Blood And Blood Groups

Question 1

1- Describe the constituents of blood

Answer 1

Plasma - 55%
(Proteins, electrolytes, enzymes, nutrients)

Erythrocytes (RBCs) - 45%

Leucocytes (WBCs) - less than 1%

Thrombocytes (Platelets) - less than 1%

Question 2

1- another name for RBCs

Answer 2

Erythrocytes

Question 3

1- another name for WBCs

Answer 3

Leucocytes

Question 4

1- another name for platelets

Answer 4

Thrombocytes

Question 5

1- what do thrombocytes do?

Answer 5

Clot the blood

Question 6

1- where do all blood cells originate from?

Answer 6

Pluripotent stem cells

Question 7

1- what is plasma made up of?

Answer 7

Proteins, electrolytes, enzymes and nutrients

Question 8

2- outline the production and function of erythrocytes (RBCs)

Answer 8

Biconcave discs and flexible membrane- squeeze!
Carry haemoglobin (protein that carries o2)
Hb found in cytoskeleton of the cell
Carry a little bit of co2
Membrane has glycolipids (type of antigen)- determine blood type
No nucleus- no reproduction
Only live 120 days due to wear and tear

Question 9

2- outline the production and function of leucocytes (WBCs)

Answer 9

Have a nucleus- reproduction
Plasma membranes HAVE PROTEINS called MHC- immunological purposes
Two types: Granular and Agranular
- granular= filled with granules
- agranular= develop into macrophages in tissues
Production- from myeloid stem cells or lymphoid stem cells
Most only live for a few days
Combat infection- by immune response or phagocytosis
Can leave bloodstream in order to combat (granulocytes never return! Lymphocytes do return)

Question 10

2- outline the production and function of thrombocytes (platelets)

Answer 10

Production-
-from fragments of megakaryocytes under influence of thromboprotein
-in red bone marrow
-then enter blood circulation
Disc shape
No nucleus
Lots of vesicles
Live for 5-9 days
Involves on clotting and haemostasis

Question 11

2- outline the production and function of plasma

Answer 11

90% water (10% other dissolved substances)
Plasma proteins- osmotic pressure of blood and viscosity (thickness) to keep fluid circulation
Has clotting factors
Electrolytes- transmit nerve impulses
Transport hormones- chemical messengers

Question 12

3- what is erythropoiesis?

Answer 12

=How RBCs are made!

Question 13

3- outline the process of erythropoiesis

Answer 13

Pluripotent stem cell in bone marrow
Differentiates into pro-erythroblast
Synthesis of haemoglobin
Nucleus expelled
Now a reticulocyte
Reticulocyte matures to become erythrocyte
Low o2 levels stimulate erythropoiesis
Kidneys detect low o2 and secrete erythropoietin into blood
Increases speed of maturation in bone marrow to produce more RBCs

Question 14

4- name the 4 main blood types

Answer 14

Type A
Type B
Type AB
Type O

Question 15

4- describe blood group A

Answer 15

People with surface antigen A on erythrocyte
Anti A antibody will react with antigen A
Plasma contains anti B antibody (does NOT contain antibodies that will react with antigens of its own erythrocytes)

Question 16

4- describe blood group B

Answer 16

People with surface antigen B on erythrocyte
Anti B antibody will react with antigen B
Anti A antibody in plasma (plasma does NOT contain antibodies that will react with antigens of its own erythrocyte)

Question 17

4- describe blood group AB

Answer 17

People with surface antigens A and B on erythrocyte
Anti A and anti B antibodies will react with antigen A and antigen B
Neither antibodies in plasma (presence of this would cause a reaction as the erythrocyte contains both surface antigens, plasma does NOT carry antibodies that will create reaction to erythrocyte)

Question 18

4- describe blood group O

Answer 18

People with no surface antigens on erythrocyte
Has neither A nor B antigen on surface of erythrocyte
Has both anti A and anti B antibodies in the plasma (as there are no surface antigens on the erythrocyte for it to react with)

Question 19

4- how is blood group determined?

Answer 19

Erythrocyte surface has coating that is genetically predetermined (made of glycoproteins and glycolipids)
Glycoproteins and glycolipids act as antigens
Antigens= reactivity to antibodies

So… categorisation is determined by the presence or absence of the antigens on the cell surface

Question 20

4- explain blood grouping in terms of dominance and co-dominance

Answer 20

Inheritance if blood type is due to multiple allele inheritance

Blood types A and B DOMINANT to blood type O
Blood types A and B are CO-DOMINANT

Question 21

5- outline the importance of Rhesus factor in grouping blood

Answer 21

3 inherited alleles code for the rhesus antigen: C,D or E
D is responsible specifically for someone’s Rh status
Presence of D antigen on RBC membrane= Rh+

Rh+ is dominant to Rh- in regards to inheritance patterns

The RBC membrane determines whether someone is Rh+ or Rh-
If they are positive then the rhesus antigen is present
85% of people are rhesus positive, the other 15% are negative and do not have the antigen

Rh+ people DO NOT MAKE anti-rhesus antibodies
Rh- people ARE CAPABLE of making anti-rhesus (only in circumstances like pregnancy or incompatible transfusion)

Question 22

6- outline the concept of ABO pregnancy incompatibility

Answer 22

Very rare (especially in Caucasian)

Mothers blood type= O
Baby’s blood type= A or B
Mothers immune system REACTS, making antibodies against baby’s RBCs

Anti A and anti B antibodies belong to IgM (a classification of antibodies)
They are unlikely to cross a placenta where mum and baby are different blood groups due to molecular size

Question 23

6- outline the concept of rhesus pregnancy incompatibility

Answer 23

Mother= Rh-
Baby= Rh+

RhD antigens from baby mix into the mothers blood
Mother then makes anti D antibodies
Due to molecular size, IgG antibodies can cross the placenta
So anti D antibodies attack baby’s RBCs that carry the surface antigen D on membrane

Question 24

6- is rhesus pregnancy incompatibility bad for mum or baby?

Answer 24

Baby
Liver swelling, iso-immunisation, anaemia
It tends to present in the form of jaundice within 48 hours