copyright © 2010 pearson education, inc. integumentary system what is the function of the...

Copyright © 2010 Pearson Education, Inc.

Integumentary System

What is the function of the integumentary system?


Incredible Human Machine: Skin

• Write down 3 interesting facts, be prepared to share your responses with the rest of the class.

• https://www.youtube.com/watch v=fXIcwm1oqQw



• Major parts:

1. Cutaneous membrane (skin)

• epidermis (epithelium)

• dermis (CT)

• subcutaneous layer (hypodermis)

– loose CT, attaches integument to structures

2. Accessory Structures – hair, nails, exocrine glands

• Anchored in dermis & extend up thru epidermis



• 6 major functions:

– Protects & prevents H20 loss

– Temp. maintenance (insulation & evaporation)

– Synthesizes vitamin D3

– Storage (adipose tissue)– Sensory reception– Excretion & secretion of salts, water, wastes by glands


Figure 5-1


BR: Write down the following words.

• Subcutaneous fat• Epidermis• Dermis• Melanin• Oil glands• Sebum

• Pores• Hair• Erector Pili• Pilometer reflex• Sweat glands


Epidermis

• Stratified squamous

epithelium

– nutrients & O2 diffuse

from capillaries in dermis

• Thin Skin - 4 layers

(strata)

• Thick Skin - 5 layers

– Palms & soles of feet


Epidermis

• 5 strata: (CELL LAYERS)

1. Stratum germinativum

2. Stratum spinosum

3. Stratum granulosum

4. Stratum lucidum

5. Stratum corneum


Stratum corneum Stratum granulosumStratum lucidum

Stratum spinosum

Dermis Epidermal Ridge Dermal papillae

Stratum germinativum


Epidermis

1. Stratum germinativum

– contains germinative (stem) cells & melanocytes

– forms epidermal ridges (extend into dermis) & dermal

papillae (extend toward surface)

• ↑ SA for diffusion

2. Stratum Spinosum– cells may continue to divide


Epidermis

3. Stratum Granulosum

– cells produce keratin – durable, H2O-resistant protein

• forms hair, nails, calluses

4. Stratum Lucidum (ONLY in thick skin)– thin cells filled w/ keratin


Epidermis

5. Stratum corneum

– 15-30 layers of dead keratinized cells

– shed & replaced every 2 weeks

– dry, oily surface inhibits microbial growth


BR

• Turn in Bell Ringers & Epidermis Chart


Skin Color• Carotene (orange-yellow)

– converted to vitamin A

• Melanin (yellow-brown or black)– stored in melanosomes

– produced by melanocytes• protects skin by absorbing

UV radiation– causes DNA mutations

& burns – skin color depends on

amount of melanin production


Figure 5-3


Skin Color

• Blood vessels dilate from heat skin reddens

• Blood flow to surface ↓’s skin pales

• Cyanosis: bluish skin tint

– caused by severe ↓ in blood flow or oxygenation


Effects of Sunlight

• Vitamin D3

– produced by epidermal cells

– liver & kidneys convert vitamin D3 into calcitriol

• aids absorption of Calcium

– insufficient vitamin D3 can cause rickets (abnormally weak,

flexible bones)


Effects of Sunlight

• Skin Cancers

a. Basal cell carcinoma – most common

– originates in stratum germ.

b. Squamous cell carcinoma

– superficial layers of epidermis

c. Malignant melanoma – more dangerous

– cancerous melanocytes metastasize thru lymphoid system


The Dermis

1. Papillary Layer• Loose CT

2. Reticular Layer• dense irregular CT• Collagen & elastin

Both contain blood & lymph vessels, nerve fibers.


