Chapter 4 Skin Body Membranes Integumentary System Skin

Chapter 4 Skin & Body Membranes

Integumentary System Skin (cutaneous membrane) Skin derivatives Skin Functions -Sweat glands -Oil glands 1. Protects deeper tissues -Hairs from: w. Mechanical damage -Nails w. Chemical damage w. Bacterial damage w. Thermal damage w. Ultraviolet radiation w. Desiccation 2. Aids in heat regulation 3. Aids in excretion of uric acid 4. Synthesizes vitamin D

Skin Structure The skin is composed of three layers: 1. Epidermis- (outer layer) composed of stratified squamous epithelium which is keratinized 2. Dermis- (middle layer) composed of dense irregular connective tissue -accessory organs: hair follicles, eccrine and apocrine glands (sweat glands), sebaceous glands (oil glands), blood vessels, nerve endings, arrector pili muscles, and capillary beds. 3. Hypodermis – (lower layer or subcutaneous layer) composed of adipose tissue contains arteries, veins, and large nerves

Layer of Epidermis Stratum basale w. Cells undergoing mitosis w. Lies next to dermis wcontains cells called melanocytes Stratum spinosum Stratum granulosum Stratum lucidum w. Occurs only in thick skin (soles of feet and palms of hands) Stratum corneum w. Shingle-like dead cells

Identify the layers of the thick skin tissue sample. Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale X - Ray. NQ

Normal Skin Color Determinants Melanin Yellow, brown or black pigments Carotene Orange-yellow pigment from some vegetables Hemoglobin Red coloring from blood cells in dermis capillaries Oxygen content determines the extent of red coloring Melanin Pigment produced by melanocytes Melanocytes are mostly in the stratum basale Amount of melanin produced depends upon genetics and exposure to sunlight-"tanning effect"

Put the layers of the skin in order from outer most to inner most. stratum granulosum stratum basale stratum lucidum dermis hypodermis epidermis stratum spinosum stratum corneum Quanecia's Integument Rythym

Dermis Two layers 1. Papillary layer ŸProjections called dermal papillae (responsible for fingerprints) ŸPain receptors ŸCapillary loops 2. Reticular layer ŸBlood vessels ŸGlands ŸNerve receptors

Appendages of the Skin Sebaceous glands §Produce oil Lubricant for skin Kills bacteria §Ducts that empty into hair follicles §Glands are activated at puberty Sweat glands: produce sweat Two types: a. Eccrine: produce watery sweat, found all over body - empty out on the epidermis surface b. Apocrine: produce sweat, fatty substances, and protein - Located in the axillary and pubic regions - Become active during puberty - body odor due to bacteria - empty into hair follicles. Modified apocrine glands: Ceruminous glands: ear, produce Function cerumen or ear wax Helps dissipate excess heat Mammary glands: breasts, produce Excretes waste products and secrete milk Acidic nature inhibits bacteria growth

Appendages of the Skin Hair -Produced by hair bulb -Hard dead keratinized epithelial cells -Melanocytes provide pigment for hair color Hair Anatomy Central medulla Cortex surrounds medulla Cuticle on outside of cortex Associated Hair Structures Hair follicle Arrector pilli Smooth muscle Sebaceous gland Sudoriforous gland

Appendages of the Skin Nails Scale-like modifications of the epidermis §Heavily keratinized §Stratum basale beneath the nail bed is responsible for growth Lack of pigment makes them colorless Nail Structures Free edge Body Root of nail Eponychium – proximal nail fold that projects onto the nail body

Label the fingers! Cuticle Nail root Lanula Cuticle Nail matrix Body of nail Free edge Nail bed Body of nail

Appendages of the Skin Nerve receptors: The skin has receptors for pressure (Pacinian and Meissner’s corpuscles), pain, and temperature. Meissner’s corpuscles are located just below the surface of the epidermis and are sensitive to light pressure or touch, these are associated with “tickling sensations”. Pacinian Corpuscles are located deep in the dermis and are associated with strong touch and pressure. Root hair plexus are associated with each hair follicle and is responsible for the pain when your hair is pulled. Free nerve endings are scattered throughout the dermis and are specialized for the reception of heat, cold, or pain.

Temperature Regulation • Your skin acts similar to a radiator on a car to disseminate heat that is produced by cellular activity in your body and muscular contraction. • This process is under the control of the hypothalamus in the brain. • Negative feedback mechanism

Temperature Regulation • body temperature goes above the set homeostatic value • the blood vessels in the dermis dilate and increase blood supply to the capillary beds located there • eccrine glands begin to secrete sweat which moves to the surface of your epidermis • heat is transferred from the blood in your capillaries, through the dermis and epidermis, to the surface of the epidermis and is absorbed by the water in the sweat and vaporizes or evaporates it • The blood has now lost heat and is at a lower temperature and returns to the inner body away form the surface to cool the inner body structures

Temperature Regulation • When the body’s temperature falls below the set homeostatic value • The arterioles constrict, forcing blood toward the interior organs • The pili arrector muscles contract, generating heat, and raising the hair trapping an insulating layer of air around the skin

