UNIT 4 Integumentary.pdf - 2/5/19 EXAM 2: Units 3c, 4, 5,...

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Unformatted text preview: 2/5/19 EXAM 2: Units 3c, 4, 5, and possibly 5a The Integumentary System Bio 201 Outline • Serous membranes • Components of the Integumentary System • Functions of Integumentary System • Anatomy of the Epidermis Important Cell Types of Skin Layers Factors affecting skin color • Dermis • Accessory Structures: Sensory Receptors, Nails, Hair, Glands • Clinical Considerations: Cancer, Androgenic Alopecia, Burns Before we start: let’s get a few things straight Cell or plasma membrane Epithelial membranes Micro Macro Connective tissue membranes Macro Synovial membrane Meninges (not shown) Serous membrane Mucous membrane Cutaneous membrane Macro-level membranes are generally a combination of different cell types to protect, cover, lubricate, nourish, etc. 1 2/5/19 Integumentary System: parietal = surround body cavities (pleural, abdominal pelvic) Skin and body membranes visceral = surround internal organs Note: We will briefly discuss mucous and synovial membranes when we cover the digestive/respiratory systems and joints 4 Serous membrane Membranes in ventral body cavity Serous membrane (also called the serosa): Thin coverings over surfaces in ventral body cavity Parietal serosa lines internal body cavity walls Visceral serosa covers internal organs (viscera) Double layers are separated by slit-like cavity filled with serous fluid help to absorb shock; protective mechanism to keep organs in their space Fluid secreted by both layers of membrane (Pathophysiology note: pericardial effusion) Outer balloon wall (comparable to parietal serosa) Figure 1.10 Serous membrane relationships Air (comparable to serous cavity) Inner balloon wall (comparable to visceral serosa) A fist thrust into a flaccid balloon demonstrates the relationship between the parietal and visceral serous membrane layers. Heart Parietal pericardium Pericardial space with serous fluid Visceral pericardium The serosae associated with the heart. 2 2/5/19 Terminology: Fascia Fascia is a general word that generally describes a sheet or band of connective tissue that lies just beneath the skin. It helps to attach the skin to underlying structures (often muscles). Fascial sheaths or coverings also help to separate individual muscles and organs from each other within the body Classifications: Superficial fascia – blends the dermis with other structures Deep fascia – separates muscles Visceral & parietal fascia / membranes (as discussed in previous slides) – supports, covers, and separate internal organs. Components of Integumentary System Note: Hypodermis - Not technically considered part of integumentary system, but shares some functions The hypodermis is adipose and areolar connective tissue 3 2/5/19 “flaking” cells are the stratum corneum Skin consists of two distinct regions: increase the surface contact b/w the structures and the sloughing of the dermis stratified squamous epithelium Epidermis (red): superficial region; epithelial tissue and is avascular Dermis (blue): under epidermis; fibrous connective tissue, vascular Hypodermis (superficial fascia): • Subcutaneous layer deep to skin; mostly adipose tissue and areolar connective tissue • absorbs shock and insulates • anchors skin to underlying structures: mostly muscles 10 Functions of Integumentary System • Protection Physical barrier Immune function UV damage • • • • • Body Temperature Regulation Synthesis of Vitamin D Excretion Sensation Immune function Skin function: Regulation of Body Temperature when you return to heat, you are somewhat dehydrated and need to consume more fluids Regulation of conductive/convective heat loss 1. 2. 1. 