What is Blood? know everything about Blood

What is Blood?

• Blood is a red-coloured fluid which carries oxygen and other necessary nutrients to the cells and transports away carbon-di-oxide and other body waste from these cells in Human and other animals.
• In other words, we can say that Blood is a medium of transport that is pumped by the heart to all the body parts of a human as well as an animal, then it travels back to the heart, and this process repeats again and again.
• Blood is a tissue as well as a fluid. Blood is a tissue because it is a collection of some specialized cells which serves a particular function and these cells are suspended in plasma, which makes it fluid.
• In the human body blood is around 7% of human body weight and an adult has approximately 5 litres of blood in the body.
• Blood in humans appears red in colour due to the presence of Hemoglobin. Every molecule has four heme groups and when they interact with other molecules is causes the alteration of the exact colour.
• The blood present in arterials and capillaries is bright red. This bright red colour is imparted by the oxygen to the heme group.
• The blood presents in the veins are a darker shade of red because it is deoxygenated blood.
• The colour of the blood is bright or dark red is due to the absorption of light by haemoglobin is different for oxygenated and deoxygenated blood. All the term related to blood in medical term often starts with hemo or hemato.

Functions of the Blood -

• Blood Supplies Oxygen to the cells and tissues.
• Blood provides nutrients-Amino Acids, Fatty Acids, and Glucose to the cells.
• Blood protects the human body from disease and infection through white blood cells.
• Blood removes impurities and waste material-Carbon-di-Oxide, Urea, etc.
• Blood helps to maintain body temperature and pH levels.
• Blood transport the hormones and work as a messenger.
• Blood also performs Immunological Functions
• Coagulation

Constituents of the Blood -

The blood is made up of plasma and formed elements. The formed elements are of two types of blood cells- the red blood cells and white blood cells and the cell fragments called platelets. The red blood cells are 45% by volume of the whole blood, the plasma is 54.3% and white blood cells are 0.7%.

Red Blood Cells - The Red blood cells present in the blood is also known as Erythrocytes. These red blood cells contain haemoglobin and distribute oxygen to the cells of the body. It is 45% of the whole blood. The surface area of all the red blood cells is combined together then it will be around 2000 times the body's exterior surface. The number of red blood cells found in males is around 4.7-6.1 million and in females are 4.2-5.4 million.

White Blood Cells - The white blood cells present in the blood is also known as Leukocytes. These white blood cells are part of the human immune system. White blood cells destroy dead and old cells and attack foreign or infectious pathogens. The number of white blood cells found in humans is around 4000-11,000 and it is 0.7% of the whole blood.

Plasma - Plasma present in the blood is also known as Platelets. These are responsible for blood clotting. It is 54.3% of the whole blood. It provides the blood liquid medium and is straw-yellow in colour. The plasmas work is to circulate dissolved nutrients and remove waste products. Other constituents of the blood are- Antibodies, Proteins, Electrolytes-Sodium Chloride, Serum Albumin.

The pH of the Blood -

• The blood's pH should be in the range of 7.35-7.45(Slightly basic in nature).
• If the pH value of the blood falls below 7.35 then it will make the blood acidic.
• If the pH value of the blood rises above 7.45 then it will make blood more basic.

Blood Circulation in Humans -

The blood in humans circulated in the whole body through blood vessels by the heart. The blood is pumped through the left ventricle of the heart through arteries to tissues and returns to the right atrium of the heart through veins. It then enters the right ventricle and is pumped through the pulmonary artery to the lungs and returns to the left atrium through pulmonary veins. Blood then enters the left ventricle to be circulated again. Arterial blood carries oxygen from inhaled air to all of the cells of the body, and venous blood carries carbon dioxide, a waste product to the lungs to be exhaled. Pulmonary arteries contain the most deoxygenated blood in the body and pulmonary veins contain oxygenated blood.

Blood Groups -

Blood is can be divided into groups based on the presence and absence of certain antigens and antibodies. Antibodies are proteins that are present in the plasma. These antibodies alert the immune system about the presence of foreign pathogens so that the immune system can attack the foreign pathogens and can save the body from the disease or infection. Antigens are also proteins present on the surface of the red blood cells.

There are two types of blood group system- 1. ABO Blood Group 2. Rh Blood Group

ABO Blood Group -ABO Blood Group is decided by two antigens & antibodies i.e., Antigen-A & Antigen-B and Antibody-A, Antibody-B. ABO Blood Group is divided into four categories based on the presence or absence of antigens on the surface of the red blood cells or plasma.

A-Group - Antigen-A found on the surface of the red blood cells and Antibody-B is found in the plasma.

B-Group - Antigen-B is found on the surface of the red blood cells and Antibody-A is found in the plasma.

AB-Group -Both A and B Antigens are found on the surface of the red blood cells and no Antibodies are found in the plasma.

O-Group - Both Antibodies-A & B are found in the plasma and no Antigens found on the surface of the red blood cells.

Rh Blood Group - Most of the population in the world have a third antigen that is Rh antigen or Rh Factor on the red blood cells surface. This Rh Factor decides that the blood group will be positive or negative. If Rh factor present in a person’s red blood surface, then that person will be Rh +ve and if not then Rh -ve. So due to this whenever we require blood, we should check combability between donor and person. Who can give blood to whom- -If a person has O-Group blood then they can donate to A, B, AB & O Groups. -If a person has A-Group blood then they can donate to A & AB Groups. - If a person has B-Group blood then they can donate to B, & AB Groups. - If a person has AB-Group blood then they can donate to AB Group only.

Disease and Disorders related to the Blood -

Blood-related disease and disorders can be very dangerous as blood circulated throughout the body and can cause the malfunction of many parts of the body. Here are some disorders and disease which are related to blood-

1. If there is a change in volume of the blood in the body-
   • If a person loses an excess amount of blood due to an injury, then coagulation will not be possible and may cause trauma to the internal organs which may result in internal bleeding.
   • Dehydration can change the amount of blood in the body by reducing the water content of the blood. This may lead to orthostatic hypotension and fainting.
2. Blood Circulation disorder-
   • Can cause blood loss, infection and poor cardiac performance.
   • Heart problems
3. Anaemia - This disease is caused by the shortage of red blood cells in the blood. As a result, cells won’t be able to transport oxygen properly. Symptoms of Anemia are fatigue and pale skin.
4. Blood-Clotting -
5. This can affect the healing process of the injuries. Sometimes it may cause heart attacks so blood clots can be dangerous.
6. Blood Cancers - Leukemia and Lymphoma are blood cancers.