Blood circulation in human body

Circulatory system: System of transportation in our body which helps to transport oxygen, nutrient, hormones, various wastes etc from one part to other part is called circulatory system.

Major organs of this system are: blood, heart and blood vessels.

A) Blood: It is fluid connective tissue. There is about 4.5 to 5:5 litre of blood in body of a normal person.

Composition of Blood

a. Blood plasma(55%)

b. Blood Cells (45%)

1. RBC
2. WBC
3. Platelets

a) Plasma: It is pale yellow transparent liquid. There is about 55% of plasma out of total volume of blood. It is composed of 90% water and 10% various organic and inorganic substances. Its major functions are:

1. It transports absorbed nutrients, hormones, various waste etc
2. It regulates amount of water in body.
3. A kind of protein called Fibrinogen present in it helps in blood clotting and prevent excess bleeding.

b) Blood cells

b.1) RBC

1. They are called Erythrocytes.
2. They are red in color, biconcave disc like in shape.
3. Nucleus is absent.
4. One ml blood contain about 45 to 50 lakhs of RBC.
5. They are formed in bone marrow.
6. They are red due to presence of haemoglobin.
7. Iron is necessary for formation of haemoglobin.
8. Shortage of iron in body decreases no. of RBC which causes ‘Anaemia’ .
9. Their average life is 120 days
10. They are destroyed in liver and spleen.

Function: It transports oxygen from lungs to various parts of body.

b.2) WBC:

1. They are also called leukocytes.
2. They are colorless, irregular in shape, provided with nucleus.
3. They are of two types:

i) Granular leukocytes. Eg, neutrophyll, basophyll

ii) Non-granular leukocytes. Eg, lymphocyte, monocyte.

4. One ml of blood contains about 6000 to 10,000 WBC.

5. Its average life is about 15 days.

6. They are formed in bone marrow, lymph node and spleen.

Functions:

1. Fight against germs that cause diseases and kills them.
2. Helps in healing of wands

[Note: Increase in no of WBC excessively causes blood cancer called leukemia.]

b.3) Platelets:

1. They are also called Thrombocytes
2. These are smallest blood cells without nucleus.
3. One ml of blood contains about 2 to 4 lakhs of platelets.
4. Its average life is about 2 to 3 days.
5. They are formed in bone marrow.

Functions: They help in blood clotting and prevent excess bleeding.

Heart: Heart is conical shaped muscular organ situated inside chest cavity (diaphragm). It Is made up of cardiac tissue having great power of contraction and relaxation. It is covered with protective membrane called Pericardium. Pericardium is filled with special fluid called pericardial fluid which protect heart from external shocks.

Heart has 4 chambers. They are

1. Right auricle
2. Left auricle
3. Right ventricle
4. Left ventricle

There are 4 main valves in heart. They are:

1. Tricuspid valve: It is the opening between right auricle and right ventricle. Blood passes from right auricle to right ventricle through this opening. It has 3 Flaps.
2. Bicuspid(mitral) valve: It is situated in between left auricle and left ventricle. It has two flaps that control the opening.
3. Aortic valve: It Is situated in between aorta and left ventricle. During  contraction of left ventricle, blood passes to aorta through this opening.
4. Pulmonary valve: It is situated in between pulmonary artery and right ventricle. Blood passes to pulmonary artery through this opening during contraction of right ventricle.

Q) Write 2 difference between auricle and ventricle.

Q) Give reason why ventricles are more muscular than auricles?

Auricle simply receives blood from outside but ventricle has ta pump blood with greater force to the different parts of body so, ventricles are more muscular than auricles.

Blood vessels: These are the special tubes through which blood flow in our body. There are 3 types of blood vessels. They are Arteries, Capillaries and Veins

Q) Write 2 difference between arteries and veins.

Capillaries: Capillaries are very fine hair line blood vessels that connect arteriole with venules. Exchange of oxygen, nutrients etc take place between body cells and blood from the wall of capillaries.

Blood circulation:

1. Pulmonary circulation: Flow of blood in between heart and lungs is called pulmonary circulation. Blood gets oxygenated during pulmonary circulation.
2. Systemic circulation: Flow of blood in between heart and various parts of blood is called systemic circulation. Blood supplies oxygen, nutrients etc to body cells during systemic circulation.

