1. Human Body Systems
Unit 2

2. Skeletal System
Skeleton- made up of all the bones in your body – 206 bones. 5 major functions:
Shape and support for body
Protects internal organs
Movement – attached to major muscles
Blood cells are formed in red marrow at center of bones
Stores minerals like calcium for later use.

3. Day #2
Skeletal System

4. Bone Structure Bones are alive, and therefore grow and develop.
Periosteum – tough membrane covering surface
Compact bone – hard, strong layer under periosteum
Spongy bone – found towards ends of long bones; with many small spaces within it:
Marrow: soft, connective tissue found in spaces. red marrow produces blood cells; yellow marrow stores fat as energy reserve.
Cartilage – rubbery layer of tissue found at ends of bones where they form joints.

6. Joints
Any place where two or more bones come together is a joint, held in place by tough band of tissue – ligament (bone to bone). Tendon connects muscle to bone.
Immoveable Joint – allows little or NO movement
Pivot Joint – one bone rotates around another
Ball and Socket – rounded end of one bone fits into cup-like structure of another
Hinge Joints – back and forth movement
Gliding Joint – one part of bone slides over another.

7. Day #2
Type of Joints
BALL & SOCKET HINGE

8. Day #2
Type of Joints
GLIDING PIVOT

9. Muscular System
Muscle: an organ that can relax and contract, providing the force to move the body.
Voluntary muscle: muscles you are able to control
Examples: bicep, abdominal
Involuntary muscle: muscles you CANNOT control
Examples: muscles in organs, heart.

10. Types of Muscle Tissue
Skeletal Muscle: Mostly Voluntary muscles attached to bones of skeleton. Tire easily.
Tendons: strong connective tissue attaching muscle to bone.
Smooth Muscle: Involuntary muscles found in internal organs. React and tire more slowly.
Cardiac Muscle: Involuntary muscle found ONLY in the heart. Does NOT get tired; contractions are your heartbeats.

11. Smooth Cardiac Skeleton
Day #2
Types of Muscles
Smooth
Cardiac
Skeleton

12. Working Together
Muscle cells can only contract, not extend. Therefore, skeletal muscles must work in pairs.
One muscle contracts (flexor),
The other muscle relaxes to its original length (extensor)