Integumentary System

Entire Notes Pakcet

Integument

• aka skin

• largest organ

• composed of two layers: epidermis & dermis

Functions of the Skin

• protection

• maintenance of normal body temp

• synthesis of vitamin D

• excretion 

• sensory receptor

Epidermis

• epithelial tissue

• keratinizing

• avascular

• mitosis

Dermis

• connective tissue

• responsible for strength of skin

• adipose cells & macrophages

• blood vessels and nerves (VASCULAR)

• includes two layers: reticular & papillary

Hypodermis (overall)

• loose connective tissue

• connects skin to muscle and bone

Stratum Basale

• deepest layer

• germinativum

• mitosis constantly occurs here

• protection (melanin)

Stratum Spinosum

• 8-10 layers or karatinocytes

• produces lamellar bodies (lipid filled organelles)

• begin to synthesize keratin

Stratum Granulosum

• 3-5 layers of flat keratinocytes

• cells stop dividing here (die)

• forms keratin

Stratum Lucidum

• 3-5 layers of dead cells

• appears transparent

• only in thick skin

• found in hairless areas: palms, soles

Stratum Corneum

• superficial layer

• very thick

• 15-30 layers or dead keratinized cells

• occurs on all exposed skin surfaces

• prevents water loss

• resist abrasions

Keratin

makes the cells hard in order to provide strength

Thick Skin

• 5 layers

• found in areas subjected to pressure or friction (palms, soles, fingertips)

• papillae of underlying dermis is parallel

Thin Skin

• 4 layers

• more flexible

• covers rest of body

• hair is found here

Callus

• found in skin subject to friction or pressure

• produces thickened area

• can develop in thick and thin skin

Pigments are Determined by…

• pigments (melanin, Hb, carotene)

• blood circulating through the skin

• thickness of stratum corneum

Melanin

• provides protection against UV rays

• accounts for color in skin, hair, and eyes

• determined by heredity, light exposure, and hormones

• differences in pigmentation come from levels of synthetic activity NOT numbers of melanocytes

Carotenemia

• yellow pigment condition (harmless)

• acquired from yellow or orange foods

• source of vitamin A

• results in yellow tint on palms and soles (only)

Jaundice

a yellowish pigmentation of the skin, the conjunctival membranes over the sclerae (whites of eyes), and other mucous

Cyanosis

appearance of a blue or purple coloration of the skin surface due to being low on oxygen

Erythema

a redness of the skin, caused by hyperemia of the capillaries in the lower layers of the skin. it occurs with any skin injury, infection, or inflammation

Hematoma

a localized collection of blood outside the blood vassels

Reticular

• deep layer (80% of dermis)

• dense irregular CT

• hair follicles, nerves, sweat and oil glands, and phagocytes

• contains collagen and elastic fibers

Papillary

• superficial layer (20% of dermis)

• blood vessels supply epidermis with nutrients

• removes waste products aids in regulating body temp

• fingertips have this pattern

• loose CT

Hypodermis (composed of)

• AKA subcutaneous tissue

• mostly adipose tissue (some areolar)

• binds skin to underlying tissue

• energy reservoir (fat)

• skin resets here which attaches to bone and muscle

Accessory Skin Structure

• hair

• hair follicles

• smooth muscle

• sweat and sebaceous (oil) glands

• nails

Characteristics of Human Hair

• hair (composed of hard keratin)

• hair found almost everywhere

• hair is made by HAIR FOLLICLES

• hair pigment is made by melanocytes

3 Different Body Hair Types

• lanugo

• vellus

• terminal

Lanugo Hair

fine, unpigmented fetal hair

Vellus Hair

fine, unpigmented hair of children and women

Terminal Hair

coarser, longer, pigmented hair or scalp, eyebrows, eyelids, axillary, and pubic regions

Zones of Hair

• bulb

• root

• shaft

Bulb of Hair

swelling at base in dermis

Root of Hair

remainder of hair with follicle; below the surface of skin

Shaft of Hair

exposed portion above skin surface

Follicle

• nerve fibers (hair receptors) encircle follicle; detect motion

• arrecter pilli muscles stimulate piloerection (goose bumps)

• bulb is where hair originates

Alopecia

thinning or baldness

Pattern Baldness

• the loss of hair from only some regions of the scalp rather than thinning uniformly

• genetic and hormonal

Hirsutism

• excessive hair growth in areas that are not usually hairy in women

• hormone imbalance

Functions of Body Hair

• too thin to provide warmth

• alert us to parasites crawling on skin

Functions of Scalp Hair

heat retention and sunburn cover

Functions of Bear, Pubic, & Axillary Hair

indicate sexual maturity and help distribute sexual scents

Functions of Guard Hairs & Eyelashes

prevent foreign objects from getting into nostrils, ear canals or eyes

Nails

• derivative of stratum corneum

• densely packed cells filled with hard keratin

Glands

• ALL EXOCRINE

• 2 types: sebaceous (oil) and sudoriferous (sweat)

Sebaceous (Oil) Glands

• dermis

• occur over entire body except palms, soles

• produces oily secretion (sebum)

• collects dirt

• soften and lubricathe hair

• protection

Sudoriferous (Sweat) Glands

• widely distributed over body

• this is a filtrate of plasma and some waste products

• 2 types: merocrine and apocrine

Merocrine (or Eccrine) Glands

• most common

• open directly onto surface of skin

• have own pores

• secretes products with no loss of cellular material

• numerous in palms and soles

Apocrine Glands

• produce sweat containing fatty acids

• found in underarms and genitalia

• active in puberty, causes body odor

• mammals use this for scent as means of communication

Other Integumentary Glands (Not Sweat or Oil)

• ceruminous glands

• mammary glands

Ceruminour Glands

• modified merocrine sweat glands

• earwax (cerumen)

• in combination with hairs, protect eardrum, prevent dirt and insects from entry

Mammary Glands

• not the same as breast

• a milk-producing gland within the breast

• only during lactation and pregnancy

First -Degree Burn

• red skin color

• only epidermis is damaged

• cool the burn

Second-Degree Burn

• blister

• epidermis & upper part of dermis are damages

• cover brunch with gauze bandage

Third-Degree Burn

• entire thickness of skin is damages (epidermis & dermis)

• permanent damage

• fat, muscle, and bone may be affected

• burned area appears gray-white, red, or black

• no initial pain (nerve endings are destroyed)

• treated with IV

Acne

• disease of hair follicles of the face, chest, and back

• NOT caused by bacteria

• caused by elevated sebum production & the maturation of skin cells

Dermatitis (Eczema)

• inflammatory condition of the skin

• caused by allergies, genetics, and irritations

• red, itchy, rash, crust

Psoriasis

• inflammatory skin disease

• no known cause

• scaly skin thought to result from abnormal lymphocytes

Albinism

a genetic lack of melanin

Vitiligo

condition that causes depigmentation of sections of skin. It occurs when melanocytes die or are unable to function