Cardiovascular physiology wrap up lecture completed1.pdf

Cardiovascular physiology Summary of activities for the week Complete the following questions and we will discuss answers in the lecture 1. In skeletal muscle, every muscle fibre must be innervated so it can contract. In cardiac muscle, the intrinsic conduction system does not connect to every car...

Cardiovascular physiology Summary of activities for the week Complete the following questions and we will discuss answers in the lecture 1. In skeletal muscle, every muscle fibre must be innervated so it can contract. In cardiac muscle, the intrinsic conduction system does not connect to every cardiac myocyte. Why is this not necessary? Cells are intercalated and connected by gap junctions, share ions for AP’s 2. Compare and contrast action potentials in cardiac pacemaker tissues versus cardiac muscle Unstable RMP (Na leakage channels) Plateau phase (Ca in K out) Slow Ca channels Stable RMP http://www.pathophys.org/physiology-of-cardiac-conductionand-contractility/ Fast Ca channels Sequence of ion movements in events similar: Sodium in, calcium in, potassium out 3. Explain the events occurring in the heart during the following phases of an ECG recorded on Lead II A. The P wave B. The QRS complex C. The T wave 4. Explain what will happen to an ECG in the following events: a. The SA no longer fires and therefor the AV node is the pacemaker No atrial depolarisation Bradycardia 4. Explain what will happen to an ECG in the following events: a. There is a second pacemaker in atrial tissue from ectopic tissue Multiple P waves 4. Explain what will happen to an ECG in the following events: a. There is a second pacemaker in ventricles from ectopic tissue Ventricular waves take over Ventricular tachycardia https://www.mayoclinic.org/diseases-conditions/ventriculartachycardia/symptoms-causes/syc-20355138 • 5. Compare pressures in the pulmonary vein, the left atrium, the left ventricle and the aorta in the following phases of the cardiac cycle: • Passive ventricular filling • Atrial contraction • Isovolumetric ventricular contraction • Ventricular ejection • Isovolumetric ventricular relaxation Phase 1 passive ventricular filling • Pulmonary vein pressure: highest atrium • Atria pressure: lower than Pul vein, higher than ventricle ventricle AV valves open • Ventricular pressure very low (lower than atria) Semilunar valves closed • Aorta: high but decreasing (higher than other vessels/chambers) Atrial contraction • Pulmonary vein pressure: lower than atria atrium • Atria pressure: higher than ventricle (and pul vein) ventricle AV valves open Semilunar valves closed • Ventricular pressure very low (lower than atria) • Aorta: high but decreasing (higher than other vessels/chambers) Isovolumetric contraction ventricle • Pulmonary vein pressure: lower than atria • Atria pressure: lower than ventricle (and pul vein) atrium AV valves closed Semilunar valves closed • Ventricular pressure rising (higher than atria, lower than aorta) • Aorta: high but decreasing (higher than other vessels/chambers) Ventricular ejection • Pulmonary vein pressure: lower than atria ventricle • Atria pressure: lower than ventricle (and pul vein) atrium • Ventricular pressure high (higher than atria and aorta) AV valves closed Semilunar valves open • Aorta: increasing but lower than ventricle Isovolumetric relaxation ventricle • Pulmonary vein pressure: lower than atria atrium • Atria pressure: lower than ventricle (and pul vein) AV valves closed • Ventricular decreasing (higher than atria lower than aorta) Semilunar valves closed • Aorta: higher than ventricle • 6. Given your answers in 5, explain the following (for healthy individuals) a. Blood doesn’t flow from the aorta into the left ventricle in passive ventricular filling SL valves closed a. Blood doesn’t flow from the ventricles back into the atria during isovolumetric ventricular contraction AV valves closed a. Blood doesn’t flow from the left ventricle back into atria during isovolumetric ventricular contraction AV valves closed a. Blood can flow from the left ventricle into the aorta during ventricular ejection SL valves open a. Blood doesn’t flow into the left ventricle from the left atrium or the aorta during isovolumetric ventricular relaxation Both SL and AV valves closed • 7. Explain the what will happen to stroke volume if the following occur: a. b. c. d. A End diastolic volume increases B End systolic volume increases Preload increases increases Afterload increases decreases Increases decreases Stroke volume • Amount of blood pumped out of the ventricle in 1 beat (50-120mL) Calculated from the end diastolic volume (EDV) (volume in isovolumetric contraction) MINUS the end systolic volume (ESV) (volume in isovolumetric relaxation) Of the ventricle • 7. Explain the what will happen to stroke volume if the following occur: a. b. c. d. A End diastolic volume increases B End systolic volume increases Preload increases Afterload increases SV increased SV decreased Frank-Starling Law of the Heart (preload) and arterial pressure (afterload) Stretch on the heart = • More blood in the heart means more stretch on muscle • More stretch = stronger contraction = more blood ejected More pressure in arteries = Higher blood pressure = back pressure on ventricle • More back pressure = less blood out Called afterload • 7. Explain the what will happen to stroke volume if the following occur: a. b. c. d. A End diastolic volume increases SV increased SV decreased B End systolic volume increases Preload increases SV increased Afterload increases SV decreased 8. In terms of heart and arterial physiology what does it mean if: Stroke volume is decreased a. Pulse pressure decreases TPR increased b. Diastolic pressure rises c. Mean arterial pressure rises Overall blood pressure is increased https://www.cvphysiology.com/Blood%20Pressure/BP002 • 9. Explain what effects you would expect in the following circumstances: • Receptors on the aortic arch detect a marked increase in blood pressure • Receptors on the carotid bodies detect a marked decrease in blood pressure Response to low pressure Response to high pressure • 9. Explain what effects you would expect in the following circumstances: • Receptors on the aortic arch detect a marked increase in blood pressure Feedback to brainstem causing Increased output from cardio inhibitory centre – decrease heart rate Decrease output from vasomotor centre - vasodilation • Receptors on the carotid bodies detect a marked decrease in blood pressure Feedback to brainstem causing Decreased output from cardio inhibitory centre –increase HR increased output from cardio accelerator centre - increase HR Decrease output from vasomotor centre - vasoconstriction 10. Predict the relative blood flows in the listed arteries in the following conditions a. Mean aortic pressure is 100mmHg, mean renal artery pressure is 80mmHg, mean hepatic artery pressure is 70mmHg, mean subclavian artery pressure is 90mm Hg Flow into all arteries, but highest into hepatic artery, followed by renal artery and subclavian b. Mean aortic pressure is 90mmHg, mean renal artery pressure is 80mmHg, mean hepatic artery pressure is 90mmHg, mean subclavian artery pressure is 60mm Hg Now highest into subclavian, no flow into hepatic c. For A, how would the body increase overall blood flow into all arteries Increase cardiac output d. For A, how would the body increase blood flow to the liver but decrease blood flow to the kidneys? Vasoconstriction in renal arteries/arterioles Vasodilation in hepatic arteries/arterioles Kahoot • https://create.kahoot.it/share/cardiac-output-and-bloodpressure/4421ac92-f00f-4cd7-8f00-f5af60e6598e