Integumentary System Notes (Chapter 5) PDF

Chapter 5: Integumentary System Integumentary System (inte = whole; gumentary = body covering) Consists of: A.) cutaneous membrane = skin (epidermis + dermis layers) B.) accessory structures = hair follicles, nails, and exocrine glands Dabove G Two layers of skin are: 1. Epidermis - superfici...

Chapter 5: Integumentary System Integumentary System (inte = whole; gumentary = body covering) Consists of: A.) cutaneous membrane = skin (epidermis + dermis layers) B.) accessory structures = hair follicles, nails, and exocrine glands Dabove G Two layers of skin are: 1. Epidermis - superficial stratified squamous epithelium 2. Dermis - underlying areolar tissue and reticular layer of dense irregular connective tissue Just below the skin is the hypodermis = subcutaneous layer - composed of loose connective tissue (not part of integument, but tissue fibres are interwoven with those of dermis. anchored to thedermis Ées cells squamousEpithelial esorystructures cutaneous cystratified Of i've bytouch integument sensoryneurons activated iii a a incin nismmuscle triggerbyaeeperpressure Function of the skin and hypodermis 1. Protection; from impact, abrasion, fluid loss, chemicals 2. Excretion: of salts, water, organic wastes 3. Regulation of body temperature 4. Synthesis of vitamin D3 : a steroid (fat) that is converted into calcitriol (hormone required for Ca++ absorption from the intestine) A. Calcium is handy for the body, within the hormone we will just poop out the calcium 5. Storage of lipids : in adipocytes 6. Sensation: innervated (have nerves) tactile receptors sensitive to different levels of touch and vibration 7. Production of Melanine: protects cells from UV (ultraviolet light) 8. Production of keratin (long ropy protein) : protects from dehydration Epidermis Consists of: stratified squamous epithelium which is avascular (without blood vessels); superficial cells are inert/dead (stem cells are at the bottom). Main cell type: keratinocytes - the cell that form the strata in the epidermis (Make up epidermis) Nature of cell junctions: hemidesmosomes to basal lamina Origin andr fate of keratinocytes : newly formed cells are pushed further and further toward the surface and then eventually are shed. Waves = epidermal ridge, they are bound to the dermal papillae Dermal papillae: why that shape (nipple shape) the strength of attachment is proportional to the surface area. increase delusion and nutrients / contain blood vessel and nerves \ Strengthen the binding of epidermis and dermis Layers of the Epidermis Two types of skin : most of the body is covered with thin skin. Thin = 4 layers of keratinocytes thick covers the palms and soles of your feat Think = 5 layers of keratinocytes , thicker epidermis layer most outer translucent grainy spiney base Integumentary System - Epidermis Fiver layers: Stratum corneum Enadian te stanley Stratum lucidum (Palms and soles only) Stratum granulosum Stratum spinosum Stratum germinativum/basale = where the stem cells are. The epidermis is the thin outer layer of the skin that contains melanin (gives overall color and pigment). ◦ gives skin its color and allow for the skin to tan ◦ Carotene and oxygen rich hemoglobin also contributes to the color of skin. 0 0 ◦ The epidermis also encompasses the protein keratin which stiffens epidermal tissue to form finger nails. ◦ The outermost layer consists of 25-30 layers of dead cells. 1. Stratum germinativum (stratum basale) ◦ anchored to basal lamina by hemidesmosomes ◦ Forms epidermal ridges which interlock with dermal papillae ◦ Simple cuboidal/columnar epithelium (keratinocytes) ‣ provides strong attachment stratite Why do you get calluses and what are they? pressure, wear, and tear stimulate more rapid mitosis which leads to thickening of the epidermis (as a protective mechanism) Why do you get blisters and what are they? friction or damage to the epidermis from extreme temperatures (burns, frostbites) Chemicals causes layers (usually stratum spinosum) of the epidermis to separate and the gaps fills with fluid from underlying tissues (clear, or with blood, or with pus if infected) The fluid stimulates healing and re-growth Surface skin follows contours of epidermal ridges ridges = ensures good grip of fingers and toes -> created fingerprint ridges/patterns uniqueness = genetics + in uteri development. Twins have different exposure to the uterus so they have different fingerprint. Why do you get prune-y fingers in the bathtub? nervous system triggers blood vessels to constrict. not feefree Shrinking of the tissue. intimble form Cell types in stratum germinativum A. Basal cells = germinative cells (stem cells) B. Melanocytes = pigment producing cells ◦ Provide protection for DNA from the