Pulmonary Blood Flow, Gas Exchange and Transport (Haemoglobin and gas transport) Flashcards
How much oxygen dissolves per litre of plasma
3ml
How much does haemoglobin increase red bloods cells oxygens carrying capacity
200ml/L
How do you measure the oxygen delivery
times the oxygen solubility by the cardiac output (5L/Min)
What does arterial pressure of oxygen refers to
oxygen in plasma solution
How is oxygen solution determined in the plasma
the solubility of oxygen and the partial pressure (at alveoli) of O2 in the gaseous phase that is driving O2 into solution
Why is it important that gases do not travel in gaseous phase in the plasma
can cause a fatal air embolism
How much of the arterial oxygen is extracted by the peripheral tissue
25% of the potentially 1000ml/min delivery
What is the oxygen demand of resting tissues
250ml/min
How much oxygen binds per gram of haemoglobin and how much haemoglobin is present per litre of blood
1.34ml/g
150g/L
What form is 92% of the heamoglobin found in
HbA
What is the remaining 8% of heamoglobin made up of
HbA2
HbF
Glycosylated Hb
What is the main determent in how much haemoglobin can become saturated
The partial pressure of oxygen in the arterial blood
How does haemoglobin work
Hb pulls the oxygen in from the plasma, meaning more oxygen from the alveoli is pulled over as a partial pressure gradient is maintained
complete saturation takes 0.25s
When is haemogoblin nearly 100% saturated
normal systemic arterial PO2 of 100 mm Hg.
Is partial pressure of oxygen directly proportional to oxygen saturation?
No, if partial pressure of oxygen is changed drastically, there is only a small decrease in oxygen saturation as blood want to cary as much oxygen as possible
What is the percentage of saturation at normal venous blood (deoxygenated) 40mmHg
75% saturation
What two haemoglobins have a higher affinity for oxygen then normal adult haemogoblin
Foetal haemoglobin
myoglobin
Where is myoglobin most likely to be found
Oxidative muscle fibres, of
Why does Foetal haemoglobin need a higher affinity for oxygen?
To extract oxygen from maternal blood
Why does myoglobin have an even higher affinity than foetal haemoglobin and adult haemoglobin
As can store oxygen quickly and deliver it to exercising muscles
Define anaemia
a condition where the oxygen carrying capacity of the blood is compromised -
What are three examples of factors that can cause anaemia
Iron or vitamin B deficiency
Haemorrhage
What affect does the partial pressure have on anaemia
No effect, anaemia has nothing to do with ventilation or the diffusion of oxygen to the blood
How can iron deficiency slightly affect saturation of oxygen
decreases the number of oxygen binding sits on haemoglobin
why is it not possible to have a low partial pressure of oxygen and a normal total blood of oxygen
Partial pressure is required to push the oxygen onto the blood
What four chemical factors change haemoglobin affinity for oxygen
Temperature
CO2
pH
DPG (diphosphogylcerate)
What does metabolising tissue
Low pH, High CO2 and Temperature’s affect on Hb saturation
Decreases Hb saturation, as makes oxygen more readily available to respiring cells
What happens to the pH in exercising muscle and whats its affect on Hb saturation
acidosis, pH levels drop due to the production of lactic acid this reduces Hb affinity for oxygen so it gives oxygen to tissues quicker
What is the effect of decreasing temperature and CO2 levels and increasing the pH have on Hb saturation
the heamoglobin holds on to the oxygen tighter making it more difficult for it to give it up
Decreasing temperature increases Hb affinity and also helps what?
collection of oxygen in the pulmonary circulation.
What synthesises DPG
erythrocytes
What happens to Hb affinity for oxygen when 2-3-DPG is added
The affinity is decreased
In what situations does DPG increases, examples
situations associated with inadequate oxygen supply
example: high altitudes, chronic heart of lung disease
what is a benefit of DPG?
helps deliver oxygen to cells in hypoxic conditions,
CO binds to haemoglobin to form what?
carboxyhemoglobin
What is the problem of CO poisoning
Hb has a much higher affinity to CO, so CO binds readily and dissociates very slowly, preventing and delaying oxygen uptake
what is the minimum PCO required to start carbon monoxide poisoning
0.4mmHg
What is the characteristics of carbon monoxide poisoning
Hypoxia and anaemia,
nausea and headaches,
cherry red skin and mucous membranes
Why is the respiratory rate unaffected in CO poisoning?
The arterial partial pressure of CO2 is normal, therefore as your body is sensitive to CO2 you are still going to breathe it out normally
What is the treatment for CO poisoning
Give 100% oxygen
additionally give CO2
Why would you give CO2 in the treatment for CO poisoning
body will breathe and increase ventillation to get rid of the CO2
Define hypoxia
inadequate supply of oxygen to the tissues
What are the five main types of hypoxia
Hypoxic Anaemia Ischaemic Histotoxic Metabolic
How does Hypoxic hypoxia occur
decreased atmospheric partial pressure of O2 or tissue pathology
How does Ischaemic hypoxia occur
heart disease, inefficient pumping of blood around the body
How does Histotoxic hypoxia occur
poisoning prevents cells utilising oxygen delivered to them
How does metabolic hypoxia occur
oxygen delivery to the tissues does not meet increased oxygen demand by cells
How does anaemia hypoxia occur
reduction in 02 carrying capacity of blood due to anemia
Where does 70% , 7% and 23% of the CO2 go when diffused into the body
70%
Combines with erythrocytes and water in the systemic capillary and originally forms carbonic acid
7%CO2 dissolves in the plasma
23%
Enter the erythrocytes and combine deoxyhaemoglobin forming carbamino compounds
What happens to the products of carbonic acid in the erythrocytes
excess H+ ions bing to deoxyhaemoglobin
Bicarbonate moves out the plasma in an exchange form chlorine
what occurs in the pulmonary capillaries in CO2 transport
The reverse of the systemic capillary as CO2 Moves down conc gradient from blood to alveoli
How is normal pH stable in regards to CO2 ability to readily change the pH
All CO2 is usually expired
In what situation can CO2 change the ECF pH
Hyper and Hypo ventilation
How does Hypoventilation affect the ECF pH
Whats is called
retain CO2 , decreases the pH
Respiratory acidosis
How does Hyperventilation affect the ECF pH
Whats is called
blow of more CO2, increases pH
Respiratory alkalosis
What is the symptoms of carbon monoxide poisoning
Hypoxia anemia nausea headache cherry red colour mucous membrane