CHAPTER 8

Bones, Muscles and Skin

Section 1

Body Organization and Homeostasis

Body Organization and Homeostasis

The levels or organization in the human body consist of cells, tissues, organs and organ systems

Cells is the most basic organized part of the body

System is the most advanced

Cells

Cell is the basic unit of structure and function in a living thing

Human body contains about 100 trillion cells

Cell membrane forms on the boundary of the cell

The nucleus is the control center that directs the cells activities

The material within a cell is the cytoplasm, it is clear and jelly-like

Cells

Inside the cytoplasm are structures called organelles

Cells carry on the processes that keep the organism alive

Cells grow and reproduce They rid the organism of waste and

helps break down food to release energy

Tissues

Tissue is a group of similar cells that perform the same function

Muscular tissue can shorten and contract

Nervous tissue directs and controls the body using electrical messages

Connective tissue provides support and connects all its parts

Epithelial tissue covers you body inside and out

Organ and Organ Systems

Organ is a structure that is composed of different kinds of tissue

Organs perform a specific job like a tissue, but is more complex than a tissue

An organ system is a group of organs that work together to perform a major function

Homeostasis

The different organ systems work together and depend on one another

All the systems of the body work together to maintain homeostasis, to keep the internal balance

Homeostasis is the process by which an organism’s internal environment is kept stable in spite of changes in the external environment

Homeostasis

Very simply even when its cold out, your body will always have the same temp. Body temp. will drop when you are sick

Your body has various ways to maintain homeostasis When it is warm out, you sweat to help cool

off your body When it is cold, your body shivers, the

shivering helps to provide heat for your body

Section 2

The Skeletal System

What the Skeletal System Does Our skeleton is our framework It is made up of all the bones in our

body The number of bones in your body

depends on how old you are. A newborn has 275 bones An adult has 206 bones As babies grow, bones in the body fuse

together.

What the Skeletal System Does Your skeleton has 5 major functions

Provides support and shape for the body Enables you to move Protects your organs Produces blood cells Stores minerals and other materials until

your body needs them

What the Skeletal System Does The backbone, or vertebral column ,

is the center of the skeleton. If you run your fingers down the

length of your back you will feel 26 vertebrae

Most of the bones in your body are associated with muscles

Bones also protect vital organs Bones also produce certain blood

cells, and store other vitamins and minerals.

Joints of the Skeleton

A joint is a place in the body where 2 bones come together

Joints allow bones to move in different ways

There are 2 different types of joints, moveable and immoveable.

Immovable are joints that allow for little or no movement The bones in the skull are held together

by immovable joints

Joints of the Skeleton

Most of the joints in the body are moveable joints.

Moveable joints allow for a wide range of motion

The joints in the body are held together by strong connective tissues called ligaments

Most joints have a second connective tissue called cartilage, which is more flexible than bone

Joints of the Skeleton

Cartilage covers the ends of the bones and keeps them from rubbing together

There is also a fluid that helps to lubricate the ends of the bones

Bones- Strong and Living

The word skeleton comes from a Greek word meaning “a dried body”

Bones are actually complex living structures that undergo growth and development

The longest bone in your body is your Femur, it is also the toughest to break.

Blood vessels and nerves enter and leave the bone through the membrane.

Bones- Strong and Living

Beneath the bone’s outer membrane is a layer of compact bone, which is hard and dense, but not solid.

These small canals carry blood vessels and nerves from the bone’s surface to the living cells within bone.

Spongy bone has many small spaces within it

This structure makes spongy bone tissue lightweight.

Bones- Strong and Living

Inside many bones contain a soft, connective tissue called marrow.

There are 2 types of marrow, red and yellow Red bone marrow produces most of the

body’s red blood cells. As a child most of your marrow is red, as

a teenager, only the ends of femurs, skull, hip bones, and sternum

Yellow marrow stores fat as an energy reserve

Bones- Strong and Living

Bones are strong and lightweight, stronger than concrete or granite rock. Only 20% of an adults weight is bone

Even when you get old, your bone tissue will continue to grow

So even when you break a bone, new bone tissue forms and the healed region will be stronger than before.

