Transcript Chapter 5
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 __________________: Stratum ______________: Middle 3-5 layers keratinocytes undergoing apoptosis Keratohyalin keratin Lamellar granules= lipid rich secretion ______________ layer (cells are dying) 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 _____, present on most skin except palms, palmar surface of fingers, soles, and plantar surface Scalp, eyebrows, axillae, external gentalia figure 5.4 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. 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 Apocrine Axilla, groin, areolae, bearded regions of face. SubQ Hair follicle More viscous, same components as eccrine plus lipids and proteins Eccrine Regulation of body temperature and waste removal vs. Apocrine 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 __________- yellow-orange pigment, precursor to vitamin A (pigments for vision) UV light enzymatic activity Tan is lost when melanin containing keratinocytes reach stratum corneum 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 Damage by excessive _______, _________, ______________, or corrosive ___________________ ___________________ in skin cells Destroy: figure 5.9 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