Integumentary System (Skin)

Unit 6.3 (6th Edition) Chapter 7.3 (7th Edition)

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Learning Objectives

• Identify the major components (anatomy) of skin • Differentiate between the two types of skin glands • Explain the seven functions (physiology) of skin • Correctly name three abnormal skin colors and identify causes • Describe most common skin eruptions • Describe the main diseases of the integumentary system (pathophysiology)

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Skin Anatomy

• Largest Organ • Three Main Layers • Epidermis

– Outermost layer – Cells constantly shed/replaced

• Dermis – “true skin” – framework of elastic connective tissue – contains blood vessels, nerves, glands, hair follicles

• Hypodermis (subcutaneous fascia) – connects to underlying muscles – elastic and connective, fatty tissue

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Two Types of Glands

• Sudoriferous Glands – sweat glands – coiled tubes in dermis – open on surface of skin at pores

• Sebaceous Glands – oil glands that open onto hair follicles – produce sebum (oil that keeps skin and hair from becoming dry and brittle) – sebum is antibacterial and antifungal – when an oil gland becomes plugged, accumulation of dirt and oil result in pimple

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Hair and Nails • Hair

– consists of a root that grows in a hollow tube called a follicle – helps protect the body – covers all body surfaces except for palms and soles – alopecia (baldness/genetic hair loss)

• Nails – protect fingers and toes from injury – made of dead, keratinized epidermal epithelial cells – cells are packed closely together to form thick surface – if lost, nails will regrow if the nail bed is not damaged

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1 cm2 of Skin Contains

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Skin Physiology (Functions) • Protection

– barrier to UV rays – protects against invasion of pathogens/germs – holds moisture in – prevents deeper tissues from drying out

• Sensory Perception – nerves in skin help body respond to pain, pressure, temperature, and touch sensations

• Body Temperature Regulation – blood vessels help body keep/lose heat – glands also help cool body through perspiration

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Skin Physiology Continued • Storage

– skin tissues store fat, sugar, water, vitamins, & salts – adipose (fatty) tissue is a source of energy

• Absorption – certain substances can be absorbed through skin – transdermal medications for motion sickness, nicotine

• Excretion – skin helps body eliminate salt &small amounts of waste – excess water and heat through perspiration

• Production – vitamin D production (matures in liver)

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Pigmentation (Skin Color) • Basic skin color is determined by pigments in epidermis • Melanin

– Brownish/black pigment – Varying amounts lead to black, brown, or yellow skin tint – absorbs UV light and tans the skin – small, concentrated areas of melanin form freckles

• Carotene – yellowish-red pigment – also determines skin color

• Albino – person missing color pigments – skin has pinkish tint – hair is pale yellow or white – eyes lack pigment and are red in color

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Abnormal Skin Colors • Erythema

– reddish color that can be caused by burns – also caused by congestion of blood in vessels

• Jaundice – yellow discoloration of skin – can indicate bile in blood as result of liver or gallbladder disease – occurs along with diseases involving destruction of red blood cells

• Cyanosis – bluish discoloration of skin – caused by insufficient oxygen – can be associated with heart, lung, and circulatory problems

• Gray/Brown Discoloration – can be caused by chronic poisoning

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Skin Eruptions • Macules

– flat spots on skin, such as freckles • Papules

– firm, raised area such as pimples – also seen in some stages of chickenpox and syphilis

• Vesicles – blisters (fluid-filled sacs) such as those seen in chickenpox

• Pustules – pus-filled sacs such as those seen in acne

• Crusts – areas of dried pus and blood – commonly called “scabs”

• Wheals – itchy, elevated areas with an irregular shape – hives and insect bites

• Ulcer – deep loss of skin surface that may extend into dermis (scars)

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Pathophysiology (Diseases) • Acne Vulgaris

– inflammation of sebaceous (oil) glands • Athlete’s Foot

– contagious fungal infection usually affecting feet • Skin Cancer

– basal cell carcinoma, squamous cell carcinoma, and malignant melanoma

• Dermatitis – inflammation of skin in response to irritating substance

• Eczema – noncontagious, inflammatory reaction irritant

• Impetigo – highly contagious skin infection caused by bacteria

• Psoriasis – chronic, noncontagious, inherited disease; scaly

• Ringworm – highly contagious fungal infection of skin/scalp

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