Homeostasis

network of nerve cells that send signals and nerve impulses b/w parts of the body

components:skull brain's armourmeninges tissue surrounding the brain and spinal corddura matter - outerarachnoid matter - middlepia matter - innerblood brain barriermade by glial cells, blood vesselsseparate NS and bloodprotect brain from bad subs and toxinsoxygen and glucose can passcerebrospinal fluidfrom blood plasma, in brain ventricles, central canal of sctransport nutrients,white blood cells, nutrients across bbbshock absorptionspinal cordbundle of nervessend messages b/w brain and bodysensory neurons carry info towards (dorsal root)motor neurons carry info away (ventral root)protected by meninges, CSF, and vertebraeinterneurons in nerve tracts - connect sc and brain

hindbraincerebellum Limb movements, balance, fine motor skills, reflexes ponspass info b/w neurons of L and R of brainmedulla oblongatajoins the spinal cord to the cerebellumjoin PNS and CNSco‐coordinate autonomic nervous system/homeostasis (heart rate, dilation of blood vessels, breathing)mid brainprocess/relay sensory info from neurons-> eyes -> nose -> forebrain and hindbrainforebrainthalamusneurons that connect parts of brain"relay station"hypothalamusneurons that control BP, HR, body temperatures, thirst, hunger, emotions link nervous and endocrine system, coordinate actions of pit gland -> hormone release"control center of homeostasis"cerebrumfrontal lobe - integrate info from parts of braintemporal lobe - process visual info, auditory receptionparietal love - recieve/process sensory info from skinoccipital love - receive/analyze visual info

somatic systemconsious controlsensory neurons carry info from external environment (receptors)motor neurons carry info to skeletal musclesautonomic systemunconsious controlneurons control glandular secretions, cardiac muscle, smooth musclemaintains homeostasis, adjust variablescontrolled by hypothalamus and medulla oblongatasympathetic nervous systemactivated in stressful situation - fight or flightrelease norepinephrineexcitatory on musclesincrease BP, HR,slow digestion, constrict bladderparasympathetic nervous systemactivated when body is calm - rest and digestrelease acetylcholineslows HR, reduce BP, promote food digestion

neurons:unit of NSorganized tissues= nervesglial cells:structurenourishmentwaste removalprotect against infectiondendritesrecieve info from sensory or motor neuronsaxon and terminalscarry nerve impulses away from cell body -> neuronsmyelin sheathprotect axonsspeed up rate of nerve impulseschwann cellstype of glial cell, makes myelin sheathnodes of ranviergaps b/w myelin sheathnerve impulses jump, node -> nodeneurilemmamem surrounding schwann cellsregenerate damaged axonsin white mattergrey matter does have myelin sheath or neurilemmadoesn't regenerateMULTIPLE SCLEROSISmyelin sheath's mem wraps around axon is destroyed by infalmmation and scarring

receptor -> sensory neuron -> interneuron in the spinal cord -> the motor neuron -> effector heat detected -> sensory neurons carries nerve impulse -> interneuron sends signal to motor neuron -> motor neuron takes signal, sends to effector -> hand contracts from heat

action potential:rapid change in polarity across a membrane as nerve impulse occursresting mem potential resting neuron (-70mV)inside cell is - , outside cell is +3 NA+ leave, 2 K+ come inuse NA+/K+ pump to maintainrising action potentialthreshold potential (-50mV)depolarizationNA+ channels open, K+ channels closeNA+ down conc grad, comes into cellinside of cell is +fall action potentialcell reached +40mVrepolarizationNA+ channels close, K+ channels openK+ move down conc grad, leave axon by diffusionmem is -hyperpolarizationK+ keeps leaving until mem potential is more - than resting potential-90mVK+ channels closerefractory periodNA+ and K+ channels closedresting mem pot. -70mV by the pump and diffusionmem cant undergo another action potentialstops signals from travleling backwards

b/w two neurons or b/w neuron and muscle/gland (effector)neurotransmitterscarry neural signal neuron -> neuronchem messenger secreted by neuron to carry the signalexcite or inhibtDopamine, Seratonin, Endorphins, Norepinephrineexcitatoryion channels OPENNA+ INmem is depolarizedinhibitoryion channels CLOSEK+ OUTmem is hyper polarized (-)       

