PBL 5

Question 1

Pa02

Answer 1

this is the pulmonary arterial tension, it is a measure of partial pressure of oxygen and is a measure of the oxygen in the arterial blood

Question 2

Vo2max

Answer 2

this is the maximal oxygen uptake, this is usually seen in intense exercise

Question 3

ergospirometery

Answer 3

this is a procedure that is done which measures the respiration and gas metabolism during exercise

Question 4

hydrotherapy

Answer 4

this is exercising in a pool in order to treat certain conditions

Question 5

SpO2

Answer 5

this is the amount of oxygen that is present in the blood, it is the amount of oxygen that is joined to haemoglobin to form oxyhaemoglobin

Question 6

what is the primary function of the airways

Answer 6

gas exchange

Question 7

how does diffusion of oxygen and carbon dioxide occur

Answer 7

• occurs passively

Question 8

what happens when the subject lines supine to blood flow in the lung

Answer 8

apical blood flow increases, whereas blood flow to the basal zone remains mostly unchanged

Question 9

what happens on mild exercise to blood flow in the lungs

Answer 9

both upper and lower zone blood flows increase, and the regional differences become less

Question 10

what are the 3 sections of the lungs

Answer 10

apex
middle
base

Question 11

what is pulmonary blood pressure

Answer 11

15mmHg

Question 12

what does a low pulmonary blood pressure mean

Answer 12

it means that gravity has a larger effect on the blood and where it goes, this means that the blood travels towards the base of the heart therefore there is higher perfusion of the lungs in the base rather than in the apex where there is a lower blood supply

Question 13

describe the apices of the lungs

Answer 13

• In the apices of lung there is higher alveolar pressure than capillary pressure, this causes the capillaries to be squished and therefore there is a lack of blood supply, this only happens during expiration when alveolar pressure is at its greatest therefore during inspiration there is some flow to the apices of the lungs

Question 14

what happens in the middle section of the lung

Answer 14

• In the middle section of the lung the flow of blood is pulsatile therefore the ventilation and perfusion relationship vary, for example when the person is inspiring the capillary pressure is greater than the alveolar pressure so there is more influx of blood, when the person is expiring the alveolar pressure is greater than the capillary pressure therefore there is less flow of blood. Pulsatile means that it varies when breathing

Question 15

what happens in the base of the lung

Answer 15

• At the base of the lungs the blood flow is continuous therefore the capillary pressure is higher that the alveolar pressure this is where the gas exchange takes place at the greatest

Question 16

what is the perfusion pressure at the base of the lung equal to when a person is standing upright

Answer 16

• When the person is standing upright the perfusion pressure at the base of the lung is equal to the mean pulmonary arterial pressure + hydrostatic pressure between pulmonary artery and lung bases

Question 17

what is the V/Q ratio

Answer 17

this is the ratio of the gas flow compared to blood flow

Question 18

what is the V/Q ratio in the apices

Answer 18

• The V/Q is greater than 1 in the apices when the gas flow is greater than blood flow

Question 19

what is the V/Q ratio in the base

Answer 19

• The V/Q ratio is less than 1 in the bases when the blood flow is greater than gas flow

Question 20

describe the V/Q ratio graph

Answer 20

On this graph it shows at the base of the lung that blood flow and ventilation are both higher at the base this shows that at the base of the lung is where the maximum amount of gas exhcnage that takes place
This graph also shows that blood flow decreases more steeply as we get towards the apex of the lungs and how the ventilation becomes more predominant
The V/Q ratio line shows that the base of the lung has a V/Q ratio less than 1 whereas the apex of the lungs has a V/Q ratio greater than 1

Question 21

describe air flow and how it enters the body

Answer 21

• Air flows in through the nose, then goes through the larynx and in the trachea and then into the lungs through the bronchi

