SKELETON, MUSCLES, AND SKIN

The Skin (Largest organ of the body) is composed of all four types of body tissues:

EPITHELIUM – lining of organ

CONNECTIVE – made of collagen and elastin protein fibers

NERVE – transmit impulses

MUSCLE – associated with hairs

The Skin’s Roles

1. Regulates Body Temperature

A. Blood vessel dilation and constriction

B. Sweat cools the body

2. Protects body from injury and disease

3. Sense Organ

6. Produces Vitamin D when exposed to sunlight

4. Removes wasteproducts

5. Layer of fat insulatesthe body

I. EPIDERMIS Outer thin layer

A. OUTER LAYER – Dead cells

B. INNER LAYER – Living cells

1. MELANOCYTES – Produce melanin (colors and protects skinby absorbing UV light)

2. KERATINOCYTES – Produce keratin (tough fibrous protein that waterproofs the skin)

Structures of the Skin

II. DERMIS – inner, thicker layer of skin; contains collagen fibers, blood vessels, smooth muscle, nerves, sweat glands, hair follicles, and oil glands

*Sweat Glands Regulate body temperature and excrete wastes in sweat

*Sebaceous Glands Produce sebum (oily) – Keeps skin flexible and waterproof

III. SUBCUTANEOUS LAYER (hypodermis) –

Below the dermis;

Contains fat which cushions, insulates, retains heat and stores energy

FANCY WORD FORFAT!!!!

HAIR

HAIR FUNCTIONS - 1. Protects and provides insulation

2. Prevents particle from entering the body (in nose and ear)

*Produced from hair follicles in thedermis *Hair is dead cells filled with keratin

*Oil glands keep hairs from becoming brittle

HAIR FOLLICLE

OIL GLAND

Nails form from nail rootMade of keratin

NAILS

Fingernails grow 4X as fast

as toenails!

SKIN DISORDERS

CARCINOMAS – Skin cancers in non-pigmented cells Usually high cure rate

MALIGNANT MELANOMA –In pigmented cells Usually low cure rates

ACNE –Clogged oil duct and infection

PSORIASIS – Inherited; Rapid growth of Epidermal cells causing scaly white skin

FUNCTIONS OF THE SKELETAL SYSTEM

1. Provides a framework

2. Protects internal organs

3. Efficient movement

4. Produces blood cells

5. Stores minerals

STRUCTURE OF BONE

COMPACT BONE -Hard layer of bone under the membraneSPONGY BONE -Less dense bone; adds strength without mass; under compact bone at ends of long bones and in middle of short flat bones

PERIOSTEUM – Outside membrane; supplies nutrients and oxygen to bone

Soft tissue filling center spaces in most large bones

Two Types:1. RED MARROW - Makes blood cells;Mainly found in flat bones and ends of long bones

2. YELLOW MARROW - Mainly fat, can make blood cells if needed; in center of long bones

BONE MARROW

GREEN BOXESSHOW MARROW

CAVITY

BONE STRUCTURE

Formation of Bones - Ossification

Bone from cartilage cells which are in protein fibers of tough collagen and flexible elastin

Immature bones (OSTEOBLASTS) secrete minerals that replace cartilage in response to force

In compact bone, layers of collagen and calcium salts form around hollow channels called HAVERSIAN CANALS that contain blood

vessels and nerves

Bone cells are trapped in the rings and are then called OSTEOCYTES (mature bone cells)

HAVERSIAN CANAL

OSTEOCYTE

OSTEOCLASTS break down bone so it can be rebuilt by osteoblasts

Growth Plates

In the ends of long bones

Cartilage grows causing an increase in thelength of the bone

Growth continues until cartilageis replaced by bone

In adults, cartilage is still found in ears, nose, where ribsattach to sternum

GROWTH PLATES IN THE HAND AND WRIST

AFFECTS OF AGE ON THE SKELETAL SYSTEM

OSTEOPOROSIS - Loss of bone mass; more common in older woman

When work of osteoclasts and osteoblasts isn’t balanced, bones are weakened.

HEALING OFBROKEN BONES

HUMAN BODY HAS 206 BONES

Two Main Parts -

1. AXIAL SKELETON - Bones of skull, vertebrae, ribs and sternum

2. APPENDICULAR SKELETON - Arms, legs, shoulders, pelvis

JOINTS – Where two bones meet

Can be movable or immovable (fixed)

STRUCTURES OF MOVABLE JOINTS:

LIGAMENTS (connect bone to bone)TENDONS (connect muscle to bone)SYNOVIAL MEMBRANE – produces synovial fluid to lubricateBURSA – sac of SYNOVIAL FLUID for shock absorption and reducing friction CARTILAGE – end of bones

THREE MAIN TYPES OF JOINTS

1. IMMOVABLE – Little or no movement – skull

2. SLIGHTLY MOVABLE – Limited movement- vertebrae

3. FREELY MOVABLE – AllowsMovement in one or more directions:

A. Ball and socket- shoulderB. Hinge- kneeC. Pivot- neck to headD. Saddle- thumbE. Gliding- foot

Pivot - A ring of bone rotating around another bone. For example, the neck. Ball-and-Socket - Allows movement in all directions. For example, the shoulder joint. Hinge - Allows the joint to bend and straighten, but does not rotate. For example, the elbow joint. Ellipsoid - A less flexible version of the ball-and-socket joint. For example, the wrist joint. Saddle - Fit together to allow all movements except rotation. For example, the thumb joint. Gliding - Two generally flat surfaces gliding over each other. For example, the joints between the tarsals of the foot.

TYPES OFMOVEABLE

JOINTS

COMMON PROBLEMS WITH JOINTSSPRAINS - Injury due to forcible twisting

ARTHRITIS -Inflammation of joint

BURSITIS -Inflammation of the bursa

RHEUMATOID ARTHRITIS –Immune system attacks joints and deposits bone in them

THREE TYPES OF MUSCLE

1. SMOOTH - Found in internal organs and blood vessels

Involuntary slow contractions

2. CARDIAC MUSCLE -

Found in heart

Striped (Striated)

Involuntary

interconnected for rhythmic contractions

3. SKELETAL MUSCLE -

Attached to bones to move them

Voluntary and consciously controlled by the central nervous system

Striped (Striated)with dark and light bands

MAKING THE SKELETON MOVE

ORIGIN – End attached to stationary bone

INSERTION – End attached to moving bone which moves toward the origin

Muscles work in opposing pairs (ANTAGONISTIC)–

FLEXOR – Bends the joint

EXTENSOR – Straightens the joint

STRUCTURE OF SKELETAL MUSCLES

Skeletal muscle is composed of MUSCLE FIBERS, Composed of smaller structures (MYOFIBRILS)

Muscle fiber

Composed of two types of smaller structures (FILAMENTS):

A. Thick Filaments - Protein MYOSIN

B. Thin Filaments - Protein ACTIN

Alternating myosin and actingive striped appearance ofmuscle

SARCOMERE – Section of myofibril containing actin and myosin and bound by Z lines which are discs attached to actin

SLIDING FILAMENT THEORY

Actin filaments slide towards each other during contraction as myosin heads attach to actin bending inward

MYOSIN

Exercise tones muscle and increases strength by increasing the size of the fibers

Energy comes from ATP from aerobic cellular respiration

When there isn’t enough oxygen

Anaerobic respiration

Lactic acid (causes cramping until more oxygen is available)

Muscle Sprain – Torn or overly stretched muscle, ligament or tendon

Muscle Strain – Pulled muscle; overstretching usually because not warmed up

Tendonitis – Inflammation of tendons

Muscle Injuries