HONORS ANATOMY & PHYSIOLOGYCHAPTER 5

HUMAN ANATOMY & PHYSIOLOGY

INTEGUMENTARY SYSTEM

Includes: Skin Nails Hair Sweat & Oil Glands

Integumentary System

FUNCTIONS

1. Protection: chemical barriers: skin secretions:

acidic: hostile to most bacteria some bactericidal melanin: chemical pigment shield protects

DNA from damage by UV rays physical barrier:

continuity of skin & hardness of keratinized cells

stratum corneum: multiple layers of dead cells (brick) and water-resistantglycolipids (mortar)

Substances that Penetrate Skin

1. lipid-soluble substances: )2, CO2, Vit A,D,E,K

2. oleoresins: poison ivy, poison oak3. organic solvents: acetone, dry-cleaning

fluid, paint thinner all dissolve cell lipids4. heavy metal salts: Pb, Hg5. selected drugs: nitroglycerine, nicotine,

fentanyl, seasickness meds, estrogen6. penetration enhancers: help carry other

drugs into body thru skin

Functions – Protection cont’d

3. Biological Barriers: dendritic cells of epidermis

active elements of immune system agn presenting cells

dermal macrophages phagocytes viruses or bacteria agn presenting cells

DNA e- can absorb some UV rays heat

body temperature homeostasis when body overheated blood flow to skin

increases & some heat radiates off body, sweating (sensible losses)

when body cold less blood flows to skin, more to trunk, goose bumps

@normal temps sweat glands lose ~500 mL/dthru insensible losses

Functions of Skin -2

Functions of Skin - 3

Cutaneous Sensation (sensory receptors): exteroceptors: sense stimuli from outside body Meissner’s corpuscles: in dermal papilla, feel

light touch Pacinian corpuscles: deep dermis or hypodermis,

feel deep touch hair follicle receptors: feel breezes, insect free nerve endings: pain from irritants or extreme

cold or heat

Functions of Skin - 4

Metabolic Functions: Sun light nrg powers some chemical reactions:1. modified cholesterol Vit D precursor 2. keratinocyte enzymes

“disarm” cancer-causing chemicals activate some steroid hormones (cortisone

cream cortisol a more potent anti-inflammatory)

3. synthesize important proteins collagenase

Functions of Skin - 5

Blood Reservoir dermal vessels can hold up to 5%of blood

vol. vessels constricted when

other organs need extra blood constriction shunts blood to areas in need

excretory function: sweat contains urea, uric acid (breakdown

products of proteins) NaCl + water lost with profuse sweating

Functions of Skin- 6

made of 2 kinds of tissues1. Epidermis2. Dermis

Structure of the Skin

made of stratified squamous epitheliumsome keratinized, some notavascularCells:

Keratinocytes majority of cells make keratin

Melanocytes Langerhans Cells

Immune System aka dendritic cells

Epidermis

Cells of the Epidermis

1. stratum basale deepest layer constantly undergoing cell division/ cells

pushed upward

2. stratum spinosum3. stratum granulosum4. stratum lucidum (only in thick skin)

clear, flatter, more keratin

5. stratum corneum (cornified = keratinized)

outermost layer/ 20-30 dead cells thick

Epidermal Layers

Layers of Epidermis

Thick Skin

areas subject to abrasion palms soles finger tips

Thin Skin

covers rest of bodythinnest skin (thinner subcutaneous

layer) eyelid: 0.02mm bridge of nose ankles knuckles

pigment (yellow to brown to black)

produced by melanocytes most are in stratum basale

cells stimulated to make more melanin when skin exposed to sunlight shields DNA from damaging effects of UV

radiationfreckles & moles: seen where melanin

concentrated in 1 spot

Melanin

Freckle

a strong, stretchy envelope that helps to hold the body together leather is the dermis of whatever animal it was

made frommade of dense CT: strong& flexiblerich blood supply2 regions:1. Papillary2. Reticular

