Concept C - Integumentary System

Epidermis

Outermost superficial region

• Strariefied squamous epithelium(keratinized)

• Avascular

• Composed of several layers or strata containing keratinocyets

Dermis

Middle Region

Subcutaneous(Hypodermis)

Deepest region

Stratum Corneum

• Outermost layer of epidermis

• Dead cells contain keratin

• Cells sloughed(shed) from surface and continually replaced from deeprer layers

Stratum Basale

• Deepest layer of epidermis firmly attached to dermis

• Contains melanocytes

  • Produce the pigment melanin

  • Skin color- the more active the melanocytes the darker the skin

  • Melanin absorbs ultraviolet radiation and protects against DNA damage

• Contains stem cells fom which all new epidermal cells are formed

Thick skin

• Epidermis has 5 layers

• Found on palms of hand and soles of feet

  • Stratum lucidum

Thin skin

• Epidermis has 4 layers

• No Stratum lucidum

Dermis

• Papillary layer

• Reticular layer

Papillary Layer

• Composed of areolar(loose) connective tissue

• Contains capullaries to nourish epidermis

Reticular layer

• Composed of dense irregular connective tissue

• Collagen and elastic fibers give skin strength and elastic recoil

Subcutaneous layer (Hypodermis)

• Not a part of the skin

  • Connects skin to the muscles which lie beneath

• Abosrobs shock

• Prevents heat loss from body; insulates the deep body structures

• Common site of injection because little blood flow in fatty tissue & substances absorbed more slowly

1st Degree: Superficial Burn

• Only the outer layers of epidermis damaged

• Symptoms include localized redness, swelling, and pain

• Heals in 3-10 days

• Sunborn

2nd Degree: Partial Thickness Burn

• Epidermis and papillary layer of dermis are damaged

• Symptoms mimic first degree burns, but fluid filled BLISTERS also appear

• Healing in 3-4 weeks

3rd Degree: Full Thickness Burn

• Epidermis and all of dermis are damaged

  • Hypodermis is affected

• Burned area appears gray-white, cherry red, or black

• No initial edema or pain (since nerve endings are destroyed)

• Fluid loss is great

• Gradting often necessary in larger burns

4th Degree: Full Thickness Burn

• Extends through entire integument(epidermis, dermis, subcutaneous layer) into underlying tendons, ligaments, muscle & bone

• Black, charred or leathery gray appearance

• Amputation of appendages often required

• Very challenging to survive

Merocrine sweat glands

• Palms, soles of the feet, and forehead

• Water-like sweat

Apocrine sweat glands

• Axillary and genital areas

• Sweat contains fat and protein leading to body odor

Sebaceous Glands

• Secrete sebum(oil)

• Most commonly found on face, neck, and trunk

• Not present on palms or soles

• Softens and lubricates hair & skin

• Controlled by hormones and become active during puberty

Hair Follicle

Tube surrounding hair root (part within skin)

Shaft

Superficial portion of hair (above epidermis)

Hair Pailla

Indentation of hair bulb containing blood vessels

Arrector pili

Bundle of smooth muscle cells

• Makes hair ‘stand on end’

• Triggered by sympathetic nervous system in response to fear

• Also for insulation

Meissner’s corpsucle

• Superficial part of dermis

• Touch, tickle

Bare nerve endings

• Pain, heat, and cold.

Pacinian corpsucle

• Larger and deeper in dermis/hypodermis

• Pressure