Chapter 13 Bones Muscles and Skin Body Organization

Chapter 13: Bones, Muscles, and Skin

Body Organization and Homeostasis • Levels of Specific 1. 2. 3. 4. Broad 5. organization in the body: Cell Tissue Organ System Organism

Cells • Remember cell structure and function (cell membrane, nucleus, cytoplasm, other organelles) • Functions of cells 1. Undergo chemical reactions 2. Grow and reproduce 3. Get rid of wastes

Tissues A tissue is a group of cells that perform the same function. There are 4 main types. • Muscle Tissue- can contract or shorten • Nervous Tissue- directs and controls the body

• Connective Tissue- supports your body and connects its parts. • Epithelial Tissue- covers the surfaces of your body (skin, digestive tract, etc. )

Homeostasis • Maintaining a stable internal body environment. • Your body temp is close to 98. 6° no matter what the temp is outside. • When you are hot you sweat, when you’re cold you shiver. • Stress- your body’s reaction to potentially threatening events.

The Skeletal System • Your skeleton is made up of all of the bones in your body. • A newborn baby has about 275 bones. • An adult has about 206 bones. • As a baby grows, some of its bones fuse together.

Five major functions of the skeleton • Provides shape and support Vertebrae- 26 bones of the spine • Enables movement • Protects organs • Produces blood cells • Stores minerals and other materials

- The Skeletal System Joints of the Skeleton • A joint is a place in the body where two bones come together. Joints allow bones to move in different ways.

• Ligaments- connect bones together • Cartilage- covers the ends of bones and keeps them from rubbing together. • Compact Bone- hard and dense • Spongy Bone- beneath compact bone, contains many small spaces

• Marrow- soft connective tissue 1. Red Marrow- produces most of the body’s red blood cells. You have more red marrow as a child than as an adult. 2. Yellow Marrow- stores fat that can serve as energy reserves.

- The Skeletal System Bones—Strong and Living • Bones are complex living structures that undergo growth and development.

Bone Care • Eat a balanced diet and exercise • Osteoporosis- mineral loss in the bones; they get weak and easily break • To prevent osteoporosis, eat lots of calcium-rich foods!

The Muscular System • Involuntary Muscles- Muscles that you DON’T control (heartbeat, breathing, digestion) • Voluntary Muscles- muscles that you DO control (smiling, moving, talking)

Three Types of Muscle Tissue Smooth Muscle Skeletal Muscle Cardiac Muscle

Skeletal Muscle • Attached to bones • Provide force for movement • Voluntary Muscles • Tendon- connective tissue that attaches muscle to bone • Striated muscle- skeletal muscle is called striated because the cells appear to be banded.

Smooth Muscle • On the inside of many organs • Involuntary muscle • Not striated

Cardiac Muscle • Found only in your heart • Involuntary muscle • Striated muscle • Never gets tired (good thing!)

Muscles at Work - The Muscular System • Because muscle cells can only contract, not extend, skeletal muscles must work in pairs. While one muscle contracts, the other muscle in the pair relaxes to its original length.

The Skin Functions of the skin: • Protects the body from injury, infection, and water loss • Homeostasis • Eliminates wastes • Gathers info about environment • Produces vitamin D

Layers of the Skin • The Epidermis- outer layer, usually thin, no blood vessels or nerves - Melanin- pigment that gives skin color • The Dermis- inner layer, has nerves and blood vessels - Pores- openings in the skin - Follicles- where hairs grow on the skin

- The Skin The Epidermis • The skin is organized into two main layers: the epidermis and the dermis.

Caring for the Skin • Three simple habits can help keep your skin healthy: 1. Eat a healthy diet 2. Keep your skin clean and dry 3. Limit sun exposure - Cancer- when body cells divide uncontrollably - Wear hat, sunglasses, and sunscreen - Don’t go out between 10 am & 4 pm