Dermis

upper dermisdermal papillae: uneven projections into

lower epidermis that contain:1. capillaries2. pain receptors3. touch receptors: Meissner’sCorpuscles4. in thick skin: form ridges (fingerprints)

that improve gripping ability genetically determined

Papillary Layer

Dermal Papillae

deepest skin layerContains:1. sweat & oil glands, hair follicles, blood

vessels2. Pacinian corpuscles (deep touch

receptors)3. many phagocytes4. fibers: elastic: give young skin elasticity collagen: make dermis tough &

keeps skin hydrated by binding to water

Dermis: Reticular Layer

Dermis

Striae

extreme stretching of skin white scarsaka stretch marks

Blisters

fluid –filled pocket separating epidermis/dermis

3 pigments contribute to skin color:1. Melanin

amount & kind (yellow black)

2. Carotene orange – yellow pigment stratum corneum & subcutaneous layers

3. Hemoglobin amount O2 bound to it in RBCs in dermal blood

vessels has greater affect in light skinned people

Skin Color

cyanosis: blue hue to skin; due to poorly oxygenated blood

erythema: redness, due to increased blood flow (infection, inflammation); burn, HT, blushing

pallor: paleness, due to emotions, anemia, low BP, decreased blood flow

jaundice: yellow; usually from liver disease (not clearing bilirubin)

hematomas: bruising (bleeding under skin)

Skin Color in Sickness & in Health

Appendages of the Skin

derivatives of epidermis: hair& hair follicles nails sweat glands sebaceous glands

Hair & Hair Follicles

areas of skin with no hair: palms soles lips nipples parts of external genitalia

Functions of Hair

sense insects b/4 they biteprotects against heat loss (scalp)protects against sunshield eyesfilter air inhaled through nose

Hair

“pili”produced by hair folliclesconsist of dead keratinized cellskeratin here compared to keratin in epidermis:

tougher & more durable individual cells do not flake off

Hair

3 concentric layers of keratinized cells1. Medulla

innermost large cells & air space absent in fine hair

2. Cortex surrounds medulla layers of flattened cells

3. Cuticle 1 layer overlapping cells provides strength

Hair Pigment

melanocytes @ base of follicle to cortical cells

differing proportions of melanins of different colors give different hair colors

melanin production decreases (delayed-action genes) replaced by air bubbles gray white

Hair Follicle

fold down from epidermis dermis forming hair bulb

sensory nerve ending : root hair plexus surrounds hair bulb bending hair

stimulates plexus sensitive touch

receptors

Hair Follicle

dermal papilla: bit of dermal tissue protruding into base of follicle capillaries

matrix: actively dividing cells produces hair

arrector pili: smooth muscle from dermal part of follicle epidermis @ angle contraction goose

bumps

VELLUS TERMINAL

pale, fine hair children and

females

coarse long hairseyebrows, scalp@ puberty:

Types of Hair

Factors the Influence Hair Growth

1. Nutrition poor nutrition

poor growth2. Hormones 3. local inflammation

increased growth

normal growth~2.5 mm/wk

fastest growth teens 40’s then slows

each follicle goes thru cycle:

1. active growth phase wks yrs

2. regressive phase matrix cells die

3. resting phase 1 – 3 mos

Hirsutism

excessive hairinesscould be from ovarian

or adrenal gland tumor secreting high levels of androgens

Alopecia

hair thinningstarts @ anterior

hairline posteriorlymales:

by age 35: 40% by age 60: 85%

Male Pattern Baldness

most common type of baldness

X-linked recessive inheritance: delayed-action gene

switches on in adult & changes hair follicle response to testosterone follicles very short growth cycle may get vellus hair

Alopecia Areata

immune system attacks hair follicleshair falls out in patches

Nails

scalelike modification of epidermis forming clear protective covering on dorsal

surface of distal digitshard keratinFunctions:1. pick up small objects2. scratch3. protect tips of digits

Parts of a Nail

1. free edge2. nail plate or body3. nail bed

proximal portion = matrix: nail growth

4. proximal root5. nail folds:

proximally :eponychium (cuticle)

Nail Abnormalities

yellow: thyroid or respiratory problem

thickened yellow: fungus infection

outward concavity: iron deficiency (spoon nail)

horizontal lines: malnutrition

Sweat Glands

aka sudoriferous glands

over entire skin surface except: nipples parts of external

genitalia2 types:1. Eccrine Sweat

Glands2. Apocrine Sweat

Glands

secretory cells surrounded by myoepithelial cells: contract when stimulated by nervous system sweat goes thru duct to skin

Eccrine Sweat Glands

more numerous than apocrine

abundant on palms & soles of feet

secretory cells in dermis

sweat released thru pore (not skin pore)

