Chapter 1 Muscle Physiology

Front 1

ATP

Back 1

the universal energy-carrying molecule manufactured in all living cells as a means of capturing and storing energy

Front 2

Actin

Back 2

thin protein filaments that, with myosin, contracts muscle fibers

Front 3

A Band

Back 3

These are dark bands. They are made of thick myosin filaments which overlap thin actin filaments

Front 4

Concentric muscle action

Back 4

Concentric training is the muscle contraction when a weight is lifted

Front 5

Cross Bridge

Back 5

A distinctive structure consisting of two globular heads on each myosin molecule which interact in the presence of calcium ions with specific sites on a thin actin filament. The cross-bridges contain ATPase and generate the tension developed by a muscle fibre during a muscle action

Front 6

distal

Back 6

Anatomically located far from a point of reference, such as an origin or a point of attachment

Front 7

eccentric muscle action

Back 7

A muscle action in which a muscle exerts a force while
lengthening. Such actions are used to resist external forces, such as gravity

Front 8

endomysium

Back 8

The connective tissue layer surrounding an individual skeletal muscle fiber

Front 9

epimysium

Back 9

The external sheath of connective tissue surrounding a muscle

Front 10

fasciculus

Back 10

A bundle of anatomical fibers, as of muscle or nerve. Also called fascicle

Front 11

H Zone

Back 11

The central portion of an A band in a sarcomere; characterized by the presence of myosin filaments

Front 12

I Band

Back 12

The band on either side of a Z line; encompasses portions of two adjacent sarcomeres and is characterized by the presence of actin filaments

Front 13

Inferior

Back 13

Located beneath or directed downward

Front 14

Insertion

Back 14

The point or mode of attachment of a skeletal muscle to the bone or other body part that it moves

Front 15

Isometric Muscle Action

Back 15

This occurs when the tension in the crossbridge equals the resistance to shortening.

Front 16

Length tension relationship

Back 16

The relationship between the length of a muscle and the contractile tension that it can exert.
A muscle can usually exert its greatest contractile tension when it is at its resting length, but in normal muscle, a greater overall force is produced when the muscle is stretched, which seemingly contradicts the general length-tension relationship. However, the apparent increase is due to the contribution of the elastic components of the joint tissues and not to an increased muscle tension

Front 17

M Bridge

Back 17

A line in the centre of the H zone of a muscle sarcomere

Front 18

Myofibril

Back 18

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

Front 19

Motor unit

Back 19

A motor neuron and the muscle fibers it innervates- all the muscle fibers of a motor unit contract together when they are stimulated by the motor neuron.

Front 20

Muscle fiber

Back 20

muscle cells that are:
* long sometimes the entire length of the muscle
*cylindrical 50-100 um; human hair
*have many nuclei on periphery
*straiated under low magnification

Front 21

myofibril

Back 21

these contain the apparatus that contracts the muscle cell
*they are 1 um in diameter (1/100 diameter of human hair)
*dominate the sarcoplasm

Front 22

myofilament

Back 22

protein filaments that make up the myofibrils of the skeletal muscle cells

Front 23

myosin

Back 23

*protein
*composes the major portion of the thick filament
*it includes 2 heads (cross bridges) and a tail region

Front 24

neuromuscular junction

Back 24

the junction between the motor neuron (nerve cell) and the muscle fibers in innervates is called both the :
motor end plate
neuromuscular junction

Front 25

origin

Back 25

usually defined as its proximal (toward the center of the body) attachment

Front 26

pennate

Back 26

muscles fibers that align obliquely with the tendon

Front 27

perimycium

Back 27

the connective tissue wrapping that surrounds each fascicle

Front 28

periosteum

Back 28

a specialized connective tissure covering all bones

Front 29

preloading

Back 29

high tension development in the early part of the range of motion even before movement occurs when lifting weights to insure the weight is supported isometrically.

Front 30

proximal

Back 30

closer to the trunk

Front 31

sarcolemma

Back 31

the plasma membrane of the muscle cell

Front 32

sarcomere

Back 32

myosin and actin filaments are organized longitudinally in this smallest contractile unit of skeletal muscle

Front 33

sarcopenia

Back 33

reduced muscle size and strength

Front 34

sarcoplasm

Back 34

the cytoplasm of the muscle fiber contains:
*contractile components- which consist of protein filaments
*other proteins
*stored glycogen and fat particles
*enzymes
*specialized organelles such as mitochondria and the SR

Front 35

sarcoplasmic reticulum

Back 35

The ER of the muscle cell
*intricate system of tubules
*terminates as vesicles in the ficinity fot he z lines

Front 36

sliding filament theory

Back 36

*actin filaments at each end of the sarcomere slide inward on myosin filaments
*pull the z lines toward the center of the scaromere
*thus shortening the muscle fiber
*Actin filaments slide over myosin
*both the H zone and Iband shrink
*the flexion of myosin cross bridges pulling on the actin filaments causes the movement of the actin filament
***because only a super small displacemtn of the actin filament occurs with each flexion of the myosin crossbride, ver rapid, repeated flexions must occur in many crossbridges throughout the entire muscle for measureable movement to occur.

Front 37

stretch shortening cylcle

Back 37

It is the increase in force production
*Prestretching a muscle just prior to a concentric action can enhance force production during the contraction*

Front 38

superior

Back 38

closer to the head

Front 39

tendon

Back 39

attaches the muscle to the bone

Front 40

triad

Back 40

this is a pattern of T tubulesspaced between and perpendicular to two sarcoplasmic reticulum vesicles

Front 41

tropomyosin

Back 41

protein molecule
it runs along the length of the actin filament in the grove of the double helix

Front 42

troponin

Back 42

a protein situated regualar intervals along the actin filament that has a high affinity for Ca 2+ ions

Front 43

T tubule

Back 43

Short for: transvers tubules, run perpendicular to the sarcoplasmic reticulum and terminate in the vicinity fo the Z line between tow vesicles

Front 44

Z line

Back 44

at both ends of the sarcomere, its where actin filaments are aligned