O2/ CO2 exchange and transport Flashcards
What is ventilation?
Ventilation is the process by which air moves in and out of the lungs
What is perfusion?
The process by which the cardiovascular system pumps blood throughout the lungs
What is the partial pressure of a gas?
The pressure that would be exerted by one of the gases in a mixture if it occuiped the same volume on its own
What is the average alveolar partial pressure of O2?
100
What is the average alveolar partial pressure of CO2?
40
What is the effect of exercise on alveolar ventilation?
Increases the need for oxygen so the overall venous O2 levels drop, this increases the diffusion gradient allowing more O2 to be delivered
What ratio gives optimal gas exchange?
the ratio of ventilation to blood flow
What are the two main oxygen carrying proteins?
haemoglobin and myoglobin
What are some differences between haemoglobin and myoglobin?
Myoglobin is found in vertebrae muscle cells and only has one haem group so it can only carry one oxygen molecule
What is left shift?
High ppO2 in the lungs facilitates the binding of oxygen
What is right shift?
Low ppO2 facilitates the release of oxygen
What factors cause the left shift?
Decreased Temperature, Increased pH, Decreased 2,3 DPG
What factors cause a right shift?
Increased Temperature, Increased pH, Increased levels of 2,3 DPG (changes the shape of the haemoglobin)
What is 2,3 DPG?
A metabolic by product of glycolysis
What is carboxyhaemoglobin?
A protein that binds to CO 210x more strongly than it binds to O2
What is methahaemoglobin?
A protein where the Iron is in a Fe3+ state rather than Fe2+, can be a result of genetics or drugs
What are the three different ways that CO2 can be transported in animals?
Dissolved in plasma, bound to haemoglobin or as a bicarbonate
What is the VQ ratio like in quadrapeds?
uniform V/Q
What kind of oxygen carrying protein is found in vertebrae muscle cells?
Myoglobin
What is diffusion?
The process by which gas is exchanged between the alveoli and the capillaries (spontaneous movement of gases)
What are some things that the lungs do during exercise in order to increase the ventilation rate?
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
What factors cause the left shift of the dissociation curve to occur?
High pH
decreased temp
decreased ppCo2
decreased 2,3-diphosphoglycerate
What part of the brain contain sthe respiratory centre?
The medulla oblongata
When is breath holding possible until?
It is possible until the pCo2 stimulus overrides
What is the name of the neurons that initiate inspiration?
pacemaker inspiratory neurons
What is the name of the neurons that are responsible for forced contraction?
Expiratory neurons
What is the name of the complex that is responsible for the breathing rhythm?
Pre-botzinger complex
Where are the peripheral chemoreceptors found?
at the bifurcation point of the carotid bodies (where the common carotid arteries bifurcate)
Why is it that chemoreceptors detect arterial CO2 and not H+?
because Co2 can freely diffuse over the blood brain barrier
What is the name for low arterial Co2 and what does it do to membranes?
Hypoxia, causes mucous membranes to have a blueish colour
What are 5 acclimitisation factors at high altitudes?
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
