BLOOD

    From the starting of the animal kingdom itself as we move along the line of phyla we observe that right from within a single cell to amongst many cells to amongst organs there is a transport system. Every cell needs nutrition and oxygen. We, humans, being a part of Vertebrata, Mammalia we have a complex transport system in our bodies-Blood. Blood is the transport fluid of our bodies. It carries not just nutrition but also oxygen, carbon dioxide, water, waste products, hormones, etc. Such an important connective tissue of our bodies that travels throughout but in a closed system (only within veins and arteries) and double circulation (from different parts of the body to heart, from the heart to lungs, from lungs to heart- Blood comes twice into the heart) which ensures blood which is oxygenated and deoxygenated is separated and can be efficiently oxygenated.

 

Illustration: Red Blood Corpuscle.

Blood consists of plasma and cellular components.

1. Plasma is the liquid component of blood. Why liquid? Because it contains sugar, fat, protein, salts and the most important water! This water helps our blood to move around the body within the arteries and veins.

2. Now with the blood moving around the body it will also carry/transport various other materials e.g. blood cells, waste products, nutrients etc.

3. Cellular components consist of Red Blood Cells (RBCs), White Blood Cells (WBCs), Platelets (Thrombocytes).

    Plasma: - As discussed above plasma is the liquid component of the blood. It is a straw-coloured fluid; it can be obtained when RBCs (Erythrocytes), WBCs (Leukocytes), and platelets (Thrombocytes) are separated.

Now an important question we need to ask ourselves- What would be remaining in the plasma when all these cellular contents are separated?

    The answer to this is clear- 91-92% is water hence, fluid. Now a clear straw coloured fluid it means the other contents that comprise the plasma has to be in the dissolved form. Yes, it is. But there are also insoluble contents. Always remember blood is a solution made of different solutes and solvents, hence in plasma, we can say that water is the solvent and solutes are the components that are present.

    Now, in order for us to clearly remember the contents of plasma we will explain to them as follows:-

1. Water: - Present 91-92% the chief component of plasma and a suspending medium for components of blood.

2. Proteins:- Albumin, Globulins, Fibrinogens, hormones

3. Vitamins

4. Lipids, Amino acids.

5. Electrolytes- Na+, K+, Ca2+, Cl-, HCO3- etc.

6. Clotting factors.

7. Respiratory gases- Oxygen, Carbon dioxide.

8. Nitrogenous waste- Urea, Creatinine.

Blood serum is plasma without clotting factors. This can be obtained by centrifugation of fresh blood with an anticoagulant.

We will discuss all the above components of plasma and their functions in detail in the next discussions.

References:

• Encyclopædia Britannica
• https://www.britannica.com/science/plasma-biology

• AMERICAN SOCIETY OF HEMATOLOGY
• https://www.hematology.org/education/patients/blood-basics