Integumentary System PDF

Integumentary System KIN 131 001 Nov 2023 Paige Jackson MPT, MKIN, CSCS Integumentary System The integumentary system consists of the skin and its accessory structures, Cutaneous membrane: Skin is the largest organ in the body Epidermis...

Integumentary System KIN 131 001 Nov 2023 Paige Jackson MPT, MKIN, CSCS Integumentary System The integumentary system consists of the skin and its accessory structures, Cutaneous membrane: Skin is the largest organ in the body Epidermis and dermis layers Accessory structures: Hair Nails Exocrine (sweat, oil, etc. glands) https://openstax.org/books/anatomy-and-physiology-2e/pages/5-1-layers-of-the-skin Functions Protection Melanin production Keratin production From trauma From fluid loss Chemicals, pathogens Excretion Lubrication Body temperature regulation Vitamin D synthesis Lipid storage* Sensation Touch movement Skin Anatomy Two main layers of cutaneous tissues form the skin. One subcutaneous layer provides supportive functions. Epidermis Outer most layers (4-5) Densely packed stratified squamous epithelial cells Dermis Inner layers (2) dense irregular connective tissue & areolar tissue Contains blood, lymph, glands, nerves, hair follicles Hypodermis Subcutaneous layer Highly vascularized Loose areolar connective tissue, adipose tissue Connects skin to underlying fascia Epidermis Most superficial layers of the skin. Epidermis has 4 or 5 layers Thin skin (4) layers covers most of body avascular Thick skin (5) layers covers palms of hands Primarily composed of keratinocytes and soles of feet Provides hardness & water-resistant properties Deeper layers gradually progress Fingernails are epidermal tissue that outwards until they are sloughed off, contains mostly keratin that causes them to cycle repeats be very stiff. Layers of the Epidermis (deep to superficial) Deepest Layer: Stratum Germinativum àaka stratum basale Single layer of basal cells Cuboidal-shaped stem cells Precursor to keratinocytes Contains Merkel cells & melanocytes Attaches epidermis to basal lamina https://openstax.org/books/anatomy-and-physiology-2e/pages/5-1-layers-of-the-skin Layers of Epidermis (deep to superficial) Second layer: Stratum Spinosum à’spiny’ layer 8-10 layers of keratinocytes Keratin synthesis initiated in this layer scleroprotein Insoluble to water and organic solvent compounds Prevents water loss from body, makes skin relatively waterproof Contains Langerhans cells Functions as a macrophage https://openstax.org/books/anatomy-and-physiology-2e/pages/5-1-layers-of-the-skin Layers of Epidermis (deep to superficial) Third layer: Stratum Granulosum à’grainy’ layer 3-5 layers of keratinocytes Produce large amounts of keratin Produce keratohyalin Cells become flatter, thinner, and begin to die https://openstax.org/books/anatomy-and-physiology-2e/pages/5-1-layers-of-the-skin Layers of Epidermis (deep to superficial) Fourth layer: Stratum lucidum Only in palms, soles, digits Cells are flattened and dead Packed with eleidin Fifth layer: Stratum corneum Most superficial layer 15-30 layers of k-cytes Layers of dry, dead cells Helps prevent microbes from entering body, and reduces dehydration of underlying layers Entire layer replaced every ~4 weeks https://openstax.org/books/anatomy-and-physiology-2e/pages/5-1-layers-of-the-skin Skin Pigmentation Skin colour is determined by a number of pigments: melanin, carotene, and hemoglobin. Melanin Produced by melanocytes Packaged into melanosomes and passed on to keratinocytes In individuals with darker skin, the melanosomes are larger and travel farther up the epithelial layers before being broken down Protects DNA in skin cells from UV damage Stimulated by UV exposure Carotene Orange/yellow pigment Too much melanin interferes Can be converted to vit A with vitamin D production https://openstax.org/books/anatomy-and-physiology-2e/pages/5-1-layers-of-the-skin Skin Pigmentation Skin colour is also influenced by dermal circulation and temperature. Oxygenated blood is bright red d/t oxyhemoglobin Deoxygenated blood is dark red, but appears bluish through skin = cyanosis Temperature can affect cutaneous blood flow. Vasodilation in hot environments and during exercise Vasoconstriction in cold environments Frostbite: Frostnip: red skin, numbness, impaired mobility Superficial frostbite: white, pale skin; ice crystals in epidermis & dermis Deep frostbite: deep tissue damage The Dermis The dermis is beneath the epidermis, and has two layers: àcontains both elastin & collagen fibres Papillary layer: Superficial layer, forms dermal papillae Loose areolar connective tissue Contains fibroblasts, adipocytes, capillaries, lymph vessels, phagocytes, sensory neurons Reticular layer: Dense irregular connective tissue Contains hair follicles, sweat and oil glands, blood & lymph vessels, nerve fibres https://openstax.org/books/anatomy-and-physiology-2e/pages/5-1-layers-of-the-skin Integumentary Accessory Structures: Hair Hair is a keratinous filament that grows out of the epidermis. Made of dead, keratinized cells Originate in hair follicle Epidermal extension in the dermis Contains hair bulb, hair matrix, and hair papilla Hair root is the part of the hair below the surface of the skin Hair shaft is not anchored to follicle, the part of hair outside the skin Part of hair: medulla, cortex, cuticle Basal cells of hair bulb divide and push cells superficially in the hair root. https://openstax.org/books/anatomy-and-physiology-2e/pages/5-1-layers-of-the-skin Hair Follicle transitions to resting phase Function: Protection Hair loses Active phase lasts attachment to Sensory input 2-7 years. Hair follicle in resting phase, becomes club grows ~ Thermoregulation 0.33mm/day hair Communication