sun! C. Merkel cells - sensitive to light touch, activate nerve endings by realizing chemicals. fromUV Protect 2. Stratum spinosum (spiny layer) 8-10 layers of keratinocytes joined by desmosomes Includes langerhans (dendritic) cells phagocytes = macrophage - they look for damage cells and engulf them and get rid if them. (Cancer) Defends against: microorganisms and superficial skin cancer 3. Stratum granulosum = “grainy layer” 3-5 layers of keratinocytes Cells make large amounts of protein keratin = keratinocytes and keratohyalin (protein) which accumulates in granules, promotes dehydration, and cross links between keratin fibres. As cells move upwards through stratum granulosum — they get thinner, flatter and less permeable creating a tightly interlocked layer of cells; cells begin to die in this layer. Cells superficial to the stratum granulosum are dead. Losing their organelles 4. Stratum Iucidum clear (in thick skin only) Cells are densely packed with keratin and devoid or organelles (dead cells) 5. Stratum corneum Horn 15-30 layers of keratinized, dead cells tightly interconnected by desmosomes Water resistant - insensible water loss (500 ml/day) = still losing water ◦ Directly through skin (not through sweat glands and respiration) Skin Colour Pigments of epithelium: A.) carotene — an orange / yellow pigment (also found in orange vegetables [can be converted to vitamin A]) ◦ Humans can not make carotene ◦ Found in adipocytes Tryrosineis converted by tyrosinaseenzyme B.) Melanin — a yellow / brown pigment (made from Tyrosine amino acid) ◦ Produced by: melanocytes in stratum germinativum = provides umbrella for UV protect. * Three things that contribute to the colour of the skin: melanin, keratinocytes, hemoglobin ◦ Melanin packaged into vesicles = melanosomes ◦ melanosomes passed to keratinocytes Difference as to when the melanosomes are broken down: Light skinned: breakdown of melanosomes by fusion with lysosome (and then gets destroyed) ◦ Occurs in strata germinativum and spinosum (because the melanin gets broken down quickly = they are lighter) ‣ Everyone has approx. the same # of melanocytes (doesn’t matter is light or dark skinned) Dark skinned: breakdown in stratum granulosum (3rd layer before they are broken down) ◦ More melanosomes and they’re larger in size ◦ More closer to surface, therefore more visible Freckles and moles Regions of the body where melanosomes are more active. Liver spots = melanocytes when older functions abnormally  Function of melanin: protection from effects of UV radiation -> burns ◦ (Suntan : UV stimulates greater melanin production) ◦ Exposure of the skin to UV radiation from sun and tanning beds is considered a risk factor for the development of skin cancer. ‣ They cause thymine dimers - causes cancer ◦ UV -> damage to DNA in stratum germinativum So when you are lighter = the skin is more efficient to produce vitamin D when there’s not much UV. For calcium absorption, female needs more calcium esp. when pregnant = thats why they are whiter than man. What is vitiligo? vitiligo results from loss of melanocytes, causing white patches on the skin Cause is unknown, but may result from an autoimmune disease, genetic factors, or other factors. Dermal circulation also influences skin colour Increase in blood -> flush (due to blood vessel is more dilated) A.) oxygenated hemoglobin — bright red ◦ Noticeable in light skinned individuals especially when exercising or flushed ( and capillaries are dilated) - bringing in a lot of blood. B.) if cold temperature — skin capillaries constrict making you look paler (*also if blood is restricted/damaged = paler) poor blood flow C.) low oxygen — deoxygenated hemoglobin 8 ◦ Appears dark red and through pale skin ◦ Blue called cyanosis Production of Vitamin D3 (cholecalciferol) required for normal absorption of Ca++ from digestive tract Vitamin D3 produced by epithelial cells (in stratum spinosum and stratum germinativum) in response to sunlight. Then the liver then converts cholecalciferol (vit D3) into a product (intermediate prod.) that the kidney turns into calcitriol. (Required for Ca++ absorption) ◦ Hormone that travels to intestine and help intestine to absorb calcium from food! Before we figured this out lots of kids got: Rickets usually they live in area that are less exposed to sun (no vit D exposure) caused by Vit D3 deficiency results in the bending of abnormally weak and flexible bones under the weight of the body. ◦ Vitamin = essential organic nutrient. Most countries add this to their dairy products Dermis Two layers: Papillary and reticular layer 1. Papillary layer: Aerolar tissue ◦ Thrown into folds on the surface = dermal papillae ◦ Contains capillaries, lymphatics and sensory neurons that supply the surface of the