Blood + Blood Groups

Question 1

How often are red blood cells produced and what are their life span?

Answer 1

3 trillion every second

Life cycle is 120 days

Question 2

When do red blood cells reach maturity?

Answer 2

They are released not fully mature - reach maturity after a week.

Question 3

Why do red blood cells have to be removed from the circulation after 3 months?

Answer 3

They are constantly circulating under pressure generated by the heart.

They press against each other and the artery walls = shear stress.

This causes the membranes to wear down and they have to be removed or they would burst and cause intravascular clotting.

Question 4

How are red blood cells broken down?

Answer 4

Macrophages in the liver break down RBC’s.

When broken down haemoglobin releases bilirubin which is converted and excreted in the bile.

Iron from RBC’s is absorbed by small intestine, excess iron stored in liver and transported back to red bone marrow.

Question 5

What is present on all body cells that makes them unique?

Answer 5

Proteins (antigens)

Question 6

How many types of antigens are on red blood cells + what are the most important?

Answer 6

35 types

A + B are the most important - they give us the ABO system of blood grouping.

Question 7

How does ABO system work?

Answer 7

A antigens on RBC surface = GP A blood

B antigens on RBC surface = GP B blood

A + B antigens = GP AB blood

No antigens = GP O blood

Question 8

What antibodies do each blood group create?

Answer 8

GP A = Anti-B antibodies

GP B = Anti-A antibodies

GP AB = No antibodies

GP O = Anti-A + Anti-B antibodies

Question 9

What other system is used to determine whether a transfusion reaction will occur?

Answer 9

The Rhesus system.

Question 10

in theory, what blood types can each blood group receive?

Answer 10

GP A = A, AB, O

GP B = B, AB, O

GP AB = AB, O

GP O = O

Question 11

What is Rhesus factor?

Answer 11

Rhesus D (Rh) Protein

Question 12

If someone has Rh protein what are they?

Answer 12

Rh+ (Rhesus positive)

Question 13

If someone does not have Rh protein what are they?

Answer 13

Rh- (Rhesus negative)

Question 14

What is the most common blood type?

Answer 14

O+

Question 15

How does the Rhesus factor affect pregnancy?

Answer 15

If an Rh- mum carries a Rh+ body then the baby’s red blood cells contain the Rh antigen which the mum does not have.

No issue during pregnancy as there is no mixing of blood between mum + baby (separated by placenta).

Question 16

When does the Rhesus factor become an issue in pregnancy?

Answer 16

Mixing occurs during delivery and the mum will create Rh antibodies.

If the mum got pregnant again with a Rh+ baby then the mum’s Rh antibodies will attack the baby’s red blood cells as antibodies can cross the placenta.