Lecture 16

Question 1

What is the composition of air?

Answer 1

Dry and wet at standard atmospheric pressure of 760 mmHg

Question 2

What is Dalton’s law?

Answer 2

The total pressure of a mixture of gases is the sum of their individual partial pressures

Question 3

What can partial pressure information influence?

Answer 3

How much gas we have in a solution

Question 4

Concentration of a gas dissolved in a solution is determined by…

Answer 4

Henry’s law

Question 5

What is the equation of Henry’s law?

Answer 5

Concentration of dissolved gas = Solubility coefficient x Partial pressure of gas

Question 6

Does plasma carry a lot of oxygen?

Answer 6

no

Question 7

What is the molecular weight of haemoglobin?

Answer 7

68 kD

Question 8

What is the globin chain combination for adult haemoglobin?

Answer 8

2 alpha chains and 2 beta chains

Question 9

What is the globin chain combination for fetal haemoglobin?

Answer 9

2 alpha chains and 2 gamma chains

Question 10

What is a haem unit?

Answer 10

Porphyrin ring containing a single iron atom

Question 11

What enzyme converts Fe (3+) to Fe (2+) in the haem unit?

Answer 11

Methaemoglobin reductase

Question 12

How much of hemoglobin is saturated in arterial blood?

Answer 12

98%

Question 13

What is the effect of temperature on hemoglobin saturation?

Answer 13

If temperature increases, curve shifts to the right
- hemoglobin carries less oxygen
If temperature decreases, curve shifts to the left
- hemoglobin carries more oxygen

Question 14

What is the effect of pH on hemoglobin saturation?

Answer 14

pH and CO2 are closely interlinked factors
CO2 (weak acid)
Increase in CO2: acidification - shifts to the right
(less oxygen)
Alkalization - shifts to the left (more oxygen)

Question 15

What is the name for changes in saturation due to pH changes?

Answer 15

Bohr effect

Question 16

What is the effect of 2,3-Diphosphoglycerate (2,3-DPG)?

Answer 16

Interacts with beta-chain and changes the interaction of hemoglobin with oxygen
- an increase in 2,3 DPG concentration shifts curve to the right, decrease shifts to the left
2,3, DPG tends to bind more to hemoglobin in an deoxygenated state
- changes affinity for oxygen so that it aids oxygen offloading

Question 17

What is fetal hemoglobin like?

Answer 17

Globin chains are insensitive to 2,3 DPG

Fetal hemoglobin is like adult hemoglobin at 0 concentration of 2,3 DPG

Question 18

What is the advantage to the insensitivity to 2,3 DPG in fetal hemoglobin?

Answer 18

Helps fetus scavenge oxygen from mother’s blood more efficiently

Question 19

How does the blood carry CO2 as?

Answer 19

Dissolved CO2
Carbonic acid
Bicarbonate (largest component)
Carbonate
Carbamino compounds (CO2 interacts with proteins in the lung)

Question 20

How is bicarbonate efficient as a buffering system?

Answer 20

22~25 bicarbonate in plasma
1.2 mM
ph 7.4
helps maintain that pH within tight barriers
Hyperventilating: blowing of CO2 - effect on plasma pH

Question 21

How much of CO2 stays in the plasma?

Answer 21

10% stays in plasma

Question 22

How much of CO2 remains dissolved?

Answer 22

6%

Question 23

How much of CO2 combines with proteins to form carbamino compounds?

Answer 23

less than 1

Question 24

What enzyme speeds up process of bicarbonate formation?

Answer 24

Carbonic anhydrase type 2

Question 25

What are channels used for CO2 transport?

Answer 25

aquaporin 1, Reces A (50% of transport)

Question 26

What happens when CO2 binds to hemoglobin?

Answer 26

Proton formed

• local acidification in RBC
• favors oxygen being released from iron group
• leaves RBC
• supply to tissues

Question 27

What role does AE 1 (band 3 - anchoring chain) have in bicarbonate transport?

Answer 27

Important role in anchoring cytoskeleton (contributes to shape of RBC)

• Cl moves in and HCO3 out
• Hamburger shift (Cl shift)
• all processes are in reverse in lungs - higher affinity to bind to oxygen