skin 2. Reticular layer of dermis ◦ Dense irregular connective tissue; interwoven mesh work of both collagen and elastic fibres ◦ Also contains: Hair follicles, sweat glands, lymphatic vessels, nerve fibres dermal strength and elasticity ◦ Collagen — very strong, resists stretching ◦ Elastic fibres - stretchy ◦ Water content of skin = skin turgor Lines of cleavage collagen and elastin in dermis arranged in parallel bundles Bundles oriented to resist forces normally applied to skin Established lines of cleavage ◦ a line of cleavage will usually remain close and heal with little scarring. ◦ Whereas severed elastic fibres recoil creating greater scarring. Dermal Blood supply dermis well supplied with blood vessels Network of arteries and veins betweeen dermis and hypodermis: cutaneous plexuses These feed into subpapillary plexuses that supply capillaries extending into papillae = source of O2 and nutrients for epidermis. Bruises you got hit / there damage Because the hemoglobin got out from the blood vessels that ruptured. Hemoglobin = purple/blue, after few days they degraded = yellow to green colour, then eventually disappeared. Innervation to the skin Nerve cells regulate: blood flow, adjust gland secretion rates, and monitor sensory receptors. tells sweat glands if they should produce lots or few sweats. You don’t sweat not only when you are hot, sometimes when you are nervous and etc. sensory receptors respond to: light touch, deep pressure, vibration, chemicals, temperature and damage (pain) Hypodermis Tissue types: aerolar and adipose tissue Functions: elasticity, reduce heat loss, energy reserve (lots of lipid), blood reservoir lots of blood vessels here! Appendages of the skin hair follicles and hair, nails, sweat glands, sebaceous glands, ceruminous glands. Terminal hair = on head Specialized terminal hair = eyelash and brown Vellus hair = body hair Lanugo = baby hair clear 1. Hair insulted and protects scalp from damage Protects nostrils and ear canals for debris Detects movement — through hair plexus sensory nerve Arrector pili muscle stands up = goose bump 9determines colour Armpit hair development of terminal hair hormones sex 4 phases of hair growth cycle: 00 11 1. The active phase lasts 2-5 years. During the active phase, the hair grows continuously at a rate of approximately 0.33 mm/day 2. The follicle then begins to undergo regression and transitions to the resting phase 3. During the resting phase the hair loses its attachment to the follicle and becomes a club hair 4. When follicle deactivation occurs, the club hair is shed and the hair dead matrix begins producing a replacement hair. vessels Blood Sebaceous glands secrete oil through holocrine secretion Two types: ◦ simple branched alveolar glands ‣ share duct with hair follicle and squeezed by arrector pili muscle ‣ They get squeezed and the oil then lubricates ◦ Sebaceous follicles ‣ not attach to hair / not associated with hair follicles Secretions of sebaceous glands: sebum (lipids + electrolytes + proteins + cholesterol) Inhibits bacterial growth due to its acidity (protects skin) Lybricates and protects keratinized cells (hair and skin) Newborn’s vernix caseosa = full term birthm, last few weeks they produce lots of sebum Can fail to discharge, collecting sebum in “whiteheads” or “balckheads” which can become inflamed causing acne in teenagers (due to hormones) Sweat glands sudoriferous glands 1. Merocrine sweat glands (= eccrine sweat glands) - structure : coiled tubular ducts - uses exocytosis - controlled primary by the brain’s thermoregulatory Center (hypothalamus [hormone production: homeostasis] Center of the brain) - and emotional Center (limbic system) (nervous) Sweat: watery Function: cooling surface of skin to reduce body temperature Excrete water and electrolytes Flushes chemicals Contains dermicidin (antibiotic protein) to discourage microbes 2. Apocrine sweat glands; includes ceruminous glands of ear and mammary milk producing glands. distribution: axillae, pubic region, around nipples Structure: coiled tubular structures that open into hair folllicles Secretion: sticky, cloudy, odorous influenced by hormones Function: nutrient for bacteria which intensifies odour Myoepiyhelial cells are contractile cells that squeeze the gland 3. Ceruminous glands modified apocrine sweat gland Location: external ear secretion: cerumen = ear wax Function: trap foreign particles protecting ear drum do apocrine sweat glands use apocrine secretion? ◦ No! It use merocrine secretion ◦ Fill up the apical surface of your cell with the product that want to secrete ‣ the that portion breaks off ‣ Cell will then regrows  malignancyEaterspread mostmalignantP  blisters don'tburst  priority inhospital put in antibiotic put cover grafts growing