Chapter 5 Flashcards by Julia Gilmour

Describe the composition of the integumentary system

The cutaneous membrane (skin) is made up of the epidermis and the dermis.

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The epidermis is made up of this type of tissue.

Epithelial tissue

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The dermis is made up of this type of tissue.

Connective tissue

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List the functions of the skin

Protection
Gland excretion
Maintain body temp
Melanin production
Keratin production (water repellent)
D3 synthesis (for Ca 2 metabolism)
Storage (lipids)
Detection (touch, pressure, pain, temperature)

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The epidermis components

Avascular stratified squamous epithelium ( top layer)
Basal surface (more metabolic demands)
Basal Lamina (separates from dermis)

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Cells of epidermis

Keratinocytes
Melanocytes
Merkel cells
Langerhans cells

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Keratinocytes

Majority of epidermis
Makes keratin
Abrasion resistant
Reduce H20 loss
Have some melanin

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Melanocytes

Produce brown/black pigment
Skin color/ uv protection
Transfer melanin granules to keratinocytes
Everyone has the same amount (some just work harder than others)

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Merkel cells

Touch sensation

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Langerhans cells

Dendritic
Immune response

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5 layers of epidermis

Stratum basale / germinative
Stratum spinosum / spiny layer
Stratum granulosum / grainy layer
Stratum lucidum / clear layer
Stratum corneum / horn layer

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Stratum basale/ germinative layer

Youngest/deepest
Bind epidermis to dermis
Keratinocytes bound to basal Lamina
Keratin intermediate filaments
Hemidesmosomes: attach cell to extracellular matrix
Desmosomes: attach cell to cell
Specialized cells: Merkel cells + melanocytes

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Stratum spinosum / spiny layer

8-10 layers of keratinocytes (usually thickest layer )
Produced by stratum basale division
Specialized cells: langerhans cells (phagocytic)

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Stratum granulosum /grainy layer

3-5 layers of flattened keratinocytes
No cell division
Keratin + keratohyalin produced which form dense granules, cross -links keratin
Cells dehydrate, no nutrients (disintegrate)
Thick skin (hand/feet)

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Stratum lucidum / clear layer

Flattened packed dead cells full of keratin
Palms, soles, fingertips

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Stratum corneum / horn layer

Exposed surface
15-30 layers of dead cells
Water resistant
Shed every 2 weeks
Callous

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Thin skin

No stratum lucidum
Hairy parts of body
4 layers

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Thick skin

Thick stratum corneum
Palms, soles, hairless
5 layers

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Epidermal ridges (stratum basale)

Increase surface area of skin
Increase friction, secure grip

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Dermal papillae (dermis)

Increase surface area of basement membrane
Stronger attachment of dermis to epidermis

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The dermis

Between epidermis and hypodermis
Anchors epidermal accessory structures
Outer papillary layer
Deep reticular layer

Papillary layer tissue is

Thin areolar connective tissue

Papillary layer functions

Cells wander + defend (lymph nodes)
In blood, sensory neurons
Ex. Dermatitis, bruises

The reticular layer is this tissue

Dense irregular connective tissue

Reticular layer functions

Larger blood vessels, nerve fibers Contains fibroblasts Collagen provides strength and prevents too much stretch Ex. Stretch marks, wrinkles

Cleavage lines

Collagen in reticular region orient more in one direction than others Ex. Surgeons pay attention to this while stitching to avoid scars

Hypodermis

Attached to bone Adipose and areolar (fat + blood vessels) 1/2 body fat reserves Blood reserves but no vital organs Ex. This is where injections are placed

Skin color pigments

Carotene Melanin Hemoglobin

Carotene

Epidermal cells Fatty tissue Can be converted into Vitamin A Ex. Makes skin orange if you eat too many carrots

Melanin

Melanocytes in stratum basale In keratinocytes, phagocytes, and melanosomes Ex. Vitiligo - random dark/light patches b/c the immune system attacks melanocytes

Hemoglobin

Red pigment from RBCs

How does melanin protect DNA from UV rays?

Melanin gathers around the nucleus, more UV = more melanin

What is melanoma?

The most dangerous skin cancer, caused by DNA damage in melanocytes

How do we get vitamin D3?

Through UV radiation or when epidermal cells produce it from steroids

What does vitamin D3 do?

It gets converted to calcitriol in the liver and kidneys, and then aids calcium and phosphorous absorbed in the GI tract Difficiency: rickets

First degree burn hits this layer of skin

Epidermis

Second degree burn hits this layer of skin

Dermis

Third degree burn hits this layer

Subcutaneous tissue

Name 3 integumentary accessory structures

hair, sweat glands, nails

Hair function

Protect Insulation Guard openings Signal sexual maturity

Hair follicles

Invagination of epidermis into dermis Wrapped with dense connective tissue sheath Root hair plexus (why you can feel your hair move) Arrector pili (smooth muscle cells causing goose bumps)

What is secreted from sebaceous glands?

Sebum (oil)

How does sebaceous gland release sebum?

Whole cell ruptures and releases sebum into hair follicle or directly to skin

What is sebum made of and what is its purpose?

Triglycerides, cholesterol, proteins, electrolytes Inhibits bacteria growth Lubricate/protect Prevent dehydration

What are the two types of sudoriferous glands?

Apocrine and merocrine

Where do we have apocrine glands?

Armpit, groin, nipples

Apocrine secretion

Pinch off part of cell Sticky, cloudy, and odorous Begins at puberty in response to hormones and nervous system

Where do we have merocrine glands?

Forehead, palms, and soles

Merocrine gland purpose

Exocytosis Sweat (99% water, waste, electrolytes) Cool body Protection

Nail components

Stratum corneum with keratin Nail bed: epidermis stratum basale Hyponychium: thickened stratum corneum (fingertip)