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1、PHAR306/PHSC466 Lecture Notes Spring 2008 Page 27 of 111PHAR 306 / PHSC 466 - Anatomy and Physiology - Spring 2008Lecture NotesUnit ICardiovascular System: Blood and HeartUnit IICardiovascular System: Circulation, Regulation and PathologyUnit III Urinary SystemUnit IVRespiratory and Digestive System
2、sUnit VEndocrine and Reproductive Systems, Human DevelopmentUNITS I & IIOverview of cardiovascular physiologyIntrinsic regulationHeart: autorhythmicity of the SA nodeBlood vessel autoregulation: local vasoconstrictor and vasodilator signals (paracrine/autacoid)Extrinsic regulationNervous SystemCNS I
3、ntegration: Cardiovascular center in medulla oblongataAfferent (sensory) signals: from baroreceptors and chemoreceptorsEfferent (motor) signals: via sympathetic and parasympathetic pathwaysEndocrine systemKidneys and adrenal glands: Renin/Angiotensin/Aldosterone system (RAA)Heart: Atrial Natriuretic
4、 Peptide (ANP)Hemodynamics: MAP = CO x TPRTPR is regulated by changing the diameter of arterioles. sympathetic tone arteriolar vasoconstriction via a1 adrenergic receptors TPRPoiseuilles Law: R is proportional to 1/r4small changes in radius produce large changes in resistancemajor exception - smooth
5、 muscle of blood vessels supplying skeletal muscle epinephrine via b2* adrenergic receptors causes vasodilation ACh from cholinergic postganglionic sympathetic fibers causes vasodilation* receptor specificity, simplified: a1, b1 adrenergic receptors - norepi and epi b2 adrenergic receptors - only ep
6、i Cardiac output and venous return CO = venous returnCO is proportional to metabolismCO = HR x sv (heart rate x stroke volume)ANS regulation of HRnorepinephrine and epinephrine via b1 adrenergic receptors HRacetylcholine via muscarinic cholinergic receptors HRRegulation of svsv can be increased by p
7、reload contractility afterloadPreload (the load contained by the ventricles just before contraction starts) (end diastolic volume = EDV, stretch and Starlings Law)The heart pumps what it gets; therefore, the heart will pump more when it gets more bloodto increase preload: venous return Typically:flu
8、id retention by kidneys blood volume Psf venous return sympathetic tone venous vasoconstriction (a1 adrenergic receptors) Psf venous return Contractility increased by positive inotropic agents ( cytosolic Ca+ in muscle fibers)e.g., norepinephrine and epinephrine via b1 adrenergic receptorshypertroph
9、y of myocardium ( muscle mass)Afterloadafterload = the load the heart has to contend with after contraction startsthe load that cardiac muscle fibers must overcome before they can begin to shorten,before the heart can eject bloodMajor causes of afterloadhigh TPR / high MAP high local resistance: e.g
10、., aortic stenosisSee the last PowerPoint slide in the first lesson for Katzungs summary diagram of cardiovascular regulation.Unit ICardiovascular System: Blood and Heart Review of Autonomic nervous system (ANS)I.Autonomic vs. SomaticII.Sympathetic and Parasympathetic DivisionsA.FunctionsB.Nerve pat
11、hwaysIII.Major neurotransmittersA.AcetylcholineB.NorepinephrineIV.Fiber typesV.Receptor typesVI.Regulation of Autonomic FunctionAutonomic reflexesvisceral reflex arc similar to somatic: sensory input from viscera via posterior root, motor output via anterior rootSomatic - 1 motor neuron from spinal
12、cord effector tissue: skeletal muscleAutonomic - 2 motor neuronspreganglionic (synapse at ganglia) postganglionic effector tissues: cardiac muscle, smooth muscle, glands2 autonomic divisions : Sympathetic and ParasympatheticSympathetic - thoracolumbar: fight or flight mechanismsmass activation possi
13、blee.g., vasoconstriction and heart rate blood pressure blood flow to muscles blood flow to skin, viscerae.g., glucoseblood (glycogenolysis)Parasympathetic - craniosacral: vegetative functionsno mass activation, individual responsese.g., heart ratee.g., GI activity (secretion and motility)Antagonist
14、ic effects: e.g., heart (BUT, no rule as to which stimulates and which inhibits - pupil)Cooperative effects: sexual functionSympathetic divisionpreganglionic fiber leaves spinal cord via spinal nerves T1 through L2, leaves nerve and travels to a ganglion of sympathetic chain (trunk), and branchesbranches of preganglionic fiber can do any of three thingssynapse in that ganglionascend or descend to another trunk ganglion and synapse therepass through chain to a prevertebral ganglion (celiac, sup. mesenteric and inferior mesenteric ganglia)effects of branching