2. • Blood vessels to skin : constrict (if cold) or dilate (if hot) to regulate blood flow to skin • Skin blood flow regulated primarily by neural mechanisms internal increase in blood pressure, urge to pee in cold weather Regulation of evaporative heat loss • Neural regulation of activity of sweat glands 4 2/5/19 Skin function: Vitamin D3 synthesis calcitriol: stimulate absorption of calcium and phosphate principle inorganic molecules for bone remodeling, bone resorption 1,25-dihydroxyvitamin D3 or Vitamin D3 lack of Vitamin D could lead to softening of the bone leads to condition called osteomalacia in children Rickets: weak structurally abnormal bone due to lack of calcium and phosphorus Epidermis: Outermost Layers of Skin Stratified squamous epithelium Epidermis ranges in thickness - Thin skin à 0.10 - 0.15 mm - Thick skin à 0.5 - 4.5 mm palms of your hand and soles of your feet: Thick skin has stratum lucidum everywhere else: Thin skin (located where?) (located where?) stratum corneum — outermost dead layer of the skin does not have a capillary network related to it; decrease the amount of metabolic demand • Separated from underlying dermis by basement membrane • Avascular: what does this mean in terms of metabolic demand? • Epidermal ridges project into dermis (why?) establishing a great amount of surface contact Epidermis: Cell Types • Keratinocytes: skin cell produce an intermediate – most abundant cell type filament called keratin – synthesize and accumulate the protein, keratin (an intermediate filament) – produce lamellar granules, or lipid secretions • Langerhans (dendritic) cells: in stratum spinosum layer – immune cells (phagocytic) that respond against microbes and cancers; also can ”call” other immune cells to location • Merkel (tactile) cells: in stratum basale layer cell; changes in movement, pressure, – mechanoreceptor: make contact with sensory neurons touch to elicit sensation of light touch associated with desmosomes keeps skin oily and moist have the ability to call other cells (chemotaxis) based on mechanical movement of the • Merkel’s disc = Merkel cell + nerve ending • (only sensory cell in epidermis) • Melanocytes: in stratum basale layer – produce melanin (pigment) • Stem cells (basal cells): in stratum basale layer – attaches to dermis active in cell division – give rise to keratinocytes metabolically active cells, get energy from diffusion 5 2/5/19 Epidermis of the skin: 4-5 layers called the stratum spinosum (prickle cells) as the cells divide, the daughter cells get pushed up into the upper layer Cell renewal Stratum corneum: 15- 30 layers dead keratinocytes lacking nuclei; water resistant, protects deeper layers against environment 7d: basale to corneum; 14d at corneum Superficial Deep (Stratum lucidum): layer of densely packed dead keratinocytes present in thick skin) – this layer helps to reduce friction Stratum granulosum: 3-5 cell layers of keratinocytes transition between metabolically active cells and superficial dead keratinized cells; lamellar granules released here; disintegration of organelles here transitional layer produces a number of substances helps in part to keep the skin lubricated, water-proof Stratum spinosum: 8-10 cell layers of keratinocytes. Keratinocytes here appear spikey (called prickle cells); cells contain web-like system of intermediate filaments attached to desmosomes to resist forces and pulling acting about the skin produce keratin in large amounts melanocytes and langerhans cells also located here Stratum basale: single layer of cuboidal / columnar cells source of cell renewal (stem cells) location of melanocytes and Merkel cells 21 days for a cell to migrate from the stratum basale to the stratum corneum; stratum corneum = 14 days borders the dermal area vasculature through diffusion provide nutrients Melanocytes Located in stratum basale layer specialized cell Contain melanosomes (organelle) • synthesis of the pigment melanin from the amino acid tyrosine • vesicles which are released at the surface of the melanocyte Melanosomes delivered intact to neighboring keratinocytes • granules surround nucleus to protect epidermal cell DNA from damage by UV light • eventually degraded by lysosomes in the keratinocytes increase of activity Exposure to UV light stimulates production of melanin à tanning helps to protect the keratinocytes from UV radiation Some Factors affecting skin color Epidermal pigmentation Melanin; yellow-brown, brown-black pigment differing rates / amounts / type / distribution of melanin = differences in skin color among individuals (Note: within an individual, areas that are more darkly pigmented than others may be due to differing densities of melanocytes) Carotene- orange-yellow pigment to your skin accumulation in epidermal cells: effect in pathological conditions or with