EXSC 224 Unit 3 Practice Assignment Answers will become available the evening prior to the test! Answers Only! Problem Set A: SV = EDV – ESV 123 mL – 57 mL = 66 mL EF% = SV/EDV (66 mL/123 mL) x 100 = 54% Q = HR x SV 72 cpm x 66 mL = 4,752 mL/min MAP = Q x R 90 mmHg = 4752 mL/min x 0.018939 mmHg/mL/min Problem Set B: MAP = DBP + 1/3(SBP – DBP) MAP = 86 mmHg + 1/3(132 mmHg – 86 mmHg) MAP = 101.33 mmHg MAP = Q x R MAP = HR x (ESV-EDV) x R MAP = 62 cpm x (140 – 62 mL/c) x 0.021 mmHg/mL/min MAP = 101.56 mmHG Jane is most likely borderline hypertensive. Problem Set C: Resting: SV = EDV – ESV 153 mL – 72 mL = 81 mL EF% = SV/EDV (81 mL/153 mL) x 100 = 52.9% Q = HR x SV 55 cpm x 81 mL = 4,445 mL/min MAP = Q x R 89.1 mmHg = 4,455 mL/min x 0.02 mmHg/mL/min Exercise: SV = EDV – ESV 173 mL – 65 mL = 108.0 mL EF% = SV/EDV (108 mL/173 mL) x 100 = 62.4% Q = HR x SV 120 cpm x 108 mL = 12,960 mL/min MAP = Q x R 106.17 mmHg = 12,960 mL/min x 0.008192 mmHg/mL/min • Withdraw of PNS and increased SNS activity will increase heart rate and increase contractility due to chronotropic effect. Additionally, SNS activity will raise intracellular calcium and increase number of cross bridges formed. • Radius and Resistance are inversely related, as radius increases resistance decreases. As resistance decreases afterload also decreases. The reduced afterload will increase SV due a lower ESV. • As preload increases EDV increases. The increased EDV increases SV. Furthermore, the increased EDV places a stretch on the ventricular myocardium resulting in greater contractility and reduced ESV.Problem Set D: • Venous return decreases reducing EDV and contractility. SV decreases causing a reduction in Q and MAP. • Baroreceptors detect pressure based on the degree of stretch. The drop in pressure reduces the stretch of the baroreceptors generating fewer action potentials in axon of afferent neurons that influence the cardioacceleratory centers (SNS centers) in the Medulla oblongata. The neurotransmitters secreted by these neurons generate IPSPs in the Medulla. Reduced AP’s decrease the secretion of neurotransmitters resulting in less inhibition of SNS. SNS activity rises to decrease radius via alpha1 receptors causing an increase in R, and will increase HR, contractility, SV, Q and MAP. • RAAS will be activated by altered baroreceptor activity and by the drop in blood pressure detected by the kidneys. Renin secretion will ensue ultimately leading to AngII production causing vasoconstriction (decreased radius) and increased R, while also promoting more SNS activity and water reabsorption via mineral corticoids and ADH. The short and long-term effects raise MAP by causing a rise in R and EDV. Problem Set E: Resting: SV = EDV – ESV 135 mL – 62 mL = 73.0 mL EF% = SV/EDV (73 mL/135 mL) x 100 = 54.1% Q = HR x SV 62 cpm x 73 mL = 4,526mL/min MAP = Q x R 90.5 mmHg = 4526 mL/min x 0.02 mmHg/mL/min Immediate Standing: SV = EDV – ESV 110.5 mL – 62 mL = 48.5 mL EF% = SV/EDV (48.5 mL/110.5 mL) x 100 = 43.9% Q = HR x SV 62 cpm x 48.5 mL = 3,007 mL/min MAP = Q x R 60.14 mmHg = 3,007 mL/min x 0.02 mmHg/mL/min 1-Minute Post Standing: SV = EDV – ESV 110.5 mL – 55 mL = 55.5 mL EF% = SV/EDV (55.5 mL/110.5 mL) x 100 = 50.2% Q = HR x SV 100 cpm x 55.5 mL = 5,550 mL/min MAP = Q x R 120.3 mmHg = 5,550 mL/min x 0.021683 mmHg/mL/min • The decrease in EDV due to a change in body posture (from supine to standing) decreased Q and MAP. • Baroreceptors first RAAS a distant second. • Increased sympathetic activity due to reduced SNS inhibition by Baroreceptors would decrease radius of blood vessels vis alpha1’s, increase HR and contractility by Beta1’s to in R and Q which will increase MAP. • The increase in HR is the most obvious change in autonomic activity suggesting a rise in SNS activity. Problem Set F: • α1 adrenergic receptors are found in the arteries, arterioles, and the veins of the systemic circulatory system minus the coronary arteries. They may also be present in the pulmonary blood vessels, too. (there may be other locations in the body that are not relevant to ourdiscussion topic). Promote smooth muscle contraction (vasoconstriction) when activated and relaxation (vasodilation) when activation is reduced. • β1 adrenergic receptors are located in the SA node, AV Node, and ventricular myocardium (and possibly other locations not relevant to our discussion topic). Promotes a faster change in membrane potential due to movement of Na+ across the membrane that reduces the time to reach threshold and generate an action potential. Also promote greater release of Ca++ into cytosol leading to increase contractility due to increased cross-bridge formation. Greater contractility reduces ESV and increases SV. • β2 adrenergic receptors are located in the coronary blood vessels (and possibly other locations not relevant to our discussion topic). Promote smooth muscle relaxation (vasodilation) when activated and contraction (vasoconstriction) when activation is reduced. • All adrenergic receptors bind the catecholamines. Problem Set G: Before: SV = EDV – ESV 143 mL – 69 mL = 74 mL EF% = SV/EDV (74 mL/143 mL) x 100 = 51.7% Q = HR x SV 85 cpm x 74 mL = 6,290 mL/min MAP = Q x R 100.6 mmHg = 6,290 mL/min x 0.016 mmHg/mL/min Before: SV = EDV – ESV 143 mL – 75 mL = 68 mL EF% = SV/EDV (68 mL/143 mL) x 100 = 47.6% Q = HR x SV 75 cpm x 68 mL = 5,100 mL/min MAP = Q x R 81.6 mmHg = 5,100 mL/min x 0.016 mmHg/mL/min 1. HR decrease with the Beta blocker because of reduced Beta1 stimulation. The reduction in HR reduced contractility through the chronotropic effect. 2. The beta blocker also reduced Beta1 activation in the ventricular myocardium and lead to lower intracellular calcium levels and reduced contractility. 3. The reduced contractility lead to a greater ESV and lower SV. 4. Β-blockers are an inexpensive and effective antihypertensive medication. Problem Set H: Resting: SV = EDV – ESV 143 mL – 62 mL = 81 mL EF% = SV/EDV (81 mL/143 mL) x 100 = 56.6% Q = HR x SV 62 cpm x 81 mL = 5,022 mL/min MAP = Q x R 105.5 mmHg = 5,022 mL/min x 0.021 mmHg/mL/min After: SV = EDV – ESV 140 mL – 62 mL = 78 mL EF% = SV/EDV (78 mL/140 mL) x 100 = 55.7% Q = HR x SV 62 cpm x 78 mL = 4,836 mL/min MAP = Q x R 87 mmHg = 4,836 mL/min x 0.018 mmHg/mL/min • AngII stimulation will reduce blood