Katie Holloway
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A-Level Biology Mind Map on A2 Level OCR: Communication & Homeostasis, created by Katie Holloway on 20/11/2015.

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Ollie O'Keeffe
Created by Ollie O'Keeffe over 9 years ago
Katie Holloway
Copied by Katie Holloway over 9 years ago
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Secretes steroid hormones e.g. glucocorticoidsCortex (Outer)Secretes catecholamine hormones e.g. adrenaline (when stresed)Medulla (Inner)Secreted when blood glucose is low (e.g. when stressed)Causes cascade of enzymes, that makes glucose more available to cellCatalyses production of cyclic AMP inside cellsActivates adenylate cyclaseGlucose binds to receptors on cell membranesIncreases blood glucoseCardiac muscle contracts faster & w/ more force, increasing heart rateDiaphragm & Intercostals contract w/ more force, increasing rate & depth of breathingVasoconstriction at gut & skin, vasodilation at skeletal muscles, heart and lungsMuscles in broncioles relax, airways widen, deeper breathingGlycogen to glucoseAdrenalineAdrenal glandControl blood glucoseGlycogenolysisGlycerol + amino acidsGluconeogenesisDecrease rate of respiration of glucoseAlpha cells secrete glucagon to increase blood glucoseGlycogenesisIncrease rate of respiration of glucose1. Increased glucose = Increased ATP inside cell2. Increased ATP causes K+ channels to close3. K+ ions build up inside cell membrane. Membrane becomes polarised4. Ca2+ channels open, and Ca2+ diffuses into cell5. Vesicles fuse with cell membrane, insulin is secreted by exocytosisBeta cells secrete INSULINIslets of Langerhans (endocrine)e.g. Amylase breaks down starchLeads to duodenumSecrete digestive enzymes into pancreatic ductAcinar cells (exocrine)PancreasHormonal System & GlandsCold blooded animals e.g. lizardsCan't internally control body temperatureBask in sun to increase heatGo to shade/underground to decrease heatMore active at high temperatureActivity level depends on internal temperature (therefore external temperature)Don't generate much heatVariable metabolic rateEctothermsWarm blooded animals e.g. humansRelatively constant, high metabolic rateHomeostasis used to maintain constant internal temperatureHairs lie flatMore heat lost by radiation as more blood flow to skin surfaceVasodilationHeat evaporates off skinSweatingChange behaviour (e.g. strip)TOO HOTMuscles release more energy from glucose, so heat releasedShiveringLess heat lost by radiationVasoconstrictionAir is a poor conductor of heatForms insulating layer of air above skinHairs become erectLess sweatingAdrenaline & thyroxine increase metabolism, therefore more heat energy releasedHormonesTOO COLDThermoreceptors in hypothalamus detect internal temp.Peripheral thermoreceptors detect external temp.Receives impulses from sensory neurones, sends impulses to effectors via motor neuronesHYPOTHALAMUSEndothermsControl of body temperaureLikely to be inheritedAuto-immune diseaseImmune system attacks Beta cells in pancreasInsulin not produced by bodyCan cause death if untreatedBlood glucose remains high after eatingRegular, controlled injections of insulinStem cells is a possibiltyTreatmentType 1Linked w/ obesityCells don't respond properly to insulin, so cells don't take up glucoseBody doesn't produce enough insulin, or cells don't react to insulinDietExerciseIf diet & exercise not enough, can take glucose lowering tabletsTreatmentType 2More effective than pig insulin, and less likely to be rejected by immune systemCheaper than extracted insulin from pig pancreasLarger quantities can be produced than pig insulinVegetarians may object to use of animalsSome religions object to use of insulin from pigsEthical issuesGM InsulinDiabetesRate at which SAN fires is unconciously controlled by cardiovascular centre in Medulla OblongataDetect blood pressureBaroreceptors (in Aorta, vena cava & carotid arteries)Detect Oxygen level, Carbon dioxide level, & pHChemoreceptors (in aorta, carotid arteries, and MOb.Internal stimuli1. Baroreceptors detect high pressure, send impulses to MOb. via sensory neurones2. MOb. secretes ACh3. ACh binds to receptors on heart, heart rate DECREASESHigh blood pressure1. Chemoreceptors detect stimuli2. MOb. secretes noradrenaline3. Noradrenaline binds to receptors on heart, heart rate INCREASESLow blood OxygenAcetylcholine (ACh)Parasympathetic systemNoradrenalineSympathetic systemControl of Heart RateA2 Level OCR: Communication & HomeostasisDouble click this nodeto edit the textClick and drag this buttonto create a new node