Changes in Hemoglobin Oxygen Affinity

Question 1

How is fetal hemoglobin different from adult hemoglobin?

Answer 1

Has two gamma subunits instead of beta subunits

Question 2

How are the gamma subunits in fetal hemoglobin an adaptation?

Answer 2

It has higher oxygen affinity than the beta subunits, which lets the fetal blood pull oxygen from the mother’s blood

Question 3

Why don’t adults have the gamma subunit?

Answer 3

It would be problematic if it stuck around, so production of the gamma subunit drops off after birth and beta subunit production increases

Question 4

What are the two hemoglobin subunits present only in the embryo?

Answer 4

Zeta and epsilon

Question 5

Does production of the alpha subunit change during development?

Answer 5

No, it is relatively constant throughout

Question 6

What are the 3 things that affect affinity of hemoglobin for oxygen?

Answer 6

pH/proton concentration, temperature, BPG

Question 7

What are the cells doing when there is a decrease in blood pH?

Answer 7

Metabolically active and producing more CO2

Question 8

What happens to the oxygen binding curve of hemoglobin if pH increases?

Answer 8

Shifts to the left and holds on to O2

Question 9

What happens to the oxygen binding curve of hemoglobin if pH decreases?

Answer 9

Shifts to the right and lets go of O2

Question 10

What is the Bohr effect?

Answer 10

A drop in pH shifts the curve to the right

Question 11

Why does pH affect hemoglobin affinity for oxygen?

Answer 11

Protons are allosteric modulators that changes Hb to the T state to lower its affinity for oxygen and release it to the tissues

Question 12

What is the Root effect?

Answer 12

A decrease in pH causes an extreme shift to the right and a reduction in the carrying capacity of the blood. Seen in some teleost fish and a few invertebrates

Question 13

What happens to the oxygen binding curve of hemoglobin if temperature increases?

Answer 13

Shifts to the right

Question 14

What happens to the oxygen binding curve of hemoglobin if temperature decreases?

Answer 14

Shifts to the left

Question 15

Why does an increase in temperature decrease the oxygen affinity of hemoglobin?

Answer 15

Metabolically active tissues produce heat, and the hemoglobin will let the oxygen go for the metabolically active cells to use

Question 16

How do reindeer keep their legs from freezing if hemoglobin is affected by temperature?

Answer 16

Their Hb isn’t as affected by temperature change

Question 17

What happens to the oxygen binding curve of hemoglobin if BPG is completely absent?

Answer 17

Hb acts as a hyperbolic curve

Question 18

What is the equivalent of BPG in birds?

Answer 18

Inositol bisphosphate

Question 19

What is the equivalent of BPG in fish?

Answer 19

GTP and ATP

Question 20

What happens to the oxygen binding curve of hemoglobin if BPG increases?

Answer 20

Shifts to the right

Question 21

What happens to the oxygen binding curve of hemoglobin if BPG decreases?

Answer 21

Shifts to the left

Question 22

What happens to BPG concentrations during exercise?

Answer 22

Increases at the tissues but not the lungs, so oxygen loading remains unaffected

Question 23

Does a right shift affect the saturation of systemic capillaries?

Answer 23

Yes, lowers it from 75% to 58%

Question 24

What is the result of the right-shifted curve?

Answer 24

Increased oxygen unloading to metabolically active tissues

Question 25

Which direction is the oxygen binding curve shifted in fetal hemoglobin compared to adult hemoglobin?

Answer 25

Left