Unit 2

Chapter 5: Integumentary system

Functions: integumentary system Body temp regulation Reservoir for blood Protection from external environment Cutaneous sensations Excretion and absorption Vitamin D synthesis

Epidermis = 5 layers, fig 5.3 Keratinized, ____________________ epithelium 4 types of cells: Figure 5.2

_______________- produce keratin- tough fibrous protein protects the skin and underlying tissue from heat microbes,& chemicals, water repel

_______________- produce pigment Langerhans cells- from red bone marrow, immune

response against microbes Merkel cells- in deepest layer, associated with

sensory neurons.

5th layer where friction is greatest

Stratum ____________: deepest layer single row of cuboidal or columnar keratinocytes ___________________ Hemidesmosomes and desmosomes All cell types found here AKA stratum germinativum

Stratum _____________: Superficial to basale 8-10 layers keratinocytes Cells become flattened, spiny Arrangement allows for _______________________

Stratum __________________: Middle 3-5 layers keratinocytes undergoing apoptosis Keratohyalin keratin Lamellar granules= lipid rich secretion ______________ layer (cells are dying)

Stratum ______________: Present only in thick skin: fingertips, palms, soles, 5 layers of flat, _________, dead keratinocytes

Stratum ____________: 25-30 layers flat, dead keratinocytes Continuously shed and replaced _____________= abnormal thickening of this layer

Dermis figure 5.1 2nd, deeper layer of skin ____________ - collagen and elastic fibers __________: fibroblasts, macrophages,

adipocytes Blood vessels, nerves, glands, hair follicles 2 regions:

___________ region ___________ region

Papillary region superficial, 1/5 of dermis Areolar CT w/fine elastic fibers _______________= fingerlike projections that increase

surface area Indent into epidermis Contain capillary loops and tactile receptors -sense tactile

Free dendritic receptors: sense temp, pain, itch, tickle Reticular region

Deeper; irregular CT w/ bundles of collagen interlaces in a netlike manner, coarse elastic fibers, adipose, hair follicles, nerves, oil and sweat glands

Fibers- _______________ and ___________________

Subcutaneous (subQ) = hypodermis Areolar and adipose tissue Fibers that extend from dermis anchor the

skin to subQ layer, which attaches to underlying tissue and organs.

__________________ Large b.v. that supply the skin Pacinian corpuscles -sensitive to pressure

Hair figure 5.4 _____, present on most skin except palms, palmar

surface of fingers, soles, and plantar surface Scalp, eyebrows, axillae, external gentalia

Genetic and hormonal influences determine thickness and distribution in these areas

1 hair= columns of dead, keratinized cells bonded by E.C.proteins

Shaft- superficial portion projecting from surface Root- deep to shaft, penetrates dermis or subQ Follicle- surrounds the root, near surface has all

epidermal layers, near bottom only stratum basale

Hair structures Bulb- base of follicle Matrix- germinal layer inside bulb ______________ glands assoc. with hairs Arrector pili- smooth muscle extending

from superficial dermis to side of follicle FUNCTIONS: ___________ from: sun,

heat loss from scalp, brows, lashes, nostril and ear hair protect from foreign particles, sensation of light touch

Glands Sebaceous- oil glands,connected to hair follicles

Secreting portion in dermis, opens into neck of hair follicle

Directly open to skin in: lips, glans penis, labia minora, eyelids

Absent in palms and soles Secrete sebum = mixture of ____________,

cholesterol, proteins, inorganic salts Coats surface of hairs to keep them from drying Prevents excessive evaporation of water, Keeps skin soft and pliable, Inhibits growth of some bacteria

____________– sweat glands, 3-4 million. Exocytosis of sweat into hair follicles or onto

skin surface by pores 2 types based on:

Structure Location Type of secretion

Table 5.3 classifies eccrine vs. apocrine ___________- modified sweat glands in

external ear that produce wax, glands in subQ Sticky barrier to impede entrance of foreign

bodies

Eccrine vs. Apocrine Thru skin except lips,

nail beds, glans penis, clitoris, labia minora, eardrums

Secretory: dermis Excretory: epidermis Less viscous: water,

Na+, Cl-, urea, uric acid, ammonia, a.a., glucose, lactic acid

Axilla, groin, areolae, bearded regions of face.

