Unit 2 Organ Systems that provide Support and Movement

Chapter 4 – Skin and Body Membranes Chapter 5 – The Skeletal System Chapter 6 – The Muscular System

Chapter 4 Skin and Body Membranes

Classification of Body Membranes Membranes cover surfaces, line body cavities, form protective sheets around organs 2 classifications: epithelial membranes, connective tissue membranes Epithelial –Cutaneous, mucous, serous Connective –synovial

Epithelial membranes Figure 4.1 All types contain an epithelial sheet with an underlying layer of connective tissue Cutaneous –Skin –Epidermis - Composed of keratinized stratified squamous epithelium –Dermis – Composed of dense connective tissue –Dry membrane

Mucous (mucosa) –Composed of stratified squamous epithelium or simple columnar epithelium resting on loose connective tissue – lamina propria or areolar tissue (p 93) –Epithelium is adapted for absorption or secretion –Lines all body cavities that open to exterior –Wet or moist membranes that are bathed in secretions

Serous (serosa) –Composed of simple squamous epithelium on layer of areolar connective tissue –Lines cavities that are closed to the exterior –Occur in pairs: parietal, visceral Membrane is continuous and folds on itself Layers are separated by serous fluid which reduces friction between parietal & visceral parts

Parietal layer is to the outside, visceral layer is on the organ Abdominal serosa - parietal and visceral peritoneum Pleural (surrounding lungs) serosa – parietal and visceral pleura Pericardial (surrounding heart) serosa – parietal and visceral pericardium

Connective Membrane Figure 4.2 Synovial membrane Composed of areolar connective tissue Line fibrous capsules surrounding joints Provide smooth surface and lubricating fluid

Integumentary System Organs of the Integumentary System include the skin, sweat and oil glands, hair, and nails

SKIN Skin functions: Table 4.1 –Insulates & cushions deeper body organs –Protects body from mechanical damage, chemical damage, thermal damage, ultraviolet radiation, and bacteria –Helps regulate body temperature –Excretes some waste products –Synthesizes important biochemicals –Sensory receptors provide information about external environment

Skin structure – Figures 4.3 & 4.4 –Epidermis – stratified squamous epithelium capable of keratinizing –Dermis – dense connective tissue –Subcutaneous or hypodermis – adipose tissue Anchors skin to organs Shock absorber and insulator

Epidermis Composed of 5 strata –Stratum basale, spinosum, granulosum, lucidum, corneum Avascular Keratinocytes –Cytoplasm fills with keratin which is a tough, fibrous, waterproof protein –Older, dead cells that were produced in stratum basale and pushed toward stratum corneum

Melanocytes –Found in stratum basale –Produce the pigment melanin –Sunlight stimulates the melanocytes to produce more melanin – tanning –Melanin protects DNA in the nucleus of cells from ultraviolet light of the sun Overexposure to sun can alter DNA causing skin cancer

Dermis Contains dense connective tissue in 2 major areas: papillary and reticular Contains collagen and elastic fibers –Collagen keeps skin tough and hydrated –Elastic fibers provide elasticity Abundant supply of blood vessels –Important in body temperature homeostasis Rich supply of nerve endings

–Papillary layer – in the upper dermal region fingerlike projections called dermal papillae indent into epidermis contains blood supply and nerve endings –Meissner’s corpuscle – touch sensory Pattern is genetically determined, responsible for fingerprints

–Reticular layer Deepest layer Contains blood vessels, sweat and oil glands Contains Pacinian corpuscles – pressure receptors

Skin Color Normal skin color is a result of pigments –Melanin, carotene, oxygen-rich hemoglobin Abnormal skin color –Cyanosis – poorly oxygenated hemoglobin –Erythema – reddened skin –Pallor – pale skin –Jaundice – yellow cast –Bruises – hematomas in tissue spaces

CUTANEOUS GLANDS All cutaneous glands are exocrine glands that are either sebaceous (oil) glands or sweat glands Contained in the dermal layer of skin Sebaceous glands –Ducts usually empty into hair follicle –Secrete sebum, an oily substance, which keeps skin soft and moist, kills bacteria –Blocked duct causes acne –Overactive gland causes seborrhea

