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Flashcards in Muscles 2 Deck (45):
0

Latent period

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

1

Threshold

Minimal voltage necessary to produce muscle contraction

2

Twitch

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

3

All-or-none law

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

4

Motor unit

Motor neuron + all the fibers it innervates

5

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

It differs as more motor units join in

6

Treppe

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

7

What is Treppe probably due to?

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

8

Example of something that exhibits Treppe

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

9

Refractory period

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

10

What happens during the refractory period

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

11

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

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

12

what happens during temporal summation

The muscle will achieve a higher level of tension

13

When will temporal summation (wave summation) occur

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

14

Incomplete tetanus

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

15

Complete tetanus

If there is no time to relax AT ALL between stimuli

16

Isometric contraction

Muscle contracts but does not change length (NO MOVEMENT)

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Isotonic contraction

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

Ex: curls

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Concentric contraction

Muscle contracts with force greater than resistance and shortens

19

Eccentric contraction

Muscle contracts with force less than resistance and lengthens

20

What accumulates during anaerobic fermentation when O2 is limited

Lactic acid

21

Phosphagen system

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

22

How do we get immediate energy

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

23

What are the two phosphagen groups and what do they do

Myokinase and creatine kinase and they recruit phosphate groups

24

Short term energy

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

25

Long term energy

Aerobic respiration (cellular respiration with oxygen)

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Where does lactic acid go

Back and forth between muscle and liver

27

What happens as glycogen is consumed

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

28

What do too many potassium ions do

Reduces membrane potential, muscle fatigue

29

Why can't we continue to live off of fermentation

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

30

What happens if motor nerve fibers use up either ACh?

The CNS fatigues for unknown reasons

31

What does physical endurance depend on?

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

32

Oxygen debt

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

33

What do we use oxygen inhaled after exercise for?

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

34

What does muscle strength depend on

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

35

Slow twitch fibers

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

Dark meat

36

Fast twitch fibers

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

37

Can athletic conditioning change genetic component of ability?

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

38

Resistance exercise (weight lifting)

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

39

Endurance (aerobic) exercise

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

40

Cross training

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

41

What is delayed muscle soreness due to

Micro trauma

42

Cramps

CNS occasionally triggers these painful spasmodic contractions

43

What are cramps initiated by

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

44

Smooth muscle

Involuntary and ANS (autonomic nervous system) controls it