Blood Circulatory System in Humans acts as the transport system of our body that helps in transporting gases, food, hormones and waste material from one part of the body to the other. It mainly consists of blood, blood vessels and heart.It is an important topic for ICSC biology class 6. This chapter has three parts. Links for each part are provided in this article.
Which are the main components of blood?
There is 4-6 litres of blood in the human of body. The colour of blood is red due to the presence of a pigment known as haemoglobin. Blood is a fluid connective tissue.
The main components of blood are -
1.Plasma - Plasma is the liquid component of the blood. Its colour is pale yellow. It consists of proteins (7.8%), inorganic salts (1%), water (90.92%). It also consists of digested food, waste materials and chemicals.In an average adult person the total volume of plasma is nearly 2.5 to 3.0 litres.
2.Blood Corpuscles - Blood corpuscles which are also known as blood cells constitute 40-45% of the total blood volume. These are of the following three types -
(a) Red Blood Corpuscles - These are also known as erythrocytes or red blood cells. These are disc shaped or biconcave. These cells are produced in the bone marrow. They occur in a larger amount than the other components of blood. Each 1 mm3 blood consists of about 5-6 million of red blood cells.Nucleus is not present in mature RBC. The life span of the red blood cells is about 120 days. They consist of haemoglobin which makes them red in colour. Haemoglobin consists of iron.It transports oxygen from the lungs to the other parts of the body.
Oxygen + Haemoglobin ➡ Oxyhaemoglobin
(b)White Blood Corpuscles - These are also known as leucocytes or white blood cells.Their size is larger than the red blood cells. They don't have any particular shape and often change their shape .They consist of a nucleus.These are colourless as they don't have haemoglobin like the red blood cells.They are formed in the lymph nodes and red bone marrow.The average life span of white blood cells vary from 12 hours to 12 days. They are found in lesser amount than the red blood cells. They help in fighting against infection by engulfing foreign bodies or germs that enter inside the body. They can reach easily the site of infection because of their ability to change the shape.
(c) Blood Platelets - These are also known as thrombocytes.They don't have any nucleus and are colourless.Their size is smaller than the red and white blood cells. The life span of blood platelets is about 3-7 days.They are formed inside the bone marrow.They help in the process of blood clotting.
What are the functions of blood?
The main functions of blood are as follows -
1.It helps to transport nutrients from one part of the body to the other.
2.It helps to transport oxygen from lungs to all the parts of the body.
3.It helps to remove carbon dioxide formed during the process of respiration.
4.It helps to remove waste products from the body. Blood carries metabolic wastes to the kidneys for excretion in the form of urine.
5.White blood cells help in protecting the body from pathogens by destroying them.
6.It transports hormones to the target organ from the site of production.
7.It helps to maintain the balance of water and salts in the body.
8.It helps to distribute the heat produced in the tissues and thus helps in regulating the body temperature.
Which are the different types of blood groups?
Antigens - The proteins present on the surface of red blood cells are known as antigens. They are of two types A and B.
Antibodies - The proteins present on plasma are known as antibodies. They are also of two types A and B.
Blood is divided into different groups on the basis of the presence of antigens and antibodies present in it. These blood groups are as follows -
Blood Group Antigen Antibody
A A B
B B A
AB A and B none
O none A and B
People with blood group AB are known as universal recipients.
People with blood group O are known as universal donors.
Blood transfusion - The process by which the blood of a person is transferred to another person is known as blood transfusion.It is important to match the blood groups of the persons before transferring the blood.
Rhesus Factor - Rhesus factor was firstly discovered in the rhesus monkeys which is a type of protein that is present on the surface of red blood corpuscles. Rhesus factor is inherited genetically from the parents.People having this protein are known as rhesus positive while those who don't have this protein are known as rhesus negative. The positive and negative signs in our blood group are based on this rhesus factor.
To check part 2 of this chapter click on this link : https://lessonstobelearneda-z.blogspot.com/2022/03/structure-and-function-of-heart.html
To check the part 3 of this chapter click on this link : https://lessonstobelearneda-z.blogspot.com/2022/03/pulse-and-blood-pressure.html
Note - If you want to follow the chapter only then just click the link for part 2 of this chapter. No need to follow other external links given in between the chapter.
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