Follicle reactivation causes club hair to Hair Growth: shed, replacement hair starts to form Happens in 3 phases: Anagen: 2-7 years, cells at root divide rapidly, push hair shaft up & out Catagen: 2-3 weeks, transition from active growth, follicle regresses Telogen: 2-4 months, follicle resting, no new growth occurs àas new anagen phase begins, old hair shed https://openstax.org/books/anatomy-and-physiology-2e/pages/5-1-layers-of-the-skin Integumentary Accessory Structures: Sweat Glands Sweat glands are sudoriferous glands and there are two main types: Eccrine (type of merocrine gland) Coiled, tubular ducts in dermis Secrete sweat via exocytosis into duct then exits skin via sweat pore Secretion is watery & clear Contains dermicidin Primary in thermoregulation Apocrine Secrete into hair follicle Used as nutrient for bacteria on skin Secretion is cloudy, sticky, odorous Under nervous & hormonal control https://openstax.org/books/anatomy-and-physiology-2e/pages/5-1-layers-of-the-skin Integumentary Accessories: Oil Glands Sebaceous glands are oil glands that are found all over the body. Secrete into hair follicles Secrete sebum Provides lubrication to upper layers of epidermis Antibacterial properties Waterproofing of skin https://openstax.org/books/anatomy-and-physiology-2e/pages/5-1-layers-of-the-skin Integumentary Accessories: Nails Nails form at tips of toes and fingers. -densely packed, dead keratinocytes Nail body forms at nail root Matrix of cells from stratum basale Lateral nail folds anchor nail to body Nail fold that meets proximal end of nail body forms the cuticle (eponychium) Nail bed rich in blood vessels, except at lunula (small crescent of white) Hyponychium is furthest from cuticle, has no nail bed underneath Integumentary System: changes with age Fewer melanocytes Decreased germinative cell division Fewer elastic fibres, thinner dermis Less active sweat glands Increased risk of overheating Reduced cutaneous blood flow Impaired thermoregulation Increased cold sensitivity Increased heat intolerance Less active hair follicles And melanin stops being produced in hair follicles Decreased sebaceous gland function Reduced sex hormones Lines of Cleavage Topological lines in the skin that indicate the orientation of underlying collagen and elastin fibres. Also called tension lines or Langer lines Arrangement of these fibres in parallel bundles creates resistance to forces applied to skin Clinical significance: Incision made parallel to lines is more likely to remain closed and heal with minimal scarring Incision made perpendicular or at an angle may be more likely to be pulled open by recoil of elastic fibres Longer healing time, greater scarring https://openstax.org/books/anatomy-and-physiology-2e/pages/5-1-layers-of-the-skin Albinism and Vitiligo Albinism is a genetic disorder that affects the colouring of skin, hair, and eyes. Results from abnormal melanocyte function Increased risk of skin cancer May have light sensitivity and vision problems Vitiligo similar to albinism, but only occurs in some areas of the skin. Parts of skin completely unaffected, others have little to no melanin Thought to be result of autoimmune condition à Neither have direct impact on lifespan Skin Cancer Skin cancer involved uncontrolled, abnormal growth of skin cells. àUsually caused by UV exposure 1. Basal cell carcinoma Most common form of skin cancer Mutations in stratum germinativum Metastasis rare; high survival rate 2. Squamous cell carcinoma Second most common form of skin cancer Mutations in stratum spinosum Non-life-threatening, unless left. untreated 3. Melanoma Least common, most dangerous Cancerous melanocytes grow rapidly and metastasize via lymph system Survival rate depends on how early it is caught Skin cancer: melanoma diagnosis & treatment Moles are assessed with the following acronym: A = asymmetry B = borders C = colour D = diameter E = evolving Confirmed by taking a biopsy to test for cancerous cells. Treatment: Excision of affected and surrounding tissue More advanced cases: Removal of lymph nodes, if necessary Targeted chemo- or radiation therapy Burns A burn is tissue damage due to intense heat, electricity, chemicals, or radiation. Stages: 1. First degree Superficial, damage to epidermis only Skin is red, swollen heals in days 2. Second degree Damage to epidermis and dermis More swelling, blistering Heals in weeks 3. Third degree *full thickness burn Damage to epidermis, dermis, hypodermis Requires medical intervention Not painful Burns affecting >15-20% of 4. Fourth degree* full thickness burn body are considered a major Structures deep to hypodermis also damaged injury and require hospitalization Skin unable to repair itself Requires medical intervention Skin Wounds A wound is damage to the integrity of biological tissue. Skin wounds involve damage to the skin. Closed wounds Skin surface intact, underlying tissues damaged Ex. Bruises, pressure ulcers stage 1 Secondary intention healing Open wounds Skin is split and underlying tissues are exposed Ex. Cut, stab, scrape Healing Primary intention – wound edges are approximated Secondary intention – edges cannot be approximated and wound is left to heal from bottom up Tertiary intention – combination of primary & secondary Scars & Scar Tissue Most wounds lead to scar formation. Scar Collagen-rich skin formed after wound healing Different from normal skin Scarring occurs with damaged skin that fails to regenerate the original skin structure Atrophic scar Lack of collagen, pitted appearance Hypertrophic scar Scar stays within the borders of the injury, but is raised (not flat or sunken) Scar may heal/improve over time Keloid Scar Spread beyond borders of injury Do not regress Firm, rubbery, shiny