

Tetanic contraction

Question 18

how does rigor mortis work?

Answer 18

when you die, you have depolarization of the cells which release Ca+ → Ca+ binds troponin, displaces tropomyosin → myosin binds actin → cell is dead/no more energy production → NO ATP to detach myosin → muscle stays contracted!

Question 19

what is the max efficiency of muscle contraction?

Answer 19

30%

Question 20

________ is the basal metabolism in resting state
_________ is the heat over resting heat produced during contraction

Answer 20

Resting heat
Initial heat

Question 21

________ is what heat is produced in excess of resting heat after the contraction has stopped

Answer 21

Recovery heat

Question 22

how long does metabolism increase after strenuous exercise?

Answer 22

1 hour

Question 23

how many waves of macrophages come into the muscle? what do they do?

Answer 23

2!

1st wave: Remove debris
2nd wave: repair fibers

Question 24

________ blocks sensory inhibitory impulses from muscles leading to unopposed contraction. what does this cause?

Answer 24

Tetanus
-Causes constitutive muscle contraction

Question 25

_________ blocks activity of ACHesterase. what does this cause?

Answer 25

Organophosphate
-Constitutive muscle contraction

Question 26

_______ inhibits muscle contraction by blocking nicotinic ACH receptor activity. what does this cause

Answer 26

Curare
-paralysis

Question 27

___________ prevents fusion of vesicle with membrane at axon terminal and thus the release of ACH. what does this cause?

Answer 27

Botulin
-paralysis

Question 28

what can large doses of Ryanodine cause?

Answer 28

paralysis