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 membranesFigure 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 MembraneFigure 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 1st , 2nd, 3rd

degree burns

• 1st degree– Only epidermis is damaged– Easily healed – sun burn

• 2nd degree– Injury to epidermis and upper dermis– Regrowth of epithelium possible

• 3rd 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