Skeleton System, Muscular System & Integumentary System (Skin)

Skeleton System Skeletal system *All the bones in your body (206 of them!) make up the skeletal system *Skeleton gives shape & support to the body. *Bones protect the internal organs. *Major muscles are attached to bones. *Blood cells are formed in the marrow in the center of the bone. *Calcium & phosphorous compounds are stored in the skeleton for later use.

Skeleton System cont… Bone Structure –1. Periosteum is a tough, tight-fitting membrane that covers the bone’s surface. Contains small blood vessels carrying nutrients into the bone Contains cells involved in growth & repair of bone. –2.Compact Bone is the hard, strong layer under the periosteum. Gives bone strength Has a flexible framework containing deposits of calcium phosphate.

Skeletal System Cont… Bone structure cont.. –3. Spongy bone is found toward the ends of long bones Many small, open spaces that make bones lightweight Filled w/marrow, which produces blood cells –4. Cartilage is a rubbery layer of tissue found at the ends of the bones, where joints are formed. Cartilage acts as a shock absorber & reduces friction between bones when they rub together. People w/damaged cartilage feel pain when they move their joints.

Skeletal System Cont… Your skeleton begins as cartilage, which is gradually broken down & replaced by bone. –Healthy bone tissue is always being formed & re-formed –Osteoblasts build up bone by depositing calcium & phosphorus, which make bone tissue hard. –Osteoclasts break down bone tissue.

Skeletal System Cont… Joints are any place where two or more bones come together. Bones must be kept just far enough apart so not to rub against each other. Ligaments are tough bands of tissue that hold bones in place.

Skeletal System Cont… Types of Joints –1. Immovable Joint (also called fixed joint) Allows little or no movement Ex: joints of bones in the skull –2. Pivot Joint One bone rotates in a ring of another stationary bone. Ex: turning your head –3. Ball-&-socket Joint The rounded end of bone fits into a cuplike cavity of another bone; Ex: hips and shoulder

Skeletal System Cont… Types of Joints cont… –4. Hinge Joint Back-&-forth movement; Ex: elbows, knees 5. Gliding Joint Part of a bone slides over another bone; Ex: wrists, ankles, vertebrae Most used joint in the body.

THE MUSCULAR SYSTEM

Muscular System Muscle is an organ that can relax/contract, & provide the force to move your body parts. 2 Types of Muscles –1. Voluntary muscles that you are able to control –2. Involuntary muscles that you cannot control

Muscular System Cont… Three types of muscle tissue –1. Skeletal Muscles Move bones Most common type Tendons are thick bands of tissue that attach muscle to bones. Voluntary muscles Contract quickly & tire more easily Looks striped, or striated.

Muscular System Cont… Types of Muscle Tissue –2. Smooth Muscles In internal organs; Ex: Intestines They are involuntary muscles Contract /relax slowly. –3. Cardiac Muscle Only in the heart. Is striated, like skeletal muscle.

Muscular System Cont… We move because pairs of muscles work together. When one muscle contracts, the other relaxes. Muscles always pull on bones Over time, muscles can become larger or smaller, depending on how they are used. Blood carries energy-rich molecules to the muscle so they can do their work.

THE SKIN INTEGUMENTARY SYSTEM

Skin The skin is the largest organ of your body. Skin is made up of three layers of tissue. –Epidermis –Dermis –Fatty layer

Skin Cont… Epidermis is the outer, thinnest layer –The outermost cells of your skin are dead & rub off when you touch anything. –New cells are constantly produced at the base of the epidermis. –Cells produce melanin, which is a pigment that protects your skin & gives it color.

Skin Cont… Dermis is the middle layer –Is thicker than the epidermis –It contains blood vessel, nerves, muscles, oil, sweat glands & other structures. Fatty layer insulates the body.

Skin Cont… Skin has many functions: –1. Protection forming a protective cover over the body that prevents injury Many disease-causing organisms cannot pass through the skin Prevents excess water loss –Sensory response where nerve cells in the skin detect & relay info to the brain. –Formation of vitamin D, which helps your body absorb calcium.

Skin Cont… Cont… Skin functions: –Regulation of body temperature Blood vessels in the skin help release or hold heat Perspiration from sweat glands eliminates excess heat that has been produced by muscle contractions. –Elimination of wastes through sweat glands

Skin Cont… When injured, the skin produces new cells & repairs tears. –Bruises happen when tiny blood vessels beneath the skin burst & leak into surrounding tissues –When you have a cut, a scab forms to prevent bacteria from entering your body Cells in the surrounding blood vessels fight infection Skin cells beneath the scab grow to fill in the gap of the torn skin

Skin Cont… Injured/Repaired Skin Cont… –Doctors are able to repair severe skin damage: Skin grafts are pieces of skin that are cut from one part of a person’s own body & moved to the injured area. Doctors sometimes use skin from cadavers to prevent infections until a victim’s skin heals Doctors are beginning to grow large sheets of epidermis from small pieces of the victim’s healthy skin.