Chapter 15

Support, Movement, and Responses

I. The Skin Skin is the largest organ of your bodyA. Skin Structures

1. Three layers of tissuea) epidermis – outer, thinnest layerb) 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

B. 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.

C. Skin Injuries and Repairs

1. Injuries include bruises, scratches, burns, rips, and exposure to harsh conditions like cold dry air.

D. Diseases of the Skin

1. Chickenpox, shingles, acne, psoriasis, melanoma, hives, ringworm, BO

E. 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.

II. The Muscular System

A. 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

b) Involuntary Muscles – muscles you cannot consciously control

cardiac and smooth muscles are involuntary muscles

c) Tendons – thick bands of tissue that attach muscles to bones

B. 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.

C. 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.

D. Skeletal Muscles (Look at picture)

III. The Skeletal System

A. 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.

B. 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 absorberLink to bone picture

C. 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

D. Joints Joint – any place where 2 or more

bones come together Ligaments – tough bands that hold your

bones together

1. 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

E. The Skeletal System

(Look at the picture)

IV. The Nervous System

A. 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 Cellsa) sensory neurons – receive

information and send messages to brainb) motor neurons – conduct

messages from brain to musclesc) interneurons – relay messages from sensory neurons to motor

neurons3. Synapse – small space between nerve

cells

B. 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)

C. 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

D. The Senses1. Vision

a) cornea – the transparent section at the front of the eye

b) lensc) 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. Hearinga) an object vibrates producing

sound wavesb) sound waves travel through airc) sound waves funnel down ear

canal to middle eard) eardrum vibratese) hammer, anvil, and stirrup vibratef) fluids in cochlea vibrateg) hair cells in cochlea moveh) 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