Muscle Physiology

Front 1

A-Band

Back 1

Alignment of myosin or thick myofilaments(6)

Front 2

Actin

Back 2

Thin myofilaments

Front 3

Action Potential

Back 3

Electrical Nerve Impulse(7)

Front 4

Concentric Muscle Action

Back 4

Resistance is less than muscle force.(8)

Front 5

Cross-Bridge

Back 5

Globular heads that protrude away from the myosin filament at regular intervals.

Front 6

Distal

Back 6

Farther from the trunk(4)

Front 7

Epimysium

Back 7

Fibrous connective tissue that covers the skeletal muscles(4)

Front 8

Tendons

Back 8

A tough, inelastic tissue that connects muscle to bone(4)

Front 9

Periosteum

Back 9

A specialized connective tissue covering all bones

Front 10

Proximal

Back 10

closer to the trunk

Front 11

superior

Back 11

closer to the head

Front 12

Inferior

Back 12

closer to the feet

Front 13

Orgin of a muscle

Back 13

its proximal attachment

Front 14

insertion of a muscle

Back 14

its distal attachment(4)

Front 15

Muscle Fibers

Back 15

Muscle Cells(4)

Front 16

Fasciculus

Back 16

A bundle of muscle fibers(4)

Front 17

Perimysium

Back 17

Connective tissue that surrounds the Fasciculi

Front 18

Endomysium

Back 18

Connective tissue that surrounds each muscle fiber.

Front 19

Sarcolemma

Back 19

A muscle fiber's membrane that encircles and is continuous with the endomysium

Front 20

Neuromuscular Junction

Back 20

motor end plate(5)

Front 21

Motor Unit

Back 21

A motor neuron and the muscle fibers it innervates

Front 22

Sarcoplasm

Back 22

Cytoplasms of the muscle fiber that contains contractile components like protein filaments, stored glycogen and fat particles, enzymes, and specialized organelles like mitochondria and sarcoplasmic reticulum

Front 23

Myofibrils

Back 23

Any of the threadlike fibrils that make up the contractile part of a striated muscle fiber

Front 24

Myosin

Back 24

Thick Myofilaments

Front 25

Actin

Back 25

Thin Myofilaments

Front 26

Cross-bridges

Back 26

Globular heads that protrude away from the myosin filament at regular intervals.

Front 27

Sarcomere

Back 27

The smallest contractile unit of skeletal muscle. Contains the Myosin and Actin filaments.

Front 28

M-bridge

Back 28

Where myosin filaments anchor to each other in the center of the sarcomere.

Front 29

H-zone

Back 29

The center of the sarcomere where only myosin are only found.

Front 30

Z-line

Back 30

The end of the sarcomere where the actin filaments are anchored.

Front 31

A-band

Back 31

The area of dense myosin filaments.

Front 32

I-band

Back 32

An area of the sarcomere where only actin filaments are found.

Front 33

Sarcoplasmic Reticulum

Back 33

System of tubules that store Calcium ions.

Front 34

Transverse Tubules

Back 34

(T-tubules) Run perpendicular to the sarcoplasmic reticulum and terminate in the vicinity of the Z-line. They carry the action-potential throughout the muscle fiber.

Front 35

Triad

Back 35

The pattern of a T-tubule spaced between and perpendicular to two sarcoplasmic reticulum vesicles.

Front 36

Sliding-Filament Theory

Back 36

States that the actin filaments at each end of the sarcomere slide inward on myosin fliaments.

5 Phases:
Resting
Excitation-Contraction
Contraction
Recharge
Relaxation

Front 37

Resting Phase of the Sliding-Filament Theory

Back 37

No tension is developed in the muscle.

Front 38

Excitation-Contraction Phase of the Sliding Filament Theory

Back 38

Sacroplasmic Reticulums releases Calcium that binds with troponin, found on the actin filament, which causes a shift to occur in the tropomyosin, also found on the actin filament, which allows cross-bridge flexion to occur.

Front 39

Contraction Phase of the Sliding-Filament Theory

Back 39

ADP connects to the cross-bridge causing the the cross-bridge to flex and the actin to slide toward the center of the sarcomere. ATP releases the cross-bridge and causes the actin to slide away from the center of the sacromere.

Front 40

Recharge Phase of the Sliding-Filament Theory

Back 40

So long as Calcium, ATP for the uncoupling of the myosin from the actin, and sufficient active myosin ATPase is available for catalyzing the breakdown of ATP will the muscle continue to shorten.

Front 41

Relaxation Phase

Back 41

Occurs when the stimulation of the motor nerve stops. Calcium is pumped back into the sarcoplasmic reticulum, which prevents the link between the actin and myosin filaments.

Front 42

Type I muscle

Back 42

Slow Twitch that resist fatique by having a large number of mitochondria and dense capillary concentration

Front 43

Type IIa

Back 43

Fast-twitch oxidative glycolytic, muscle fiber has more mitochondria, greater aerobic enzyme activity, and greater capillary density than Type IIb muscle fibers.

Front 44

Type IIb

Back 44

Fast glycolytic, muscle fiber fatigues rapidly and has relatively few mitochondria, low aerobic enzyme activity, and few capillaries.

Front 45

Isometric muscle actions

Back 45

Resistance is equal to muscle force.

Front 46

Eccentric muscle action

Back 46

Resistance is greater than muscle force.

Front 47

Gauge of Force Production

Back 47

The number of myosin cross-bridges that are attached to actin filaments at any instance in time dictates how much force is being produced in that muscle.

Front 48

Motor Unit Recruitment
(Force Production)

Back 48

Force production is controlled in two main ways:
1)Frequency of stimulation of motor units
2)The number of motor units activated.

Front 49

Preloading
(Force Production)

Back 49

It takes time for all the potential myosin cross-bridge heads to make contact with actin filaments. High tension is developed in a muscle even before movement occurs when lifting weights because the weight must be supported isometrically.

Front 50

Cross-Sectional Area relating to Force Production

Back 50

Thicker muscles have greater potential for generating force.

Front 51

Velocity of Shortening relating to Force Production

Back 51

The longer the muscle the increase in velocity of shortening. (2 sarcomeres in series can shorten in the same time that 1 sarcomere can but move 2 times as far.)

Front 52

Force Production related to speed of concentric actions

Back 52

Less force production is possible during faster movements. More force is possible during slower movements.

Front 53

Force Production related to speed of eccentric actions

Back 53

As the velocity of eccentric actions increases, maximal force production also increases.

Front 54

Angle of Pennation relating to force production

Back 54

The greater the angle from parallel to the tendon the more sarcomeres in parallel and the fewer in series and so the muscles are able to generate more force but they will have a lower maximal shortening velocity.

Front 55

Pennate muscle

Back 55

Has muscle fibers that align obliquely with the tendon.

Front 56

Length-Tension Relationship

Back 56

Peak force production is at resting length or slightly greater than resting length. Shorter or longer negatively affects its ability to produce force.

Front 57

Stretch-shortening cycle

Back 57

Prestretching a muscle just prior to a concentric action can enhance force production during the subsequent contraction.

Front 58

Delayed-onset muscle soreness

Back 58

(DOMS)
1) Normally occurs 24 to 72 hours after exercise
2)Eccentric muscles induce the most DOMS.
3)Normally associated with strength loss
4)Probably happens from an inflammation -induced increase in fluid in the muscle.

Front 59

Sarcopenia

Back 59

Reduced muscle size and strength.