INTEGUMENTARY SYSTEM

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Functions

protection - injury , UV rays , pathogens, chemicals

Regulate body temp- sweating

Synthesize Vitamin D

Prevents water loss

Cushion/ insulation

Gather and transmit sensory

Blood reservoir

Non verbal communication

Epidermis (Fig 5.3)

Keratinized (makes keratin protein) stratified squamous epithelium or keratinocytes

makes antibiotics- kill bacteria

enzymes - detox chemicals

make keratin- water resistant and durable

Four or five distinct layers of keratinocytes in epidermis (surface down) (Fig)

Stratum corneum- 30 layers , water resistant, insensible perspiration , sensible perspiration - sweat glands

(Stratum lucidum)- thick skin only , palms + soles of feet

Stratum granulosum- keratin wraps into bundles , cell death occurs in this layer --> water resistant

Stratum spinosum “spiny layer”- make keratin

- dendritic cells - phagocyte

- immune response

Stratum basale- stem cells

Melanocytes -everyone has the same amount of melanocytes but produce different amounts of melanin , make a protein called Melanin (absorbs uv radiation , protecting DNA), cell found in the layers

Tactile cells- touch receptors

Epidermal ridges- extend into dermis, give us fingerprints and footprints

Clinical notes:

When cells move too fast from stratum basale to stratum corneum, keratinocytes make abnormal keratin which forms scales, flakes = psoriasis

7 to 10 days for new cells to move to surface

psoriasis- cells move too fast and make abnormal protein

blisters- damage between layers

callus - response to mechanical stress

Skin color (Figs 5.4 etc)

Melanin- produced by melanocytes

Hemoglobin- pinkish/bluish , carries oxygen

Carotene- orangish / yellow

Albino- no production of melanin , either no melanocytes or genetic issues

Vitilligo- immune system attacks and destroys melanocytes

Freckles - over production of melainin at one point

Vitamin D3

CELLS IN STRATUM SPINOSUM AND STRATUM BASALE MAKE VIT d3 --> LIVER USES THIS TO MAKE A THING TO HELP REGULATE CALCIUM LEVELS

lack of vit d leads to rickets

Dermis: (Fig 5.1, 5.8)

Two layers:

Papillary layer: capillaries + sensory receptors , areolar tissue;

Reticular layer: dense , irregular connective tissue

Lines of cleavage – (Fig 5-9)

Subcutaneous Layer (Fig 5-11)

also called the hypodermis

Areolar + adipose tissue here

larger arteries and veins found here

fxn: supportive, acts as blood reservoir , and energy source

Accessory structures of the skin

Cutaneous glands (exocrine glands)

Sebaceous Glands (Fig 5.13)

secrete sebum (fats, cholesterol, proteins, salts)

location everywhere except palms and soles of feet

start function at puberty

holocrine method of secretion

protection (trap and kill bacteria), decreases water loss,, conditions skin

keeps hair healthy

secreted into hair follicles on skin surface

acne is an inflammation of this gland

Sweat or Sudoriferous Glands (Fig 5-14)

Apocrine –sweat glands ,

found in axillary + pubic regions,

secrete into hair follicles ,

function at puberty ,

clear, viscous secretion , proteins create body odor

merocrine method of secretion

Merocrine or eccrine –

sweat glands, true sweat glands ,

are located everywhere, palms soles and forehead,

clear watery , salty,

start at birth

regulate body temp, waste release, enviorment protection

merocrine method of secretion

Control of secretion and role in homeostasis

Review questions from the book:

1. What is the major histological difference between thick skin and thin skin? Where on the body is each type found?

Thick Skin: Covers the palms, soles, and corresponding surfaces of the fingers and toes - Epidermis is about 0.5 mm thick, due to a very thick surface layer of dead cells called the stratum corneum - Serves to resist pressure and friction to which the palms and soles are especially subjected - Has sweat glands but no hair or sebaceous glands

Thin Skin: An epidermis of about 0.1 mm thick, with a thin stratum corner - Possesses hair, sebaceous glands, and sweat gland

2. How does the skin help to adjust body temperature?

skin regulates the body temperature through blood vessels and through the process of sweating

3. List the five cell types of the epidermis. Describe their locations and functions.

Stratum basale

-A single layer of cuboidal to low columnar stem cells and keratinocytes resting on the basement membrane

•Stratum spinosum

-Produce more and more keratin filaments which causes cell to flatten; the higher up in this stratum, the flatter the cells appear

•Stratum granulosum

-Consists of three to five layers offlat keratinocytes

•Stratum lucidum

-Seen only in thick skin, transparent

•Stratum corneum

-Up to 30 layers of dead, scaly, keratinized cells

4. List the five layer of epidermis from deep to superficial. What are the distinctive features of each layer? Which layer is often absent?

* Stratum corneum

* Stratum lucidum (absent)

* Stratum granulosum

* Stratum spinosum

* Stratum Basale

COME LETS GET SOME BOOTS

5. What are the two layers of the dermis? What type of tissue composes each layer?

papllary layer loose CT , Areolar tissue and the reticular layer > dense irregular CT

6. How do merocrine and apocrine sweat glands differ in structure and function?

7. What other type of gland is associated with hair follicles? How does its mode of secretion differ from that of sweat glands?

the sebaceous glands, they have holocrine method of secretion unlike other sweat glands that are mostly merocrine secretion

8. Why is it important for the epidermis to be effective, but not too effective, in screening out UV radiation?

It is important for the epidermis to be effective because UV light can damage DNA and cause cancer, however UV light is necessary in production of Vitamin D; which is necessary in the body for many roles.