Chapter 16:
Bones, Muscles, and Skin
Pages 438 – 457
Date
The Skeletal System (pg. 440)
1. Skeletal system = all the bones in
your body
2. 5 functions:
1.
2.
3.
4.
Gives shape & support
Protect internal organs
Muscles R attached, allow bones 2 move
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, & holes
1. 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 meet
1. 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 movement
4. Movable joint = allows 4 a wide range of
movement
1. 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 organ
2. Epidermis = surface of the skin, top is
dead cells
1. New cells R formed @ the bottom of
epidermis
2. 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 & disease
2. Prevents excess water loss
3. Serves as a sensory organ
4. Forms vitamin D, which helps absorb
calcium, & produce from UV rays
5. 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 wastes
1. Sweat glands release water, salt, & urea
All Done!