Muscle Physiology

Question 1

3 general functions of muscle physiology:

Answer 1

• movement
• heat production
• posture

Question 2

3 technical functions of muscle physiology:

Answer 2

• excitability
• contractility
• extensibility

Question 3

Ability to be stimulated

Answer 3

Excitability

Question 4

Ability to contract or shorten

Answer 4

Contractility

Question 5

Ability to extend or stretch and return to resting length after contraction

Answer 5

Extensibility

Question 6

Muscle fiber (muscle cell)

Answer 6

Myocyte

Question 7

Myocytes have more than one _______ due to each fiber being made up of multiple cells combined into one

Answer 7

Nucleus

Question 8

Stem cells that can fuse with myocytes during strength training to make bigger muscle fibers

Answer 8

Satellite cells

Question 9

____ can become active post injury to produce more muscle fibers.

Answer 9

satellite cells

Question 10

muscle cell plasma membrane

Answer 10

sarcolemma

Question 11

muscle cell cytoplasm

Answer 11

sarcoplasm

Question 12

muscle cell smooth ER

Answer 12

sarcoplasmic reticulum

Question 13

_______ is sandwiched between sacs of the sarcoplasmic reticulum

Answer 13

Triad T-tubule

Question 14

The cytoskeleton of the muscle fiber

Answer 14

myofibrils

Question 15

Bundles of very fine filaments packed closely together that extend lengthwise along mm fiber

Answer 15

myofibrils

Question 16

contractile unit that extends between 2 z discs

Answer 16

sarcomere

Question 17

extensions of sarcolemma (the electrical wiring)

Answer 17

T tubules

Question 18

protein that binds O2 in sarcoplasm

Answer 18

Myoglobin

Question 19

regions of dense protein that separate sarcomeres

Answer 19

z discs

Question 20

The 3 kinds of protein that make up a myofibril:

Answer 20

• contractile
• regulatory
• structural

Question 21

____ and _____ are contractile proteins.

Answer 21

Myosin and actin

Question 22

____ and ____ are regulatory proteins.

Answer 22

• tropomyosin

- troponin

Question 23

several kinds of proteins that assist to stabilize the position of thick and thin myofilaments are this kind of protein

Answer 23

structural

Question 24

thin, twisted protein strands that have sites that attract myosin heads

Answer 24

actin

Question 25

thick fibers that have "heads" that cross bridge to actin active sites

Answer 25

myosin

Question 26

thin strands that block actin active sites

Answer 26

tropomyosin

Question 27

globular proteins that hold tropomyosin in place

Answer 27

troponin

Question 28

specialized nerve cells that release ACh

Answer 28

motor neuron

Question 29

folded aspect of sarcolemma where motor neuron connects

Answer 29

motor endplate

Question 30

____ binds to receptors on mm fiber

Answer 30

ACh

Question 31

junction between motor neuron and motor endplate

Answer 31

neuromuscular junction

Question 32

1. Signal travels down motor neuron 2. ACh released from end of motor neuron into synaptic cleft 3. ACh binds to receptors on motor endplate 4. Electrical impulse is transmitted to the sarcolemma

Answer 32

Excitation process of the sarcolemma

Question 33

1. impulse travels through T tubles to sacs of ER 2. Ca++ released into sarcoplasm and binds to troponin 3. Tropomyosin molecules shift and expose active actin sites 4. Myosin bridges and binds to actin to pull actin filaments toward center of sarcomere 5. Myosin heads release and bind to next active site and pull again which results in shortening

Answer 33

Contraction

Question 34

muscle fibers contract to __% of their starting length.

Answer 34

80

Question 35

1. SR starts pumping back Ca++ into its sacs almost immediately after releasing them 2. Ca++ removed from troponin molecules shutting down contraction

Answer 35

Relaxation

Question 36

If no nerve pulse follows after contraction, the muscle ____.

Answer 36

relaxes

Question 37

A small amount of ____ is present inside resting muscle fibers

Answer 37

ATP

Question 38

If more ATP is needed the muscle has 3 ways to produce it:

Answer 38

- from creatine phosphate - anaerobic glycolosis - aerobic respiration

Question 39

consists of a somatic motor neuron ans all the skeletal muscle fibers it stimulates

Answer 39

motor units

Question 40

a single somatic motor neuron comes in contact with an average of ____ skeletal muscle fibers

Answer 40

150

Question 41

containing only a few muscle fibers per neuron

Answer 41

fine motor

Question 42

large scale and powerful movements have many fibers per neuron

Answer 42

gross motor

Question 43

brief contraction of all muscle fibers in a motor unit in response to a single impulse

Answer 43

twitch contraction

Question 44

gradual, steplike increase in strength f contraction when series of twitch contractions occur about a second apart

Answer 44

Treppe

Question 45

A muscle contracts with more force after it has contracted a few times. This is called

Answer 45

Treppe

Question 46

smooth, sustained contractions, also called multiple wave summation. Muscle doesn't have time to relax before the next contraction starts

Answer 46

Tetanic contractions (Tetanus)

Question 47

Tension is not sustained at a constant level

Answer 47

incomplete tetanus

Question 48

continual, partial contraction in a muscle organ. A small number of fibers in a muscle contract to produce tautness. Motor units fire in relays to achieve this tone.

Answer 48

Tonic contraction

Question 49

small amount of tautness due to weak, involuntary contraction of motor units.

Answer 49

muscle tone

Question 50

4 factors that contribute to graded strength principle:

Answer 50

- metabolic condition - recruitment of motor units - effect of muscle length on strength - effect of load on strength

Question 51

_____ activity is separate from muscle contraction but can positively and negatively effect contraction

Answer 51

Metabolic

Question 52

maximal strength a muscle can develop bears a direct relationship to the initial length of its fibers

Answer 52

length-tension relationship

Question 53

the heavier the load the stronger the contraction. This is...

Answer 53

effect of load on strength

Question 54

muscle shortens, tension stays the same

Answer 54

concentric contraction

Question 55

muscle lengthens, tension stays the same

Answer 55

eccentric contraction

Question 56

muscle length does not change, tension changes

Answer 56

isometric contraction

Question 57

type of muscle fiber that relies on oxygen to produce ATP, highly vascular and fatigue resistant, high concentration of myoglobin, myosin is slow acting and ATP production is able to keep up. found in postural and endurance type muscles

Answer 57

slow oxidative fibers (red)/ slow twitch

Question 58

rely on oxygen and glycogen o produce ATP, some myoglobin and vascularity, myosin is moderately fast but more fatigue resistant than fast twitch fibers, sprint muscles

Answer 58

fast oxidative-glycolytic fibers/intermediate fibers

Question 59

relies on glycogen to produce ATP, low concentration of myoglobin and decreased vascularity, myosin is fast so rapid depletion of ATP, short duration contractions found in muscles of fingers and eyes

Answer 59

Fast twitch (white fibers)