overconsumption of carotene rich foods Blood Flow to the skin: Pigment in bloodà Hemoglobin Oxygenated = Bright red Deoxygenated = Dark red/purple Redness/Flushing : Increased blood flow to skin Note: Erythema- localized area of redness, due to excess blood in dilated vessels blushing lack of oxygen Bluish Coloration (Cyanosis): Decreased oxygen content of blood Pale: Decreased blood flow to skin, decreased amount of hemoglobin in blood 6 2/5/19 Dermis Location of • blood vessels • lymph vessels • nerves / sensory receptors • hair follicles • oil & sweat glands Papillary layer (layer of nutrient delivery) • presence of dermal papillae • vascular areolar CT Reticular layer deeper layer of connective tissue with abundant collagen and elastin fibers ground substance 80% thickness of dermis Papillary layer: superficial layer of areolar connective tissue consisting of loose, interlacing collagen and elastic fibers and blood vessels Dermal papillae: fingerlike projections up into epidermis containing capillary loops, free nerve endings, and Meissner’s corpuscles) In thick skin, dermal papillae lie on top of dermal ridges, which give rise to epidermal ridges Collectively ridges are called friction ridges, which enhance gripping ability, contribute to sense of touch Epidermis Papillary layer Reticular layer Dermis Reticular Layer Makes up ~80% of dermal thickness difference between papillary layer and reticular layer areolar connective tissue Consists of coarse, dense fibrous connective tissue Elastic fibers provide stretch-recoil properties Collagen fibers provide strength and resiliency bind water, keeping skin hydrated Cutaneous plexus: network of blood vessels between reticular layer and hypodermis 7 2/5/19 Accessory structures: Sensory receptors in the skin Mechanoreceptors: physically disrupted Merkel’s discs (stratum basale): touch and pressure on especially on glabrous skin Meissner’s corpuscle (dermal papillae): sensitive to fine touch and pressure Ruffini corpuscle (deep dermis): sensitive to skin distortion and pressure Pacinian corpuscle (deep dermis/hypodermis): sensitive to deep pressure and vibration; Nerve endings surrounding hair root, sensitive to hair movement glabrous skin: skin that has no hair (i.e, nipples, palms, soles of feet, lips) neuron wrapped around every hair shaft Nociceptors: sensitive to painful stimuli, free nerve endings pain receptors prostiglandins Thermoreceptors: sensitive to temperature, free nerve endings bag of cells surrounding a neuron What’s a corpuscle? becomes flat on top so it’s not constantly stimulating the neuron Accessory structures: Nails vaginations: folding of the deeper layers Nails are dense layers of dead, heavily keratinized, keratinocytes Function: protection, limit distortion, tools Nail root: deep epithelial / epidermal fold (purple); contains a stratum basale that gives rise to the nail Nail body: visible portion of the nail Nail bed: the epidermal layer just below the nail body Lunula: base of nail where blood vessels are not visible Cuticle (eponychium): extension of stratum corneum from the root over base of nail 8 2/5/19 Accessory Structures: Hair • Consists of dead keratinized cells • Functions: – Warning system: example: bug on skin – Protect from heat loss – Protect from physical trauma (hair on head) – Protect from sunlight Glabrous skin: contain no hair (palms, soles, lips, nipples, and portions of external genitalia) Accessory Structures: Hair deeper layer: hair root, hair shaft: what you can see Hair: dead, keratinized cells, which project above surface of skin Keratin: a fibrous protein (intermediate filament) that protects epithelial cells in the skin. Keratinized tissue is extremely tough (similar to chitin in an insect’s shell) smooth muscle grouping of cells controlled by autonomic nervous system Produced in organs within the dermis called hair follicles Types of hair: Vellus hair: small, short, and delicate peach fuzz Terminal hair: large, course, and usually pigmented (note: distribution of melanin into hair as it is produced) hair, arms, external genitalia Accessory Structures: Hair stem cells located in hair matrix Follicle: Specialized invagination of epidermis within surrounding connective tissue sheath Base of follicle: • Hair papilla: