The Skeletal and Muscular Systems

Structures of the Body• cells: the building blocks of life

– make up your body– many types of cells

• bone cells, muscle cells, blood cells, and nerve cells

• tissue: cells of the same type working together– bone cells make bone tissue/muscle cells make

up muscle tissue

• organs: body parts that do special jobs– tissues of different kinds work together in organs

• bone tissue and other tissue form organs of bones• muscle tissue and other tissue form organs of muscles

• systems: groups of organs working together– bones (type of organ) work together to make

the skeletal system– muscles (type of organ) work together to

make the muscular system

The Skeletal System• your body is made up of many

bones– bones support your body and give

it shape– help you move and protect the

organs inside your body– bones meet at joints– some open and close like hinge of

a door• your knee

– other joints let a bone move in many directions

• your shoulder

The Muscular System• body has 3 types of muscles

– skeletal muscles• move head, arms, legs, fingers, toes• can’t push, only pull• work in pairs • control skeletal muscles by thinking

– cardiac muscles• muscle your heart is made of• muscle works without your thinking about it

– smooth muscles• help organs inside your body do their job• muscle works without your thinking about it

• all muscles move parts of your body• do this by getting longer and shorter

A Closer Look at Muscles

• striated muscles– skeletal muscle with light and dark stripes

• stripes patterns made by working parts of muscle cell

– fibers in skeletal muscle can be up to 30 cm (12in) long

– some muscles have more than 2000 fibers packed together

• smooth muscle– does not have stripes– found in walls of organs

• stomach,intestines, blood vessels, bladder

– work by squeezing and relaxing slowly and smoothly– fibers are shorter than skeletal muscles

• cardiac muscle– stripes but not as many as skeletal (striated)– makes up walls of heart– squeezes and relaxes without ever stopping– never gets tired

Summary

• the body is made up of basic parts called cells– cells make up tissues– tissues make up organs– organs make up systems

• skeletal and muscular systems work together to help the body move