Chapter 17: Structure and Movement

Aim: What are the 5 functions of the skeletal systems?

Skeletal System All the bones in your body make up the skeletal system It is the framework of your body 5 major functions: Copy from pg 484

Aim: What are the characteristics of our bones?

Characteristics of Bones Different sizes and shapes Have bumps, edges, round ends, rough spots, pits and holes Muscles and ligaments attach to many of the pits Blood vessels and nerves enter and leave through the holes

Parts of the Bone 1. Periosteum Is a tough, tight fitting membrane that covers the bone’s surface Small vessels carry blood into the bone cells that aid in growth and repair of the bone are present 2. Compact Bone Directly under the periosteum Hard, strong layer

Contain calcium phosphate, which makes the bones hard Bone cells and blood vessels found here Keeps bones from being brittle 3. Spongy Bone Located towards the end of bone Has many small, open spaces, which makes bones light weight Cavities filled with marrow Red marrow produces blood cells

4. Cartilage Cover the end of bones Is a smooth, slippery and thick layer of tissue Is flexible and important to joints Makes movement easier by reducing friction Damaged cartilage causes pain

Aim: What is the difference between movable and immovable joints?

Joints A joint is any place where two or more bones come together Cartilage keeps bones from rubbing together Ligaments hold bones in place 2 types of joints I. Immovable Joints Allows little or no movement Ex: bones in skull and pelvis

II. Movable Joints All movements require movable joins 4 types of movable joints: i.Pivot: One bone rotates in a ring of another bone that does not move ◦ Ex: turning your head ii.Ball and socket: Consists of a bone w/ a rounded end that fits into a cuplike cavity of another bone ◦ Allows a wide variety of motions ◦ Can be easily dislocated ◦ Ex: movement of legs and arms

iv. Hinge Joint Has a back and forth movement Ex: elbows, knees and fingers v. Gliding Joint one part of a bone slides over another bone Found in wrists and ankles Are used the most in your body

Aim: What is the major function of the muscular system?

Muscular System Muscles help make all your movements possible A muscle is an organ Muscles do 3 things: 1. Relax 2. Contract 3. Provide force to move your body More than 600 muscles in your body

2 types of muscles: 1. Voluntary muscles: Muscles that you can control Exs: face, legs, hand and arm muscles 2. Involuntary muscles: Muscles you can’t control Work all day, everyday Ex: heart, stomach

Aim: What are the types of muscles?

Types of Muscles 3 types: 1. Skeletal Muscles Attached to bones by tendons Most common type They are striated (looks striped) Voluntary muscles 2. Cardiac Muscle found only in the heart Striated Contracts about 70 times per minute

3. Smooth Muscles Found in intestines, bladder, blood vessels and other internal organs They are nonstriated They are involuntary Slowly contract and relax Internal organs are made up of several layers of smooth muscle

Aim: How does muscle action result in the movement of body parts?

Aim: What are the layers of the skin?

Skin Structures The skin is made up of 3 layers of tissue 1. Epidermis-outer, thinnest layer The cells are dead and water repellant Cells produce melanin, which protects your skin and gives it color Different amounts of melanin result in different skin colors When exposed to UV rays more melanin is produced and your skin gets darker

2. Dermis Is thicker than the epidermis Contains blood vessels, nerves, muscles, oil and sweat glands 3. Fatty Layer Insulates the body This is where fat is deposited when someone gains weight

Aim: What are the functions of the skin?

Functions of the Skin Skin is the largest organ of your body 1. The most important function is protection It helps prevent physical and chemical injury Glands in the skin secrete fluids that help kill certain bacteria As long as the skin is not open, bacteria can not enter

2. Nerve cells in the skin make it a sensory organ too 3. Vitamin D also forms in the skin Vitamin D helps the body absorb calcium into your body from food 4. The skin also helps regulate your body temperature Blood vessel help hold or release heat 5. Sweat glands help excrete wastes and regulate your body temperature

Perspiration removes heat from your body and helps it cool Sweat glands releases wastes such as, water, and salt It is important to stay hydrated during periods of sweating and extreme heat, to keep yourself from fainting

Aim: How does the skin heal itself?

Skin Injuries and Repair 1. Bruises A bruise occurs when the tiny blood vessels under your skin have burst The blood releases hemoglobin, which breaks down in the tissue into pigments The pigments cause your skin to turn different colors When the bruise starts to turn yellow, it is beginning to heal The yellow color comes from the breakdown of pigment in red blood cells

2. Cuts A cut is any tear in the skin Blood flows out until it clots A scab forms to prevent bacteria from entering The skin cells under the scab grow to fill the part that was injured When the new skin has fully formed, the scab falls off

3. Skin Grafts Are used when the skin has been severely burned or injured Pieces of skin are cut from one part of the body and moved to replace the injured skin It is kept alive by blood vessels and becomes part of the surrounding skin They can also be made from a cadaver or a victim’s healthy skin