Bones develop from cartilage into bone, but not everywhere

Taking Care of Your Bones

A combination of a balanced diet and regular exercise are important for a lifetime of healthy bones

A healthy diet has calcium and phosphorus Meats, whole grains, leafy vegetables,

and dairy products. We try to prevent against

osteoporosis Condition in which the body’s bones

become weak and break easy.

Section 3

Diagnosing Bone and Joint Injuries

Common Skeletal System Injuries 3 common skeletal system injuries

are fractures, dislocations, and sprains.

A fracture is a break in the bone. Simple=> cracked or completely broken

in 2 or more pieces. Compound=> the bone is sticking out of

the skin Dislocation occurs when the end of a

bone comes out of its socket Sprain is when ligaments stretch to

far

Identifying Injuries

There are 2 ways to identify injuries of the skeletal system, X-rays and MRI

X-rays are a form of energy that travels in waves A lead apron is used to protect from

unnecessary exposure The X-rays pass thru soft tissue but

not the bones One limitation is that it can not be used to

observe soft tissue damage

Identifying Injuries

An MRI, magnetic resonance imaging, is a large machine that contains magnets

The subject is exposed to short bursts of magnetic energy This causes atoms in the body to vibrate

or resonate. A computer then analyzes the vibration

patterns.

Treating Injuries

In addition to wearing a cast, 2 other ways to treat skeletal system injuries include surgical procedures such as joint replacement and arthroscopy

Joint replacement usually happens to people with arthritis, a disease of the joints.

Treating Injuries

Arthroscopic surgery Doctors make a small incision and insert

a slim, tube shaped instrument called an arthroscope.

Attached to the arthroscope is a small camera that is connected to a small monitor.

Once the problem area is found, doctors make another incision and use small instruments to make necessary repairs.

Section 4

The Muscular System

Types of Muscles

There are about 600 muscles in the human body.

Some muscles are easy to control, others are impossible to control

The beating of your heart and breathing are muscles you are unable to control, these are called involuntary muscles.

Types of Muscle

There are 3 types of muscle tissue Skeletal muscle Smooth muscle Cardiac Muscle Some are voluntary, some are

involuntary

Types of Muscles

Skeletal muscles are attached to the bones of your skeleton and provide the force that moves your bones

Skeletal muscle is striated, meaning its in badns and gets tired

At the end of a skeletal muscle is a tendon A tendon is a strong connective tissue that

attaches muscle to bone Because you are able to control the

muscles in your arms and legs, they are a voluntary muscle

Types of Muscles

Smooth muscle are inside many internal organs such as the stomach and blood vessels.

Since you can not control your stomach, these muscles are involuntary

Smooth muscles tire more slowly than skeletal muscle

Types of Muscle

Cardiac muscle is found only in your heart

Cardiac muscle has some characteristics with both smooth and skeletal muscle

Cardiac muscle never gets tired like skeletal muscle, but is striated.

It is also involuntary

Muscles at Work

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.

Section 5

The Skin

The Body’s Tough Covering

The skin protects the body from injury, infection, and water loss.

The skin also helps regulate body temperature, eliminate wastes, gather info. About the envir., and produce vitamin D.

The Epidermis

The skin is organized into 2 main layers, the epidermis and dermis.

The epidermis is the outer layer of the skin

Epidermis is usually thinner than the dermis

The epidermis does not have any blood vessel or nerves This is why shallow scratches do not

bleed or hurt

The Epidermis

Epidermal cells have a life cycle The skin cells we see, and come off

as dead skin cells, were once living when at the bottom of the epidermal layer

The Epidermis

In some ways, the cells of the epidermis are more valuable dead than alive.

Most protection is due to the layer of dead cells on the surface

Shedding of dead skin cells carries away bacteria and other substances on your skin.

Skin also produces melanin, a pigment, or colored substance that gives skin its color

The Dermis

The dermis is the inner layer of the skin.

The dermis is about a layer of fat but beneath the epidermal layer.

The fat layer helps to pad the internal organs and helps keep heat in the body.

The dermis is the layer of skin that has nerves, blood cells, sweat glands, hairs and oil glands.

The Dermis

Sweat glands produce perspiration which reach the surface through pores.

Strands of hair grow within the dermis in structures called follicles

The hair you see about the epidermal layer is made up of dead cells

Caring for your Skin

3 simple habits can help you keep your skin healthy Eat a healthy diet Keep your skin clean and dry Limit your exposure to the sun

The End