Respiratory Physiology 4

Question 1

Why is blood flow low at the apex of the lungs?

Answer 1

Arterial pressure is less than alveolar pressure. The opposite is true at the base of the lungs.

Question 2

How do blood flow and ventilation differ from the top to the bottom of the lung?

Answer 2

They both decline with height but blood flow faster than ventilation.

Question 3

Where does the majority of the ventilation perfusion mismatch happen?

Answer 3

Apex

Question 4

How does the body try to match ventilation and perfusion?

Answer 4

Diverts blood to better ventilated areas by constricting arterioles around underventilated alveoli.

Question 5

Shunt meaning?

Answer 5

Describes the passage of blood through areas of lung that are poorly ventilated.

Question 6

What does respiratory sinus arrhythmia ensure?

Answer 6

That ventilation perfusion ratio remains close to 1.

Question 7

What is physiological dead space?

Answer 7

Alveolar dead space + anatomical dead space

Question 8

How is oxygen transported through the blood?

Answer 8

Mainly through haemoglobin (197ml out of 200) with the rest dissolved in plasma. 3ml per litre.

Question 9

How is carbon dioxide transported in the blood?

Answer 9

77% in plasma
23% in haemoglobin

Question 10

What is anaemia?

Answer 10

Any condition where the oxygen carrying the capacity of the blood is compromised.

Question 11

What causes a decrease in the affinity of haemoglobin for oxygen?

Answer 11

Decrease in pH, increase in PCO2, or temperature increase.
- the affinity is also decreases by binding 2,3-diphosphoglycerate this happens in situations associated with inadequate oxygen supply.

Question 12

Why is carbon monoxide in the blood life threatening?

Answer 12

It binds to Haemoglobin with an affinity 250 times that ox oxygen and dissociates very slowly.

Question 13

What are the symptoms and treatment of carbon monoxide in the blood?

Answer 13

Hypoxia, anaemia, nausea, headache, cherry red skin and mucous membranes. Treatment involves providing 100%.

Question 14

Which oxygen carrying molecules have higher affinity for oxygen than HbA?

Answer 14

HbF (foetal haemoglobin) and myoglobin

Question 15

What are the different types of hypoxia?

Answer 15

1. Hypoxaemic Hypoxia: most common. Reduction in O2 diffusion at lungs either due to decreased PO2atmos or tissue pathology.
2. Anaemic Hypoxia: Reduction in O2 carrying capacity of blood due to anaemia (red blood cell loss/iron deficiency).
3. Stagnant Hypoxia: Heart disease results in inefficient pumping of blood to lungs/around the body
4. Histotoxic Hypoxia: poisoning prevents cells utilising oxygen delivered to them e.g. carbon monoxide/cyanide
5. Metabolic Hypoxia: oxygen delivery to the tissues does not meet increased oxygen demand by cells.