BLOOD GROUP
Antigens on surface of RBCs- Agglutinogens
Agglutinogens are genetically determined & are of 2 Types:- Type “A” & Type “B”.
People have natural Antibodies –Agglutinins is of 2 types i.e. type “a” & type “b”
Blood group – based on presence or absence of various antigens
At least 24 blood groups and more than 100 antigens ◦ABO and Rh
| Blood groups | Agglutinogen in RBCs | Agglutinin in plasma |
| A | A | b |
| B | B | a |
| AB | A & B | No Agglutinin |
| O | No Agglutinogen | a & b |
BLOOD TRANSFUSION
A Blood transfusion is taking out blood from one person and injecting it into vein of another person.
Who can give you blood?
People with TYPE O blood are called Universal Donors, because they can give blood to any blood type.
People with TYPE AB blood are called Universal Recipients, because they can receive any blood type.
Rh + à Can receive + or –
Rh – à Can only receive
RH FACTOR
Scientists sometimes study Rhesusmonkeys to learn more about the human anatomy because there are certain similarities between the two species.
While studying Rhesus monkeys, a certain blood protein was discovered. This protein is also present in the blood of some people. Other people, however, do not have the protein.
The presence of the protein, or lack of it, is referred to as the Rh (for Rhesus) factor.
Types
- Rh positive: Have these antigens present on surface of RBCs
- Rh negative: Do not have these antigens present
BLOOD CLOTTING
Blood clot :-
“The fluid or solution form of the blood is changed into semisolid gel form known as blood clot.”
| Factor | Synonym |
| 1 | Fibrinogen |
| 11 | Prothrombin |
| 111 | Tissue factor / tissue thromboplastin |
| IV | Calcium ions |
| V | Labile ions |
| VI | Does not exist |
| VII | Stable factor |
| VIII | Antihaemophilic factor ‘A’ |
| IX | Antihaemophilic factor ‘B’ |
| X | Stuart factor |
| XI | Antihaemophilic factor ‘C’ |
| XII | Antihaemophilic factor ‘D’ OR Hageman factor |
| XIII | Fibrin stabilising factor |
CLOTTING MECHANISM OF BLOOD
Step- I
Formation of Thrombin
Prothrombin + Calcium +Thromboplastin = Thrombin (Active)
Step- II
Formation of Fibrin
Thrombin + Fibrinogen = fibrin (fine threads)
Step- III
Formation of Clot
Fibrin + Blood cells = Clot
NORMAL COUNTS
| Erythrocytes (RBCs) | Male | about 5.4 million RBCs/ cu.mm of blood |
| Female | about 4.8 million RBCs/ cu.mm of blood | |
| Leukocytes (WBCs) | 6000 – 10000 per cu.mm of blood | |
| Thrombocytes (Platelets) | 3 – 4 lakhs per cu.mm of blood | |
| Haemoglobin | Infants | 14 – 20 gm/100 ml of blood |
| Adult female | 12-16 gm/100 ml of blood | |
| Adult male | 13.5 – 18 gm/100 ml of blood |
Low haemoglobin in female is due to menstruation cycle, pregnancy & lactation.
In male, testosterone secretion stimulates formation of RBC, hence Hb is higher than female.
DISEASE RELATED TO BLOOD
Anaemia-
Deficiency of hemoglobin leads to decreased oxygen carrying capacity of blood called anaemia.
Causes of anaemia- Diet & haemorrhage etc.
1.Aplastic anemia
Aplastic anemia is a condition that occurs when your body stops producing enough new blood cells.
Aplastic anemia leaves you feeling fatigued and with a higher risk of infections and uncontrolled bleeding.
A rare and serious condition, aplastic anemia can develop at any age.
2.Megaloblastic anemia
Megaloblastic anemia is a condition in which the bone marrow produces unusually large, structurally abnormal, immature red blood cells (megaloblasts).
3.Hemolytic anemia
Hemolytic anemia is a disorder in which red blood cells are destroyed faster than they can be made. The destruction of red blood cells is called hemolysis.
4.Iron deficiency anemia
A condition in which blood lacks adequate healthy red blood cells. Iron deficiency anemia is due to insufficient iron.
5.Sickle cell anemia
A group of disorders that cause red blood cells to become misshapen and break down.
6.Pernicious anemia
A decrease in red blood cells when the body can’t absorb enough vitamin B12.
Common causes include a weakened stomach lining or an auto-immune condition.
Symptoms include fatigue and weakness.
Untreated pernicious anaemia can cause heart and nerve damage. Treatment involves vitamin B-12 shots or pills.
Polycythemia-
Polycythemia (also known as polycythaemia or polyglobulia) is a disease state in which the hematocrit (the volume percentage of red blood cells in the blood) is elevated.
Haemolysis-
the rupture or destruction of red blood cells.
Bleeding time:-
it is time interval between skin puncture and cessation of flow of blood.
Normal bleeding time is 1 to 3 min.
Clotting time:-
it is time interval between onset of bleeding and appearance of jelly like semisolid mass i.e.blood clot
Normal clotting time is 4 to 9 min.
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