A&P Exam 1 (5-6) PDF
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This document appears to be a chapter summary of the integumentary system, including the functions of the skin, temperature regulation, and sensation.
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Chapter 5 - Integument Pirmary Functions of the Skin - 1) Protection - A) Chemical - Sweat & oily secretions kill bacteria - Sweat is acidic so it can kill organisms...
Chapter 5 - Integument Pirmary Functions of the Skin - 1) Protection - A) Chemical - Sweat & oily secretions kill bacteria - Sweat is acidic so it can kill organisms on the skin - Melanin prevents damage caused by UV light - B) Physical - Skin prevents entrance of bacteria - C) Biological - Dendritic cellspatrol dermis to stop anything thatpasses through epidermis - Macrophagesdestroy large-sized “invaders” - Specialize inphagocytosis(digesting large pathogens/debris) - Clear out debris so it can be replaced - 2) Temperature regulation - Insensible perspiration:unnoticeablesweat loss duringthe day - Important for temperature regulation (smaller changes) negative feedback mechanism - Sensible perspiration:noticeablesweat loss thatoccurs when excess heat needs to be lost by body - On warmer day, physical activity when you need to make larger changes to regulate temperature - When environmental temperature is cold, blood vessels in skin contrict → pulls blood away from the skin - Blood is mostly water and water absorbs heat - If external temp is low, blood will go to deep body tissues, and keep visceral organs warm (heart, liver, kidneys) - Process will help preserve internal body heat and keep visceral organs working - 3) Sensation - Exteroceptors:cutaneous sensory receptors - Respond to stimuli arisingoutsidethe body - Mechanoreceptors: respond to mechanical stress: touch,pressure etc. - Thermoreceptors:tells you when it’s warm or cold - Nociceptors:gives you a response of pain - 4) Metabolic functions - Involved invitamin Dproduction - Have to be exposed to sunlight to produce vitamin D - Important for calcium absorption - Helps with neurotransmitter release - Important for health of skeleton - 5) Blood Reservoir - ~5% of total blood volume can be found in integument - Can be “moved” by central nervous system - Contrict or dilation of blood vessels so body temp is regulated - 6) Excretion/waste elimination - Sweat allows for some elimination of certain nitrogenous wastes (urea, ammonia, uric acid) Integument (Skin) - Two layers present in skin: - 1) Epidermis - Unvascularized, outermost portion - Made up of stratified squamous epithelia, 40-50 layers - 2) Dermis(thicker layer) - Vascularized - Makes up most of integument by mass - Hypodermis:made mostly of fat cells (adipose tissue) - Subcutaneous - Lies deep to the the dermis, but→ not a true structureof the integument - Composed mostly of adipose tissue - Important functions: - 1) Storage:easy-to-access energy source for the body - Short on glucose can pull from adipose to make ATP - 2) Protection/shock absorption:prevents physical trauma to internal organs - 3) Insulation: prevents excessive heat loss - Serves thermal regulation function - 4) Anchor:holds skin to underlying muscle tissue - Is still flexible!! - Epidermis - Cell types found in the epidermis - 1) Keratinocytes:produce keratin protein - Keratin is a dry protein - why our skin is dry - Keratin is a tough protein - why our skin is tough - Linked by desmosomes (with some tight junctions) - Helps with preventing water loss - Reproduce mitotically in response toepidermal growthfactor - Keep some of thekeratinocytes active - Reproduce from the bottom up - Millions of cells lost/day→ we “grow” new epidermisevery 25-45 days - Persistent friction in certain areas of body =callusformation - Function:gives epidermis its protective qualities(tough & dry) - 2) Melanocytes - Containmelanosomes - Producemelaninpigment, which istransferred to keratinocytes - Melanin migrates to the “sunny side” of keratinocytes - Which protects nucleus from sunlight - Melanocytes don’t keep the melanin they produce, they ship it off to keratinocytes - 3) Dendritic cells (Langerhans cells) - Immune system cells - Move to epidermis from bone marrow - “Presenting” cells→ patrols the integument - If it comes in contact with some type of pathogen, it will bund to it and show it to other immune cells and tell