The Integumentary SystemThe Integumentary System

AHCP

SOME FACTS ABOUT THE SOME FACTS ABOUT THE SKIN THAT YOU ARE IN…SKIN THAT YOU ARE IN…

Its Waterproof, Stretchable,Washable, yet Tough!

Its automatically repairs small cuts, rips & burns & is guaranteed to last a lifetime

It weighs 7% of your body weight!

Functions of the Integumentary SystemFunctions of the Integumentary System

1. Protection: provides 3 types of barriersA. Chemical: acid secretions slows bacterial growth

(ring tarnish!)

B. Biological: Macrophages = wbc’s patrol skin

C. Physical barriers: few things able to enter: Some Fat-soluble substances Poisons (poison ivy) Solvents- paint thinner Heavy metals- lead & mercury

FYI: Transdermal patches are soaked in oils/solvents to carry drug Across - nicotine, birth control & motion sickness!

FunctionsFunctions

2. Temperature Control

3. Makes Vitamin D - sunlight converts cholesterol in dermis to Vit. D3 which is needed for calcium uptake

4. Sensation - touch, pressure, pain & temp

5. Storage - fats

6. Excretion (wastes) & Secretions (milk)

What Is The Structure of Skin?What Is The Structure of Skin?3 Layers: Epidermis

– Composed of epithelial tissue (stratified squamous)– avascular

Dermis – underlies the epidermis– Tough leathery layer composed of fibrous connective tissue– Good supply of blood

Hypodermis (a.k.a subcutaneous layer -not considered skin)– Made of adipose and loose connective tissue– Stores fat, anchors skin, protects against blows

Epidermis

DermisBasement membrane

What are the different types of What are the different types of cells in the epidermis?cells in the epidermis?

1. Keratinocytes

Make the protein keratin =

tough & water resistant Are formed in lowest levels & push up by production of new cells below

Become dead and scale-like, millions rub off everyday

FYI: Everything you see on a person is dead! Outer 20-30 cells thick. Average person sheds 40 pounds of these in a lifetime!

What are the different types of What are the different types of cells in the epidermis?cells in the epidermis?

2. Melanocytes

melanocyte

Melanin in keratinocytes

Absorbs ultraviolet light so skin is not

damaged

Make pigment melanin (melan = black)

What are the different types of What are the different types of cells in the epidermis?cells in the epidermis?

3. White blood cells

Langerhans’cell

They Macrophages, which patrol & eat

bacteria/viruses

What are the different types of What are the different types of cells in the epidermis?cells in the epidermis?

4. Sensory Cells

Connected to nerve cells

from dermis Sense touch.

Characteristics of the DermisCharacteristics of the Dermis Connective tissue has lots of collagen & elastic

fibers - gives skin strength

Extensibility = able to stretch (elbow skin)

Elasticity = able to return to its original shape after extension/contraction (pregnancy & swelling)

Thickest =

Thinnest =

Palms/soles

Eyelids

More Characteristics…More Characteristics…

Sense Receptors: touch & pressure receptors

Ridges formed from papillary layer form finger prints.

http://bio.rutgers.edu/~gb102/lab_5/104bm.html

What are the major structures What are the major structures in Dermis?in Dermis?

Sweat glands

Sebaceous glands

Hairs

Nails

Sweat GlandsSweat Glands1. Common sweat (merocrine)

Watery sweat Heat & waste loss (all over skin - lots on palms/soles)

2. “Funky” sweat (apocrine) Milky/yellow thick sweat - thought to be scent glands Starts at puberty Armpits & groin

3. Ear wax! (ceruminous)

4. Milk (mammary)

Sweat GlandsSweat Glands1. Merocrine (common sweat glands)

Watery sweat Heat & waste loss (all over skin - lots on palms/soles)

2. Apocrine (“funky”)

Sweat glandsSweat glands

Sebaceous GlandsSebaceous Glands Sebum = oil - around hair follicles, none on palms/soles

Softens and lubricates hair and skin

Slows water loss and kills bacteria

Blackheads - built up sebum

Pimples - Built up sebum is a nutrient for bacteria (puss!)

Sebaceous GlandsSebaceous Glands

HairHairMade of dead keratinized skin cells

2 parts = shaft & rootFunction = Protection!

FYI on Hair: You have about 100,000 hairs on your head You lose about 100/day It grows ~0.5 in/month - goes through cycles Hirsutism = excessive hair growth (often in

women due to disease)

HairHair

You have about 100,000 hairs on your head You lose about 100/day It grows ~0.5 in/month - goes through cycles Hirsutism = excessive hair growth (often in

women due to disease)

Hair Follicles

Hair Follicles

NAILSNAILS

A scale-like modification of the epidermis

Made of tightly compressed keratinized cells

Useful tools to pick up small objects or scratch an itch.

Nail matrix is the region responsible for nail growth.

FYI: Nails & Hair DON’T grow after death - skin just shrinks!

What causes the color of What causes the color of skin?skin?

1. Melanin Range in color from yellow to reddish-brown to black Everyone has the same # of melanocytes but make

varying amounts & colors Sunlight increases production! Clusters create moles & freckles

2. Carotene-yellow to orange pigment found in foods. Most in the palms or soles.

3. Hemoglobin- Red blood (from dermal layer)gives a pinkish hue to fair skin

3 pigments contribute to skin color

Aging Skin (A billion dollar Aging Skin (A billion dollar industry!)industry!)

Major Age-Related Changes– Injury and infection increase– Immune cells decrease– Sun protection diminishes– Skin becomes dry, scaly– Hair thins, grays– Sagging, wrinkles occur– Heat loss decreases– Repair slows

= loses melanin & fills with air!

Skin Injury & RepairSkin Injury & Repair

Skin Injury & RepairSkin Injury & Repair

Skin CancerSkin CancerBenign lesions 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

Types of Skin CancerTypes of Skin Cancer

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

Squamous Cell carcinoma- –Grows rapidly and metastasizes if not removed–Small red rounded elevation on the skin

Basal Cell Carcinoma

Squamous cell carcinoma

Lesion removed from patient

Basal Cell Carcinoma

Skin Cancer Types cont.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?What is the ABCD rule?

Used for recognizing melanoma

Third-degree burn

Second-degree burns