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3. Homeostasis (2).docx - 3. Homeostasis Intro to ANS and...

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3. HomeostasisIntro to ANS and Endocrine SystemTABLE OF CONTENTS3.1 Main Characteristics of Homeostasis........................................................................................................................33.1.1 Definition + Examples....................................................................................................................................33.1.2 Three Essential Components of A Homeostatic Control MEchanism...........................................................33.1.3 Positive Vs. Negative Feedback; Homeostatic Imbalance.............................................................................4Negative Feedback.........................................................................................................................................4Positive Feedback...........................................................................................................................................4Homeostatic imbalance:................................................................................................................................43.2 Nervous system.........................................................................................................................................................53.2.1 Autonomic and Somatic Nervous Systems....................................................................................................5Autonomic Nervous System...........................................................................................................................53.2.1.1 Autonomic NS in terms of Effectors, pathways, ganglia, Transmitter Effects....................................53.2.2.1............................................................................................................................................................63.2.2.2 Sympathetic Tone, Parasympathetic Tone.........................................................................................73.2.2.3 Interactions of the Autonomic Divisions............................................................................................7UnIque Roles of Sympathetic NS...................................................................................................................7DIfferences of ANS and PNS...........................................................................................................................83.2.2.4 Levels of Regulation of Autonomic Function.....................................................................................8The Endocrine System....................................................................................................................................93.3.1.1 Hormones..........................................................................................................................................9Mechanism of Hormone Action:....................................................................................................................92 main mechanisms of hormone action:.....................................................................................................10
Half-Life, Onset and Duration of Hormone Activity.....................................................................................11Control of Hormone Release........................................................................................................................12Hormonal Stimulus Example........................................................................................................................12In Summary..................................................................................................................................................13
3.1 MAIN CHARACTERISTICS OF HOMEOSTASIS3.1.1 DEFINITION + EXAMPLESDefinition (Walter Cannon): ability of the body“to maintain relatively stable internal conditions eventhough there is continuous change in the outside world”Dynamic State of Equilibrium in involving the following systems:1.Adequate blood levels of vital nutrientsBlood pH level, blood sugar level, blood sodium level, blood calcium level, levels ofvarious components of blood, blood water content,2.Heart activity/blood pressure monitored & adjusted as neededHeart rate, blood distribution (ex. more to muscles during exercise, more to GI tract aftereating)3.Wastes must not accumulateMonitoring waste levels (CO2, Urea must be excreted)4.Body temperatureMust maintain core body temperature constant (core much more vital than extremitiessuch as fingers)3.1.2 THREE ESSENTIAL COMPONENTS OF A HOMEOSTATIC CONTROL MECHANISM1.Receptor:osensesstimulus(what causeschange)osends info alongafferent pathway(carriesinputto control center)2.Control Centre:odeterminesset point(correct value)forvariable(factor or event beingregulated)oCell or group of cells that knows whatthe parameter should be andstimulates proper adjustmentoAnalyzes info and determines correct response3.Effector:oprovides means forresponse(adjustment, reaction) alongefferent pathway(carries output fromcontrol center)Feedbacktells receptor and thus the control center that a correction to change has been madeNegative: allows for regulation within a rangePositive:allows for enhanced response
3.1.3 POSITIVE VS. NEGATIVE FEEDBACK; HOMEOSTATIC IMBALANCENEGATIVE FEEDBACKGoal:Prevent sudden, severe changesNeed to fix problem and notify control center thatproblem has been resolvedOutput reduces or shuts off stimulus – 2 options:1.one hormone regulating a processnegative feedbackdecreasessecretion2.process regulated in opposite directions by 2different hormones – e.g. blood glucoseEXAMPLE: Control of blood glucose leveloinsulinstimulates movement of glucose into cells

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Term
Fall
Professor
CARNEGIE
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