O2/ CO2 exchange and transport

Question 1

What is ventilation?

Answer 1

Ventilation is the process by which air moves in and out of the lungs

Question 2

What is perfusion?

Answer 2

The process by which the cardiovascular system pumps blood throughout the lungs

Question 3

What is the partial pressure of a gas?

Answer 3

The pressure that would be exerted by one of the gases in a mixture if it occuiped the same volume on its own

Question 4

What is the average alveolar partial pressure of O2?

Answer 4

100

Question 5

What is the average alveolar partial pressure of CO2?

Answer 5

40

Question 6

What is the effect of exercise on alveolar ventilation?

Answer 6

Increases the need for oxygen so the overall venous O2 levels drop, this increases the diffusion gradient allowing more O2 to be delivered

Question 7

What ratio gives optimal gas exchange?

Answer 7

the ratio of ventilation to blood flow

Question 8

What are the two main oxygen carrying proteins?

Answer 8

haemoglobin and myoglobin

Question 9

What are some differences between haemoglobin and myoglobin?

Answer 9

Myoglobin is found in vertebrae muscle cells and only has one haem group so it can only carry one oxygen molecule

Question 10

What is left shift?

Answer 10

High ppO2 in the lungs facilitates the binding of oxygen

Question 11

What is right shift?

Answer 11

Low ppO2 facilitates the release of oxygen

Question 12

What factors cause the left shift?

Answer 12

Decreased Temperature, Increased pH, Decreased 2,3 DPG

Question 13

What factors cause a right shift?

Answer 13

Increased Temperature, Increased pH, Increased levels of 2,3 DPG (changes the shape of the haemoglobin)

Question 14

What is 2,3 DPG?

Answer 14

A metabolic by product of glycolysis

Question 15

What is carboxyhaemoglobin?

Answer 15

A protein that binds to CO 210x more strongly than it binds to O2

Question 16

What is methahaemoglobin?

Answer 16

A protein where the Iron is in a Fe3+ state rather than Fe2+, can be a result of genetics or drugs

Question 17

What are the three different ways that CO2 can be transported in animals?

Answer 17

Dissolved in plasma, bound to haemoglobin or as a bicarbonate

Question 18

What is the VQ ratio like in quadrapeds?

Answer 18

uniform V/Q

Question 19

What kind of oxygen carrying protein is found in vertebrae muscle cells?

Answer 19

Myoglobin

Question 20

What is diffusion?

Answer 20

The process by which gas is exchanged between the alveoli and the capillaries (spontaneous movement of gases)

Question 21

What are some things that the lungs do during exercise in order to increase the ventilation rate?

Answer 21

The lungs expand to decrease diffusion distance
as the venous O2 is lower the gradient is higher
there will be more capillary recruitment and distension
cardiac output increases by 4-8 fold

Question 22

What factors cause the left shift of the dissociation curve to occur?

Answer 22

High pH
decreased temp
decreased ppCo2
decreased 2,3-diphosphoglycerate

Question 23

What part of the brain contain sthe respiratory centre?

Answer 23

The medulla oblongata

Question 24

When is breath holding possible until?

Answer 24

It is possible until the pCo2 stimulus overrides

Question 25

What is the name of the neurons that initiate inspiration?

Answer 25

pacemaker inspiratory neurons

Question 26

What is the name of the neurons that are responsible for forced contraction?

Answer 26

Expiratory neurons

Question 27

What is the name of the complex that is responsible for the breathing rhythm?

Answer 27

Pre-botzinger complex

Question 28

Where are the peripheral chemoreceptors found?

Answer 28

at the bifurcation point of the carotid bodies (where the common carotid arteries bifurcate)

Question 29

Why is it that chemoreceptors detect arterial CO2 and not H+?

Answer 29

because Co2 can freely diffuse over the blood brain barrier

Question 30

What is the name for low arterial Co2 and what does it do to membranes?

Answer 30

Hypoxia, causes mucous membranes to have a blueish colour

Question 31

What are 5 acclimitisation factors at high altitudes?

Answer 31

1)Increased pulmonary ventilation – the peripheral chemoreceptors are stimulated by low pO2 levels which results in increased ventilation 2) Increased number of RBCs – this is mediated via erythropoietin. Blood volume can increase by about 20-30% as well 3) Increased vascularity in pulmonary capillaries and increased diffusing capacity of lungs – mediated via angiogenesis of new vessels in the lungs and increased pulmonary vessel pressure 4) Increased levels of 2,3-DPG – right shift of HbO2 dissociation curve 5) Increased cellular components - more mitochondria/cell and cellular oxidative enzymes – leads to efficient utilisation of oxygen