There are over 600 muscles in the human body that are categorized as either voluntary or involuntary. Voluntary muscles are skeletal muscles that are attached to bones and controlled consciously, while involuntary muscles include smooth muscles inside organs and cardiac muscles in the heart. The three main types of muscle are skeletal, smooth, and cardiac muscles, which have different structures and functions.

1. Muscular System

2. There are about 600 muscles in your body.

3. Muscle Control Involuntary Muscle: Not under conscious control. Heart beat, digestion Voluntary Muscle: Under your control. Walking, jumping, etc.

4. 3 Types of Muscle Skeletal Smooth Cardiac

5. Skeletal Muscle Attached to bones of the skeleton. Voluntary Striated(lines)

6. Smooth Muscle Inside many internal organs Involuntary Not striated

7. Cardiac Muscle Heart Involuntary Striated Does not get tired

8. Muscles at Work Skeletal muscles work in pairs. One muscle contracts The other lengthens

9. Muscle Cells

10. Skin

11. Functions Regulates body temperature Stores water and fat The largest organ sensory organ Prevents water loss Prevents entry of bacteria

12. Layers of Skin Epidermis – the thin outer layer of skin that sheds Dermis – the middle thick layer- contains sweat glands, nerves, and blood vessels Subcutaneous – the deepest layer that contains fat and helps protect body from injury and conserve heat

13. Facts About Skin An adult has more than 20 square feet of skin – about the size of a blanket. You shed about 40 pounds in a lifetime. Every minutes 30,000 to 40,000 dead skin cells fall from your body.

14. Facts About Skin In a month time your body has made a new layer of skin There are over a million dust mites on your mattress and pillow chomping on dead skin cells that fell off you last night. The eyelid has the thinnest skin, the palms and soles are the thickest.

15. Parts of the Skin

16. Muscle, Skin, Bone Cells Bone Cell Muscle Cell Skin Cell