them to kill off this pathogen if they see it - 4) Tactile cells (Merkel cells) - Present in epidermal - dermal junction - Tactile - in reference to touch - Associated with nerve endings→ sensory receptor function - **can perceive light touch and vibration - Layers of the Epidermis - 1) Statum Basale(base layer): innermost layer - Simple layer of stem cells attached to dermis (single layer) - Rapid division of cells seen here - Regenerates from the bottom up, helps maintain the thickness of skin - Composedmostly of keratinocytes - 10-25%of cells aremelanocytes - 2) Stratum Spinosum(spiny layer) - Stratified layer - Cells look spiny - Cells containpre-keratinprotein→ thick bundlesof filaments that resist tension - Pre-keratin not as strong as keratin - Dendritic cells are most abundant here - Desmonses here provide stong intercellular adhesion to have resist mechanical stress - 3) Stratum granulosum (granular layer) - Keratinization begins at this layer - Accumulation of two granule types in cells of this layer - Kertohyaline:helps with the formation of keratinin the upper layers of epidermis - responsible for binding keratin together to make tissue stronger - Lamellar granules:contains water- resistant glycolipid - lycolipids help prevent water loss from the skin (prevents G dehydration) - Cells here are especially tough, and water resistant - 4) Stratum lucidum(cell layer) - Cells at this layer arenot living - Avascular, rely on diffusion from underlying tissues to keep them alive - Dead but still joined together, preventing them from falling apart - Not found in thin skin - Skin on fingertips - 5) Stratum corneum(horny layer): outermost layer(30-40 layers) - Cells here are not living - Makes up most of the epidermal thickness - Heavily keratinized (super tough) - Glycolipids between cells help to waterproof this layer - Keratin inside cells protects from friction/abrasion - Melanin only deposited in the first3 layers - Cells are dead and melanin only needs to protect the outside Dermis - The “hide” of the body - Made up of strong & flexible connective tissue - Fibroblasts & macrophages dominate here - Semifluid matrix - Makes dermis mobile - Fibers are abundant here - 2 layers make up the dermis: - 1) Papillary dermis - Thin areolar connective tissue - Fibers are thine so defensive cells can wander freely here - The papillary dermis forms peaks and valleys - Has projections calleddermal papillae - Can have pain receptors or tactile corpuscles (sensory receptors) - Projections indent the overlaying epidermis→ formsfriction ridges - Genetically determined feature→ fingerprint - 2) Reticular dermis - Lies deep to papillary dermis - Composed of dense irregular connective tissue - Lots of fibers - Formscleavage linesin skin - Not visible externally - Lines formed by alternating dense & less dense regions of fibers - Surgeons will cut parallel to the cleavage lines - Formsflexure linesat/near joints - Also called skin folds - Dermis is tightly anchored at the flexure line - and does not move as easily - Dermis is forced to fold, forming creases that are visible externally - Ex:palms of hands Skin Color - 3 pigments will determine skin color:melanin, carotene,& hemogloblin - 1) Melanin:polymer that comes in two forms (reddishyellow, brownish black) - Synthesized by protein calledtyrosinase - Skin pigment isdependent on amount of melanin producedby melanocytes - Everyone has the same amount of melanocytes - Skin gets darker with exposure to sunlight - Keratinocytes release chemical to activate melanocytes - Tells melanocytes that they are damaged causing more melanin to be produced - 2) Carotene:yellow-orange pigment - accumulation of stratum cornem & adipose tissue - Can be used by body to produce vitamin A→ used forvision, epidermal health - 3) Hemoglobin:pink/red pigment - Oxygenated pigment→ color comes from blood supplyto the dermis - Not a true skin pigment - Substance in blood that carries oxygen to your tissues - Melanin and carotene is darker in color so it can overpower the reddish-pink tint of hemoglobin - Homeostatic Imbalances of Skin Color - Skin color can be affected by genetics, diet, drugs, illness, etc. - Illness:Jaundice(liver failure) - Genetic: Albanism/melanism - Albinism eyes tend to be red because you can only see blood supply - Drugs:Argyria (silver)→ consumption of silver turnsyou blue Skin Appendages - Are