1. Muscular System and Skin

2. Types of Muscles About 600 muscles Types Involuntary muscles
Muscles that are not under your conscious control
Ex: breathing and digesting
Voluntary muscles
Muscles that are under conscious control
Ex: skeletal muscles

3. Three Types of Muscle Tissue
Skeletal muscle
Attached to bones of skeleton
Provide force that moves your bones
Tendon connects muscle to bones
Striated or banded
React quickly and tire quickly
Smooth muscle
Inside internal organs like stomach and blood vessels
Involuntary
Not striated
React slowly and tires easily
Cardiac muscle
Found in your heart
Involuntary
Striated
Don’t tire

4. Types of Muscle Tissue

5. How Muscles Work Can only contract Don’t extend
Skeletal muscles must work in pairs.
While one contracts, the other muscle in the pair relaxes to its original length.
Ex:
Biceps contract to bend elbow
Triceps contract to extend arm

6. Healthy Muscles Exercise keeps muscles strong and flexible
It makes muscles grow in size which is stronger.
Stretching helps prepare your muscles for exercise or play.
Muscle strain-pulled muscle
Occurs when muscles are overworked or overstretched
Cramps
Muscle contracts strongly and stays contracted

7. Skin’s Functions Protects the body Maintaining temperature
Barrier that keeps microorganisms out
Keeps substances inside the body
Maintaining temperature
Blood vessels enlarge when warm
Sweating
Eliminating wastes
Perspiration has wasted made from the breakdown of proteins
Gathering information
Pressure, pain, and temperature
Send warnings to brain
Producing vitamin D
Made in presence of sunlight and is important for healthy bones (helps absorb calcium)

8. Skin

9. Epidermis Outer layer Thinner No blood vessels or nerves
Cells die after about two weeks
Layer of dead cells on top of skin and remain on skin for about two weeks until shed
Provides protection and cushions
Cells produce melanin, which is a pigment in skin.
Protects skin from UV

10. Dermis Inner layer Found above fat layer or hypodermis
Pads organs
Keeps heat in the body
Contains nerves, blood vessels, sweat glands, hairs, and oil glands
Sweat reaches surface through pores
Strands of hair grow within follicles
Oil helps to waterproof your hair and helps keep skin moist

11. Caring for Your Skin Healthful diet Keep your skin clean
Provides energy and raw materials needed for growth and replacement of hair, nails, and skin cells
Drink plenty of water to replace water lost in perspiration
Keep your skin clean
Get rid of dirt and harmful bacteria
Helps control oiliness
Limit your exposure to the sun
Too much can cause skin cancer