Hypodermis: Subcutaneous

– Allows independent movement

– Shock absorption & E storage

– has few capillaries & no vital organs site of subcutaneous injections


Hair

• Fxns:

– protects & insulates

– Guards against foreign

particles

– Sensitive to very light

touch (warning system)


Figure 5-5

• papilla: CT containing capillaries &

nerves

– stem cells surrounding hair

papilla form hair

• root: anchors hair into skin

• shaft: part of hair on surface

• arrector pili muscle: causes

goose bumps


Hair Follicles

Figure 5-5


Exocrine Glands

1. Sebaceous (Oil) Glands (holocrine)

– discharge sebum into hair follicles or directly onto

skin

• Lubricates and inhibits bacterial growth

• Cause Acne


Exocrine Glands2. Sweat Glands

Apocrine• secrete products into

hair follicles• sticky, cloudy

secretion • can cause odors• Armpits, groin, &

around nipples

Merocrine (Eccrine)• discharge directly onto

skin, cool the body• H20 (99%), electrolytes,

organic nutrients, waste products (urea), dermicidin (antibiotic)

• flush microorganisms & chemicals from skin


Figure 5-7


Nails

• Nail body consists of dead, keratinized cells

• nail growth occurs at nail root (epidermal fold below surface)

Figure 5-8


Repair

Figure 5-9


Repair of Skin Injuries


Effects of Aging• epidermis thins skin injuries & infections more common• dermis thins sagging & wrinkling of skin

• vitamin D3 production ↓’s weaker muscles & bones

• melanin production ↓’s • gland activity ↓’s skin becomes dry & scaly• hair thins & loses color• blood supply to skin ↓’s, sweat glands less active ability

to release heat ↓’s• skin repairs more slowly

The Integumentary System in Perspective

Functional Relationships Between the Integumentary System and Other Systems


• The Skeletal System provides structural support• The Integumentary System

synthesizes vitamin D3, essential for calcium and phosphorus absorption (bone maintenance and growth)

The Skeletal System


The Muscular System

• The Muscular System’s facial muscles pull against skin of face, producing expressions important in communication

• The Integumentary System synthesizes vitamin D3 , essential for normal calcium absorption (calcium ions play an essential role in muscle contraction)


The Nervous System

• The Nervous System controls blood flow and sweat gland activity for thermoregulation; stimulates contraction of arrector pili muscles to elevate hairs

• The Intergumentary System’s receptors in dermis and deep epidermis provide sensations of touch, pressure, vibration, temperature, and pain


The Endocrine System

• The Endocrine System includes the sex hormones that stimulate sebaceous and apocrine gland activity, and develop secondary sexual characteristics; suprarenal hormones alter blood flow to skin and mobilize lipids from fat cells

• The Integumentary System synthesizes vitamin D3, precursor of calcitriol, a hormone produced by the kidneys


The Cardiovascular System

• The Cardiovascular System provides oxygen and nutrients; delivers hormones and cells of immune system; carries away carbon dioxide, waste products, and toxins; provides heat to maintain normal skin temperature

• The Integumentary System’s mast cells produce localized changes in blood flow and capillary permeability


The Lymphatic System

• The Lymphoid System assists in defending the integument by providing additional macrophages and mobilizing lymphocytes

• The Integumentary System provides physical barriers that prevent pathogen entry; macrophages resist infection; mast cells trigger inflammation and initiate the immune reponse


The Respiratory System

• The Respiratory System provides oxygen and eliminates carbon dioxide

• The Integumentary System’s hairs guard entrance to nasal cavity


The Digestive System

• The Digestive System Provides nutrients for all cells and lipids for storage by adipocytes

• The Integumentary System synthesizes vitamin D3, needed for absorption of calcium and phosphorus


The Urinary System

• The Urinary System excretes waste products, maintains normal body fluid pH and ion composition

• The Integumentary System assists in elimination of water and solutes; keratinized epidermis limits fluid loss through skin


The Reproductive System

• The Reproductive System’s sex hormones affect hair distribution, adipose tissue distribution in subcutaneous layer, and mammary gland development

• The Integumentary System covers external genitalia; provides sensations that stimulate sexual behaviors; mammary gland secretions provide nourishment for newborn infant


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