D6 Gas exchange

Question 1

How many polypeptide chains does haemoglobin consist of?

Answer 1

4

Question 2

How many O2 molecules can each haemoglobin bind?

Answer 2

4Hb + 4O2 -> HbO8

Question 3

Oxygen and haemoglobin binding is cooperative. What does this mean?

Answer 3

Each subsequent oxygen bind more easily than the last

Question 4

Where will haemoglobin have high oxygen affinity?

Answer 4

Oxygen rich areas - promotes oxygen loading

Question 5

Where will haemoglobin have low oxygen affinity?

Answer 5

Oxygen starved areas - promoting oxygen unloading

Question 6

What relationship does an oxygen dissociation curve show?

Answer 6

Between oxygen (partial pressure) and haemoglobin saturation

Question 7

Describe the oxygen saturation curve of an adult

Answer 7

Vaguely S shaped
Low saturation where O2 levels are low and high saturation where O2 levels are high

Question 8

Describe the oxygen saturation curve of a foetus

Answer 8

Similar to an adult curve but shifted to the left as the oxygen affinity is greater un foetus
(slightly different haemoglobin)

Question 9

Describe the oxygen saturation curve of myoglobin

Answer 9

Myoglobin is not capable of cooperative binding and is thus logarithmic and far left as it become saturated at lower O2 levels

Question 10

What is myoglobin?

Answer 10

Oxygen binding molecule in the skeletal muscle tissue

Question 11

In which ways is CO2 transported through the body and in what proportions?

Answer 11

~5% dissolved in water
~20% binds to haemoglobin
~75% diffuses into erythrocytes and is converted to carbonic acid

Question 12

How does the presence of carbon dioxide in the erythrocyte effect O2 levels?

Answer 12

CO2 combines with water and carbonic acid -> H2CO3 -> H+ and HCO3-
H+ increases acidity causing Hb to release O2 and absorb H+ ions as a buffer to maintain intracellular pH

Question 13

How does the bicarbonate ion produced in the erythrocyte due to CO2 get to the lungs?

Answer 13

HCO3- is pumped out in exchange of Cl-
Na in the blood plasma binds and NaHCO3 travels to the lungs
Bicarbonate is reabsorbed in the lungs

Question 14

What is used as a buffer to maintain pH of blood stable?

Answer 14

Plasma proteins

Question 15

Which two organs can control blood pH?

Answer 15

Lungs can regulate ventilation rate to regulate CO2 dissolved
Kidneys can control reabsorption of bicarbonate from the filtrate

Question 16

Define the Bohr shift

Answer 16

Decrease in blood pH causes oxygen dissosciation curve right

Question 17

What is partial pressure?

Answer 17

Pressure exerted by every single type of gas in a mixture

Question 18

Define emphysema

Answer 18

A lung condition whereby the alveolar walls lose their elasticity due to damage
(decrease SA and pulmonary bullae - alveolar holes)

Question 19

Major cause of emphysema?

Answer 19

Smoking