Muscular System and Skin

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

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

Types of Muscle Tissue

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

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

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)

Skin

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

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

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