ANP1105 Midterm 2.docx - Topic 3 \u2013 Homeostasis The ability of the body is to maintain relatively stable internal conditions even though there is

ANP1105 Midterm 2.docx - Topic 3 u2013 Homeostasis The...

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Topic 3 – HomeostasisThe ability of the body is to maintain relatively stable internal conditions even though there is continuous change in the outside world (Quote by Walter Cannon)Homeostasisis not unchanging, but rather a dynamic state of equilibrium involving many systems-Adequate blood levels of vital nutrients-Heart activity/blood pressure monitored and adjusted as needed-Wastes must not accumulate-Core body temperature must remain within range3 Essential Characteristicsof a Homeostatic Control Mechanism-ReceptoroSenses change (Stimulus) and sends info (ViaAfferent Pathway) to control center-Control CenteroDetermines set point for variable maintenanceoAnalyzes info and determines correct response-EffectoroProvides means for response (Gives Outputalong Efferent Pathway)oFeedback(Negative or Positive) allows for regulation within a range/enhanced responseNegative Feedback Mechanisms-Output reduces or shuts off stimulus (2 options)o1 hormone or neural pathway regulating a process (Negative feedback decreases secretion)oProcess regulated in opposite directions by 2 different hormones or neural pathways (Ex:Blood glucose)-Goal of negative feedback is to prevent sudden, severe changesPositive Feedback Mechanism-Response of mechanisms enhances original stimulus (Output will be further stimulated)oChange occurs in the same direction as the original response-There is a goal to be attained-Ex: Blood ClottingHomeostatic Imbalance-Most disease seen as a disturbance of homeostasis (A Homeostatic imbalance)
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-Aging is associated with progressive decrease in our ability to maintain homeostasis (Greater riskfor illness)Auto= SelfNom= GovernAutonomic Nervous System (ANS)-A system of motor neurons to smooth and cardiac muscle and glands to allow response usually withoutour awareness-They can shunt blood to more needy areas-They can speed/slow heart and respiratory rates-They adjust blood pressure and body temperature-They can increase or decrease gastric secretionsEffectors-Somatic = Skeletal Muscle-ANS = Smooth Muscle, Cardiac Muscle, GlandsPathways and Ganglia-SomaticoThick, myelinated axon from spinal cord to skeletal muscleoRapid conduction of impulses (No Ganglia)-ANSo2 neuron chain
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Preganglionic Neuronthat originates in brain or spinal cordTheir axons synapses with 2ndmotor neuron (Postganglionic) in ganglion outside CNSPostganglionic Neuronfound in ganglion outside CNSTheir axons sends signal to effector organ-The conduction is slowoPreganglionic axons are thin and lightly myelinatedoPostganglionic axons are thinner and unmyelinatedParasympathetic Nervous System (PNS)-Active in non-stressful situations (Rest and Digest)-Keeps body’s energy use low while regulating housekeeping activities (Digestion, Excretion)-AKA the D System (Digestion, Defecation, Diuresis) Sympathetic Nervous System (SNS)-Fight or flight systemoAlso important during exercise (Increases hear rate, Gives rapid and deep breathing, Cold sweaty skin, and dilated eye pupils)-AKA the
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