Integumentary System Chapter 4

Classification of Body Membranes Epithelial Membranes Cutaneous membrane -skin made of keratin tough protein found in skin, nails, and hair Keratinocytes - cells that make keratin Stratified squamous

Classification of Body Membranes (cont.) Mucous membrane Secretes mucus Found lining the respiratory and digestive tracts

Classification of Body Membranes (cont.) Serous membrane Simple squamous Two layers Visceral – covers outside the organ Parietal – covers the visceral layer Has serous fluid

Classification of Body Membranes (cont.) Specific names of serous membrane Peritoneum – abdominal Pleura – around lungs Pericardium – around the heart

Structure of the Skin Roles Protection from airborne pathogens Maintenance of normal body temperature Storage (of fat) Synthesis (of vitamin D) Excretion (of salts, water, and waste in sweat)

Structure of the Skin (cont.) Tissues of the skin Epidermis Stratified squamous epithelium Basement membrane Dermis Largely connective tissue Many nerves and blood vessels Smooth muscle Hypodermis Adipose tissue and more loose connective tissue

Structure of the Skin (cont.) Epidermis Stratum corneum dead, keratinized cells Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale – base Rapidly dividing cells Have melanocytes Mnemonic device Come Let’s Grab Some Beers

Skin Color Three pigments attribute to skin color Melanin Carotene Found in stratum basale Light-skinned people produce less melanin than dark-skinned people Carotene Stored in stratum corneum Produces an orange-yellow color found in vegetables Hemoglobin Found in red blood cells (erythrocytes) Provides red color in light-skinned people

Appendages of the Skin Cutaneous Glands Exocrine glands – release their secretions via ducts Two types of exocrine glands Sebaceous glands Secrete sebum (oil) Keeps the skin soft and prevents the hair from becoming brittle Has chemicals that can kill bacteria

Appendages of the Skin (cont.) Sebaceous glands Whiteheads form when sebaceous gland’s duct become blocked with sebum Blackheads form when whiteheads dry

Appendages of the Skin (cont.) Sudoriferous glands Secrete sweat Two types of sweat glands Eccrine gland – produce sweat and maintains body temperature Apocrine gland – produce musky, unpleasant odor when bacteria is present; found in armpits and groin

Appendages of the Skin (cont.) Hair and Hair Follicles Shaft – Hair that is exposed Root – Part of hair enclosed in hair follicle Follicle – Part of the scalp that produces the hair Arrector pili – small band of smooth muscle cells When muscle contracts, hair is pulled upright forming “goose bumps”

Appendages of the Skin (cont.) Nails – composed of keratin Nail plate – fingernail Nail bed – lies proximally to the nail plate Lunula – white crescent that is the basal part of the nail Cuticle – strip of hardened skin at the base and sides of a nail plate

Aging and the Integumentary System Declines in: Cell division in stratum basale Melanocyte production Glandular activity Hair follicle function Blood supply to skin Rate of repair

Problems of Skin Lesions - any abnormality of tissue in the body infections (bacterial, viral, fungal, parasitic) inflammatory reactions allergens Hyperkeratinization excessive development or retention of keratin in the epidermis Blister Epidermis and dermis separate and fluid enters the space

Burns A burn is tissue damage and cell death caused by intense heat, electricity, UV radiation (sunburn), or certain chemicals. Severity of burns First-degree – only the epidermis is damaged Second-degree – the epidermis and upper region of the dermis is damaged Third-degree – destroy the entire thickness of the skin Number one threat for burn victims Infection Burning of the palms of hands and soles of feet can result in death

Burns (cont.)