A&P Unit 2: Layers of the Skin and Integumentary System

What are the six functions of the skin?

• protection from disease

• protection from UV radiation

• Protection from desiccation—drying out!

• Non-verbal communication

• Vitamin D Synthesis

• Temperature Regulation

What are the layers of the skin?

1. Epidermis

2. Dermis

3. Hypodermis

What is the epidermis composed of?

• multiple layers of closely packed epithelial cells

• the basal layer consists of cuboidal cells

• the outer laters consist of squamous, keratinized cells

What are the five layers of the epidermis of thick skin?

1. Stratum Corneum

2. Stratum Lucidum

3. Stratum Granulosum

4. Stratum Spinosum

5. Stratum Basale

Melanocyte

a skin cell that produces melanin

Merkel Cell

a neuroendocrine cell that plays a role in touch sensation and potentially acting as a touch receptor

What is the dermis made up of?

dense irregular connective tissue that houses blood vessels, hair follicles, sweat glands, and other structures

What is the hypodermis composed of?

loose connective tissue and fatty tissue

Keratinocyte

the primary cell type found in the epidermis, responsible for producing keratin and forming a protective barrier.

What are calluses?

thick accumulations of dead keratinocytes on the hands or feet

What four important events occur in the stratum granulosum?

1. Keratohyalin granules release filaggrin—a protein that binds keratin into tough bundles

2. Cells produce tough envelope proteins beneath their membranes

3. Membrane-coating vesicles release a lipid mixture that spreads out over cells surface and waterproofs it

4. Keratinocytes’ organelles degenerate and the cells die

How is the skin waterproofed?

by tight junctions between skin cells and the waterproofing that occurs in the stratum granulosum

What does the epidermal water barrier prevent?

dehydration

Does the epidermal water barrier prevent water absorption from the skin?

No, it only prevents water loss (ex: prune fingers after a bath)

What are the two components of the dermis?

• papillary layer

• reticular layer

What are the papillary and reticular dermal layers made up of?

connective tissue with fibers of collagen extending from one to the other

What is skin pigmentation determined by?

the amount of melanin produced by melanocytes in the stratum basale and taken up by keratinocytes

What are moles?

anything from benign accumulations of melanocytes to melanomas

Where do hair follicles originate?

in the epidermis

What are the different parts of a hair follice?

the hair bulb, hair shaft, inner root sheath, outer root sheath, and sebaceous gland

Nails are an accessory structure of the _______ system.

integumentary

Sudoriferous glands

sweat glands

What are the two types of sudoiferous glands (sweat glands)?

1. Merocrine glands

2. Apocrine glands

Merocrine glands

• Sweat glands that are widely distributed over the body surface

• Function as evaporative cooling

Apocrine glands

• Sweat glands that are found in regions covered by the pubic, axillary, and male facial hair

• Function as scent glands

Sebaceous Glands

oil glands associated with hair follicles

Ceruminous Glands

glands of the ear canal that contribute to earwax

Mammary Glands

milk producing glands located in the breasts

How is the body able to achieve thermoregulation (maintain body temperature)?

• When the body is hot dermal blood vessels dilate and sweat secretion increases

• When the body is cold dermal blood vessels constrict to minimize heat loss

First Degree Burn

• involves only the epidermis and heals within days

• symptoms: redness and pain

Second Degree Burn

• this is a partial thickness burn and involves parts of the dermis

• symptoms: skin may appear red, tan, or white; blistered and painful

• takes two weeks or several months to heal

Third Degree Burn

• this is a full thickness burn and involves the epidermis, all of the dermis, and often some deeper tissue

• often requires skin grafts

• needs fluid replacement, infection control, and supplemental nutrition

What are the graft options for someone with a third degree burn?

• Autograft

• Split-Skin-graft

• Isograft

Autograft

tissue taken from another location on the same person’s body

Split-skin-graft

taking epidermis and part of the dermis from an undamaged area such as the thigh or buttocks and grafting it into the burned area

Isograft

skin from an identical twin

Tanning rays and burning rays are thought to cause ______.

cancer

Sunscreens protect you from _____, but not necessarily against cancer.

sunburn

Chemicals in sunscreen damage ____ and generate harmful free radicals

DNA

Those who use tanning beds before the age of 35 increase their chance of skin cancer by ____%

75