separating wastes from body fluids, eliminate from the bodybody makes toxic by productsureafrom protein breakdownuric acidfrom DNA, RNA breakdownurineflitrate of nephron, collecting duct -> urethraextra glucose, penicillin, creatine (metabolized)excretion of metabolic wastes N-containing waste ammonia, urea, uric acidmaintenance water-salt balanceblood volume is related to salt balance of the bodyBPIons level of potassium (K+), bicarbonate (HCO3–), and calcium (Ca2+) in bloodmaintenance of acid-base balance monitor blood pH - 7.4excrete H+ ions, reabsorb bicarb ions (HCO3-)secretion of hormones calcitriol active Vit D formpromote calcium (Ca2+) absorption from the digestive tract erythropoietin stimulate red blood cell productionreleased in response to increased oxygen demand OR reduced oxygen-carrying capacity of the bloodreninlead to aldosterone hormone secretion from adrenal cortexorgans of systemkidneyfilter waste from bloodureterstubes conduction urine, kidney -> bladderbladderstore urineurethracarry urine to body's exterior

cortexouter, composed ofmedullamiddlerenal pelvisjoin kidney and ureterblood supplyrenal arteryblood TO kidneyrenal veinblood AWAY FROM kidneyarcuate veinsurround medullainterlobular vein

filtration:blood pass through glomerulus walls permeable to water, urea, glucose, aa, ionspass into bowman'slarge mols and blood too large to filter, stay in bloodbowmans capsule surrounds glomerulushigh pressure in affarent arteriolepush ions, waste, glucose OUT of capillaries, INTO capsuletubular reabsorption: active and passive transport essential mols -> blood nutrients, ions, water move filtrate -> blood “subs move out of nephron and into blood”PCT reabsorb water, glucose, aa, ionsH leavesDescending Loop of Henlepermeable to water, impermeable to saltsalt is in filtratereabsorbs waterAscending Loop of Henlebottom of loop is impermeable to water and saltthin part is permeable to salt, impermeable to waterNA, CL, K is reabsorbedDCTNA, water, - ions, irea is reabsorbedH, K, and ammmonia is secretedCollecting Ductpermeability to water is controlled by anti dieuretic hormonebody conserves waster, ADH on DCT and collecting duct lets water be removed from urine.secretion: solutes added to urine for excretionions wastes, toxins, move blood -> filtrate“substances move from blood back into nephron”

more water intake - more urineless water intake - less urine/more reabsorptionmore water output (sweat) - less urine output/ more reabsorptionless water output - more urine output/less reabsorptionADHreleased by pit gland when hypothalamus detect low water levels in bloodincreases urine reabsorption in DCT & collecting ductcells are more permeable to waterless water leaves, blood water level increasethirst sensationshrinking hypothalamus cells = thirstmore water intakemore water consumed, lower osmotic pressuredilute blood solute conc, hypothalamus cells swell, stop signal for ADHToo little water in bloodDetected by hypothalamus ↑ ADH secreted by pituitaryKidneys absorb less water from bloodless urine producedblood water level back to normalToo much water in bloodDetected by hypothalamus↓ ADH secreted by pituitaryKidneys absorb more water from blooddilute urine producedblood water level back to normal----------------------------------------------------------------------------

pH of body - 7.35 - 7.45buffer systems use bicarb ionscarbonic acid produced, breaks down CO2 and H20CO2 goes to lungs (exhalation)carbonic acid breaks down bicarb ions and H+prevents pH changestarts when CO2 is AT from pertibular capillaries -> cell of nephron, and combines w H2Okidneys excrete H+ and reabsorb HCO3 - in urine, H+ excreted bc its acidicIf blood too acidic -> H+ excreted, H2CO3 reabsorbedIf blood too basic -> H+ not excreted, H2CO3 not reabsorbedmaintain blood pH is important, maintain internal envi, cell enzymes function properly

second messenger system of the bodynervous is firstuse chem messages (hormones) that are released into the bloodendocrinologyorgans that produce chemicalsfunctions:ReproductionGrowth and developmentMobilization of body defensesMaintenance of homeostasisRegulation of metabolismRegulation of stress responseRegulation of blood sugarRegulation of water balanceexocrine glands:release chem subs that target glands via ducts to the surface of the body or body cavitiesimmediate product releasenot part of endocrine systemEX: tear, salivary, sweat, milk glandssendocrine glands:ductless (no tubes) secrete hormones directly in bloodstreamblood hormone conc is lowEX: pituitary, thyroid gland