Question 22

describe ventilation and chemoreceptors

Answer 22

• When you exercise you need more oxygen in order to supply the muscles for aerobic respiration and carbon dioxide needs to be removed
• In the initial stage of exercise ventilation has a steep rapid increase then there is more gradual increase over time
• As you exercise you increase the amount of carbon dioxide in the blood, this decreases the blood pH and the CSF pH (as carbon dioxide can pass through the blood brain barrier into the CSF and breakdown into hydrogen ions) this is sensed by central chemoreceptors that are on the ventral surface of the medulla, this forms a feedback loop responding to the lowering of the pH and causes the ventilation rate in the lungs to increase in order to get rid of the excess carbon dioxide therefore increasing the pH making the blood less acidic, this is why ventilation increases during exercise (6)
• The main drive which causes ventilation to increase is hypercapnia
• Peripheral chemoreceptors have a faster response to a lowering of pH in the blood but central chemoreceptors are the ones that are mainly used
• The decreased pH shift shte oxygen haemoglobin curve to the right, this allows it to get rid of oxygen more easily for the muscles that are respiring and pick up carbon dioxide and get rid of it easily

Question 23

describe perfusion

Answer 23

• Cardiac output increases during exercise in order to pump more oxygen around the body to increase oxygen input to the muscles for aerobic respiration
• Pulmonary output therefore has to equal the output to the systemic system meaning that pulmonary output increases but it does not do this by increasing the pulmonary arterial pressure.
• Pulmonary arteries are thinner than the aorta therefore when the right ventirlce starts to pump out more blood during exercise they easily distend which generates a reflex relaxation of the arterial smooth muscle therefore the vessel dilate and enlarge which reduces the vascular resistance
• There is increased ventilation that occurs at the start of exercise and increases the saturation of oxygen in the alveoli this causes dilation to happen even further thus reducing vascular resistance and increasing flow
• There are also atrerio-venous shunts that are open in the lungs which allow blood to go directly into the pulmonary veins
• The increase in cardiac output is directly proportional to the increase in oxygen consumption (6)
• Heart beat and stroke volume constitute to the rise in cardiac output (6)
• During exercise more blood flows to the apex of the lung (7)
• There is increased blood flow
• Dilation of the pulmonary arteries happens

Question 24

How does exercise effect ventilation

Answer 24

• ventilation might increase from resting values of around 5–6 litre/min to >100 litre/min.
• The increase in pulmonary ventilation is attributable to a combination of increases in tidal volume and respiratory rate and closely matches the increase in oxygen uptake and carbon dioxide output.
• Oxygen consumption:
• As work rate is increased, oxygen uptake increases. However, there is an upper limit to oxygen uptake and, therefore, above a certain work rate oxygen consumption reaches a plateau. This is termed the maximal oxygen uptake (VO2max).

Question 25

How does exercise effect circulation

Answer 25

* The cardiac output is increased by both a rise in the heart rate and the stroke volume attributable to a more complete emptying of the heart by a forcible systolic contraction. * The increase in heart rate is also mediated by vagal inhibition and is sustained by autonomic sympathetic responses. * The efficacy of systolic contraction is particularly important in trained athletes who can achieve significant increases in cardiac output as a consequence of hypertrophy of cardiac muscle. Increased maximal cardiac output in endurance trained athletes is a function of greater stroke volume rather than an increase in maximal heart rate, which is, in fact, lower in these athletes. * Oxygen utilization by the body can never be more than the rate at which the cardiovascular system can transport oxygen to the tissues.

Question 26

what happens to the VQ ratio when exercising

Answer 26

- Iight exercise improves V/Q ratio (7) | - Heavy exercise results in V/Q inequality

Question 27

what does the 3 west zone model state

Answer 27

- The lung is structured into 3 sections according to the west 3 zone model, these are the apices, the middle and the base (or zone 1, 2, 3) This states that - Apices have an intermittent flow – this means that blood flow occurs at certain periods - Middle section is pulsatile this means that it varies with breathing - Base is continuous blood flow

Question 28

what happens to exercise in elite atheletes

Answer 28

* Exercise increases the amount of O2 extracted from arterial blood in the systemic circulation, * Therefore, more O2 needs to be taken up in the lung * Exercise also increases pulmonary blood flow, * The combined effect is that more O2 needs to be taken up in less time. At very high cardiac outputs, the transit time might be too short for complete equilibration between PAO2 and PecO2 (ec = end capillary). * This represents diffusion limitation as a cause of hypoxaemia in athletes achieving extremely high cardiac output. * Recovery: * Physiotherapy through movement and exercise to help improve mobility and function. * exercises carried out in warm, shallow water (hydrotherapy or aquatic * therapy)