Pulmonary Blood Flow Gas Exchange And Transport 2 Part 2

Question 1

What is hypoxia

Answer 1

The inadequate supply of oxygen to tissues due to various causes

Question 2

What are the 5 main types of hypoxia

Answer 2

Hypoxaemic
Anaemic
Stagnant
Histotoxic
Metabolic

Question 3

What is hypoxaemic hypoxia

Answer 3

Caused by a reduction in O2 diffusion at lungs either due to decreased PO2atmos or tissue pathology (e.g. at the top of mount. Everest)

Question 4

What is anaemic hypoxia

Answer 4

The reduction in O2 carrying capacity of blood due to anaemia (red blood cell loss/iron deficiency)

Question 5

What is stagnant hypoxia

Answer 5

Heart disease that results in the inefficient pumping of blood to lungs/around the body

Question 6

What is histotoxic hypoxia

Answer 6

When poisoning prevents cells utilising the oxygen delivered to them (e.g. carbon monoxide/cyanide)

Question 7

What is metabolic hypoxia

Answer 7

When the oxygen delivery to tissues does not meet increased oxygen demand by cells (e.g. in exercising people acting above their exercise level)

Question 8

What is the most common type of hypoxia

Answer 8

Hypoxaemic hypoxia

Question 9

What happpens to the CO2 molecules which diffuse from the tissues into the blood

Answer 9

7% stays dissolved in the plasma and erythrocytes
23% combines in the erythrocytes with deoxyhaemoglobin
70% combines in erythrocytes with water

Question 10

What is formed when CO2 combines in the erythrocytes with deoxyhaemoglobin

Answer 10

Carbamino compounds

Question 11

What is formed when CO2 combines in erythrocytes with water

Answer 11

Carbonic acid which then dissociates to produce bicarbonate and H+ ions

Question 12

What does bicarbonate do (CO2 transport)

Answer 12

Moves out of the erythrocytes into the plasma in exchange for Cl- ions (chloride shift)

Question 13

What do excess H+ ions do (CO2 transport)

Answer 13

Bind to deoxyhaemoglobin

Question 14

What occurs in the pulmonary capillaries (CO2 transport)

Answer 14

The reverse happens

CO2 moves down its concentration gradient from blood to alveoli

Question 15

Which equation shows how CO2 is able to change ECF pH

Answer 15

CO2 + H2O ↔ H2CO3 ↔ HCO3 + H+

Question 16

Why is ECF pH normally stable

Answer 16

Because all of the CO2 produced is eliminated in expired air

Question 17

Which types of ventilation can cause CO2 to alter ECF pH

Answer 17

Hypo/hyperventilation will alter plasma PCO2 and plasma [H+] will vary accordingly

Question 18

How does hypoventilation alter ECF pH

Answer 18

It causes CO2 retention which leads to an increased [H+] causing respiratory acidosis (look at equation)

Question 19

How does hyperventilation alter ECF pH

Answer 19

It causes an increased amount of CO2 to be released which leads to a decreased [H+] causing respiratory alkalosis (look at equation)