Support, Movement, and Responses Chapter 15 Support, Movement, and Responses

I. The Skin Skin is the largest organ of your body Skin Structures 1. Three layers of tissue a) epidermis – outer, thinnest layer b) dermis – layer below the epidermis. It is thicker and contains blood vessels, nerves, muscles, oil & sweat glands, and other structures c) fatty layer – insulates the body, where fat is deposited when people gain weight Link to skin picture

2. Melanin – a pigment that protects the skin and gives it color

Skin Functions 1. Protection 2. Sensory Response 3. Formation of Vitamin D a) Vitamin D helps absorb calcium into your blood from food in your digestive tract 4. Regulates body temperature. 5. Ridding body of wastes.

Skin Injuries and Repairs 1. Injuries include bruises, scratches, burns, rips, and exposure to harsh conditions like cold dry air. Diseases of the Skin 1. Chickenpox, shingles, acne, psoriasis, melanoma, hives, ringworm, BO

Taking Care of your Skin 1. Wear sun screen with a minimum SPF 15. 2. Bathe every day. 3. Use deodorant/antiperspirant. 4. Use moisturizing lotion to prevent cracks in skin. 5. Avoid stress.

The Muscular System Movement of the Human Body You have more than 600 muscles in your body.

1. Muscle Control a) Voluntary Muscles – muscles you are able to control skeletal muscles are voluntary Involuntary Muscles – muscles you cannot consciously control cardiac and smooth muscles are involuntary muscles Tendons – thick bands of tissue that attach muscles to bones

Working Muscles Pairs of muscles work together to allow parts of your body to move (ex. biceps and triceps) When 1 muscle contracts (shortens and becomes tighter) the other muscle relaxes and turns to original length. Muscles always pull and never push.

1. Changes in Muscles a) Muscles that are used a lot become larger because there are more muscle cells added or muscle cells are larger. b) Muscles that are not used become smaller.

How Muscles Move 1. Blood carries energy rich molecules to you muscle cells. 2. Inside the muscle cells the molecules are changed from chemical energy to mechanical and heat energy. 3. During rest periods the blood supplies your muscles more energy rich molecules. Skeletal Muscles (Look at picture)

The Skeletal System Functions of Your Skeletal System 1. Gives you shape and support. 2. Protects internal organs. 3. Muscles are attached to bones and help move. 4. Forms red blood cells in bone marrow. 5. Stores calcium and phosphorus.

d) Marrow in cavities of long bones Bone Structure 1. Bone Tissue a) Periosteum – tough, tight fitting membrane that covers a bone’s surface b) Compact Bone c) Spongy Bone d) Marrow in cavities of long bones 2. Cartilage – a smooth, slippery, thick layer at the ends of bones that acts as a shock absorber Link to bone picture

Bone Formation Your bones start as cartilage. You start with 300 bones at birth but you now only have 206. osteoblasts – bone forming cells osteoclasts – cells that break down bone cells

Joints Joint – any place where 2 or more bones come together Ligaments – tough bands that hold your bones together Immovable Joints – skull and pelvis

1. Moveable Joints a) Pivot – one bone moves around another bone that doesn’t move (arm) b) Ball and Socket – a bone with a rounded end that fits in a cup-like cavity in another bone (shoulder c) Hinge – back and forth movement (elbow) d) Gliding – one part of a bone slides over another part (wrist)

3. Joint Problems a) arthritis – starts with pain, stiffness and swelling of joints The Skeletal System (Look at the picture)

The Nervous System Nerve Cell 1. Neurons – nerve cells a) Dendrites – receive messages from other dendrites and send them to cell body b) Axons – carry messages away from cell body Link to picture of neuron

2. Types of Nerve Cells a) sensory neurons – receive information and send messages to brain b) motor neurons – conduct messages from brain to muscles c) interneurons – relay messages from sensory neurons to motor neurons Synapse – small space between nerve cells

The Divisions of the Nervous System 1. Central Nervous System – includes the brain and spinal cord 2. Peripheral Nervous System – all nerves outside of the CNS that connect brain and spinal cord to other body parts. a) Somatic System – controls voluntary actions b) Autonomic System – controls involuntary actions (heart rate, breathing, digestion)

Safety and the Nervous System Every mental process and physical action of the body involves structures of the central and peripheral nervous system. Any injury can be serious. 1. Reflex – an involuntary, automatic response to a stimulus

The Senses 1. Vision a) cornea – the transparent section at the front of the eye b) lens c) retina – tissue at the back of eye sensitive to light energy -rods and cones – 2 types of cells in retina d) optic nerve – transfers messages to the brain e) brain

2. Hearing a) an object vibrates producing sound waves b) sound waves travel through air c) sound waves funnel down ear canal to middle ear d) eardrum vibrates e) hammer, anvil, and stirrup vibrate f) fluids in cochlea vibrate g) hair cells in cochlea move h) electrical impulses travel down auditory nerve to brain

3. Smell a) molecules in air enter nose b) olfactory cells are stimulated c) impulses are sent to the brain 4. Taste a) Saliva and food rush over taste buds on tongue b) impulses are sent to the brain