Chapter 11: Physiology Of The Muscular System

Front 1

Functions of muscular system

Back 1

Movement of body, heat production, posture

Front 2

Excitability

Back 2

Ability to be stimulated

Front 3

Contractility

Back 3

Ability to contract, or shorten, and produce body movement

Front 4

Extensibility

Back 4

Ability to extend, or stretch, thereby allowing muscles to return to their resting length

Front 5

Sarcolemma

Back 5

Plasma membrane of muscle fibers

Front 6

Sarcoplasmic reticulum (SR)

Back 6

ER of muscle fibers

Front 7

Muscle fiber

Back 7

Muscle cell

Front 8

T-tubules

Back 8

Network of tubules and sacs found within muscle fibers

Front 9

Myosin

Back 9

Makes up almost all the thick filament

Front 10

Actin

Back 10

Globular protein that forms two fibrous strands twisted around each other to form the bulk of the thin filament

Front 11

Tropomyosin

Back 11

Protein that blocks the active sites on actin molecules

Front 12

Troponin

Back 12

Protein that holds tropomyosin molecules in place

Front 13

Myofibrils

Back 13

Numerous fine fibers packed close together in sarcoplasm

Front 14

Sarcomere

Back 14

Segment of myofibril between two successive Z disks

Front 15

Triad

Back 15

Triplet of tubules; a T-tubule sandwiched between two sacs of SR

Front 16

Neuromuscular junction

Back 16

Motor neurons connect to the sarcolemma at the motor endplate

Front 17

Acetylcholine

Back 17

The neurotransmitter released into the synaptic cleft that diffuses across the gap, stimulates the receptors, and initiates an impulse in the sarcolemma

Front 18

Red fibers

Back 18

Muscle fibers with high levels of myoglobin

Front 19

White fibers

Back 19

Muscle fibers with little myoglobin

Front 20

Aerobic respiration

Back 20

Occurs when adequate O2 is available from blood

Front 21

Anaerobic respiration

Back 21

Very rapid, providing energy during first minutes of maximal exercise

Front 22

Motor unit

Back 22

Motor neuron plus the muscle fibers to which it attaches

Front 23

Myography

Back 23

Method of graphing the changing tension of a muscle as it contracts

Front 24

Twitch contraction

Back 24

A quick jerk of a muscle produced as a result of a single, brief threshold stimulus

Front 25

Latent phase

Back 25

Phase of twitch contraction where the nerve impulse travels to the SR to trigger the release of Ca++

Front 26

Contraction phase

Back 26

Phase of twitch contraction where Ca++ binds to troponin and sliding filaments occur

Front 27

Relaxation phase

Back 27

Phase of twitch contraction where sliding filaments ceases

Front 28

Tetanus

Back 28

Smooth, sustained contractions

Front 29

Multiple wave summation

Back 29

Multiple twitch waves added together to sustain muscle tension for a longer time

Front 30

Incomplete tetanus

Back 30

Very short periods of relaxation between peaks of tension

Front 31

Complete tetanus

Back 31

Twitch waves fuse into a single, sustained peak

Front 32

Treppe

Back 32

The staircase phenomenon; gradual, step like increase in the strength of contraction that is seen in a series of twitch contractions that occur 1 second apart

Front 33

Tonic contraction

Back 33

Continual, partial contraction of a muscle

Front 34

Flaccid

Back 34

Muscles with less tone than normal

Front 35

Spastic

Back 35

Muscles with more tone than normal

Front 36

Muscle tone

Back 36

A small number of muscle fibers within a muscle contract and produce a tightness

Front 37

Isometric contraction

Back 37

Contraction in which muscle length remains the same while muscle tension increases; Isometric = "same length"

Front 38

Isotonic contraction

Back 38

Contraction in which the tone or tension within a muscle remains the same as the length of the muscle changes; Isotonic = "same tension"

Front 39

Concentric

Back 39

Muscle shortens as it contracts

Front 40

Eccentric

Back 40

Muscle lengthens while contracting

Front 41

Syncytium

Back 41

Continuous, electrically coupled mass (cardiac muscle)

Front 42

Single-unit (visceral) smooth muscle

Back 42

Exhibits autorhythmicity and produces peristalsis; most common type, forms a muscular layer in the walls of hollow structures; gap junctions join smooth muscle fibers into large continuous sheets

Front 43

Multiunit smooth muscle

Back 43

Each fiber responds only to nervous input; does not act as a single unit but as composed of many independent cell units