Integumentary system

histology

skin

skin

largest organ of the body *typically accounting for 15-20 % of total body weight

epidermis, dermis, subcutaneous

3 layers of skin

Epidermis

consist mainly of a stratified squamous keratinizee epithelium composed of cells called keratinocytes

Langerhans cells

Arise from red bone marrow and migrate to the epidermis -Constitute small portion of epidermal cells -Participate in immune responses Easily damaged by UV light

Merkel cells

function as touch receptors in association with sensory nerve endings

Melanocytes

a mature melanin-forming cell, typically in the skin.

Albinism

inability to produce melanin

vitiligo

the complete or partial loss of melanocytes from patches of the skin resulting in irregular white spots

stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum

layers of epidermis

stratum basale

deepest, single layer of cuboidal to low columnar cells, basement membrane

stratum spinosum

normally the thickest layer

limited cell division, langerhans cells

stratum granulosum

3-5 layers of flattened polygonal cells

contains fibers and keratins

stratum lucidum

3-5 layers of clear flat dead cells

stratum corneum

the most superficial layer of the epidermis consisting of dead cells

Dermis

the deep layer of the skin;contains fibroblasts that produces and elastic fibers

papillary layer and reticular layer

two layers of the dermis

Stratum papillarosum/ papillary layer

superficial layer of dermis

composed of areolar connective tissue

stratum reticularosum /reticular layer

deeper layer, dense irregular connective tissue

subcutaneous tissue

known as hypodermis or superficial fasia

areolar connective tissue

contains mast cells that releases histamines and other chemical important in inflammation

adipose tissue

storage for energy, contributes to inflammation by producing cytokenesis that activates wbc

hair

a thread-like keratinized outgrowth from the skin

8-10mm / month

hair follicle, hair bulb, hair root, hair shaft

parts of hair

alopecia

loss of hair

lanugo, angora, definitive

types of hair

Lanugo

fetal hair

Angora

scalp hair or continuous growth hair

Definitive hair

eyebrows

pilomotor or arrector pili muscle

contracts under stress"goosebumps"

hair root plexus

nerve endings sensitive to touch; detect movement of hair

Sebaceous glands (oil glands)

produce sebum that moistens hair

comedo

a plug of sebum in the hair follicle that becomes darkened; commonly called a blackhead

Nails

hard plates of keratin grow 3- 4mm per month

body, nail bed, free edge, nail root, nail matrix, hyponychium, eponycium

parts of nails

nail bed

skin underlying the nail plate

nail root

base of the nail

nail matrix

responsible for nail growth

Hyponychium

attached to free edge to the under surface

Eponychium

covers the nail root

ceruminous glands

dermis of the ear canal

secrete cerumen or wax

Suboriferous glands

sweat glands

apocrine and eccrine

2 types of sweat glands

apocrine

This type of sweat gland is found mainly in the arm pits and groin area, display what type of secretion

eccrine

abundant in forehead, upper lip, palms and soles