Sweat glands can be eccrine sweat glands or apocrine sweat glands –Differ according to location and type of secretion

Eccrine glands –Secrete sweat – composed mostly of water, but has acidic pH which inhibits bacterial growth –Found all over body –Empty into sweat pore –Important in heat regulating homeostasis

Apocrine glands –Found in axillary and genital areas –Ducts empty into hair follicles –Secrete substances in eccrine glands and also fatty acids and proteins –Can have an odor when bacteria use the proteins and fatty acids as food source –Activated during pain, stress, sexual activity

HAIR Figure 4.7 Hair follicles produce hairs –Hair root is enclosed in the follicle –Inner epidermal sheath of epidermal cells forms the hair –Outer dermal sheath of connective tissue supplies blood vessels –Hair bulb is at the inferior end of the follicle

Hair is formed by division of epithelial cells in matrix of hair bulb –Daughter cells continue to form and are pushed up the follicle –Cells become keratinized and die –Hair shaft, part projecting from the surface of skin, is mostly protein

Hair consists of cuticle, cortex, medulla –Medulla – central core –Cortex – bulky layer surrounding medulla –Cuticle – outermost layer formed by overlapping layers of cells that are heavily keratinized – figure 4.8 Hair color is a result of melanocytes consisting of varying amount of melanin

Arrector pili muscle – smooth muscle cells that connect hair follicle to dermal tissue –Mucsle contraction causes hair to stand up – goose bumps

NAILS Stratum basale of epidermis extends beneath the nail and becomes the nail matrix Cells are produced by the matrix, become heavily keratinized, die Mostly nonliving material

Homeostatic Imbalances Infections and allergies –Athlete’s foot, boils and carbuncles, cold sores, contact dermatitis, impetigo. Psoriasis –Most common skin disorders result from allergies or infections Burns Skin cancer

Burns – 2 life-threatening problems result –Fluid and electrolyte loss – can be determined by “rule of nines”, figure 4.11 –Infection – most likely cause of death in burn victims –Classified according to severity as 1 st, 2 nd, 3 rd degree burns

1 st degree –Only epidermis is damaged –Easily healed – sun burn 2 nd degree –Injury to epidermis and upper dermis –Regrowth of epithelium possible

3 rd degree –Destroy entire thickness of skin –Nerve endings are destroyed, not painful –Regeneration is not possible, skin grafting necessary

Skin cancer –Most neoplasms are not cancerous, do not metastasize –Most important risk factor for skin cancer is exposure to uv light in sun –3 types: basal cell carcinoma, squamous cell carcinoma, malignant melanoma

Basal cell carcinoma –Most common, least malignant –Stratum basale cells cannot form keratin, invade dermis and subcutaneous tissue –Slow growing, metastasis seldom occurs

Squamous cell carcinoma –Cells of stratum spinosum –Grows rapidly, metastasizes to lymph nodes –Sun-induced –If caught early, good chance of cure

Malignant melanoma –Cancer of melanocytes –Only about 5% of skin cancers –Metastasizes rapidly to lymph and blood vessels –Survival is 50% –ABCD rule, p. 124

Development of Skin and Membranes Prenatal development –Covered with downy type hair, lost by birth Birth –Skin covered with white substance produced by sebaceous glands –Skin is very thin –During growth, skin thickens and more subcutaneous fat is deposited

Adolescence –Sebaceous glands activated, skin and hair become oily –Acne and dermatitis become common Old age –Subcutaneous tissue decreases –Skin becomes drier –Decrease in elasticity –Hair loses luster and becomes thinner

Systems in Sync, page 125 How does Integumentary System affect other body systems? How do other body systems affect the Integumentary System?

Endocrine –Activate sebaceous glands –Regulate hair growth –Maintain skin hydration Lymphatic –Prevents edema Digestive –Provides nutrients

Urinary –Activates vitamin D –Disposes of nitrogen wastes Muscular –Increases blood flow to skin –Activates sweat glands

Nervous –Regulates diameter of blood vessels –Activates sweat glands –Cutaneous sensation –Arrector pili muscle Respiratory –Exchange of oxygen aqnd carbon dioxide to cells

Cardiovascular –Transports oxygen and carbon dioxide to cells Skeletal –Supports skin