Pages 438 – 457 Date Chapter 16: Bones, Muscles, and Skin

Pages 438 – 457Date

Chapter 16:Bones, Muscles, and Skin

The Skeletal System (pg. 440)

1. Skeletal system = all the bones in your body

2. 5 functions: 1. Gives shape & support2. Protect internal organs3. Muscles R attached, allow bones 2 move4. Blood cells R formed in some bones

1. Marrow = soft tissue in the center of long bones & spongy bones

5. A lot of calcium & phosphorus are stored in bones

Bone Structure (pg. 441)1. Bones aren’t smooth; there R rough spots,

edges, pits, & holes1. These areas allow for blood vessels and nerves

to enter & leave bones

2. Compact bone = hard strong layer of bone under periosteum

3. Spongy bone = toward ends of bone, lightweight, w/ open spaces

4. Cartilage = thick, smooth layer of tissue @ the ends of bones 2 absorb shock & reduce friction

1. Arthritis = cartilage wears away causing friction & lots of pain

Bone Development (pg. 442)

1. When U were a baby, your skeleton is made of cartilage & over time is replaced by osteoblasts (bone forming cells)

2. U R born w/ 300 bones & as U grow some fuse together & as an adult U only have 206

3. Osteoblasts & osteoclasts (breaks down bone) constantly regulate calcium & phosphorus in your body

Bones Meet (pg. 443 - 444)

1. Joint = place where 2 bones meet1. Keeps bones away from each other 2 prevent friction

2. Ligament = band of tissue that holds bones together @ joints

3. Immovable joint = allows little 2 no movement4. Movable joint = allows 4 a wide range of

movement1. Pivot = 1 bone rotates in a ring of another (head

turning)2. Ball-in-socket = 1 bone has a rounded end that fits

into a cavity of another (shoulder)3. Hinge = back & forth motion (knee)4. Gliding = 2 bone slides over another (hand)

The Muscular System (pg. 447 - 448)

1. Muscle = organ that can relax & contract 2 allow movement

2. U have more than 600 muscles in your body

3. Voluntary muscles = muscles U can control

4. Involuntary muscles = muscles U cannot consciously control

Types of Muscle Tissue (pg. 450 - 451)

1. Skeletal muscles = muscles that move bone

1. Tendons = thick bands of tissue that attach muscles to bone

2. These R voluntary, the most abundant, & look striated

2. Smooth muscles = non-striated, involuntary that move many internal organs

3. Cardiac muscles = only in the heart, involuntary, look striated

Muscles at Work (pg. 451)

1. Muscles work in pairs one contracts while the other relaxes

2. Muscles always pull not push in order to move bones

3. This happens because of the energy in glucose

Skin (pg. 455 - 456)

1. Skin is the largest body organ2. Epidermis = surface of the skin, top is

dead cells1. New cells R formed @ the bottom of epidermis2. Melanin = pigment that gives skin color

1. UV rays allow for more melanin to produce

3. Dermis = thick layer of tissue under epidermis

1. Blood vessels, nerves, & oil & sweat glands are here

4. Fat is stored under dermis

Pimples

1. Pimples occur when there is an increase in oil production (from hormones)

2. Oil combines w/ dead skin cells 2 clog hair follicles resulting in a pimple

3. Everyone gets pimples, especially in teenage years

4. The amount & severity usually depend on when puberty sets in (hormones) and heredity

Functions of the Skin (pg. 456)

1. Function are:1. Forms a protective covering 2 prevent injury &

disease2. Prevents excess water loss3. Serves as a sensory organ4. Forms vitamin D, which helps absorb calcium,

& produce from UV rays5. Regulate body temp

1. Blood vessels constrict or expand to release or hold heat

2. Dermis has about 3 million sweat glands, which cool the body when sweat evaporates

6. Excrete wastes1. Sweat glands release water, salt, & urea

All Done!