Bones, Muscles & Skin

Functions of the Skeletal System Shape & support Movement Protects organs Produces blood cells Stores minerals

Two Parts: Axial: Skull & vertebral column 2. Appendicular: appendages (arms, legs, hips & shoulders)

Joints: Any place where two or more bones come together. 4 types: 1. hinge- forward & backward (knee) 2. Ball & Socket- greatest range of motion- hip & shoulder 3. Pivot: one bone rotates around another- neck 4. Gliding: one bone slides over another- wrist & ankle

Ligaments: Hold bones together at joints -end of the bones covered in cartilage to keep them rubbing together

Human Skeleton

Muscular System About 600 muscles in the human body Two Main types: Involuntary: you can not control them Voluntary: you can control them

Three types of muscle tissue: Cardiac: only in the heart, involuntary, striated, always working Skeletal: attached to bones by tendons, voluntary, striated, tires easily Smooth: involuntary, not striated, usually lines the insides of your organs

Types of muscle tissue:

How do muscles work? Muscles can only contract In order for movement to occur muscles must occur in pairs- one contracts while the other relaxes

Skin Largest organ in the human body- spread out- covers 1.5 meters square Functions: Protection Maintain temperature Eliminate wastes Gather information Produce vitamin D

Skin has two layers: Epidermis Dermis Under the skin is a layer of fat

Epidermis Top layer Mostly dead skin cells Protects the under layers Thinner than the dermis No nerves or blood vessels Does contain melanin-pigment that gives skin it’s color

Dermis Thicker, underneath layer Contains: Blood vessels Nerves Sweat glands Oil glands Hair follicles

Caring for Your Skin Eat a healthful diet & drink plenty of water Keep your skin clean using mild soap Limit sun exposure