Composition and Constituents of Blood | Zoology Optional Notes for UPSC PDF Download

Introduction

Blood is a vital component of the human body, serving multifaceted roles in maintaining homeostasis and supporting various physiological processes. Comprising red blood cells, white blood cells, platelets, and plasma, it contributes to the regulation of pH, temperature, osmotic pressure, and the distribution of nutrients and hormones.

Learning Objectives

• Identify the complex role of blood in the body.
• Compare and contrast the characteristics of red and white blood cells.
• Describe the fundamental components that constitute blood.

The Role of Blood in the Body

• Blood actively contributes to homeostasis by stabilizing pH, temperature, and osmotic pressure.
• It supports growth through the distribution of nutrients and hormones.
• Red blood cells facilitate oxygen transport, while white blood cells are integral to the immune response.
• The glycolipid and glycoprotein coating on red blood cells leads to the diversity of blood types.

Red Blood Cells

• Erythrocytes, lacking a nucleus and mitochondria, specialize in oxygen delivery through hemoglobin.
• The small size and anucleated nature of mammalian red blood cells enable efficient oxygen transport.
• Some mammals, like camels, exhibit nucleated red blood cells.
• Invertebrates use various respiratory pigments like hemocyanin and chlorocruorin for oxygen transport.

White Blood Cells

• Leukocytes, including granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes), differ from red blood cells in morphology and function.
• Granulocytes act as first responders during injury or infection.
• Agranulocytes, such as lymphocytes and monocytes, contribute to the adaptive immune response.
• B cells, T cells, and natural killer cells have unique roles in immune defense.

Components of Blood

• Beyond proteins like hemoglobin, blood encompasses plasma and cells.
• Platelets and coagulation factors are essential for blood clotting, preventing excessive blood loss.
• Blood plasma, separated into serum without coagulation factors, maintains the body's pH, osmotic balance, and immune defense.

Blood Types Related to Surface Proteins

• Red blood cells are coated with antigens, determined by genetics and grouped into different blood types.
• The ABO and Rh systems define blood types based on the presence or absence of antigens A, B, and Rh.
• Agglutination occurs when antigens and antibodies interact, influencing blood clotting.
• Understanding blood types is crucial for medical and transfusion purposes.

Conclusion

In summary, blood's intricate structure and diverse functions underscore its indispensable role in sustaining life and preserving the body's equilibrium. This understanding is crucial for medical professionals in diagnosing and treating various conditions, as well as for ensuring the compatibility of blood transfusions.