B430 CH5 LEC SLIDES

The integumentary system consists of:

Skin, hair, oil glands, sweat glands, nails, and sensory receptors.

Functions of integumentary system:

protection, thermoregulation, blood reservoir, provides cutaneous sensation, limited excretion & absorption, activation of vitamin D

What layer is the epidermis:

Superficial layer

What layer is the dermis

The layer deep to the epidermis

Function of Hypodermis:

attachment padding, insulation, energy storage, and house lamellated corpuscles

Examples of integumentary system’s protection:

germs and outside world

Example of integumentary system’s thermoregulation:

vasoconstriction/vasodilation

Example of integumentary system’s blood reservoir:

storage of blood, skin appearing to bleed

Example of the integumentary system’s providing of cutaneous sensation:

feeling anything on the skin

Example of integumentary system’s limited excretion and absorption:

sweat glands, skin absorbing vitamins (such as vitamin D)

What activation of vitamin D helps:

Absorb calcium

What type of membrane is the skin:

Cutaneous membrane

Two major layers of the skin, a cutaneous membrane:

Epidermis, Dermis

Where is the hypodermis located:

Located deep to the dermis

What is the hypodermis not?

A layer of the skin

What is Hypodermis composed of?

Areolar and adipose tissue

Function of lamellar/Pacinian corpuscle:

detect deep pressure

What is epidermis made of:

Keratinized stratified squamous epithelial tissue

What cell types the epidermis contains:

Keratinocytes (90% of cells), melanocytes, intraepidermal macrophages/Langerhans cell, Tactile epithelial cells/Merkel cell.

Function of Keratinocytes:

Produce keratin and lamellar granules, found in stratum basale

What is Keratin:

structural protein

Function of Melanocytes:

Produce melanin pigment which absorbs UV light, found in stratum basale

Functions of Intraepidermal macrophages/Langerhans cell:

Migrate from red bone, act as antigen presenting cells, found in stratum spinosum

Function of Tactile epithelial cells/Merkel cells

Help detect touch sensations, found in stratum basale

Two types of skin:

Thin skin, Thick skin

Thin skin:

hairy, has hair

Thick skin

Hairless, no hair

How many layers are in thin skin:

4 layers:

How many layers are in thick skin:

5 layers

Where is thin skin located:

Any skin that may have hair

Where is thick skin located:

Plantar surface of foot and toes, palmar region of hands and fingers.

Layers of the epidermis from deepest to most superficial:

Stratum basale, Stratum spinosum, Stratum granulosum, Stratum lucidum (thick skin only), Stratum corneum

Where does keratinization start and end:

Stratum basale to stratum corneum

Process of keratinization in the stratum basale:

One cell layer thick, composed of stem cells that make keratinocytes via mitosis. These contain tonafilaments.

What are tonafilaments?

intermediate filaments that will become keratin

Process of keratinization in stratum spinosum:

8-10 layers of cell layers thick, cells produce coarse tonafilaments.

Process of keratinization in stratum granulosum:

3-5 layers of cells thick, stains the darkest of all the strata. Keratohyalin organizes the coarse tonofilaments into bundles which = keratin. The lamellar granules contain lipids that are released to waterproof the skin (vesicles stain very well). Cells undergo apoptosis because they are full of keratin

Process of keratinization in the stratum lucidum:

4-6 layers of cells thick, dead keratinocytes, full of keratin

Process of keratinization in the stratum corneum:

±50 layers of cells thick, layers of dead cells can slough off. Function: protection from abrasion

What layer of skin is only present in thick skin:

Stratum lucidum.

Definition of keratinization:

The accumulation of keratin

How many weeks does it take for keratin to reach the surface:

4-6 weeks

Time it takes for keratin to reach the surface with psoriasis:

7-10 days

Cause of psoriasis:

immature and abnormal keratinocytes, not enough time for keratinization.

What portion of the dermis is the papillary region:

Superficial portion of dermis (1/5)

What is the papillary region made of:

areolar connective tissue with thin collagen and fine elastic fibers

What does the papillary region contain:

dermal ridges that house blood capillaries, corpuscles of touch, and free nerve endings

What portion of the dermis is the reticular region

Deeper portion of the dermis (4/5)

What is the reticular region made of:

dense irregular connective tissue with bundles of thick collagen and some coarse elastic fibers.

