Exam 2 (The Integumentary System)

The integumentary system includes the

skin and accessory structures (glands, hair, nails)

What is the largest organ in the body?

skin (integumentary system), about 16% of body weight

The integumentary system has 4 functions such as

protection, produce vitamin D, sensory net for detecting external stimuli, thermoregulation

How does the integumentary system function as protection? 

keeps out foreign invaders and keeps in fluid/avoid dehydration

Why does the integumentary system produce vitamin D?

needed for calcium absorption

What are the two main layers of the skin?

epidermis and dermis

The epidermis is the

outermost (most superficial) layer of skin that faces the environment

The epidermis is composed of

stratified squamous (flattened) epithelial cells

Cells making up the epidermis layers are called 

keratinocytes

Are keratinocytes found within the stratum basale layer of the epidermis?

no

Keratinocytes are responsible for the

manufacture/storage of the protein keratin

Keratin proteins are

fibrous proteins that give hairs, nails, and skin their hardness and water-resistant properties

Keratinocytes are… and keratin is

the living cells that make up most of the outer skin layer… the tough protein inside those cells that provides structure and strength

Does the epidermis have any blood vessels within it?

no, all the cells in this layer are dead

How many layers make up the epidermis? What are their names?

4 to 5; stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum

Which layer of the epidermis is the deepest layer?

stratum basale

The stratum basale is anchored to (epidermis or dermis), with what?

the dermis with collagen fibers

The stratum basale has a single layer of

columnar basal cells that are constantly dividing and moving superficially into other layers

What are basal cells?

precursors of (they become/turn into) keratinocytes

What two types of cells are found in the stratum basale layer?

melanocytes and merkel cells

What are the functions of melanocytes?

cells that produce the pigment melanin, which gives skin a brownish color, protect the living epidermis cells from ultraviolet radiation damage

What are the functions of merkel cells?

sensory cells that detect small/light-weighted touch

What is the second deepest layer of the epidermis?

stratum spinosum

How thick is the stratum spinosum?

8 to 10 cells

Cells from the stratum basale pushes into the stratum spinosum then

takes on a multi-sided shape and begin producing keratin and desmosomes

What are desmosomes?

cell-to-cell anchors that welds/connect adjacent cells tightly together

In what layer of the epidermis does keratinocytes actually start producing keratin?

stratum spinosum

What is the third deepest layer of the epidermis?

stratum granulosum

How thick is the stratum granulosum?

3 to 5 cells

Cells in the stratum granulosum have become

flattened (“squamous”), lost their nuclei, and produce large amounts of keratin

What is the fourth deepest layer of the epidermis?

stratum lucidum

Stratum lucidum is composed of

dead flattened cells that appear transparent under the miscroscope

Stratum lucidum is only found in

the thick skin in palms of hands and soles of feet

Cells within the stratum lucidum helps to

reduce friction and increase the protective functions of thick skin

What is the fifth deepest layer of the epidermis? (outermost layer)

stratum corneum

Keratinocytes that make up the stratum corneum are

squamous, dry, and dead; regularly slough away and are replaced by cells from the underlying layer

How thick is the stratum corneum?

15 to 30 cells

What 3 functions do the stratum corneum serve as?

protects against water loss, mechanical abrasion, and infection by pathogens and toxins

The dermis is a

connective tissue layer deep to the epidermis

The dermis is a fibrous structure composed of

collagen, elastic tissue, and other extracellular components that include blood and lymph vessels, nerve endings, hair follicles, and sweat glands

The 4 functions of the dermis are to

provide a base for the epidermis, protect deeper layers of the body, assist in thermoregulation, and assist in sensory feedback from the environment

What are the four types of cells found in the dermis?

fibroblasts, white blood cells, mast cells, and adipose cells

The predominant cells in the dermis are the

fibroblasts

What are the functions of fibroblasts?

synthesize collagen fibers (super strong thick fibers), elastic fibers (provide stretch and flexibility), and reticular fibers (form a net-like meshwork of fibers disperse force on the skin)

What is the function of the white blood cells?

immune cells that seek out and destroy invaders like bacteria and viruses

What is the function of the mast cells?

release the chemical histamine to cause inflammation to release/force threat out of body

What is the function of the adipose cells?

stores energy as fat, thermal insulation, mechanical insulation (cushions organs), and releases vital hormones to regulate metabolism

What is the hypodermis?

the layer deep into the dermis that is technically not considered as part of the skin

The hypodermis connects

the skin to the deeper muscle and bone tissue

The hypodermis is composed mostly of

connective tissue, including many adipose (fat) cells for energy storage, mechanical insulation, and thermal insulation

Accessory structure of the skin contains the

blood vessels, sweat glands