Label the diagram! Eccrine sweat gland Hair root Dermis arrector pili muscle Root hair plexus Pacinian corpuscle Adipose tissue Sebaceous gland Free nerve ending Hypodermis vein Meissner's corpuscle Epidermis Sweat pore Hair follicle artery Hair shaft

A, D E H B A H B G

Melanin Keratin T Corneum Shaft Dermis Cortex Medulla Cuticle

hair bulb hypodermis sweat gland dermal papillae dermis nerves epidermis arrector pili hair follicle stratum corneum hair shaft adipose sebaceous gland

Skin Homeostatic Imbalances Infections 1. Athletes foot Fungal infection 2. Boils and carbuncles Bacterial infection 3. Cold sores Viral Infections and allergies 4. Contact dermatitis Exposures cause allergic reaction 5. Impetigo Bacterial infection 6. Psoriasis Cause is unknown Triggered by trauma, infection, stress

Diseases and Disorders of the Skin Immunological • Acne vulgaris: Due to formation of sebum plugs (white heads or black heads) which block the sebaceous gland often trap bacteria within the gland. – Can become inflamed which can lead to the secondary infections of sweat gland or hair follicle forming pustules or pimples

Diseases and Disorders of the Skin Immunological • Chicken pox: due to a viral infection (Herpes zoster) of the skin which affects the nerve ending – results in the formation of blisters that itch

Diseases and Disorders of the Skin Immunological • Tinea: Ring worm, Athlete’s foot, and Jock itch are all the result of a fungal infection of the skin. – results in scaling, erythema (reddening), and occasional cracking of the skin that burns or itches

Diseases and Disorders of the Skin Immunological • Warts: due to infection by the human papilloma virus. – causes abnormal growth of the epidermal layer – Normally warts are benign but some forms can transform and become malignant (cervical cancer) – transmitted by direct contact from one person to another

Diseases and Disorders of the Skin Immunological • Impetigo: caused by an infection of the epidermis by Staphlococcus or Streptococcus bacteria – results in erythema, formation of weeping blisters, that form a yellow crusting on their surface – highly contagious and common in children

Diseases and Disorders of the Skin Immunological • Contact dermatitis: due to an allergic reaction with materials which the skin has made contact – characterized by erythema, edema, blistering and scaling of the skin – Itching is usually associated with the area affected – Poison Ivy is an example of this disorder

Diseases and Disorders of the Skin Immunological • MRSA infection is caused by Staphylococcus aureus bacteria — often called "staph. " MRSA stands for methicillin-resistant Staphylococcus aureus (resistant to antibiotics) – can be fatal. – Most MRSA infections occur in hospitals or nursing homes and dialysis centers. – community-associated MRSA: responsible for serious skin and soft tissue infections and for a serious form of pneumonia.

Matching 1. Characterized by dry cracked skin with burning and itching, usually between the toes. 2. Caused by the human papillomavirus. 3. A red itchy rash sometimes caused by poison ivy. 4. A bacterial infection that usually occurs in children, characterized by crusty or oozing blisters. 5. A serious staph infection. Dermatitis MRSA Tinea Impetigo Warts

Athlete's foot Dermatitis Boil Impetigo Chicken pox Herpes Warts Psoriasis MRSA (boil) Acne

Skin Homeostatic Imbalances Burns Tissue damage and cell death caused by heat, electricity, UV radiation, or chemicals Associated dangers ü Dehydration & infection ü Electrolyte imbalance ü Circulatory shock Rule of Nines Determines the extent of burns Body is divided into 11 areas-for quick estimation Each area represents about 9%

Severity of Burns • 1 st Degree burns: – epidermis only – result in redness and swelling (edema) – Usually no scarring of tissue • 2 nd Degree burns: – epidermis and dermis, some damage to accessory organs – blistering but usually little scarring. • 3 rd Degree burns: – epidermis, and hypodermis – destruction of dermal accessory organs, burn is raw or blackened in appearance – Severe scarring occurs, long healing period, usually involving skin grafting

Critical Burns are considered critical if: Over 25% of body has second degree burns Over 10% of the body has third degree burns There are third degree burns of the face, or feet

What degree of burn is shown in the pictures?

Skin Cancer – abnormal cell mass Two types Benign Does not spread (encapsulated) Malignant Metastasized (moves) to other parts of the body «Skin cancer is the most common type of cancer

Skin Cancer Types Basal cell carcinoma ü Least malignant ü Most common type ü Arises from statum basale Squamous cell carcinoma ü Metastasizes to lymph nodes ü Early removal allows a good chance of cure

Skin Cancer Types Malignant melanoma Most deadly of skin cancers Cancer of melanocytes Metastasizes rapidly to lymph and blood vessels Detection uses ABCD rule ABCD Rule A = Asymmetry Two sides of pigmented mole do not match B = Border irregularity Borders of mole are not smooth C = Color Different colors in pigmented area D = Diameter Spot is larger then 6 mm in diameter