INTEGUMENTARY SYSTEM
To be an organ
• Membranes are organs: mucous serous synovial
• Epithelial membranes: mucous + serous + cutaneous(dry membrane, exposed to air)
• Connective tissue: synovial membrane
Mucous membranes
• Line cavities that open to exterior:– Respiratory: ciliated columnar– Digestive: columnar with microvilli– Urinary: no mucus, moist with urine– Reproductive
• Rests on loose connective tissue: lamina propria
Serous Membrane
• Name by location: closed cavities
• 2 layers: visceral- on organparietal- lines inside of cavity
• Peritoneum: abdomen
• Pluera: lungs
• Pericardium: heart
Synovial membrane
• The only connective tissue membrane
• Line fibrous capsule around joint
• Line bursa: small fluid filled sac
• Line tendon sheath
Integumentary system
• Integumentary system = (organ system)skin + sweat/oil gland + hair/nails
• Skin = cutaneous membrane (organ)
Functions
• Protection from non self – bacteria from heat lossmechanical damagechemical damagethermal damageultraviolet radiation (sunlight)
Functions
• Mini excretory system
• Secretes: urea, salt, water
• Manufactures proteins for immunity and synthesizes vitamin D (needs sunlight)
Functions
• Nervous system
• Skin has receptors in it for nervous input hot/cold pressure/pain
• Nervous system controls sweat glands and capillaries
Revisit synovial membranes
• PROPRIOCEPTION
• Proprioceptors in synovial membrane report to nervous system about location of joint and amount of stretch/slack on each side of joint capsule, tendon etc.
Structure of Integument
• Skin = epidermis + dermis
• Epidermis = keratinizing stratified squamous
• Dermis = dense C.T.
• Cornified: upper layer of epidermis has lots of keratin = hardened
Hypodermis
• Deep to skin: also called subcutaneous
• Not part of skin
• Mostly adipose
• Anchors skin to organs/bones below
Epidermis
• 5 layers: strata• Corneum: 30 cell thick-dead cell remnants
constantly rubbed off- lots of keratin• Lucidum: dead, lots keratin, only in areas
of very thick skin (palms, soles of feet)• Granulosum • Spinosum• Basale: gets nourichment from dermis,
constant cell division-millions of new cells
Vascularity
• Epidermis is composed of epithelium
• Avascular: no direct blood supply
• Can scrape off many layers and not have bleeding.
• Receives blood and nourishment from dermis
• New epidermis every 25-45 days
Cells in skin
• Melanocytes: in stratum basalemake melanin (pigment)sunlight stimulates production
• Phagocytes: in stratum basaleeat foreign substances (protection)
• Sun damage: cause elastic fibers to clump = leathery skincan alter genetic material = cancer
• Darker skin: less cancer
Skin color
• Melanin: yellow - red - brown – black
• Carotene: yellow – orange
• Oxygen: bound to heme in blood. If decrease oxygen looks more blue (cyanosis)
Dermis
• Strong, stretchy = hide (of an animal)
• 2 regions
• I. papillary fingerlike projections on superior surface = papillae– Indent the epidermis above- loops, whorls– For grip and friction– Have capillary loops– Pain/touch receptors (meissner’s corpuscles)
Dermis
• II. Reticular: deepest skin layer– Blood vessels– Sweat/oil glands– Pressure receptors (pacinian corpuscle)– Many phagocytes– Collagen: strong, bind water to keep skin
hydrated– Elastic: for elasticity
• AGE
• Decrease # of collagen and elastic fibers: sag
• Decrease sub Q adipose
Dermis
• Very vascular: lots of blood vessels
• Regulate temperature homeostasis
• Body temp. high Capillaries fill with warm blood: skin red warm – blood cools
• Body temp. low Capillaries close to keep blood in warm part of body: extremities get blue
• Scalp: skin on head has many capillaries: much heat dissipated (lost) from top of head. Head injury = much bleeding
• Southern cow – bigger ears than northernto dissipate heat - elephant
Ischemia
Restriction of blood flow to skin = cell death
• Ulcers: skin breakdown with ▼ blood flow
• Decubitus ulcers = bed sores
Nervous System
• All body systems interact with each other
• Sensors in skin are:
• Nerve cells with specialized end organ
• For pressure, temperature, pain
Skin pathology
• Erythema: red skin– Blush– Inflammation– Fever– Hypertension
• Pallor or blanching: white– Stress– Anemia– Hypotension (decrease blood flow)
Skin pathology
• Jaundice: yellow– Liver disease– Excess bile pigment in tissue
• Bruise = hematoma: blood is out of circulatory system and clotted in tissue. (broken blood vessels)
Appendages