Keratinocytes

Produce fibrous protein keratin. Makes structures hard and water resistant.

Melanocytes

Cells in lower epidermia, produce pigment melanin

Langerhans cells

Macrophages that help activate immune system

Merkel cells

Touch receptors

Stratum Basale

Also known as stratum germinativium. Deepest epidermal layer firmly attached to the dermis. Undergo rapid division.

Stratum Spinosum

prickly layer of the epidermis. Cells contain a weblike system of intermediate prekeratin filaments attached to desmosomes.

Abundant melanin granules and dendritic cells.

Stratum Granulosom

Granular layer of the epidermis. Thin; 3-5 cell layers in which the cells flatten.

Keratohyaline and lamellated granules accumulate.

Stratum Lucidum

Clear layer of the epidermis in thick skin. Thin, transparent band superficial to the stratum granulosum.

A few rows of flat, dead keratinocytes

Stratum Corneum

Horny layer. 20-30 rows of dead, flat, keratinized membranous sacs.

three quarters of the epidermal thickness

Papillary layer

part of the dermis

Areolar connective tissue w/collagen and elastic fibers and blood vessels.

Contains: capillary loops, Meissner's corpuscles, free nerve endings.

Reticular layer

~80% of the thickness of the dermis, collagen fibers provide strength and resilency. Elastic fibers provide stretch-recoil properties (hair follicles and glands)

Cleavage lines

located in the reticular dermis.

Collagen fibers arranged in bundles form cleavage (tension) lines.

Incisions made parallel to cleavage lines heal more readily.

Melanin

yellow to reddish-brown to black, responsible for dark skin colors.

Produced in melanocytes; migrates to keratinocytes where it forms "pigment shields" for nuclei, freckles and pigmented moles.

Carotene

yellow to orange skin pigment.

Most obvious in the palms and soles

Hemoglobon

responsible for the pinkish hue of skin

I.E- when someone turns red from embarrassment or anger

Merocrine sweat gland

also known as Eccrine sweat gland.

abundant on palms, soles, and forehead.

sweat: 99% water, NaCl, vitamin C, antibodies, dermcidin, metabolic wastes

ducts connect to pores

function in thermoregulation

Apocrine sweat gland

confined to axillary and anogenital areas

ducts connect to hair follicles

functional from puberty onward (as sexual scent glands)

Specialized

-- Ceruminous glands- in external ear canal; secret cerumen

-- mammary gland- secrete milk (from puberty)

Sebaceous Gland

oil gland. Widely distributed. Most develop from hair follicles. Become active at puberty.

Gland ruptures and produces sebum.

Sebum

oily holocrine secretion, bactericidal, softens hair and skin, lubricate and water proofs the skin.

Arrector pili

smooth muscle attached to hair follicle.

Responsible for goosebumps.

Alopecia

hair thinning in both sexes after age 40.

Male pattern baldness is caused by follicular response to DHT (dihydrotesterone)

Functions of the Integumetary System

1. protection
2. body temperature
3. cutaneous sensation
4. metabolic functions
5. blood reservoir
6. excretion

3 types of protection barriers of the Integumentary system

1. Chemical- low pH secretions and defenses against bacterial activity
2. Physical/mechanical barriers- keratin and glycolipids block most water and water-soluble substances, plant oleoresins (i.e. poison ivy), organic solvents, salts of heavy metals, some drugs
3. Biological- dendritic cells, macrophages, and DNA
4. Body temp- thermoregulation
5. Cutaneous sensations- temp, touch (pressure) and pain
6. Metabolic functions- synthesis of vitamin D and chemical conversion of carcinogens and hormones.
7. Blood reservoir- up to 5% of body's blood volume
8. Excretion- nitrogenous wastes and salts in sweat

Basal cell carcinoma

least malignant, most common.

stratum basale cells proliferate and slowly invade dermis and hypodermis.

Cured by surgical excision in 99% of cases

Squamous cell carcinoma

2nd most common

involves keratinocytes of stratum spinosum (prickly layer)

most common on scalp, ears, lower lip, and hands

Good prognosis if reated by radiation therapy or removed surgically

Melanoma

most dangerous

involves melanocytes. highly metastatic and resistent to chemotherapy

Characteristics of skin cancer

A: Asymmetry; the 2 sides of the pigmented area do not match

B: Border exhibits indentations

C: Color is black, brown, tan, and sometimes red or blue

D: Diameter is larger than 6 mm

First degree burn

epidermal damage only

localized redness, edema (swelling) and pain

Second degree burn

epidermal and upper epidermal damage

blisters appear

Third degree burn

entire thickness of skin damage

no initial edema or pain

Skin grafting is usually necessary

Lanugo coat

covering of delicate hairs in the 5th and 6th month of fetus

Vernix caseosa

subcutaneous gland secretion; protects skin of fetus (end of 6th month of fetus)