Physiology, Health & Exercise

Lesson 4Cardiac OutputResting PulseMeasuring Blood Pressure

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Puzzle

If you have three oranges and you take away two, how many will you have?

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Puzzle- answer

Two. The two you took.

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Cardiac Output (CO)

Volume of blood pumped by each ventricle per minute

Related to heart rate (HR) and stroke volume (SV)

Measured in litres per minute

CO = HR x SV

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Cardiac Output (CO)

Exampleheart rate (HR) = 72bpm stroke volume (SV) = 70mlWhat is the CO?CO = 72 x 70 = 5040ml/min = 5.04l/min

As activity level increases CO also increases

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Average Resting pulse

60-100bpmFitter people have a lower resting pulseE.g. very fit athletes--> 30-40bpmResting pulse decreases with ageAs activity level increases pulse (& Heart rate)

increases

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Activity & CO

Activity Level

HR (bpm) SV (ml) CO (l/min)

Rest 72 70

Mild 100 110

Moderate 120 112

Heavy-highly trained athlete

200 150

Calculate the CO in each case

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Activity & CO

What is the effect on the following as the work load increases Heart rate? Stroke volume?

What is the CO principally due to?

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Blood Pressure (b.p.)

Measure of force of blood against the walls of the arteries

B.p. highest during systolic phase of cardiac cycle

B.p. lowest during diastolic phase of cardiac cycle

Measured using a sphygmomanometer and stethoscope

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Blood Pressure (b.p.)

Measured as raising a column of mercury so units mm Hg.

Reported as 2 numbers So if systolic is 140 mm Hg &

diastolic is 85 mm Hg then:

Systolic

Diastolic

140/85

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Blood Pressure (b.p.)

Systolic b.p. changes during exercise and can reach 200mg Hg

Diastolic b.p. remains approx constant Measured using a sphygmomanometer and

stethoscope

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Blood Pressure (b.p.)

First- reading- Systole -when blood spurts through an artery as the pressure in the artery exceeds the pressure in the cuff

Second reading- Diastole- more air released from cuff- initially sounds are louder, then muffle and disappear as blood flows continuously through the artery

measuring blood pressure

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Blood Pressure (b.p.)

Average healthy person range of values:

140- 10090-60

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Blood Pressure (b.p.)- changes

B.p. increases as age increasesB.p. decreases as age decreasesB.p. increases as heart is overworkingElevated b.p.- hypertension one of the most

common factors in the development of CVD (cardiovascular disease)

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Raised Blood Pressure (b.p.)

Elevated b.p.- increases chance of atherosclerosis occurring

Hypertension- symptom less in early stageshowever if it continues it puts an excessive strain

on the heart & if untreated will cause heart failure