Muscles 2

Question 0

Threshold

Answer 0

Minimal voltage necessary to produce muscle contraction

Question 1

Latent period

Answer 1

During and immediately after action potential when no visible change occurs in the muscle fiber (3-10 msec.)

Question 2

Twitch

Answer 2

When muscle is given a single, brief stimulation, it shows a twitch which is a cycle of contraction and relaxation

Contraction phase followed by relaxation phase

Question 3

All-or-none law

Answer 3

Muscle fiber exhibits a max contraction response or it exhibits none at all

Question 4

Motor unit

Answer 4

Motor neuron + all the fibers it innervates

Question 5

How is the strength of contraction of a whole muscle graded?

Answer 5

It differs as more motor units join in

Question 6

Treppe

Answer 6

(Staircase phenomenon) Muscle exhibit in response to a series of stimuli of the same strength.

Question 7

What is Treppe probably due to?

Answer 7

The inability of the muscle cells to fully return calcium to the sarcoplasmic reticulum

Question 8

Example of something that exhibits Treppe

Answer 8

Successive increase in amplitude of the first few contractions of cardiac muscle that’s received a # of stimuli of the same intensity following a quiescent period

Question 9

Refractory period

Answer 9

After a twitch, this is a brieft (1-2 msec.) period needed to restore the resting potential.

Question 10

What happens during the refractory period

Answer 10

The sarcolemma is repolarizing and won’t respond to new stimulus

Question 11

What happens if second stimulus arrived before the complete relaxation of a muscle

Answer 11

The muscle will achieve temporal summation (wave summation) and achieve a higher level of tension

Question 12

what happens during temporal summation

Answer 12

The muscle will achieve a higher level of tension

Question 13

When will temporal summation (wave summation) occur

Answer 13

If a second stimulation arrives before he complete relaxation of a muscle in the refractory period

Question 14

Incomplete tetanus

Answer 14

If the stimuli are frequent enough that the muscle cannot relax completely in between

Question 15

Complete tetanus

Answer 15

If there is no time to relax AT ALL between stimuli

Question 16

Isometric contraction

Answer 16

Muscle contracts but does not change length (NO MOVEMENT)

Question 17

Isotonic contraction

Answer 17

Muscle contracts with force greater/less than resistance and shortens/lengthens (MOVEMENT)

Ex: curls

Question 18

Concentric contraction

Answer 18

Muscle contracts with force greater than resistance and shortens

Question 19

Eccentric contraction

Answer 19

Muscle contracts with force less than resistance and lengthens

Question 20

What accumulates during anaerobic fermentation when O2 is limited

Answer 20

Lactic acid

Question 21

Phosphagen system

Answer 21

Phosphagen groups goes around recruiting phosphate to be ready to combine with ADP to make ATP

Question 22

How do we get immediate energy

Answer 22

For short, quick spurts of energy we rely on the phosphagen system to supply ATP

Question 23

What are the two phosphagen groups and what do they do

Answer 23

Myokinase and creatine kinase and they recruit phosphate groups

Question 24

Short term energy

Answer 24

After the phosphagen system is exhausted muscle relies on fermentation (glycogen-lactic acid pathway) for ATP for 30-40 seconds

Question 25

Long term energy

Answer 25

Aerobic respiration (cellular respiration with oxygen)

Question 26

Where does lactic acid go

Answer 26

Back and forth between muscle and liver

Question 27

What happens as glycogen is consumed

Answer 27

ATP synthesis declines. This shortage slows down the cells ability to maintain the resting membrane potential (NA, K pump)

Question 28

What do too many potassium ions do

Answer 28

Reduces membrane potential, muscle fatigue

Question 29

Why can't we continue to live off of fermentation

Answer 29

Lactic acid lowers the pH of the sarcoplasm and impairs the action of enzymes

Question 30

What happens if motor nerve fibers use up either ACh?

Answer 30

The CNS fatigues for unknown reasons

Question 31

What does physical endurance depend on?

Answer 31

The max oxygen uptake of the athlete and the supply of organic nutrients (glucose)

Question 32

Oxygen debt

Answer 32

Difference between the resting state of oxygen consumption and the elevated rate following an exercise (what you need vs what you got) W/o enough oxygen you're in debt

Question 33

What do we use oxygen inhaled after exercise for?

Answer 33

Used to replace the body's oxygen reserves, replenish the phosphagen system, oxidize lactic acid, and serve the now elevated metabolic rate

Question 34

What does muscle strength depend on

Answer 34

Muscle size, size of active motor units, fascicles arrangement, multiple motor unit summation (recruitment), and temporal summation (wave summation)

Question 35

Slow twitch fibers

Answer 35

Small and produce twitches up to 100 msec long. They have more mitochondria and capillaries, HIGH ENDURANCE FIBERS Dark meat

Question 36

Fast twitch fibers

Answer 36

Larger and produce twitches as short as 7.5 msec. Quick energy for stop/go activities. White meat

Question 37

Can athletic conditioning change genetic component of ability?

Answer 37

No, individuals are born with different ratios of slow to fast twitch fibers

Question 38

Resistance exercise (weight lifting)

Answer 38

Contention of muscles against a load that resists movement and is enough to stimulate muscle growth

Question 39

Endurance (aerobic) exercise

Answer 39

Improves the fatigue-resistance of muscles. Slow twitch fibers squire a greater density of blood capillaries

Question 40

Cross training

Answer 40

Optimal performance and skeletomuscular health require this which incorporates elements of both endurance and resistance

Question 41

What is delayed muscle soreness due to

Answer 41

Micro trauma

Question 42

Cramps

Answer 42

CNS occasionally triggers these painful spasmodic contractions

Question 43

What are cramps initiated by

Answer 43

``` Extreme cold Heavy exercise Lack of blood flow Electrolyte depletion Dehydration Low blood glucose ```

Question 44

Smooth muscle

Answer 44

Involuntary and ANS (autonomic nervous system) controls it