06 Integumentary System

Epidermis

protection

Dermis

inner support - nerve, blood vessels, glands hair

Hypodermis

cushion underneath - fat, insulation, energy storage

Stratum Basale

deepest layer

keratinocytes are produced

contains melanocytes and tactile (merkel) cells

Stratum Spinosum

keratinocytes are joined by desmosomes

dendritic (langerhans) cells help defend against pathogens

Stratum Granulosum

keratinization processes

cells fill with keratin, and their nuclei and organelles break down

Stratum Lucidum

only in thick skin - palms and soles

Stratum Corneum

outermost layer

many layers of dead, flattened, keratinized cells

Keratinocytes

Produce keratin for strength and water resistance

Tactile (Merkel) Cells

Detect touch

Melanocytyes

Produce melanin pigment, which helps protect DNA from UV radiation

Dendritic (Langerhans) Cells

Immune defense

Hemoglobin

Oxygen-bound

give blood colors

Melanin

Produced by melanocytes

UV exposure stimulates production

Carotene

Obtained from food

accumulates in subcutaneous fat and the stratum corneum

Albinism

inherited recessive condition in which a nonfunctional enzyme prevents normal melanin

production

Nevus

Mole, overgrowth of melanocytes

Freckles

localized areas of increased melanocyte activity

Hemangioma

benign tumor of blood vessels

Friction ridges

fingerprints

increase friction and identify individuals

Pappilary

areolar connective tissue of the dermis

Reticular

dense irregular CT of dermis

Collagen

strength

helps skin resist pulling forces

Elastic fibers

stretch and recoils

help skin return toward its original shape

Stretch marks (striae)

skin stretches beyond capabilities

collagen fibers tear

Skin

protect, preserve, produce, process, defend, control, feel

Vasoconstriction

conserve heat > skin may look pale

Vasodilation

release heat > skin may look red or blushed

Arrector pili

smooth muscle that contracts and causes goosebumps

Medulla

containing soft keratin

Cortex

layer of relatively hard keratin

Hair matrix

Cells divide to produce new hair cells

Lanugo

Fine, downy hair that appears before birth

Vellus

Fine body hair

Terminal

Coarse, longer, pigmented hair -scalp hair and eyebrows

Merocrine Sweat Glands

Cooling

Most numerous and widely distributed

Function: thermoregulation

Apocrine Sweat Glands

Odor

produce thicker secretions containing proteins and liquids

active during puberty

Sebaceous Glands

Oil

produce sebum to lubricate skin and hair

hormones stimulate secretion

Ceruminous Glands

Earwax

lubricate the canal

Mammary glands

Milk

produce milk during lactation

Regeneration

Damaged cells are replaced by the same cell type

Fibrosis

collagen rich scar tissue fills the gap and normal functio n may not fully restored

Would-healing

Bleed > Clot > Build >Cover and Scar