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ModuleTitleAutonomic and EndocrineMEDSCI 142 Flying Start

ModuleTitleModule Contents+The endocrine system+Types of hormones+The nervous system -autonomic vs. somatic+Sympathetic vs. Parasympathetic+The alarm and relaxation responseOverview of Autonomic and Endocrine Systems 1

ModuleTitleThe Endocrine System

ModuleTitle+The Hypothalamus controls the pituitary which controls the other endocrine organs such as the adrenal glands+The Hypothalamus also controls the autonomic nervous system +Functions of the hypothalamus include; control of body temperature, thirst, appetite, sleep cycles, sex drive and behavioural patterns+It achieves these functions by controlling the endocrine organs+Endocrine organs secrete hormonesThe HPA axis System

ModuleTitleEndocrine Hormones+Endocrine hormones are secreted from endocrine cells directly into the blood+Endocrine hormones are also known as circulating hormones as they travel in the blood+Endocrine hormones bind to receptors on target cells in distantorgansParacrine Hormones+Paracrine hormones are secreted from paracrine cells and act on localtarget cells by binding to paracrine receptorsHormones

ModuleTitleAutocrine Hormones+Autocrine hormones are released from autocrine cells and act on the cell which they were released from Hormones

ModuleTitleLipid-Soluble Hormones+Lipid soluble hormones are transported in the blood by transport proteins+The hormone may also bind to its receptor in the nucleus+The activated receptor-hormone complex alters gene expression -may upregulate or downregulate the expression of a gene+Must have receptors specific for the hormone+E.

g. Steroid and Thyroid hormones+SLOW!

ModuleTitleWater-Soluble Hormones+This is a much fastermechanism than for lipid soluble hormones as it is enzymedependent+Phosphorylated proteins produce physiological responses+E.g. Catecholamines, peptides and proteins

ModuleTitle+The cholera toxin irreversibly binds to a G protein thus permanently activates adenyl cyclase+This causes an increase in cAMP+Increased cAMP causes Cl-ions to enter the intestines generating an osmotic gradient so water is drawn out into the gut +Results in chronic diarrheaCholera

ModuleTitleThe Autonomic Nervous System

ModuleTitle

ModuleTitle+Bothmyelinated and unmyelinated neurons are associated with Schwaancells surrounding their axons BUT unmyelinated neurons do not have a multilayered myelin sheathNeuron Structure

ModuleTitleSynaptic Transmission

ModuleTitleThe Autonomic Nervous System (ANS) is the part of the nervous system responsible for the control of internal bodily functions and is self-governingThere are 2 divisions of the ANS -the sympatheticand parasympatheticnervous systemsSympathetic Nervous System+Is associated with the alarmor fight-or-flightresponseParasympathetic Nervous System+Is associated with the relaxationresponseThe Autonomic Nervous System

ModuleTitleAlarm Response +Increased BP and water retention+IncreasedBloodsugar+IncreasedHRandforceofcontraction+Increased secretion from sweat glands and contraction of arrector pillimuscles+Dilation of pupils+Dilation ofbrochi+Decreasedsalivation+Decreaseddigestion+Mediated by the SympatheticNervous System

ModuleTitleRelaxation Response +Dilation of peripheral blood vessels+Constriction ofbronchi+Contraction of pupils+Increased salivation+Increased digestion+Decreased HRandforce of contraction+Mediated by the ParasympatheticNervous System

ModuleTitleSomatic andAutonomic Nerves Autonomic Pathway+Preganglionic neurons are myelinatedand cholinergic(release Acetylcholine) onto nicotinicreceptors at the autonomic ganglion+Postganglionicneurons are unmyelinated and release Acetylcholine or NoradrenalineSomatic Pathway+Somatic motor neurons are myelinated, cholinergicand innervate skeletal muscle

ModuleTitlePathways only differ in their postganglionic neuronsSympathetic Pathway+The postganglionic nerve is adrenergicand releases Norepinephrineonto adrenergic receptors on all effector cells except sweat glands+The postganglionic nerve to sweat glands is cholinergic and releases Acetylcholineonto muscarinic receptors on sweat glandsParasympathetic Pathway+The postganglionic nerve is cholinergicand releases Acetylcholineonto muscarinic receptors on all effector cellsSympathetic and Parasympathetic Pathways

ModuleTitle+RaynaudDisease is caused by difficulty turning down sympathetic responses+Often triggered by cold temperatures +Causedby vasoconstriction of peripheral blood vessels+Resultsinextremitiesturningwhite due to ischaemiaRaynaud Disease

ModuleTitleDrawadiagramshowingthe differences between the sympathetic and parasympathetic nerve pathwaysMake sure to include the neurotransmitter, type of receptor and whether the nerve is myelinated or unmyelinatedList the 6 steps involved in synaptic transmissionPractice Questions

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