Chapter 6- Sesay emphasized

integumentary system

for protection- hair, skin, nails,

sweat glands

sebaceous oil glands

two distinct regions of the skin

Epidermis

Dermis

Epidermis

superficial, avascular region

epithelial tissue

Dermis

underlies dermis, vascular

mostly fibrous connective tissue

hypodermis

superficial fascia

subcutaneous layer deep to skin

mostly adipose tissue that absorbs shock and insulates

anchors skin to underlyin structure (muscle)

reticular layer

largest layer

layers of skin

top- to bottom (superficial to deep)

1- epidermis

2- Dermis

a-papillary layer

b-reticular layer

3- subcutaneous tissue/ hypodermis not part of ski

Epidermis cells

mostly keratinized stratified squamous epithelium

four types of epidermis cells

keratinocytes

melanocytes

dendritic cells

tactile cells

keratinocytes

produce fibrous keratin

tightly packed via desmosomes

Melanocytes

produces pigment melanin packed into melanosomes tat are transferred into keratinocytes where they protect DNA from UV

melanin comes in different shades. we all have apx same amount of melanocytes but different type and amount of melanin.

dendritic cells

langerhans

star shaped macrophages that patrol deep epidermis

key immune system activators

fight infection/immune system

tactile cells

merkel cells

sensory receptors/ touch

principle role of melanin is to

shield nucleus/dna from uv rays

what do dendritic cells do?

activate the immune system

how many layers does thick high abrasion area skin?

5 layers, meaning it has the stratum lucidum

layers from deep to superficial:

1-stratum basale

2-stratum spinosum

3-stratum granulosum

4-stratum lucidum (only in thick skin)

5-stratum corneum

skin structure

layers of the epidermis

Stratum basale/ basal layer

bottom layer of epidermis

AKA Stratum germinativum

keratinocyte, tactile cells, melanocyte made here

firmly attached to dermis

consisits of a single row of stem cells that actively divide (mitotic),

daughter cell jounreys to stratum corneum in 25-45 days

other daughter cell stays in stratum basale as stem cell

where basal cell carcinoma develops

Epidermis layers

Stratum Spinosum

several cell layers thick

kertinocytes in this layer are spikey/prickley

there are also melanosomes and dendritic cells

squamous cell carcinoma develops here

stratum granulosum

also 4 cells thick but cells flatten

cells flatten, nuclei and oranelles disintegrate

keratinization begins

Stratum lucidum

only in thick skin- palm and sole for protection

thin translucent band of dead keratinocytes

stratum corneum (horny layer)

20-30 layers of flat, anucleated, keratinized dead cells

¾ of epidermal thickness!

protection

prevent water loss

barrier against bio, chm, and physical assualt

epidermal cells and layers of the epidermis

Dermis

vasular!!

two layers: Papillary and Reticular (largest)

cells include: fibroblasts, macrophages, occasional mast cells and white blood cells

nerves, blood vessels, and lymphatic vessels

epidermal hair follicles, oil glands, sweat glands

Papillary layer

superficial layer of areolar connective tissue, consisting of loose, interlacing collagen and elastic fibers and blood vessels

Reticular layer

80% of dermal thickness

coarse dense fibrous connective tissue

many elastic fibers provide stretch/recoil

collagen fibers for strength

three pigments contribute to skin color

1-Melanin- 1-made by melanocytes (we all have same amt of melanocytes). 2-we have different type and quantity of melanin. 3-Melanin protects dna/nucleus.

Carotene- yellow/orange pigment. accumulates in corneum and hypodermis. can be converted to vitamin A

Hemoglobin- red in color (protein in red blood cell). Caucasian skin is more transparent so more hemoglobin shows through.

Albinism

they have normal amount of melanocytes

they are missing an enzyme (“ingredient”) to make melanin

what happens when RBC die?

Billirubin (yellow pigment produced in the breakdown of RBCs) goes up.

if too much Billirubin, liver cant process it all, and we turn yellow

Billirubin is normally processed and dumped where?

processed by liver and put into urine/feces

Jaundice

yellow coloration due to liver disorder

Cyanosis

blue skin, low oxygenation of hemoglobin

Pallor

pale skin color

anemia, low BP, fear, anger

Erthema

redness from fever, hypertension, inflammation, allergy

3 barriers of skin

chemical

physical- keratinized stratified squamous epithelium

biological barrier

what are 4 chemicals the body makes for defense on the skin?

Sweat- contains antimicrobial proteins

Sebum and Defensins- which kill bacteria

Cells- secrete the antimicrobial defensin

acid mantle- low skin PH retards bacteria

melanon- uv protection

physical skin barrier

keratinized cells of stratum corneum

Biological bariers

eidermis contains phagocytic cells:

dendtritic cells (macrophage/langerhans) of epidermis engulf foreign antigens and present to white blood cells to activate immune response

How skin synthesizes Vitamin D

skin synthesized vitamin D for caclium absorbtion in intestine

skin makes vitamin D

then goes to liver

then activated in the kidneys

Basal cell Carcinoma (will be on test)

basal layer of epidermis

least malignant and most common

squamous cell carcinoma (on test)

stratum spinosum

second most common

can metastisize

involves keratinocytes of stratum spinsosum

usually looks scly reddened papule on scalp, ear, lip, hands

malanoma (on test)

worst kind of skin cancer. highly metastic and resists chemo

cancer of melanocytes, easily into blood stream

Melanoma ABCD (on test)

A- asymmetry. two sides of the pigmented area dont match

B- border irregularity- indentations

C- color- has several colors (black, brown, tan, red, blue)

D- Diameter- larger than 6mm (size of pencil erasor)

most important thing to give burn victim?

Fluid!

immediate threat to burn victim

dehydration and electrolyte imbalance

leads to renal shutdown and chock

the rule of nines

determines the quantity of fluid needed

body is broken down into 11 sections, each representing 9% body surface (gentials are 1%)

first degree burn

epidermal damage only

localized redness, edema

second degree burns

all epidermis and half of dermis

blisters appear

partial thickness burn

third degree burn

epidermis, dermis, and hypodermis burn

full thickness burn

skin turns gray/white, cherry red, or black

nerve endings are destroyed so there is no pain

no edema

skin grafting needed

burns are considered critical if:

more than 25% of body has second degree burns

more than 10% has 3rd degree burns

face hands or feet bear third degree burns

treatment of burns includes

fluid first!

Debridement (removal of burned skin)

antibiotics

skin grafts

Sebaceous glands

oil glands

relatively inactive until puberty when stimulated by hormones (androgens)

they secrete Sebum):

oily holocrine (whole secretory disintegrates and is released) secretion

bacteria killing properties

softens hair and skin

Acne is infectious inflammation of-

Sebaceous glands are associated with Propionibacterium acnes bacterial infection."

"Whiteheads are blocked sebaceous glands. If the secretion is oxidized, it becomes a blackhead."

as we age cells…

dont regenerate as quickly

ways to delay aging

uv protection

nutrition

fluids

hygiene