Slide 1Slide 2Slide 3Slide 4Terminology -1Terminology - 2Regulation and ControlRegulation and Control Heart RateRegulation and Control Stroke VolumeRegulation and Control Mean Arterial Pressure - 1Regulation and Control Mean Arterial Pressure - 2Slide 12IE 5531IE 553 Engineering of Human WorkDr. Andris FreivaldsClass #22IE 5532IE 553 Engineering of Human WorkDr. Andris FreivaldsClass #22IE 5533Total = 619 TMU = 22.6 secIE 5534Pressure RegulationIE 5535Terminology -1•Heart rate (HR) = #QRS/min•Cardiac output (CO) = volume of blood ejected by ventricle•Stroke volume (SV) = volume of blood ejected by each ventricular beat•Oxygen uptake (VO2) = volume of oxygen extracted from inspired air•Atrio-ventricular difference (AVO2)IE 5536Terminology - 2•Systolic pressure (SP) = max pressure during ventricular ejection•Diastolic pressure (DP) = min pressure before ventricular ejection•Mean arterial pressure (MAP) = ‘average’ pressure•Total peripheral resistance (TPR) = resistance to blood flow, R = kl/r4IE 5537Regulation and ControlGoal: Maintain blood flow or pressure•Heart rate•Stroke volume•Mean arterial pressureIE 5538Regulation and Control Heart Rate1) Sinoatrial (SA) node (internal pacemaker)2) Sympathetic stimulation•Releases norepinephrine: ↑HR, ↑contractility3) Parasympathetic stimulation (vagus)•Releases acetylcholine: ↓HR, ↓contractility4) Circulating epinephrine (adrenal medulla)•Releases epinephrine (EPI): ↑HRIE 5539Regulation and Control Stroke Volume1) Sympathetic stimulation•Releases norepinephrine: ↑HR, ↑contractility2) Starling’s principle•↑ ventricular stretch → ↑ contractionIE 55310Regulation and Control Mean Arterial Pressure - 11) Intrinsic (local) control (autoregulation)•Reactive hyperemia•↑CO2 vasodilates arterioles2) Extrinsic controls•Sympathetic: NORE→α receptors vasoconstrict organ and skeletal muscle (mild) arterioles•Sympathetic: ACH vasodilate skeletal muscle and skin arterioles•Circulating EPI: → β receptors vasodilate skeletal muscle arteriolesIE 55311Regulation and Control Mean Arterial Pressure - 23) Vasomotor center•Excitatory/sympathetic vs.•Inhibitory/parasympathetic4) Barroreceptors•Stretch receptors•Aorta & carotid arteries•Inhibit vasomotor centerIE 55312Control
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