Lab Review

Question 1

What does an increase in metabolic rate require?

Answer 1

Increase in oxygen supply and carbon dioxide removal

Question 2

What is the requirement of metabolic rate being met by?

Answer 2

Increasing both the volume of gas moved in and out of the lungs per minute and the rate of the blood flow (cardiac output) through the systemic circulation

Question 3

What is the highest rate of aerobic muscular work a healthy person?

Answer 3

Depends on the highest rate at which oxygen can be delivered to the active muscle fibres

Question 4

What is the limit of the highest cardiac output which a person can attain?

Answer 4

Ventilation can increase sufficiently to keep arterial blood fully oxygenated, whatever the rate of uptake of oxygen

Question 5

What is Cardiac output?

Answer 5

CO= SV x HR

Question 6

When are increased requirements of gas exchange needed?

Answer 6

When exercising

Question 7

How can VO2 be expressed?

Answer 7

In relative and absolute terms

Question 8

What is Pulse pressure?

Answer 8

Pulse pressure= SBP-DBP

Question 9

What is mean arterial BP?

Answer 9

Mean arterial BP= Diastolic BP + 1/3 Pulse pressure

Question 10

What happens when the aortic valve opens?

Answer 10

The ventricular ejection begins, aortic pressure increases rapidly to a peak value, and then decreases

Question 11

How is part of the energy from the left ventricular contraction stored?

Answer 11

By stretching the elastic components of the aortic walls

Question 12

What is the definition of pulse pressure?

Answer 12

The difference between the maximum (systolic blood pressure, SBP) and minimum (diastolic blood pressure, DBP) blood pressure

Question 13

What is ‘mean pressure’?

Answer 13

Constant pressure which would result in the same total blood flow as arterial pressure waveform actually observed

Question 14

What does the temporary storage of part of the stroke volume serve to do?

Answer 14

During ejection period serves to smooth out the flow of blood in the circulation, so that flow continues during diastole

Question 15

What does the extent of the pressure increase in the arterial system depend on?

Answer 15

Stroke volume which the arteries have to store

The arterial compliance

Question 16

What does compliance mean?

Answer 16

Compliance is a measure of the change in volume for a given change in pressure: the more compliant the arteries are, the more easily are they distended

Question 17

What does arterial compliance depend on?

Answer 17

Physical properties of the arterial wall

Value of the mean arterial pressure

Question 18

What happens to the arterial wall at a higher pressure?

Answer 18

Arterial wall becomes less compliant as it is stretched more

Question 19

What happens to the arteries when the ventricle relaxes and ejection ceases?

Answer 19

The pressure in the arteries is maintained by elastic recoil

Question 20

What happens to the arterial walls in old age?

Answer 20

Lose elasticity and are less compliant

Question 21

What is a given stroke volume likely to produce?

Answer 21

Higher systolic
Lower diastolic
(hence larger pulse pressure in a subject aged 70 compared to age 20)

Question 22

What is a classical sphygmomanometer comprised of?

Answer 22

Valved pump

Inflatable cuff connected to a manometer by flexible tubing

Question 23

What is the standard manometer?

Answer 23

Glass U-tube containing mercury

Question 24

What does a sphygmomanometer measure?

Answer 24

Blood pressure

Question 25

How is blood pressure measured using a sphygmomanometer?

Answer 25

The cuff is wrapped around the upper arm and inflated to a pressure sufficient to squeeze shut the brachial artery, detected by the absence of the brachial pulse
Pressure is then reduced until the pulse reappears; the manometer reading is taken to equal SBP

Question 26

What else is used along side a sphygmomanometer?

Answer 26

By listening with a stethoscope to the sounds produced in the brachial artery during the gradual reduction of cuff pressure, it is possible to identify not only the SBP but also the DBP

Question 27

What are the possible variations between individual BP?

Answer 27

Nervous subjects (sympathetic discharge)
HR and BP could be higher than normal
Seeing own reading may increase sympathetic drive
Resistance peripheral resistance
Resting CO
Medication
Fitting of cuff

Question 28

How much oxygen is in the air room?

Answer 28

21%

Question 29

What is mixed expired gas collected in?

Answer 29

Douglas bag

Question 30

What does a Douglas bag help measure?

Answer 30

Collected over a known period of time and the volume of gas measured to obtain the volume expired per minute and the oxygen content (% volume) in the gas

Question 31

What is heart rate measured by?

Answer 31

Heart rate monitor positioned on the chest wall of subject

Question 32

How is blood pressure measured using an electronic cuff?

Answer 32

At rest with the subject sitting on the bike in the exercising position
Immediately on cessation of the exercise period
After 10 minutes recovery period

Question 33

What does watts equate to?

Answer 33

Watts= Joules/sec

e.g. 100 watts = 100 J/sec = 6000 J/min = 6kJ/min

Question 34

What is found indirectly by measuring the oxygen consumption?

Answer 34

The rate of total energy output during exercise

Question 35

What does increase Ventilation cause?

Answer 35

Increased alveolar PO2, therefore oxygen consumption rises

Question 36

What is the H+ buffered by in the blood?

Answer 36

Bicarbonate forming carbonic acid

Question 37

What are two main drawbacks of the linear extrapolation method?

Answer 37

Assumption 220-age

Assumption that HR and VO2 relationship remains linear as exercise intensifies

Question 38

What is VO2?

Answer 38

Measure of the maximum volume of oxygen that an athlete can use

Question 39

What happens after faster light exercise?

Answer 39

Metabolic recovery takes longer
Repayment of the oxygen debt
HR remains higher for longer in order to help clear the build up of lactate following heavy exercise increased blood flow