• Covers body and external
•  Skin, Kidneys, trachea, glands.
• Cells close together
• form most glands

• Protects
• Acts as barrier
• Diffusion and Filteration
• Secretion of sweat glands
• Absorption in the small intestine

• Simple Epithelium- 1 layer of cells
• Stratified Epithelium- many layers of cells
• Simple Squamous- 1 layer of flat, tile like cells
  • diffusion and filtration, blood vessels, lungs, heart kidneys
• Simple Cuboidal- 1 layer of square-shaped cells
  • Secretion, glands, ovaries, kidneys
• Simple Columnar- 1 layer of tall, narrow cells
  • secrete mucus and absorption, stomach intestines, resp. tract
• Pseudostratified Columnar-1 layer of tall, narrow
  • Secrete mucus and propel debris out of resp tract (cilia), nasal Cavity and trachea.

• Stratified Squamos- many layrs of flat, tile-like cells
  • protects and acts as barrier, Skin mouth, throat, esophagus
• Transitional- special type of stratified epi. changes shape (stretched squamos, not stretched cuboidal
  • holds fluid, urinary bladder

• Surface not in contact with other cells
• smooth to reduce friction, ex. blood vessels
• Mircovilli
  • Increases cell's surface area, small intestine
• Cilia
  • Move materials across cell's surface, trachea
• Goblet cells
  • produce mucus, Stomach

Cell Connections:

Tight Junctions

• Bind adjacent cells together, Ex. Intestines

Desmosomes

• Small channels that allow molecules to pass between cells
• allows cells to communicate
• Most common

• Structures that secrete substances onto a surface, into a cavity or into blood.

• Exocrine Glands
  • glands with ducts ex. sweat or oil
• Endocrine Glands
  • no ducts, directly into bloodstream, thyroid, thymus, pituitary glands

• Simple: no branches
• Compound: many branches
• Tubular: end of duct
• Alveolus: sac-like structure

Connective Tissue Characteristics

• Cells far apart
• contains large amounts of extracellular matrix
• Classified based on type of extracellular matrix and function. Ex. Blast cells build, clast cells carve
• Extracellular matrix contains 3 components: protein fibers, ground substance, fluid
  • Ground Substance: proteins and sugars

• Collagen Fibers- look like ropes and flexible but resist stretching
• Reticular fibers- supporting network that fills spaces between organs and tissues
• Elastic Fibers- recoil after being stretched

1. Enclose and seperate- Ex. around organs and muscles

2. Connective tissues-

Ex. Tendons: connective bone to muscle

Ex. Ligaments: connect bone to bone

3. Support and Movement- Ex. Bones

4. Storage- ex. bones store calcium and adipose tissue stores fat

5. Cushion and insulate- Ex. adipose tissue protects organs and helps conserve heat

6. Transport- ex. blood

7. Protect- ex. immune cells

• Loose: between organs, muscles, glands, skin
  • Structure: collagen fibers far apart
  • Function: support and protect

• Dense: tendons, ligaments, skin
  • Structure: collagen fibers packed close together
  • Function: connective and can withstand pulling forces

• Adipose: under skin and around organs
  • Structure:Collagen and elastic fibers, cells filled with lipids
  • Function: storage, insulate, cushion

• Type of connective tissue
• composed of chondrocytes
• contains collagen
• Withstands compressions
• Provides support, flexibility, strength

Types of Cartilage

• Hyaline Cartilage
  • Location- covers ends of bones
  • Structure- some collagen fibers
  • Function- reduces friction (cushion)

• Fibrocartilage
  • Location- between vertebra
  • Structure- lots of collagen fibers
  • Function- can withstand compression

• Elastic Cartilage
• • Location- ear and tip of nose
  • Structure- elastic fibers
  • Function- can recoil

• Hard Connective Tissue
• 2 Types: compact and spongy
• Composed of osteocytes

• Liquid connective tissue
• Erythrocytes, leukocytes, platelets
• Transport food, Oxygen, waste, hormones

• Skeletal (muscle)--Many Nucleus --peripheral location-- striated

• Cardiac (heart)-- 1 nucleus-- centrally Location-- striated

• Smooth (organ)--1 nucleus --centrally location -- non-striated

• Consists of neurons or nerve cells
• found in brain, SP, and PNS
• COntrols and coordinates body movements
• Includes axons, dendrites and cell bodies

Substitution of dead cells for viable cells

Regeneration: cells of same type develop (no scar)

Replacment: cells of a different type develop (scar)

• Occurs when tissues are damaged
• Signals the body's defenses ( white blood cells) to destroy foreign materials and damaged cells so repair can occur.

