Chapter 9 Muscular System

Front 1

Major Functions of Muscles

Back 1

1) Body Movement
2) Maintenance of Posture
3) Respiration
4) Production of Body Heat
5) Communication
6) Constriction of Organs and Vessesl
7) Heart Beat

Front 2

Major Functional Properties

Back 2

1) Contractility
2) Excitability
3) Extensibility
4) Elasticity

Front 3

Contractility

Back 3

The ability of muscle to shorten forcefully

Front 4

Excitability

Back 4

The capacity of muscle to respond to a stimulus

Front 5

Extensibility

Back 5

Muscles can be stretched beyond its normal resting length and still be able to contract

Front 6

Elasticity

Back 6

The ability of muscle to recoil to its original resting length after it has been stretched

Front 7

Types of Muscles

Back 7

Skeletal
Smooth
Cardiac

Front 8

Skeletal Muscle

Back 8

40% of the body's weight

Responsible for locomotion, facial expressions, posture, respiratory movements

Controlled voluntarily or involuntarily by the nervous system

Front 9

Smooth Muscle

Back 9

Most widely distributed - Greatest variety of functions

In the walls of hollow organs and tubes, the interior of the eye, the walls of blood vessels

Controlled Involuntarily by the ANS

Front 10

Cardiac Muscle

Back 10

Found only in the heart

Contractions provide the major force for moving blood through the circulatory system

Does not require hormonal or nervous stimulation for contraction

Controlled Involuntarily by the ANS

Front 11

Skeletal muscles

Back 11

Composed of muscle fibers

Front 12

Muscle Fibers

Back 12

Single, long, cylindrical cell containing several nuclei around the periphery of the fiber near the plasma membrane

Front 13

Myoblasts

Back 13

Less mature multinucleated cells from which Muscle Fibers develop from

Develop muscle fibers when contractile proteins accumulate within their cytoplasm

Front 14

What causes the increase of muscle fiber size

Back 14

Muscle fiber size is caused by hypertrophy - size can increase due the muscles response to exercise

Front 15

Striated

Back 15

A striped appearance of alternating light and dark band

Front 16

Connective Tissue

Back 16

Provides muscle fibers with a solid structure to which they attach

Front 17

Sarcolemma

Back 17

The outer plasma membrane of a muscle fiber

Front 18

External Lamina

Back 18

The deeper and thinner layer

One of the 2 delicate connective tissue layers located outside the sarcolemma

Front 19

Endomysium

Back 19

The thicker second layer that consists mostly of reticular fibers

Front 20

Perimysium

Back 20

A tissue that wraps around a bundle of muscle fibers (Fascicles)

Front 21

Fascicules

Back 21

Each bundle of muscle fiber ensheathed by perimysium

Front 22

Epimysium

Back 22

The tissue surrounding an entire muscle

Front 23

Fascia

Back 23

A connective tissue on the surface of muscles that extends onto tendons and bone

Front 24

Muscular Fascia

Back 24

Separates and compartmentalizes individual muscles or groups of muscles

Front 25

Motor Neurons

Back 25

Specialized cells that stimulate muscles to contract

Located in the Brain, Spinal Chord, and their axons extend to skeletal muscle fibers through nerves

Innervates more than one muscle fiber and every muscle fiber receives a branch of an axon

Front 26

Muscle Fiber

Back 26

The muscle cell itself

Front 27

Sarcoplasm

Back 27

The cytoplasm without myofibrils

The cytoplasm within the muscle fiber

Front 28

Myofibril

Back 28

A threadlike structure that extends from one end of the muscle fiber to the other

Front 29

Myofilaments

Back 29

A protein filament - consists of 2 types: Actin & Myosin

Major component of myofibrils

Front 30

Actin Myofilament

Back 30

Thin myofilaments within the myofibril

Composed of 2 strands of Fibrous Actin (F Actin) / Tropomyosin Molecules / Troponin Molecules

Front 31

Myosin Myofilament

Back 31

Thick myofilaments within the myofibril

Attaches to and wounds around the elastic filaments within a myofibril

Front 32

Sacromeres

Back 32

Highly ordered units form by actin and myosin myofilaments - joined end to end to form myofibrils

Front 33

F Actin

Back 33

2 strands coiled to form a double helix

Each strand: Globular unit - Globular Actin (G Actin)

Front 34

G Actin

Back 34

Composes one strand of F Actin

Each Monomer has an active site - where myosin molecules can bind during muscle contraction

Front 35

Tropomyosin

Back 35

Elongated protein that winds along the groove of the F actin double helix

Composed of 3 Subunits:
1) binds to actin
2) binds to tropomyosin
3) binding site for Ca2+

Front 36

Troponin

Back 36

Combined with Tropomyosin - regulates the interaction between active sites on G actin and myosin