the integumentary system ~ layers of epidermis

is the hypodermis considered part of the integumentary system?

no ~ but its connective tissue fibers are interwoven with those of the dermis

the inner dermis is what?

underlying area of connective tissues

What is the tough, fibrous protein which is the basic structural component of hair and nails in humans? It is Produced in the stratum granulosum.

Keratin

What is the formation of a layer of dead, protective cells filled with keratin? This occurs on all exposed skin surfaces except the eyes.

Keratinization

What are the most abundant cells in the epidermis that contain large amounts of *keratin*?

Keratinocytes

What are dense granules made up of cross-link keratin fibers?

Keratohyalin

the integumentary system has connections to the ---- system with blood vessels in the dermis and connections to the ---- system with sensory receptors for pain, touch, and temperature.

cardiovascular ; nervous

deep to the dermis, the ---- separates the integument from the deep fascia around other organs, such as muscles and bones.

hypodermis

what is also referred to as the superficial fascia or subcutaneous layer?

hypodermis

what two parts make up the integument?

1) cutaneous membrane (skin) 2) accessory structures

The dendritic cells of the Stratum Spinosum participate in the immune response by stimulating defense against what 2 things?

1) microorganisms that sneak into epidermis 2) superficial skin cancers

what are the 2 components of cutaneous membrane?

1) outer epidermis 2) inner dermis

The five strata (layers) of keratinocytes in thick skin from the basal lamina to free surface skin are what?

1) stratum basale 2) stratum spinosum 3) stratum granulosum 4) stratum lucidum 5) stratum corneum

the integumentary system is ------ m^2 in area

1.5 to 2

How many days does it take for a cell to move from the stratum basale to stratum corneum?

15-30 days

the integumentary system is ---% of your body weight

16

What are the dominant cells found in the stratum Basale?

Basal calls (also called germinative cells)

Why is the Stratum Spinosum called the "spiny layer"?

Bc cells look spiny due to the fact that the cells cytoplasm shrank, but left their cytoskeletal elements and desmosomes intact, resulting in this pin-like appearance

Keratinization is also called what?

Cornification

What are tiny, nipple-shaped mounds that increase the area of the basement membrane and strengthen the attachment between the epidermis and dermis?

Dermal papillae

In the Stratum Spinosum, 8 to 10 layers of keratinocytes are bound together by ———-.

Desmosomes

Because the epidermis is avascular (no blood vessels), nutrients and oxygen —— from capillaries in the dermis.

Diffuse

-avascular stratified squamous epithelium -dominant cells = keratinocytes

Epidermis

——— attach the cells of the stratum basale to the basement membrane

Hemidesmosomes

-contain the pigment melanin -scattered throughout stratum basale

Melanocytes

-found in hairless skin -respond to touch (trigger nervous system)

Merkel cells

What other specialized cells are found in the stratum basale?

Merkel cells (aka tactile) and melanocytes

the functions of the skin include: 1) ——- of underlying tissues and organs against impact, abrasion, fluid loss, and chemical attack 2) ——— of salts, water, and organic wastes through glands 3) ———— of body temp through either insulation or evaporation 4) production of ——-, which protects against ultraviolet radiation 4) production of ———, which protects against abrasion and serves as a water repellent 5) synthesis of ————, which is a steroid that is converted to calcitriol which is essential for normal calcium metabolism 6) ——- of lipids 7) ——- of touch, pressure, pain, and temperature

Protection ; excretion ; maintenance; melanin ; keratin ; vitamin d3 ; storage ; detection

The epidermis consists of five —— (layers) with various functions

Strata

-attached to basement membrane by hemidesmosomes -forms a strong bond between epidermis and dermis -forms epidermal ridges (ex= fingerprints) -has dermal papillae (nipple shaped mounds) -has many basal cells or germinative cells

Stratum basale

What is the innermost epidermal layer?

Stratum basale

-the "Horn layer" -exposed surface of skin -15 to 30 layers of keratinized cells -water resistant -shed and replaced every 2 weeks

Stratum corneum

What else is the stratum basale called?

Stratum germinativum

-the "grainy layer" -by the time keratinocytes reach this layer, most have stopped dividing and have started to make large amounts of the proteins *keratin* and *keratohyalin* -the cells of this layer produce protein fibers, dehydrate and die, and create tightly interlocked layers of keratin surrounded by keratohyalin

Stratum granulosum

-the "clear layer" -found only in thick skin -covers stratum granulosum

Stratum lucidum

The fifth layer found in thick skin is called what?

Stratum lucidum

-called the "spiny layer" -produced by division of stratum basale -eight to ten layers of keratinocytes bound by desmosomes -cells shrink until cytoskeletons stick out, which is why they look spiny -cells continue to divide, increasing the thickness of epithelium -contain dendritic cells (langerhans), which are active in immune response

Stratum spinosum

What is the function of basal cells?

They are stem cells whose divisions *replace superficial keratinocytes that were lost or shed at the epithelial surface*

-covers the palms of the hands and soles of the feet -has five layers of keratinocytes

Thick skin

-covers most of the body -has four layers of keratinocytes

Thin skin

T/F: cells of the stratum lucidum are flattened, densely packed, largely devoid of organelles, and filled with keratin

True

T/F: each time a stem cell in the stratum basale divides, one pd the daughter cells is pushed superficial into the stratum spinosum

True

what includes hair, nails, and multicellular exocrine glands? these structures are located primarily in the inner dermis and protrude through the epidermis to the skin surface.

accessory structures

the outer epidermis is what?

superficial epithelium (epithelial tissues)

what is the largest system of the body?

the integumentary system