indentation in connective tissue (blood vessels) • Hair bulb: surrounds papilla and is site of production Smooth muscle Sensory nerve endings Hair root: anchors hair, extends from base to halfway to skin surface Hair shaft: extends from halfway point to surface 9 2/5/19 Hair Growth Hair grows continually ~ 0.33 mm/day (scalp) eumelanin: true melanin pheomelanin: combination that gives hair its different color has 3 life cycles Hair matrix: most highly active region within the hair bulb site of epidermal stem cells (divide, pushed up, keratinized) Medulla, cortex, and cuticle inner to outer layers = less to more keratin Keratinization complete at border of root and shaft Androgenic Alopecia largely influenced by hormones due to higher levels of testosterone Hormonal influence of hair growth on a genetically prone scalp (age also a factor) Males: “male patterned” baldness Hair loss from top of head first, and may then be followed by loss at sides Female hair loss in a different pattern: more diffuse over the top of scalp and rarely leads to total baldness not as common 5a reductase Testosterone Dihydrotestosterone (DHT) DHT shortens the growth phase. In early stages hair still present but smaller. Over time hair disappears Finasteride (i.e., Propecia): Pharmacological treatment for male patterned baldness - 5a reductase inhibitor Minoxidil (i.e., Rogaine): over the counter pharmacological treatment for androgenic alopecia - vasodilator 10 2/5/19 Accessory structures: Modes of Glandular Secretion salivary glands, sweat glands losing part of the cells mammary glands skin child ingests cellular matter bursting/destroying of the cell Accessory structures: Glands Sebaceous (oil) glands / Sebaceous follicles: • Widely distributed, except for thick skin of palms and soles • Most develop from hair follicles and secrete into hair follicles • Holocrine secretion called sebum: complex mixture of lipids water, lipids • Function: waterproofing layer, moisturizing, antimicrobial action Holocrine: secretions produced in cytoplasm and released by rupture of pl. mem. (destroying cell) Accessory structures: Glands Sweat (sudoriferous) glands not associated w/ a hair follicle 1. Eccrine sweat gland • 99% water, salts, vitamin C, antibodies, dermcidin (microbekilling peptide), metabolic wastes • regulated by nervous system • thermoregulation and excretion • NOT connected to a hair follicle • merocrine secretion 2. Apocrine sweat gland: • associated with a hair follicle • found in the axillary (armpits) and anogenital areas • release glandualar contents by merocrine function NOT apocrine • associated with scent merocrine secretion 11 2/5/19 Dermal connective tissue Sebaceous gland duct Sweat pore Sebaceous gland Hair in hair follicle Eccrine gland Secretory cells Photomicrograph of a sectioned sebaceous gland Accessory structures: Glands Ceruminous glands (“cera” is root for wax); ear canals Secretions from these glands combine with sebum to form a wax-like, thick substance Mammary glands For milk production / secretion (Reproductive system) Skin cancers • Non-melanoma – Basal cell carcinoma: most common type of skin cancer ( ~75% of all skin cancers), but least lethal (rarely metastasizes) stratum basale layer that becomes carcinogenic – Squamous cell carcinoma: second most common type of skin cancer, more aggressive than basal cell carcinoma. • keratinocytes Melanoma – Malignant MELANOMA: cancerous melanocytes, most aggressive form of skin cancer 25% of those infected are malignant(?) A: assymetry B: border C: color D: diameter Nonuniform appearance Irregular outline Mixture of colors Larger growths >5 mm diameter ~ pencil eraser E: evolving Watch for changes In Rules ABC&D Early detection of melanoma: ABCDEs 12 2/5/19 Burns Classified based on the depth of the burn 37 Skin graft 2nd Degree 4th Degree Rule of Nines 38 Totals 4 1 ⁄2 % How much surface area has been burned on a person’s body? Must be able to calculate Anterior and posterior head and neck, 9% Anterior and posterior upper limbs, 18% How much surface area (skin) was burned over the body? 4 1 ⁄2 % 4 1 ⁄2 % Anterior trunk, 18% 9% 9% Anterior and posterior trunk, 36% Perineum, 1% Anterior and posterior lower limbs, 36% 100% 13 ...
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