Human Biology

The Muscular System

The Muscular System… The muscular system

allows body movement and maintains posture

Your body has more than 600 muscles

Your muscles work even when you are asleep

The Muscular System… Most muscles, or muscle tissue, are

composed of muscle fibers that run beside, or parallel to, one another

These muscle fibers are held together in bundles of connective tissue

Each muscle fiber is actually a single cylinder-shaped cell

The Muscular System… The function of muscle tissue is to contract, or

shorten

The Muscular System… Types of Muscles

There are three types of muscle tissue in the human body Skeletal muscle Smooth muscle Cardiac muscle

Each type of muscle tissue has a characteristic structure and function

The Muscular System… Skeletal muscle

Attaches to and moves bones By contracting, skeletal muscle causes your arms,

legs, head, and other body parts to move

The Muscular System… Under a microscope,

skeletal muscle appears banded, or striated Skeletal muscle is

also known as striated muscle

The Muscular System… Skeletal muscle

moves only when you want it to Voluntary muscle

Skeletal muscles react quickly when you want them to

Skeletal muscles tire easily

The Muscular System… Smooth muscle

Help control breathing, blood pressure, and the movements of the digestive system

Has no bands-hence the name In general, smooth muscles can contract

without your actively causing them to Involuntary muscle

The Muscular System… Smooth muscles react

slowly Smooth muscles tire

slowly

The Muscular System… Cardiac muscle

Found only in the heart

Branches out in many directions, weaving a complex mesh

Contractions of cardiac muscle cause the heart to beat

The Muscular System…

Cardiac Muscle Involuntary muscle

Does not tire

The Muscular System… Action of skeletal muscles

Muscles do work only by contracting In order for muscles to cause any kind of

movement, they must work in pairs Nerves carry messages from the brain and

the spinal cord to the muscles, signaling them to contract

The Muscular System… Injuries to the muscular system

Strain, tear

The Muscular System… Review

Muscle tissue is made of fibers bundled together by connective tissue

Muscle tissue moves only by contracting There are 3 types of muscle tissue

Skeletal Smooth Cardiac

The Muscular System… Skeletal muscle

Permits voluntary movement Are connected to bone

Smooth muscle Help control breathing, blood pressure, and

movements in the digestive system Cardiac muscle

Makes the heart beat

The Muscular System… All skeletal muscles work in pairs

When one contracts, the other relaxes