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Animal Systems
Muscle System
Muscular System
 Function-- to move the animal about, to provide
movement for the proper functioning of the organs.
 Meat production -- muscles are processed into
meat; 30-40% of the animal’s body is muscle.
Three types of muscle
Skeletal Muscle
 Movement -- movement for the bones of the
skeleton and other voluntary movement; composed
of long, striated bundles that contract and relax
 Tendons -- connect muscles to bones
 Red Muscle -- contain many mitochondria; lots of
blood; contract for long periods of time
Skeletal Muscle
 White Muscle -- Fewer mitochondria;
contract faster; fatigue faster.
Smooth Muscle
 Movement -- Controls movements of the
internal organs; involuntary; non-striated
sheets.
 Examples-- Digestive tract, urinary tract
Cardiac Muscle
 Movement -- muscles that control the heart;
striated and arranged in bands; involuntary; amazing
 Stamina -- # of times a heart beats in a lifetime?
D. List the Three Types of Muscles
 Skeletal Muscles

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Attached to bones
Voluntary
Striated
 The skeleton and the skeletal muscles
function together allowing an animal to move.
Skeletal Muscle
D. List the Three Types of Muscles
 In addition to skeletal muscles, other types of
muscles include:

Smooth muscles

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Found in blood vessels, digestive tracts, and
reproductive tracts
Involuntary, Not striated
Cardiac muscles

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Are found in the heart.
Involuntary, Striated
Smooth Muscle
Cardiac Muscle
E. Point out how Muscles aid in
Movement
 Vertebrates move by the actions of muscles
on bones.
 Muscles generally work in pairs to produce
movement:

when one muscle flexes (or contracts) the
other relaxes, a process known as
antagonism.
E. Point out how Muscles aid in
Movement
 The striations with in the muscle cell are
thread-like structures called myofibrils.
 Within each myofibril there are dense lines
called Z lines.
 A sarcomere (or muscle functional unit)
extends from Z line to Z line.
E. Point out how Muscles aid in
Movement
 Each sarcomere has thick and thin filaments.

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The thick filaments are made of myosin and
occupy the center of each sarcomere.
Thin filaments are made of actins and anchor
to the Z line.
Sarcomere
E. Point out how Muscles aid in
Movement
 Muscles contract by shortening each
sarcomere.
 The sliding filament model of muscle
contraction has thin filaments on each side of
the sarcomere sliding past each other until
they meet in the middle.
 Myosin filaments have club-shaped heads
that project toward the actin filaments.
Contraction of a Sarcomere
E. Point out how Muscles aid in
Movement
 Myosin heads attach to binding sites on the actin
filaments.
 The myosin heads swivel toward the center of the
sarcomere, detach and then reattach to the nearest
active site of the actin filament.
 Each cycle of attachment, swiveling, and detachment
shortens the sarcomere 1%. Hundreds of such cycles
occur each second during muscle contraction.