The Skeletal and Muscular Systems Chapter 13 Sections 2 and 3

The Skeletal and Muscular Systems

Chapter 13 Sections 2 and 3

The Skeletal System

Five functions:1. Provides shape and support2. Enables you to move3. Protects your organs4. Produces blood cells5. Stores mineral and other materials

Backbone

a.k.a Vertebral ColumnMade of 26 bones (vertebrae)

Joint: where two bones come together

Joints allow bones to move in different ways

Backbone

LigamentsConnective tissue that

holds bones together

CartilageConnective tissue that

is more flexible than bone

Covers the ends of the bones

Prevents friction

Bones are Living!Bones grow and develop over timeBones have an outer membraneBlood and nerves enter the bone through this

membrane

Layers of boneCompact bone: Dense, but not solidSpongy bone: Has many small spacesMarrow: fills large spaces in the bone

Red marrow produces blood cellsYellow marrow stores fat (energy reserve)

Layers of bone

Bone characteristicsBones are…

StrongLightweightHard (contain phosphorus and calcium)Continually forming new bone tissue throughout your life

Keeping your bones healthyEat a balanced diet (get enough calcium!)Exercise regularlyAs you age, you lose minerals

This can lead to osteoporosis

The Muscular System

.• You have more than 600 active muscles in your body.

• Voluntary: you control their movements

• Involuntary: move without your conscious control

• 3 types of muscle [smooth, skeletal, and

cardiac.]

Skeletal Muscle

• Skeletal muscles are attached to your bones

• Tendon: connective tissue that attaches muscle to bone

• Skeletal muscles are also called striated muscle because they look striped!

Skeletal (Striated) Muscle

Smooth Muscle

• Smooth muscle is involuntary

• Smooth muscle lines many internal organs

• Smooth muscle allows your esophagus and stomach to move and digest your food

http://dante.med.utoronto.ca/skeletalmuscle/publicationpictures4.htm

• Smooth muscle tires less easily than skeletal muscle.

Cardiac Muscle

• Cardiac muscle is found only in the heart

• Cardiac muscle does not get tired!

http://www.bio.psu.edu/faculty/strauss/anatomy/skel/atlas.htm

Muscles Contract!

• Muscles work by contracting (getting shorter)

• They cannot stretch out again, so they have to work in pairs.

• After a muscle contracts, it’s partner contracts to stretch the first one out.

Exercise!

• Exercise makes muscle cells grow wider, thicker, and stronger.

• It helps your flexibility and strength.

• If you get a strain or a cramp, rest the injured muscle to allow it to heal.