The Integumentary SystemThe Integumentary System

Anatomy and Physiology

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!

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)it can transfer the pigment to

keratinocytes

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

3. Langerhans’ cells

Langerhans’cell

They are a type of

Macrophage

(White blood cell),which

patrol & eat

bacteria/viruses

Formed in bone marrow &

Move to the skin

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

4. Merkel Cells

Connected to nerve cells

from dermis Function as sensory receptors

for touch.

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!

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

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 receptors (Meissner’s Corpuscles) & pressure receptors (Pacinian Corpuscles)

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. Merocrine (common sweat glands)

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

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

3. Ceruminous - make ear wax!

4. Mammary - make milk!

Sweat glandsSweat glands

Sebaceous GlandsSebaceous Glands Oil glands (sebum) - 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!)

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)

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!

Hypodermis (Subcutaneous)Hypodermis (Subcutaneous)Loose connectiveStabilizes skin position - loosely connected to dermis above & muscle below

Lots of fat cells for padding & insulation

Functions of the Integumentary SystemFunctions of the Integumentary System

1. Protection: provides 3 types of barriersA. Chemical barriers: low pH of secretions slows bacterial

growth (ring tarnish!)

B. Biological: Macrophages

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 Regulation

3. Vitamin D Synthesis - 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)

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

What are the 3 types of What are the 3 types of burns?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.

BurnsBurns

Third-degree burn

Second-degree burns