Exam (elaborations) 6220 ADVANCED PATHO STUDY GUIDE FINAL /Advanced Pathophysiology for Nurse Practitioner

6 2 2 0 A D V A N C E D P A T H O S T U D Y G U I D E F I N A L SPR I N G SE M T E R 2 0 2 0 I N S T R UC T O R : D R . C H E R Y L T O UL O US E SESSION 7: INTEGUMENTARY SYSTEM Describe normal skin and its function a.Skin is an organ b.Three layers i.Epidermis - composed of keratinocytes and scattered melanocytes 1.Epidermis undergoes keratinization, second most important protective mechanism 2.Epidermal cells produce keratins which are cytoskeletal proteins that are highly resistant to mechanical and chemical injury a.The keratin layer represents the final stage of epidermal cell differentiation b.Varies in thickness on diff anatomic sites c.Most prominent on the palms and soles 3.Keratinized epidermis provides limited protection against sunlight by preventing the penetration of light through the skin a.Keratinocytes are the principal cells of the epidermis i.They are aided by melanocytes , the pigment-producing cells 1.Located in basal layer 2.Produce a brown pigment packed into membrane-bound cytoplasmic 1 bodies(melanosomes) and transferred through the cytoplasmic process into keratinocytes 3.This transfer of pigment is was causes browning of skin when exposed to sunlight b.Keratinocytes with melanin are more resistant to UV light and protect the body against the sunlight more efficiently than non pigmented keratinocytes ii.Dermis -composed of connective tissue, blood vessels, nerves, and hair follicles , and skin adnexal glands, sebaceous glands (oil glands- connected to hair follicles and secrete sebum made of fatty acids and waxy esters, lubricates skin, softens hair shaft, and is slightly acidic helps deter pathogens) , sweat gland, iii.Subcutis/hypodermis- composed of fat tissue *Describe various skin infections* (on Final Study Guide) 1.Bacterial Infections a.Impetigo i.Caused by streptococcus pyogenes or staph. Aureus ii.Most often found on face of small children - the mouth and nose iii.Characterized by superficial pustules that rupture, leaving honey-colored scabs 1.“Pustule”= vesicle filled with pus 2.Yellow-honey looking crusting blisters containing pus 3.Skin lesions are itchy iv.Highly contagious ; but responds well to systemic antibiotic therapy and can heal without scars b.Folliculitis i.Caused by staph aureus ii.Common form of infection limited to hair follicles 2 1.Typically involves hairy areas such as the beard 2.More common in men than females 3.Bacteria produces a purulent exudate that fills lumen of hair follicle a.The infection extends into the perifollicular tissue, a furuncle (boil) develops b.The infection can spread to adjacent hair follicles and the original abscess enlarges to include several hair follicles and a larger boil evolves, called a carbuncle ; mostly located in neck c.Acne Vulgaris i.Pathogenesis not fully understood ii.Heredity, hormones and general cleanliness play a role 1.Begins at puberty, probably from sex hormones particullarly androgens a.Androgens stimulate development of sebaceous glands on the face, neck, chest and back 2.Pathogenesis- keratin plugs, sebum, bacterial overgrowth a.Sex hormones stimulate the developement of sebaceous glands on the face, neck, chest, and back b.Secretion of sebum is increased , evidenced by greasy skin c.Sex hormones promote hyperkeratosis at the orifice of hair follicles i.This blocks the discharge of sebum ii.The stagnant sebum is colonized by anaerobic bacteria ( propionibacterium acnes ) iii.This results in formation of comedones , which occur in two forms 1.Open to the surface comedo (blackhead) 2.Closed comedo (whitehead) 3 iv.Through the action of bacterial lipases, the fat of the sebum is broken down to glycerin and free fatty acids 1.Release into tissue causes inflammation v.Entire obstructed follicle and surrounding connective tissue are transformed into pustules or larger abscesses 1.May persist and become confluent ( acne conglobata ), transform into dermal cysts, or heal with scarring ( keloid acne ) vi.Scratching, picking or pressing of these lesions may predispose individual to secondary infections d.Treatment focuses on decreasing the keratinization of follicles with retinoic acid or keratinolytic agents and controlling the infection with local or systemic antibiotics e.OVERVIEW: Hyperkeratotic epidermal plug (keratin plugs) prevent the discharge of sebum. The retained sebum is colonized by bacteria. Bacterial action expands the follicle and ultimately leads to rupture and discharge of infected purulent sebum into the adjacent dermis. d.Fungal Infections i.Dermatophytosis- fungal infections of the skin ii.Fungal pathogens= dermatophytes ten to live in “dead tissues” iii.Common sites: feet, head, nails, axillae, groin 1.Tinea pedis - athlete's foot= begins between the toes and spread locally 2.Tinea unguium = chronic nail infection 3.Tinea corporis= circular or irregularly shaped patches on the skin and have a pale center and spreading margins 4