• Chemical mediators
  • Released after injury
  • Cause dilation of blood vessels

1. Redness: blood vessels dilate
2. Heat: due to increased blood flow
3. Swelling: from water and proteins
4. Pain: nerve endings are stimulated by damage and swelling

• Integumentary System Functions

• Protection: water loss, mircobes, UV light
• Sensation: hot, cold, pain, pressure
• Temperature Regulation: helps maintain homeostatis
• Excretion: removes waste
• Vitamin D production: UV light stimulates production

Epidermis

• 1st Major Skin Region (outside)
• Composed of stratified squamos epithelium

Kerantinization

• Process in which new cells with keratin push old cells to surface
• 40-56 days for new cells to reach surface

Strata Corneum- outermost layer of epidermis

Callus- forms when stratum corneum has frequent friction

Stratum basale- deepest layer of epidermis, single layer of cells, firmly attached to dermis

• 2nd major skin region
• Dense connective tissue
• contains collagen, elastic fibers, fibroblasts, nerve endings, smooth muscles, blood vessels and hair follicles

Cleavage Lines:

• area where skin is most resistant to stretching
• due to orientation of collagen fibers, important to scarring

contains: arrector pilli, hair follicle, nerve, veins and arteries, sweat glands

Papillary Layer- thin connective tissue layer that contains blood vessels

Dermal Papillae

Projections that extend up into epidermis

Remove waste and helps regulate temp

ridged on hands and feet (fingerprints)

pattern is genetically determined

Reticular Layer

Deepest layer of dermis

Accounts for 80% of dermis

Below dermis

foundation of skin

attaches skin to underlying muscle and bone

contains loose and adipose tissue

contains 1/2 of body's fat

yellow-orange pigment found in plants

Accumulates in stratum corneum

Gives pinkish-red color

found in red blood cells

Redness: fever, hypertension, inflammation, allergies

Pallor: anemia or low blood pressure

Jaundice: liver disorder (yellow)

Bronzing: addison's diease (kidney diease)

Bruising: broken blood vessels

Hair/shaft: flexible strands of kerantized cells

Root: below skin

Hair bulb: base of root where hair produced

Hair follicle: groups of cells surround root and bulb, gives hair different shapes

Arrector Pilli- smooth muscle that surrounds each hair follicle, contracts and hair stands on end (goose bumps)

Sebaceous gland- connected to hair follicle, sebum is the oily substance that lubricates hair and skin to prevent drying

Eccrine sweat glands

All over body and open into sweat glands, water and salt secretions

Apocrine Swear glands

opens into hair follicle, only in armpits and genitalia

thick, rich secretions

becomes active during puberty and causes body odor

-Thin plate with layers of dead stratum corneum w/ hard keratin

Cuticle- stratum corneum that extends into nail body

Nail Matrix- continuation of nail root gives rise to nails

Nail bed- attaches to nail and is distal to nail matrix

Lunula- part of nail matrix, whitish crescent shaped area

Vitamin D production

1. UV light causes skin 2 produce precursor Vitamin D
2. precursor  carried by blood to liver where modified
3. Next to kidneys where its modified again to active Vitamin D

• stimulates intestine absorbtion of calcium, and phosphate, bone growth and muscle function

Rates of chemical reactions altered by changed in temp

To cool body: Blood vessels in dermis dilate and hate is transferred from deep into tissues to skin and sweat is produced

To heat body: blood vessels constrict to reduce blood flow to skin and heat is retained.

1st Degree: damags epidermis, redness, swelling pain

2nd degree: damages epidermis and upper dermis, blisters

3rd Degree: destroys epidermis and dermis, very cherry to black color, nerve endings destroyed

Basal Cell Carcinoma- cells in stratum basale, removed by surgery

Squamos cell carcinoma- cells abose stratum basale effected, can cause death

Malignant Melanoma- arises from melanocytes in a mole, rare type, can cause death