Double circulation: At a same time, heart pumps blood in two different directions and maintain pulmonary and systemic circulation, this is double circulation.

Heart beat: Rhythmic Contraction and relaxation of heart is called heart beat. For a normal person, heartbeat rate is about 72 to 80 per minute. Heart beat rate may change according to condition, age and sex of body. Eg, heart beat rate increases during fear, exercise, sickness etc.

Blood pressure: Pressure exerted by the the blood into the wall of blood vessels is called blood pressure. There are 2 types of blood pressure. They are:

1. Systolic pressure: Pressure of blood at the time of contraction of heart (ventricle) is called systolic pressure. In a normal person, systolic pressure is 120 mm Hg.
2. Diastolic pressure: The pressure of blood at the time of relocation of heart is called diastolic pressure. For normal person, diastolic pressure is 80 mmHg.

Name of device used to measure blood pressure is sphygmomanometer.

Causes of high blood pressure:

1. Smoking, excessive intake of alcohol.
2. Over weight, lack of physical exercise.
3. Stress, aging, genetics
4. Chronic kidney diseases, adrenal disorder.

Preventive measures of high blood pressure:

1. Regular exercise.
2. Diet low in fat and salt.
3. Avoid smoking, alcohol.
4. Avoid stress.
5. Regular health checkup.

Diabetes: Symptoms:

1. Frequent urination.
2. Frequent hunger, thirst
3. Blurred vision, delay in wound healing.

Preventive measures:

1. Regular exercise.
2. Balanced diet.
3. Avoid stress.
4. Avoid smoking, alcohol.

Uric acid: It is bi-product formed in our body during decomposition of Purine, a kind of protein. Uric acid helps to maintain inner wall of blood vessels as well as o remove harmful substance from body. Uric acid is removed by kidney in the form of urine from our body.

When the rate of forming uric acid in our body exceeds rate of removal of it from body, its concentration increases in the blood due to which crystals of uric acid get deposited in joint causing painful swelling of joint, this condition is called gout.

Symptoms:

1. Painful swelling of joints like toe, ankle, tea etc.
2. Difficulties in movements.
3. Red rashes on skin with burning sensation.

Preventive measures:

1. Drink sufficient water.
2. Drink baking powder, lemon juice etc
3. Avoid food items rich in purine like red meat, sea food, legumes etc.
4. Take cherries which contain anthocyanin that reduce pain.
5. Regular exercise, maintain body weight.

Solved question:
a. A person suffering from anaemia feels tired even of a short walk.

When a person suffers from anaemia, blood (RBC) cannot supply sufficient oxygen to the body cells to release energy due to the decease in no. of RBC. so, a person suffering from anaemia feels tired even of a short walk.

b. Blood doesn’t clot in blood vessels.

For clotting of blood, an enzyme called thromboplastin is required but it is absent in blood vessels so blood doesn’t clot in blood vessels.

c. Right auricle is larger than left auricle.

This is because right auricle receives from all parts of our body but left auricle receives oxygenated blood only from lungs.

d. Veins have valves.

Valves present inside the vein help to check the backward flow of blood.

e. Pulmonary vein is not an artery though it carries oxygenated blood.

All the arteries carry blood away from heart but pulmonary vein carries blood towards the heart. So, pulmonary vein isn’t an artery.

f. Arteries are elastic in nature.

In artery, blood flows with greater pressure so in order to prevent its bursting, it is elastic in nature.

g. Cut in an artery is more dangerous than that in vein.

Blood pressure a relatively high in artery and valves are absent so when bleeding starts, it takes long time for blood clotting due to which it is dangerous in artery.

h. The colour of blood flowing in arteries and veins are different.

Oxygenated blood having bright red colour flow in arteries whereas deoxygenated blood with blueish tint flows in veins. So, they have different colours.

i. The wall of left ventricle is thicker than the wall of right ventricle.

Right ventricle pumps blood only upto lungs but left ventricle pump has to pump blood upto all parts of body with greater force. So, wall of left ventricle is thicker than that of right one.

j. Pulmonary artery isn’t a vein although it carries deoxygenated blood.

All the vein carry blood towards heart but pulmonary artery carries blood away from heart upto the lungs. So, it is not a vein.

k. Differentiate between systolic pressure and diastolic pressure.

l. Differentiate between left ventricle and right ventricle.