structures that are associated with skin (without actually being the skin itself) - 1) Hair (pili) - Grow fromfollicles - Two regions of a hair: - 1)Root:part of hair embedded in skin - prevent s hair from being shed or lost - 2) Shaft:part of hair projecting out of skin - Functions: - 1) Sensory structures:nerves associated with hairfollicles - If something brushes against you - 2) Protection:scalp, eye, nose (filters bugs, dirt,etc.) - Protects scalp from sun damage - Consist of dead, hard-keratinized cells - Keratin makes hair tougher - Hair has 3 layers: - A)Medulla:central core composed of large cells andair space - Absent in thin hair - Innermost region - B)Cortex:several layers of flatten cells - Individuals unable to stick to each other well, prevents hair from getting too thick - C) Cuticle:outermost layer that is most heavily keratinized - Cells in layer are stacked like roof shingles - Structures associated with hair: - A)Hair Follicle:Results from fold extending fromepidermal surface into dermis - Each follicle is composed of 3 layers - 1)Peripheral sheath:outermost later composed ofdermis - Gives hair it’s shape - 2) Glassy membrane:“basement membrane” joining the peripheral sheath to the root sheath - Root sheath could potentially turn outwards without a glassy membrane - 3) Root Sheath:innermost later derived from epidermis - B)Root hair plexus (refers to nervous system)foundat base of hair follicle (hair bulb) - Contains nerve ending - Gives hair sensation, allows us to know what’s happening in the external environment - C)Dermal papilla:provides capillaries to hair follicle - You need blood supply in order to have hair growth - D)Arrector pili:smooth muscle cells attached tohair follicle - Contraction pulls hair follicles upright - Is what gives you goosebumps→ no function in humans - Shape and color of hair - Shape of hair is dependent on hair follicle shape at skin surface: - Round = straight hair - Oval = wavy/slighty curly - Flattened = very curly/coiled - Color dependent on melanin deposition to cortex (outermost layer) of hair - Heavy deposition = darker hair - Exceptions: - Red hair results frompheomelanin - Gray/white hair: melanin production decreases with age, cortex fills with air bubbles instead - Hair growth - Hair matrix:composed of rapidly dividing cells fromhair bulb of the hair follicle - New cells push oil cells up and out - Most growth is cyclical→ our hair goes through phases - Growth phase: hair making new cells and new cells pushes the old cells up - Resting phase: hair matrix is not active, hair is just sitting in follicle - Shedding phase: hair root physically detaches - Then will go back to growth phase - **all hair is not at the same phase→ or we’d be bald - Types of Hair: - 1) Vellus hair:thin/fine hairs - Amount dependent on age and sex - Infants and children tend to have more vellus - Tend to only find vellus hair in females - 2) Terminal hair:thick/coarse hairs - Typically darker in color than fine hairs - More common on adults, particularly males (beard hair) - Hair loss/balding - Hair thinningis experienced by most people at olderages→ hair loss exceeds hair replacement - True baldnessis usually influenced by the sex chromosomesand genetically determined (“male-pattern baldness”) - Hair follicles respond to androgen hormones differently with time → hair become vellus(thinner) may shed before emergingfrom the follicle - **Males are more likely to be bald because they only have one X chromosome, so they have nothing to buffer it - 2) Nails - Found on distal portions of fingers and toes→ madeup of dead cells - Containhard keratin →what makes them so tough - Composed ofroot, nail plate, free edge - Nail matrix responsible for nail growth - Function:protective covering for distal portionsof fingers and toes, contributes to dexterity Skin Glands - 1) Sweat Glands - Cells in sweat glands aremyoepithelial cells - Myo - muscle → able to contract - Specialized cells that will contract when stimulated - Squeezing sweat to the surface - Secretory cells pull materials needed to produce sweat from blood - Mostly water, but also contains salts, metabolic wastes, etc. - wo types: (both merocrine in the mode of secretion)→ release sweat via T exocytosis - A) Eccrine Glands:especially abundant on palms, solesof feet, forehead - More common, mostly found on your forehead - Simple tubular glands that