Chapter 17

Structure and Movement

Skeletal, Muscular & Integumentary Systems

Ch 17.1 – The Skeletal System

A. All the bones and cartilage in your body make up your skeletal system which has 5 major functions:

1. Gives body shape and support

2. Protect internal organs

3. Attaches to muscles for movement

4. Forms red blood cells in marrow

5. Stores calcium and phosphorus compounds for later use

B. Bone Structure

1. Periosteum – tough tight-fitting membrane that covers bone surface

a) contains small blood vessels that carries blood to bones

b) contains cells involved in bone growth and repair

2. Compact Bone – hard, strong layer

of under the periosteum

a) gives bone its strength

b) has framework containing calcium phosphate deposits

3. Spongy Bone – found toward the ends of long bones

a) has many small open spaces that make bones lightweight

b) filled with marrow that produces blood cells

4. Medullary/Marrow Cavity – hollow space in the center of long bones

a) contains marrow which produces blood cells

5. Cartilage – rubbery layer of tissue found at the ends of bones

a) acts as a shock absorber and reduces friction b/w bones

b) people with damaged cartilage feel pain when they move their joints called arthritis

C. Your skeleton begins before birth as cartilage, which is gradually broken down and replaced by bone

1. Healthy bone tissue is always being formed and re-formed

a) Osteoblasts build up bone tissue by depositing calcium and phosphorus

b) Osteoclasts break down bone tissue releasing calcium and phosphorus into the blood

F. Human Bones

1. Human body has 206 bones

2. Babies born with 300

a) Most of a baby’s skeleton is still cartilage with only small bones in between; as they grow the cartilage continues turning into bone and small bones fuse into larger ones

Ossification of Cartilage

Osteoporosis

D. Joints – any place where two or more bones come together

1. Bones must be kept just far enough apart so they don’t rub against each other

2. Ligament – tough band of tissue that holds bones together and in place

E. Types of joints

1. Immovable joint – allows little or no movement

a) Ex: bones of skull

2. Movable joint – allows for movement

a) Pivot Joint – one bone rotates in a ring of a stationary bone

Ex: Neck; turning your head

b) Ball-and-Socket joint – rounded end of one bone fits into cuplike cavity of another

Ex: hips & shoulders

c) Hinge joint – allows back and forth movement

Ex: elbows & knees

d) Gliding Joint – one part of a bone slides over another bone

Ex: wrists, ankles & vertebrae

e) Saddle Joint – moves back and forth up and down

Ex: thumbs

Bones of the Human Body

Ch 17.2 – Muscular System

A. Muscle – organ that can contract and relax which provides the force to move body parts

1. Human body has over 600 muscles

B. 2 types of muscles:

1. Voluntary Muscles – you are able to control

2. Involuntary Muscles – you cannot control

C. 3 types of muscle tissue:

1. Skeletal Muscle (moves bones)

a) most common type of muscle

b) attached to bones by tendons

c) voluntary muscle

d) contracts quickly & tires easily

e) looks striped or striated

2. Cardiac Muscle (makes up heart)

a) found only in the heart

b) involuntary muscle

c) looks striated

3. Smooth Muscle (internal organs)

a) involuntary muscle

b) contracts and relaxes slowly

c) ex: intestines, stomach, uterus etc.

D. You move because pairs of muscles work together

1. Muscles always pull on bones (never push)

2. When one muscle of a pair contracts the other is relaxing

3. Blood carries lots of energy rich molecules to muscles to do their work

4. Muscles can become larger or smaller (atrophy) over time depending on use

Ch 17.3 – Integumentary System

A. Your skin is the largest organ of your body

B. Skin is made of 3 Layers:

1. Epidermis – the outer, thinnest layer

a) ridges produce finger prints

b) cells in base produce pigment called melanin which protects and gives color

c) new cells are constantly produced at the base and pushed up

d) outermost layer are dead cells that rub on when you touch anything

2. Dermis – middle layer

a) thickest layer

b) contains blood vessels, nerves, hair follicles, muscles, oil glands and sweat glands

3. Hypodermis (subcutaneous layer) – bottom most layer

a) fatty layer that insulates the body

C. Skin Functions

1. Protection – forms covering to:

a) prevent injury

b) keep out disease causing organisms

c) prevent excess water loss

2. Sensory Response – nerve cells in skin detect and relay info to brain

3. Vitamin D Formation – produced when skin is exposed to sunlight and needed for absorption of calcium

4. Regulation of Body Temp -

a) perspiration from sweat glands eliminates excess body heat

b) blood vessels in skin help release or hold heat

5. Eliminates Waste – through sweat glands

D. Skin injuries – produces new cells to repair tears

1. Bruises happen when tiny blood vessels beneath the surface of skin burst and leak into surrounding tissue

2. Cuts on skin surface

a) scab forms to prevent bacteria from entering body

b) WBC’s in surrounding vessels fight infections that may have entered

c) new skin cells grow beneath

cut and move upward to fill in

gap and push off scab

3. Skin Burns

a) 1st degree burn – damages only epidermis; redness and some swelling may occur

Ex: sunburn

b) 2nd degree burn – damages epidermis and part dermis; redness, swelling and blistering will occur

Ex: severe sunburn, cooking burn

c) 3rd degree burn – damage all the way down to hypodermis

Ex: burn victim from fire

4. Severe damage repair

a) skin grafts – pieces of healthy skin cut from a person’s body to cover the damaged area

b) cadavers skin may be used to cover areas and prevent infection until victim heals