The Skeletal and Muscular Systems Chapter 13 Sections 2 and 3

The Skeletal System Five functions: 1.Provides shape and support 2.Enables you to move 3.Protects your organs 4.Produces blood cells 5.Stores mineral and other materials

Backbone a.k.a Vertebral Column Made of 26 bones (vertebrae) Joint: where two bones come together Joints allow bones to move in different ways

Backbone

Ligaments Connective tissue that holds bones together Cartilage Connective tissue that is more flexible than bone Covers the ends of the bones Prevents friction

Bones are Living! Bones grow and develop over time Bones have an outer membrane Blood and nerves enter the bone through this membrane

Layers of bone Compact bone: Dense, but not solid Spongy bone: Has many small spaces Marrow: fills large spaces in the bone Red marrow produces blood cells Yellow marrow stores fat (energy reserve)

Layers of bone

Bone characteristics Bones are… Strong Lightweight Hard (contain phosphorus and calcium) Continually forming new bone tissue throughout your life

Keeping your bones healthy Eat a balanced diet (get enough calcium!) Exercise regularly As 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 Smooth muscle tires less easily than skeletal muscle.

Cardiac Muscle Cardiac muscle is found only in the heart Cardiac muscle does not get tired!

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.