SubQ Hair follicle More viscous, same

components as eccrine plus lipids and proteins

Eccrine vs. Apocrine Regulation of body

temperature and waste removal Insensible and

sensible perspiration

Soon after birth

Stimulated during emotional stress and sexual excitement “cold sweat”

puberty

Acne

Inflammation of sebaceous glands Usually begins at puberty when these

glands in size and sebum production Androgens stimulate glands Occurs in follicles colonized by bacteria Infection can cause a cyst- destroy and

displace epidermal cells.

Skin as a thermal regulator 2 ways of regulation:

_____________________ Evaporation of sweat from skin surface helps

lower body temp (at low temp sweat is decreased)

_____________________of blood in dermis During moderate exercise blood flow thru skin

which amount of heat radiated from body During intense exercise skin b.v. constrict &

divert blood to skeletal muscles & heart so, heat is lost thru heat radiation thru skin temp

Pigmentation Melanin, carotene, & hemoglobin affect __________= produce melanin, projections

transfer melanin granules to keratinocytes. More numerous in mucous membranes,

areolae, penis, face, limbs # same in all people, pigment amount varies

__________ = black-brown pigment, contributes to skin color, absorbs UV light Form veil around nuclei to protect DNA Cause variation from yellow to black

Melanocytes produce melanin in a melanosome w/ enzyme – tyrosinase UV light enzymatic activity Tan is lost when melanin containing keratinocytes

reach stratum corneum __________- yellow-orange pigment, precursor

to vitamin A (pigments for vision) Found in stratum corneum, fatty areas of dermis and

subQ If little melanin or carotene epidermis- translucent,

white people may appear pink or red due to … ____________- red color, oxygen carrying

pigment inside RBC Dependent upon amount of oxygen

Burns- figure 5.9 Damage by excessive _______,

_________, ______________, or corrosive ___________________

___________________ in skin cells Destroy:

protection against microbes and desiccation thermoregulation

Graded according to severity

1st degree- _________________ Mild pain Erythemia (redness) but no blisters Skin functions intact Healing 3-6 days, flake, peel. EX. Sunburn

2nd degree- destroys portion of epidermis and _______________________ Some skin function lost Redness, blister, edema, pain If no infection can heal w/out skin graft 3-4

weeks

3rd degree (_______________) – destroys portion of epidermis, dermis and associated structures. Most skin functions lost Edema, numb - loss of sensory nerve endings Regeneration slow, skin graft may be req’d

Life threatening if systemic effects involved Lose water, plasma&plasma proteinsshock Bacterial infection Reduced circulation of blood Decreased urine production Diminished immune response

Rule of nines

Process of wound healing, 5.6 Epidermal

Abrasions and minor burns Response: basal cells break free of basement

membrane, enlarge, and migrate across the wound…migration stops when the cells encounter one another = ________________. Epithelial growth factor secreted to cause basale

stem cells to divide until wound is resurfaced

Deep wound- dermis and subQ More complex healing- 4 phases

Deep wound healing Inflammatory phase

Blood clot forms, loosely unites wound edges Vascular & cellular response to eliminate microbes,

foreign material and dying tissue Neutrophils monocytes macrophages mesenchymal cells fibroblasts

Migratory phase (granulation tissue forms) Clot becomes scab, epithelial cells migrate beneath Fibroblast synthesize scar tissue B.v. begin regrowth

Deep wound healing (2)

Proliferative phase Extensive growth of epithelial cells beneath scab Deposition of collagen by fibroblast, cont’d b.v.

growth

Maturation phase Scab sloughs off, epidermis restored Collagen becomes organized Fibroblasts decrease B.v. restored to normal

3 types of skin cancer Excessive sun exposure usual cause _________________________- 78% of all

Tumor arises from stratum basale Rarely metastasize

________________________ - 20% of all Arise from squamous cells of epidermis Variable tendency to metastasize Most arise from pre-existing lesions of

damaged tissue on sun exposed skin

These first 2 types: nonmelanoma skin cancer, & are 50% more common in males

______________________ - 2% of all Arise from melanocytes Most prevalent life threatening cancer in

young women Lifetime risk: 1 in 75 (double from 15 yr ago) Likely due to ↑UV, ozone depletion Metastasize rapidly, can kill w/in months Early detection! ABCD-- assymetry, border

(irregular), color(uneven), diameter (>1/4 in)

Risk factors Skin type- light skin, always burn Sun exposure- sun, altitude= UV Family history- rates higher in some

families Age- older people = longer total exposure

to sunlight Immunological status- immunosuppressed

have incidence