Integumentary System More than just Skin. This unit will consist of guided activities, readings, model building, your 1 st dissection & a look at integumentary.

Integumentary System

More than just Skin

• This unit will consist of guided activities, readings, model building , your 1st dissection & a look at integumentary diseases.

I. Overall Function of the Skina) Protection: The outer dead layer protects

delicate living tissue underneath from abrasion and infection.

b) Excretion: Involved in the secretion of salts, wastes and water

c) Sensation: Nerve endings in the skin are involved in the perception of touch, pain, pressure, and temperature

d) Regulation: Blood flow throughout the skin and sweat (water), help to regulate the body temperature (part of homeostasis).

e) Storage: Nutrients are held in the skin, typically in the subcutaneous fat layer.

f) Synthesis: Vitamin D3 is produced in the skin

Skin Structure

Figure 4.4

II. Skin Structure• Surface of the skin:

• Sheds every MINUTE we loose 30,000-40,000 skin cells OR 40,000,000 – 60,000,000 cells a day. ewwwww

1.1st line of defense against infection

2.Plus sweat which is acidic

Figure 4.3

Layers of the Epidermis

Stratum corneum

• Outermost layer, flat dead cells

• 2nd thickest.

• Glycolipid layer waterproofs it. Can be washed off…this is why/where you “prune”

• Keritin & thick plasma membrane resist abrasion.

• Shed.

Stratum lucidum

• Flat cells, dead

• Located in thick skin only.

• Provides shock absorption

Stratum granulosum

• Drastic changes but still living

• Cells flatten, organelles & nuclei disintegrate

• Begin to keratinize (harden) & lamellate (waterproof) & PM gets thicker.

Stratum Spinosum

• Thickest layer

• Keratinization begins

• Langerhan’s cells here (roaming white blood cells which “endocytosis” bacteria)

Stratum Basale

• Deepest layer

• Attaches to wavy part of dermis

• Mitosis occures here. This is where you’d find some types of adult stem cells & cancer

• Melanocytes here…give skin it’s color

• Merkel cells: touch receptors from nervous system

b. Upper epidermis is dead, but lower are alive

i. blood and nutrients provided by the dermis underneath

ii. Upper looks smooth but underneath is a series of peaks and valleys called the dermal papillae (part of the dermis)

iii. Function:

1. Increases the surface area and availability of blood. Nerves also extend into.

iv. Ridges that create fingerprints start in the dermis but are larger and occur where surface area is needed for friction

Skin 6 square

• as a table (there’s a ½ sheet supplement). Each person should design 1 of the squares. The other 2 should be done as a team of 2. These will be hung up on the walls. You will use a large piece of paper & color it.

• HW: coloring activity 1 from packet

IV. Dermis-Insidea. Irregular Dense Tissue

i. Allows skin to move in any direction and then back. Reineke fave!

b. Papillae Layer(1 of 2)- contain blood vessels and nerve endings

1. Most Merkel cells (epidemial) forms a tactile which is used in the perception of touch.

2. Meissner’s corpuscles: tough receptors

a. Reticular Layer(2 of 2)- filled with collagen fibers, fat deposits, hair follicles, nerves and blood vessels and pressure sensors

i. Gives skin it’s elasticity but only to a point.

1. Striae- or stretch marks occur for quick weight/muscle gain and pregnancy

d. Temperature

i. Cold is perceived at the bottom of the dermis and at the subcutaneous layer (made of superficial fascia which connects to the muscle)

1. Function: this is the layer that constricts the blood flow in order to prevent heat loss

ii. Heat receptors are in the middle and top layers

1. Function: to speed up reaction!

g. Deep to dermis is the hypodermis

i. Not part of the skin

ii. Anchors skin to underlying organs

iii. Composed mostly of adipose tissue

1. Shock absorber

2. Storage for energy

3. insulate

keratinocytes• Produce keritin

which is a fiberous protein that helps give the epidermis its protective properties. Basically makes the cell tough to hard (hair, nails are an example of hard. Skin is tough)

melanocytes• Spider shaped. Make

melanin which is the pigment in skin that creates darker skin, tans, or freckles.

• We will be discussing the biology of skin color later in the unit.

Langerhanns’ cells (AKA epidermal

dendritic cells• Star shaped, part of

your immune system. They are macrophages (big eaters) that activate the immune system that are hanging out in the skin.

Merkel cells• Located at the

epidermal/dermal junction. Disk/pad attached to a nerve ending. It’s basically a touch sensor in the skin.

f. Sweat and Its Function

i. Function1. Helps dissipate excess heat2. Excretes waste products3. Acidic nature inhibits bacteria growth

• Odor is from associated bacteria

e. Glandsi. Sebaceous (oil) glands-

attach to the side of a follicle. Prevents epidermal water loss, prevents brittle hair and can stop the growth of some bacteria

1. Acne

i. Sudorierous (sweat) glands- eccrine & apocrine

1. eccrine- common, release watery sweat

2. apocrine- thicker, pungent sweat (think armpit)

ii. Ceruminous glands- in the ear canal, ear wax

1. Function-prevent foreign bodies from entering and damaging the inner ear

Appendages of the Skin

a. Accessory structures

i. Keratinized cells- Keratin: A tough, insoluble protein substance that is the chief structural constituent of hair, nails, horns, and hooves.

c. Hairi. Why Hair?

http://www.youtube.com/watch?v=l7nlo-CseGQ

ii. Function: reduce heat loss, exposure to UV, keeps bus/foreign objects out of eyes, ears, nose.

1. Hair grows continuously- you loose 70-100 hairs a day.

2. 70% of your body heat is lost through your head-wear a hat!

3. Males and females have the same amount of hair- although thickness differs (chimps also have the same amount!)

ii. Structure

1. Shaft-above the surface (dead)• Hair is a long chain of dead

cells• Transverse section shows 3

layers• Cuticle-outer, squamous

cells arranged like shingles w/ edges pointing up

• Cortex- largest part of hair, filled with pigment

• Medulla- inner, pigment granules and air spaces

2. Root-below the surface (alive)

– Base of root is a wide bulb with an indentation called the papilla for capillaries

– Melanocytes at the papilla provide the melanin (color pigment)

• erector pili muscle- “goose bumps” help raise hair to insulate or “puff up” to look bigger

Figure 4.7a

b. Nails

i. Function: 1. Easier to grasp objects because add

support also protect distal phalanges.

ii. Form1. Nail root - hidden under skin. Epidermis

under nail, near root is responsible for pushing it forward about 1mm a week

2. Proximal end of the nail is the cuticle- helps attach the nail to the skin.

3. Lunula-looks like a little moon.

Nail Structures

Figure 4.9

Skin Color

• See other power point

e. Burns

i. 1st degree- sunburn, limited to the epidermis

ii. 2nd degree- blistering, damage extended into the dermis

iii. 3rd degree- loss of epidermis and part or all of dermis (destruction of tissue)

iv. 4th degree is beyond the skin layer into connective and muscle and bone

• Skin grafting• Large area burned

can be fatal (just look at all of the functions skin performs!)

• 1st issue is of dehydration…then infection…

• http://adam.about.com/surgery/100100.htm

Rule of Nines

• Way to determine the extent of burns

• Body is divided into 11 areas for quick estimation

– Each area represents about 9%

Figure 4.11a

Critical Burns

• Burns are considered critical if:– Over 25% of body has second degree burns– Over 10% of the body has third degree burns– There are third degree burns of the face,

hands, or feet