794423
Description
Flashcards by sophietevans, updated more than 1 year ago
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Created by sophietevans
over 10 years ago
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| Question | Answer |
| Strenuous exercise can increase cardiac output by how many times the resting level? | 5 or 6 times (from 5L blood pumped/min to 30L blood pumped/ min) |
| In strenuous exercise, how many times can blood flow through a skeletal muscle increase from the resting perfusion? | Up to 25x (from 3.5ml/100g/min to 90ml/100g/min). |
| Complete the equation: Cardiac Output (CO) = | Heart Rate (HR) x Stroke Volume (SV) |
| In acute exercises, what results in increases in heart rate and stroke volume (and therefore cardiac output)? | Sympathetic stimulation of the heart. |
| What is a positive inotropic effect (a result on the heart muscle from increased sympathetic stimulation)? | Increased contractility increasing stroke volume is a positive inotropic effect. (Inotropic = modifying the force or speed of contractility of muscles) |
| What is a positive chronotropic effect (an effect on the heart as a result of increased sympathetic stimulation)? | An increase in heart rate is a positive chronotropic effect. |
| At rest, what percentage of the blood volume is found in the venous circulation (particularly the large/capacitance vessels)? | Up to 75%. |
| What causes venoconstriction during exercise? | Increased sympathetic innervation of the smooth muscle in the veins (very small amount) as well as increasing the skeletal muscle pump and respiratory pump. |
| Other than venoconstriction and the muscular/respiratory pumps, what helps shift blood from the venous side to the arterial side of the circulation? | 'Unimportant' (in exercise) vascular beds such as the splanchnic (abdominal) vascular bed undergoes vasoconstriction to reduce perfusion and shift blood to where oxygen and glucose demands are highest. |
| Describing the relationship between the heart and the circulation in determining blood pressure, complete the equation: Mean Blood Pressure (MBP) = | Cardiac Output (CO) x Total Peripheral Resistance (TPR) |
| Mean Blood Pressure = Cardiac Output x Total Peripheral Resistance. If CO can increase by 500% in strenuous exercise, but MBP may only increase by less than 50%, and there is vasoconstriction and more blood shifted to the arterial circulation...how is it that TPR does not increase but must in fact decrease for MBP = CO x TPR to be true> | Despite the vasoconstriction in the 'unimportant' vascular beds (e.g. the splanchnic vascular bed) and in the capacitance vessels (which barely increases resistance given their size), there is such a large amount of vasodilation in the skeletal muscle beds that require perfusion that the minor increases in TPR are greatly offset. |
| As a generalisation, systolic pressure can be viewed as dependent on... | ...the contractile activity of the heart (the greater the stroke volume, the greater the volume of blood being pumped into the large arteries and the greater the pressure generated as the blood 'stretches' those large arteries. |
| Generally, diastolic pressure is determined by... | ...the elastic recoil of the arteries while the heart is relaxed (to maintain pressure and propagation of blood throughout the circulation). |
| At which intervals were measurements for blood pressure and heart rate taken? | Initial rest, after three minutes of rest, after six minutes of rest, and after nine minutes of rest. Then at 0 minutes exercising (50rpm against 1kg), at 3 minutes exercising (50rpm against 1kg), at 6 minutes exercising (50rpm against 1kg), and at 9 minutes exercising (50rpm against 1kg). THEN A 3 MINUTE REST IN BETWEEN ROUTINES. Then at 0 minutes exercising (50rpm against 2kg), at 3 minutes exercising (50 rpm against 2kg), at 6 minutes exercising (50rpm againgst 2kg), and at 9 minutes exercising (50rpm against 2kg). |
| What equipment was required for this lab? | A bicycle ergometer, 2x 1kg weights, an oscillometric blood pressure monitor and cuff, and a metronome at 50 ticks per minute. |
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