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

2. The Skeletal System (pg. 440)
Skeletal system = all the bones in your body
5 functions:
Gives shape & support
Protect internal organs
Muscles R attached, allow bones 2 move
Blood cells R formed in some bones
Marrow = soft tissue in the center of long bones & spongy bones
A lot of calcium & phosphorus are stored in bones

5. Bone Structure (pg. 441)
Bones aren’t smooth; there R rough spots, edges, pits, & holes
These areas allow for blood vessels and nerves to enter & leave bones
Compact bone = hard strong layer of bone under periosteum
Spongy bone = toward ends of bone, lightweight, w/ open spaces
Cartilage = thick, smooth layer of the ends of bones 2 absorb shock & reduce friction
Arthritis = cartilage wears away causing friction & lots of pain

8. Bone Development (pg. 442)
When U were a baby, your skeleton is made of cartilage & over time is replaced by osteoblasts (bone forming cells)
U R born w/ 300 bones & as U grow some fuse together & as an adult U only have 206
Osteoblasts & osteoclasts (breaks down bone) constantly regulate calcium & phosphorus in your body

11. Bones Meet (pg. 443 - 444) Joint = place where 2 bones meet
Keeps bones away from each other 2 prevent friction
Ligament = band of tissue that holds bones joints
Immovable joint = allows little 2 no movement
Movable joint = allows 4 a wide range of movement
Pivot = 1 bone rotates in a ring of another (head turning)
Ball-in-socket = 1 bone has a rounded end that fits into a cavity of another (shoulder)
Hinge = back & forth motion (knee)
Gliding = 2 bone slides over another (hand)

13. The Muscular System (pg. 447 - 448)
Muscle = organ that can relax & contract 2 allow movement
U have more than 600 muscles in your body
Voluntary muscles = muscles U can control
Involuntary muscles = muscles U cannot consciously control

15. Types of Muscle Tissue (pg. 450 - 451)
Skeletal muscles = muscles that move bone
Tendons = thick bands of tissue that attach muscles to bone
These R voluntary, the most abundant, & look striated
Smooth muscles = non-striated, involuntary that move many internal organs
Cardiac muscles = only in the heart, involuntary, look striated

18. Muscles at Work (pg. 451)
Muscles work in pairs  one contracts while the other relaxes
Muscles always pull not push in order to move bones
This happens because of the energy in glucose

20. Skin (pg. 455 - 456) Skin is the largest body organ
Epidermis = surface of the skin, top is dead cells
New cells R the bottom of epidermis
Melanin = pigment that gives skin color
UV rays allow for more melanin to produce
Dermis = thick layer of tissue under epidermis
Blood vessels, nerves, & oil & sweat glands are here
Fat is stored under dermis

22. Pimples
Pimples occur when there is an increase in oil production (from hormones)
Oil combines w/ dead skin cells 2 clog hair follicles resulting in a pimple
Everyone gets pimples, especially in teenage years
The amount & severity usually depend on when puberty sets in (hormones) and heredity

24. Functions of the Skin (pg. 456)
Function are:
Forms a protective covering 2 prevent injury & disease
Prevents excess water loss
Serves as a sensory organ
Forms vitamin D, which helps absorb calcium, & produce from UV rays
Regulate body temp
Blood vessels constrict or expand to release or hold heat
Dermis has about 3 million sweat glands, which cool the body when sweat evaporates
Excrete wastes
Sweat glands release water, salt, & urea

25. All Done!