Bohr Shift

What happens when the partial pressure of CO2 is high?

Hb has a lower affinity to O2 and unloads O2 to respiring cells more easily

What happens when the rate of unloading O2 increases?

oxygen dissociates from oxyhaemoglobin and the curve shifts to the right

What could cause a human to experience the Bohr Effect?

exercise

Where would CO2 partial pressure be low?

Lungs

Where would CO2 partial pressure be high?

Respiring tissue

What does CO2 form when it dissolves

acidic solution

Why does the Bohr Effect happen?

the dissolved CO2 makes the blood acidic.
There is a drop in pH which causes Hb to change its structure so it can unload O2 more easily

What are the values for how CO2 is transported?

5% is dissolved directly in the plasma

10% is combined with haemoglobin to form carbaminohaemoglobin

85% is transport in the form of hydrogencarbonate ions

What happens when CO2 diffuses into erythrocytes?

1. Carbon dioxide in the blood plasma diffuses into red blood cells

2. It combines with water to form carbonic acid (weak)

3. The enzyme carbonic anhydrase catalyzes this reaction.

What does the carbonic acid do next?

The carbonic acid dissociates to form Hydrogen ions and Hydrogen carbonate ions

What do the hydrogencarbonate ions diffuse to

diffuse out of the red blood cell into the plasma

Why does chloride shift happen after hydrogencarbonate ions diffuse out of RBC to plasma?

The charge inside the red blood cells is maintained by the movement of chloride ions from the plasma moving into the red blood cell.

What happens if the hydrogen ions build up within the red blood cell?

could become very acidic

How do hydrogen ions stopping the blood from being acidic?

they are removed from the blood by associating with Hb to produce haemoglobinic acid

What does haemoglobinic acid act as?

a buffer to maintain pH levels

Descrive how the hydrogencarbonate ions are produced in the erythrocytes?

CO2 diffuses from the respiring cells to the erythrocytes. CO2 binds with H2O due to the enzyme carbonic anhydrase to form carbonic acid. Carbonic acid dissociates into hydrogen ions and hydrogencarbonate ions.

High concentrations of CO2 in the blood reduce the amount of O2 transported by Hb.
Name this effect and explain why it occurs.

Bohr Effect
When CO2 is at a high partial pressure, Hb has a lower affinity for O2 and unloads more O2 to the respiring cells. It’s structure changes so it is able to unload the O2 more easily. So the dissociation curve shifts to the right of the normal O2 curve for humans.