Eccrine Sweat Gland

secretion: hypotonic (99% water) filtrate of blood

also has: salts vitamin C abys wastes: urea, uric

acid, NH3

Eccrine Sweat Gland

regulated by sympathetic division of ANSFunctions:1. prevent overheating

forehead spreads inferiorly

2. “emotional” sweating fright or extreme nervousness palms, soles, or axilla over body

Apocrine SweatGlands

axillary & anogenital areas onlylarger than eccrine glandsfound deeper in dermis/hypoderrmisempty onto hair follicleodorless until released onto skinwhere

bacteria decompose molecules musky, unpleasant odor

in addition to what is found in eccrine sweat: fatty acids proteins

Apocrine Sweat Glands

begin functioning @ pubertyactivated by sympathetic division of ANS

during: pain stress

exact function uncertain but likely analogous to animals glands that secrete pheromones

Ceruminous Glands

modified apocrine glands

secretion mixes with sebum (made by sebaceous gland) cerumen (ear wax)

Function:deters insects blocks entry of

foreign objects

Mammary Glands

specialized sweat glands that secrete milk

Sebaceous Glands

oil glandsfound with hair follicles

smaller on trunk & limbs large on face, neck, upper chest

secrete sebum: oily substance develop as outgrowths of hair folliclearrector pili contractions force sebum to skin

surfaceandrogens stimulate secretion (activity starts

in puberty)

Sebum

Functions:1. softens & lubricates skin & hair2. bactericidal action

Whitehead Blackhead

created by: sebum blocks

sebaceous gland duct

sebum in whitehead oxidizes

Acne

active inflammation of sebaceous glands

see: pustules or cysts on skin surface

associated with bacterial infection (staph)

Skin Cancer

Benign tumors such as warts and moles are not serious.

Malignant tumors can start on the skin and invade other body areas.

Crucial risk factor- overexposure to UV radiation

Skin Cancer

20% in USA will develop skin cancer (↑ing #s)#1 risk factor: Sun UV radiation

DNA damaged suppresses tumor suppressor gene new skin lotions contain liposomes initiate

repairof damaged DNA

Types of Skin Cancer

Basal cell carcinoma- most common, 30% of all white skin people get it. Arises from the stratum basale layer of the skin 99% curable if caught early Dome shaped nodules that form an ulcer in the

center.Squamous Cell carcinoma-

Arise from stratum spinosum Grows rapidly and metastasizes if not removed Small red rounded elevation on the skin

Basal Cell Carcinoma

Lesion removed from patient

Basal Cell Carcinoma

Squamous cell carcinoma

Skin Cancer Types cont.

Melanoma Cancer of melanocytes (very dangerous) 5% of skin cancers but rising fast Can arise from preexisting moles Appears as a spreading brown or black patch Chance of survival is poor if the lesion is greater than

4 mm thick

Melanoma

What is the ABCD rule?

Used for recognizing melanomaA-Asymmetry: two sides of the pigmented

mole do not matchB-Border irregularity: borders are not smoothC- Color: lesion has a multiple of colorsD- Diameter the spot is larger than 6 mm in

diameter (size of a pencil eraser)

What are the 3 types of burns?

First-degree burns: only the epidermis is damaged. Redness, swelling and pain are common. (sunburn) 2-3 days to heal

Second-degree burns: epidermis and upper layers of dermis. Blistering can occur. 3-4 weeks to heal.

Third-degree burns: involves the entire thickness of the skin. (pg. 164-165)

Third-degree burn

Second-degree burns

Burn Evaluation

Rule of 9’s:divides body into11areas each 9% of body

surface area + 1% for genitalia

Burn Treatment

patients require extra calories to replace lost proteins & allow tissue repair must add parenteral nutrition (IV)

2◦ infections main threat 24 hrs after burn wound is sterile fungi, bacteria,& other pathogens multiply

rapidly Immune system deficient infection leading cause of death in burn victims

Burn Treatment: Skin Grafts

1st debride burned tissuewash area with antibiotic in solutionapply synthetic membrane temporarilyskin graft: healthy skin applied to area

autograft: taken from the patient synthetic skin: silicone “epidermis” bound to

spongy “dermis” made of collagen fibers & ground cartilage patients own cells absorb &replace synthetic

* no rejection from immune system

Think About It