open directly to skin surface at a pore - Simple coiled tubes - Sweat is mostly water - Function: body temperature regulation, when sweatevaporates it takes heat with it - B) Apocrine Glands:located in axillary (armpit) andanogenital area - Empty into hair follicles, then released to the skin - Eccrine empties straight to skin, apocrine has to be released via hair - Same components as sweat from eccrine glands - Some also have some fatty substances (lipids) & proteins - Function: ??? is unknown - Based on other animals its a sexual sex gland - Modified versions of this gland includeceruminousglands and mammary glands - Ceruminous glands found in ear canals (ear wax) - Prevents insects from crawling into ear - Mammary glands only active and present in females during pregnancy and shortly after birth - Fun fact: where you begin to sweat depends on the circumstance! - 2) Sebaceous glands (oil glands) - Secretessebum(oily substance) - Sebum is largely lipid-based with some cell components and is released to the skin’s surface - Function: - Lubricant for skin/hair - Prevents skin and hair from drying out - Slows water loss from the epidermal surface - Kills bacteria → prevents infection - Homeostatic Imbalance of Skin: - Skin Cancer - Skin exposed to excess amounts of UV light overtime may have some cells become cancerous - This is *the* most common type of cancer - In US→ 9,500 diagnosed with cancer **per day** - 3 major forms of skin cancer - 1) Basal cell carcinoma - Most common form, butleast malignant - Slow-growing, metastasis rarely occurs - Cells in stratum basale proliferate - Found mostly on face, often colorless with “rolled” edges - 2) Squamous cell carcinoma - Second most common - Fast growing - Will usually metastasize if left untreated - Cancer of keratinocytes of stratum spinosum - Appears as flat, a scaly, red lesion on skin - Looks like wound that never heals - Found mostly on head (not facial area) and hands - Behind ears, scalp - 3) Melanoma - Lowest amount of overall skin cancer cases, but causes the most skin-cancer related deaths - Metastasizes quickly & can be chemo-resistant - Early detection is key - Use the ABCD(E) rule - A - asymmetry - difference in color - B - border - any jagged borders - C - color - cancerous moles are brown, black, blue, red, etc. - D - diameter - any spot that is greater than 6mm thats cancer! - E - evolving - rapid change in short period of time, if it changes color/size = abnormal growth - urns B - Types of burns:Refers to exposure caused by heator chemicals - 1) 1st degree burns: painful, reddened skin, inflammation - No scarring/fibrosis involved in health - Skin not actually broken - Ex: sunburn→peeling is from the burned skin butthere is new epidermis under it - 2) 2nd degree burns:pain, redness, fluid pouches(blisters) - Fluid separates the epidermis and underlying dermis - Blister allows a new layer of episdermis to be laid down - Unroofing =peeling blister before it’s ready - Takes longer to heal compared to 1st degree burn - No scarring/fibrosis→ if not picked at - 3) 3rd degree burn:full thickness burns - Haven burnt away epidermis as well as dermis - Lose their glands and sensory fibers in that area so they can’t feel pain there - Treatment usually requires IV fluids, skin grafts, heavy antibiotic use - Fibrosis occurs during healing of burns→ has to occur - ny burn more than 10% is considered critical condition A - Skin graft (epidermis and dermis) doctors don’t want to mismatch thin and thick skin - Ex:extreme heat, severe chemical/radiation exposure - **number one cause of death is dehydaration→ losefluid in body Chapter 6 - Bones and Skelatal Tissuey - Chondr- “cartilage” - Osteo- “bone” Functions of Bones - 1) Support - Holds up the body - Cradles organs→ ex:hip bone - 2) Protection - Central nervous system - The skull protects the brain - Vertebrae wraps around spinal cord - Visceral organs - Rib cage wraps around organs in thorax & upper abdominal cavity - Protects heart and lungs - 3) Attachment point - Skelatal muscles attaches to bone viatendons - Tendons are dense regular tissue - Each time muscle contracts its going to pull a bone which is going to allow movement - 4) Storage - Minerals - calcium and phosphate - Calcium gives bone that hard texture - Fat (adipose tissue) - Yellow marrowin bones of adults - Called yellow because adipose tissue has yellow in it - 5) Blood cell formation - Hematopoiesis →formation of blood cells in red bonemarrow - Includes red and white blood cells as well as platelets - 6) Hormone production - Osteocalcin →regulates insulin release, glucose homeostasis& energy expenditure - End result: increased insulin secretion from the pancreas, improved glucose regulation, enhanced energy expenditure Types of Cartilage - All 3 types of cartilage have 2 basic components - Chief cell type ischondrocyte - Types of cartilage - 1)Hyaline:most abundant type - Chondrocytes are spherical - Contain collagen fibers - Ex:Articular (ends of long bone like knees, hips,elbows), costal (ribs to sternum), respiratory (larynx, trachea, brochi), nasal (nose) - 2)Elastic - Similar to hyaline, but contains more elastic fibers - Ex:external ear, epiglottis - 3)Fibrocartilage - Contain rows of chondrocytes alternating with thick collagen brands - Most compressible, great tensile strength - Ex:vertebral discs, knee, pubic symphysis - Types of Growth - 1)Appositional:laying down new cartilage on oldcartilage - Cells just under perichondrium deposit new matrix on top of “old” cartilage - Occurs atsurfaceof cartilage tissue - 2)Interstitial: “growth from within” - Cells divide and secrete matrix in pre-exisiting cartilage - Occurs throughout cartilage tissue - Bone Tissue - Bone can be classified by location and by shape - 1) Location of bone: - Axial skeleton:makes up long axis of body - Sull, vertebral column, & ribs - Appendicular skeleton:males up limbs (aka appendages)of body & the girdles - Pectoral & pelvic girdles, arms & legs - 2) Shape of bone: - A) Long bones:longer than they are wide - Ex: all limb bones - B) Short bones:cubed shaped - Ex: bones in wrists & ankles - Sesamoid bones:bones that forms in a tendon - C) Flat bones: thin, flat, curved - Ex: sternum, scapula, ribs, most cranial bones - D) Irregular bones:anything that does not fit inan above category - Ex: vertebrae, os coxa (hip bones) - Gross Anatomy of Bone - All bones contain an outer layer of compact bone and inner layer of spongy bone - Compact bone →looks smooth and solid - pongy (trabecular) bone →has open spaces wtih needle-like pieces S of bone calledtrabeculae - Open space is filled with red marrow or yellow marrow - Trabeculae found in greatest concentration along lines of stress - Structure of flat, irregular, & short bone - Thin plate of spongy bone covered by compact bone - No well-defined large cavities for bone marrow - All bone marrow found around trabeculae of spongy bone - Covered externally by bone membrane calledperiosteum - Structure of Long Bones - All long bone share 4 similar features - 1) Diaphysis:bone shaft - Composed of compact bone “collar” with internalmedullary cavity - Medullary cavity filled with yellow marrow in adults - 2) Epiphysis:bone ends - Composed of compact bone externally, spongy bone internally - Forms joint surfaces→ ends are covered with hyalinecartilage - 3) Membranes:periosteum & endosteum - Periosteumcovers external bone surface, except atjoints - Double-layered→ outermost is fibrous, inner layer composed of osteoprogenitor cells - Very well vascularized and innervated - Articular cartilage covers bones at joints - Endosteumcovers internal bone surfaces→ trabeculaein spongy bone, cavities in compact bone - Also contain osteoprogenitor cells - 4) Vascularization & innervation - Nutrient arteryandnutrient veinserve diaphysis - Epiphyseal arteryandepiphyseal veinserve epiphyses - Nerves travel with blood vessles - Microscopic Anatomy of Compact Bone(Lamellar Bone) - Osteon:structural unit of compact bone - Function:helps bone withstand pressue/stress - single osteon is composed of several layers (calledlamella)packed A closely together - Collagen fibers run in one direction for a single lamella and opposite direction in adjacent lammella - Bone salts found on and in between fibers→ contributeto hardness and strength - Central Canals:run through center of each osteon - Contain nerve and blood vessels - Perorating canalsconnect nerve/blood supply of marrowcavity to central canal - Interstital lamellae:incomplete lamellae found inbetween complete osteons - Function:fill gaps between osteons - Circumferential lamellae:found just deep of periosteum - Extend completely around diaphysis circumference - Function:prevents twisting of bone - Hematopoietic Tissue: Blood-forming