chem messengers sent to part of body to produce an effect on a cell or organmol that alters cell activitysteroid hormoneslipid based (made from cholesterol)easily diffuse through lipid bilayer of cells, bind to receptors inside the cellproduce a proteinNP molsEX: testosterone, estrogen, cortisolwater soluble hormonesmade from aabind to receptor proteins on target cellcascade of reactions -> increase rate of cell functionP molsEX: epinephrine - trigger glycogen breakdown in liver, thyroxine, insulinhormonal stimuli of endocrine glandsactivated by hormoneshumoral stimuli of endocrine glandschange blood levels of some ions, stimulate hormone releaseneural stimuli of endocrine glandsnerve impulses stimulate hormone releasecontrolled by sympathetic nerv. sys (SNS)

hormone release controlled by release/inhibition hormones by the hypothalamusreleasing hormones stimulate pit. gland to secrete hormones to act on endocrine glandshypothalamus → pituitary → endocrine glandstropic hormones - stimulate endo. glands to release other hormonesnon tropic hormones - no endo. glands as targetanterior pituitary gland - glandular tissueTSH, ACTH, hGH, FSH, LHposterior pituitary gland - nervous tissueADH, oxytocindoesn't produce hormones, hormones are made from hypothal. and transferred to PPG by neurons

Thyroxine hormone (T4)Calcitonin (parathyroid)Parathyroid hormone (PTH)metabolic thermostatDISORDERShyperthyroidismtoo much thyroxineincrease metabolism, appetite, heat productiondecrease weightMuscle weakness, bulging eyes, increased metabolic rate, increased appetite, weight loss, excess heat production, and sweatingMood swings - nervous/hyperactive behaviourTreated by removing a portion of the thyroid (surgically or chemically)hypothyroidismtoo little thyroxinedecrease metabolism, HR, appetitefatiguedincrease weight Lower metabolic rate, decreased heat production, decreased heart rate, weight gain despite loss of appetite, decreased mental capacity, general weakness and fatigue, and poor physical development.Cold, hair loss, weight gain, sleep a lotenlarged thyroid (goiter)iodine needed to make thyroxinenot enough iodine in dietthyroid swells bc of TSH (no thyroxine made)increase thyroid size to try and make thyroxine  

glands - on top of kidneycortexouter of 3 layersaldosteroneregualte salt-water balance, BPtarget organ = kidneyacts on sweat glands, reduce salt loss and taste buds to increase salt intakestimulated by BP changes, NA and K levels in blood, and ACTH of the anterior pit glandcortisone and cortisolraise blood sugar levelpromote cell metabolismanti inflammatory on bodytoo much = autoimmune attackstoo little = central obesity, acne, sore mucles, weaknesssex hormones - testosterone/estrogenminimalmedullainner neural tissue, linked to SNSepinephrine and norepinephrinedeal w/ short term stressnon steroid

islets of the pancreas produce hormonesInsulinallow glucose to enter cells - secreted by beta cellsGlucagonallow glucose to enter the blood - secreted by alpha cellsDiabeteshypoglycemialow blood glucose - increase glucagon or glucosehyperglycemiahigh blood glucose - need insulinType Iinsulin dependentpancreas cant produce insulin bc of beta cell degeneration in isletsautoimmuneType IIinsulin independentdecreased insulin production or ineffective insulin use (resistancesymptoms of type I and IIfatiguenot enough glucose in the cells for energyuse fat and proteinthirst and urinationglucose in urine pulls water by osmosisincrease appetite, weight gain (type I)more risk of infection

gonadsproduce reproductive cells, testes produce sperm, ovary produce eggsex hormoneschem comps control reproductive func and developmentand secondary sex characteristicsfemale

made of:monitor (sensors)detect internal envi. changessend signal to control centercontrol center (integrator)sets range of values for a variable to be maintainedreceive info from sensorssend signals to effectorsregulator (effectors)respond to signals from control centerchange internal variable 

rare in homeostasisstimulus or change detected, set of events to increase/reinforce change in a variablecontractions of childbirth, blood clotting

response reverses a detected change in a variablethermoregulationmaintain body temp within range for cells to function efficiently (37c)ectotherms - fish, amphibianscan't internally regulate tempendotherms - mammals, birdsmaintain internal temp regardless of outside condition