Category: Biology Second Paper Lecture Sheet

The human heart is located on the left side between the two lungs in the thoracic cavity above the diaphragm. It is triangular in shape and reddish-brown in color. Its broad upward part is called the base and the narrow downward part is called the apex. Adult human heart is 12 cm long and 8 cm wide. Male heart weighs 250-390 grams and female 200-275 grams. A male’s heart is one-third larger than a female’s.

The organ that circulates blood throughout the body through contraction and expansion is called the heart. It is called a living pump mechanism or organ. In a healthy person’s lifetime, the heart beats 2600 million times and pumps 155 million liters (one and a half lakh tons) of blood from each ventricle.

Blood group of donor and recipient is well checked during blood collection. If not, the dangers that are likely to occur are:
(i) Blood cells will coagulate and disintegrate.
(ii) Hemoglobin will be excreted in urine.
(iii) Accumulation of hemoglobin in kidney will cause uremia and disturbance of kidney function.
(iv)) Hepatitis-B and Hepatitis-C causes outbreaks of blood jaundice.
(v) Blood of intoxicated and AIDS patient causes AIDS disease.
(vi) Patient may have problems like asthma and allergies.
(vii) Patient may have iron overload.
(viii) The patient may die.

1. ABO group is divided into four groups
2. A group consists of antigen A and antibody B
3. Group B consists of antigen B and antibody A
4. Group AB contains antigens A and B, but no antibodies
5. Group O has no antigens, but has antibodies A and B
6. It is called universal recipient as it can accept blood from all groups in group AB
7. O group is called universal donor as it can give blood to all groups

In 1901, biologist Karl Landsteiner classified human blood based on the presence or absence of antigens in the blood cells and called ABO blood groups. ABO blood group is divided into four groups.
1. A group: 23% of blood is A group.
2. B group: 35% of blood is B group.
3. AB group: 8% of blood is AB group.
4. O group: 34% of blood is O group.

The word hemoglobin is formed from heme meaning iron and globin meaning protein. The iron-containing substance in the cytoplasm of red blood cells is called hemoglobin. Due to this the blood is red in color. 33% of the weight of a red blood cell is hemoglobin. Each human red blood cell contains about 270 million hemoglobin molecules. 100 ml of blood contains 15/16 grams of hemoglobin. Each gram of hemoglobin can carry 1.36-1.40 ml of oxygen. If hemoglobin is low in the body, it is called oligocythemia. Again, if the amount of hemoglobin is increased, it is called polycythemia.

The word erythropoiesis is derived from the Greek words erythro meaning red and poiesis meaning producing. The process by which red blood cells are produced is called erythropoiesis. Red blood cells are produced from bone marrow, liver, spleen and thymus. Again, it gets destroyed in the liver and spleen. There, the red blood cells change and produce bile acids called bilirubin and biliverdin. 10 million red blood cells are produced every second, while 10 million red blood cells are destroyed every second.

The yellow fluid that remains after blood clots is called serum. The molecule contains serotonin. Serotonin is released into the serum as the molecule breaks down. It is like plasma. It contains serotonin which causes constriction of blood vessels. The branch of biology that deals with serum is called Serology. Serum does not contain fibrinogen, prothrombin, labile and antihemophilic factors.

1. Blood is always flowing at high speed.
2. Blood contains 50 types of procoagulant factor (blood clotting) and anticoagulant factor (prevents clotting).
3. Because the blood vessel walls are very smooth.
4. Anticoagulant factors include heparin and thrombomodulin, which prevent blood clotting.
5. Because active coagulant factors are always removed by the liver.

Substances that prevent blood from clotting are called anticoagulants. Blood contains 50 types of procoagulant and anticoagulant factors. Heparin (mast cells), hirudin (leeches), thrombomodulin, sodium citrate, sodium oxalate etc. are anticoagulants. Heparin, hirudin and thrombomodulin inhibit the generation of thrombin from blood prothrombin. Sodium citrate reacts with calcium ions in the blood to form calcium citrate. Calcium citrate is degraded. Sodium oxalate reacts with calcium ions in the blood to form calcium oxalate. Calcium oxalate is excreted and causes kidney stones.