In the spaces in-between fibers in the reticular region, what is contained?

adipose cells, hair follicles, nerves, sebaceous glands, and sudoriferous glands.

Three main pigments which contribute to the wide variety of skin colors:

melanin, hemoglobin, carotene

Melanin:

a pigment produced by melanocytes in stratum Basale

Tyrosinase:

an enzyme that converts the amino acid tyrosine into melanin within a melanosome, melanosomes deposited into each keratinocyte as it is produced

2 kinds of melanin:

Eumelanin, Pheomelanin

Eumelanin:

a brown to black pigment

Pheomelanin:

a yellow to red pigment

Hemoglobin:

a red pigment in red blood cells

Carotene:

a yellow-orange pigment that

Where is Carotene stored?

in the stratum corneum and adipose tissue.

What does melanin protect against?

damage from UV radiation

Melanin-ated patches in the skin

freckles, age spots, nevus

Albinism:

melanocytes cannot make tyrosinase, so they can’t make melanin (generic)

Vitiligo:

Autoimmune condition, antibodies attack and kill melanocytes in parts of the skin

Cyanosis:

blue tint to the skin because blood is low in oxygen, look at skin or nail beds

Jaundice:

buildup of bilirubin (yellow) due to liver disease or very common in newborns (60-80%). Look at skin, nailbeds, whites of eyes

Erythema:

redness of the skin due to dermal vasodilation: embarrassed, after working out, rosaceap

pallor

paleness of the skin due to shock or anemia (less blood in dermal blood vessels).

where is hair absent (specifically):

palms, palmar surfaces of fingers, plantar surfaces of feet, eyelids, and lips mainly

What influences thickness and distribution of hair:

Genetic and hormonal influences

examples of genetic influences on hair:

Getting hair from your parents

examples of hormonal influences on hair:

pregnancy, aging & testosterone

Flat pili = ?

Curly hair

Round pili = ?

straight hair

oval pili = ?

wavy

where does male pattern baldness come from

from mom’s dad

What is hair made of:

dead, keratinized epidermal cells

difference between hair shaft and hair root

the hair shaft is outside the skin, and the hair root is inside the skin

medulla:

middle

cortex:

outer layer

Hair papilla:

where skin is “alive”

sebaceous (oil) glands:

sebum is produced, moisturizes the skin, prevents microbial growth, waterproofing the skin

Eccrine sudoriferous (sweat glands):

thermoregulation

Apocrine sudoriferous glands:

actually merocrine, produces organic sweat, has lipids and proteins that bacteria can eat

Ceruminous glands:

In ear canal

Blood volume/person:

4-6 L

amount of blood that dermal vessels house:

8-10%

Keratin & protection:

Keratin provides physical protection

Lamellar granule lipids & protection:

protect from water loss

Sebum & protection

waterproofs the skin and has bactericidal chemicals

What does acidic sweat help kill:

bacteria and stuff

what do intraepidermal macrophages do:

eat bad stuff

Cutaneous sensations in detail:

skin houses tactile (touch), pain, and thermoreceptors

integumentary system excretion in detail:

minor excretion of water, heat, salts, CO2, ammonia & urea (nitrogenous waste product)

Integumentary system absorption in detail:

Limited absorption of lipid soluble substances such as transdermal drugs (patches), toxic materials, and heavy metals

lipid soluble = ?

absorbable by skinex

Vitamins that are lipid soluble:

Vitamins A, D, E, K

Integumentary system’s synthesis of Vitamin D in detail:

in the presence of UV light, keratinocytes activate a precursor molecule into the inactive form of Vitamin D.

Epidermal wound healing:

occurs when superficial wounds affect only the epidermis, no bleeding or scarring involved

Epidermal wound healing (1st step)

Basal cells in stratum basale at the wound edge detach from the basement membrane, then they enlarge and migrate across the wound.

Epidermal wound healing (2nd step)

Once basal cells touch, migration ends. This is called contact inhibition