Tissue - Found in both long bones and flat/irregular bones - flat /regular - marrow found between trabeculae - long bones - marrow found in marrow cavity of diaphysis - Red bone marrow(hematopoietic tissue) - In infants→ found in all spongy bone & marrow cavitiesof all diaphyses - In adults→ found around trabeculae of bones of skull,ribs, hips, sternum, clavicles, scapula, vertebrae, heads of femur and humerus - Yellow marrow - In adults→ found in diaphysis of long bones - Contain more fat & less blood supply than red marrow - Can be converted back to red marrow when there is a demand for blood cells Cellular Composition of Bone - 1) Osteoprogenitor (osteogenic) cells →stem cells - Mitotically active→ can maintain osteogenic cellsor differentiate to form osteocytes - Important for maintaining skeletal integrity - 2) Osteoblasts:bone-forming cells→ matrix synthesizingcell responsible for bone growth - Secrete unmineralized matrix(osteoid)that formsbone tissue - Lacks calcium phosphate - Cube-shaped cells→ secrete matrix - Flattened / squamous cells→ inactive - Only secrete matrix until surrounded and will transform into osteocyte - 3) Osteocytes:mature bone cell - Monitor and maintain bone matrix - Respond to mechanical stress on bone and chemical signals (calcium levels) - ften have several projections→ allow for communication & nutrient O exchange - - 4) Osteoclast:bone degrading cells - Portion of cells contacts bone directly - Produce degrading enzyme:collagenase → breaks downbone - Functions:maintains, repairs, and remodels bone - Important function in blood calcium homeostasis Chemical Composition of Bone - Organic:cells and osteoid - Sacrifical bondsin or between collagen moleculesstretch & break easily - Inorganic - Mineral salts→ mostly calcium phosphatepacked around collagen fibers Homeostic Imbalcne of Chemical Composition of Bone - Osteomalacia(adults) &Ricket’s(children)→ bowingknees - Less mineral salts deposited in bone→ bone is weakand soft - Caused by: deficiency of calcium and vitamin D Bone Formation:Ossification - 2 types of ossification - Intramembranous ossification→ within membrane - Endochondral ossification→ within cartilage - Occurs in most bones below the skull - Hyaline cartilage is used as a “blueprint” to form ossified bone - Mesenchymal ‘skelaton’ → cartilage model → bone Bone Growth: Length & Width - Growth in Length:accomplished byinterstitial growth - Increasing volume allows bone to lengthen - Occurs atepipyseal plate:hylaline cartilage foundbetween the epiphysis and diaphysis of a bone - Growth in Width:accomplished byappositional growth - Occurs at same time as bone lengthening Bone Growth & Hormones - Growth Hormone →controls activity at the epiphysealplate - Released byanterior pituitary gland in brain - Hypersecretion →gigantism - Hyposecretion →dwarfism - Sex hormones - Estrogen - Effects shape and growth of bone - Shape of pelvic girdle >90 degrees for birth - High levels of estrogen can→ induce epiphyseal plate closure - Causes growth spurt at puberty - Will close plate earlier in females at age ~18 - Testosterone:more influencing the shape of bone - Hips are more narrow and more square jaw causing mandible to be thicker - Males generally stop growing at age ~21 - Bone Remodeling - Bone deposition(laying down new bone) - Bone resorption(osteoblast activity, break down tissues and recycle parts) - Remodeling helps bone be the strongest - Blood calcium makes bone strong - Importance of bone remodeling - 1) Maintenance of Ca2+ homeostasis - Ca2+ is essential for excitabilty of body cells - without Ca2+ neurons do not fire & muscles do not contract - Skeleton is used to maintain normal calcium levels - 2) Bone Health - mechanical/gravitional forces acting on bone tissue drive bone remodeling→ strengthens bone exactly where it’s needed - Control of Deposition and Resorption: 2 factors involved - 1) Parathyroid hormone (PTH)released in response to decreased Ca2+ levels - Increased PTH will result in more osteoclasts, more bone broken down = more reabsorption - Too high levels of PTH will cause the skeleton to become weak and break - 2) Mechanical stress - Wolff’s Law:bones are strongest where they are under alot of pressure/stress→ due to gravity pulling you down - More trabeculae and thicker compact bone - Weightlifter = thicker bone - Astronauts = very weak bones→ no stress/gravity for months
