Define composition and function of blood.

Blood is a vital connective tissue that plays a crucial role in maintaining the overall health and functioning of the body. It consists of a fluid called plasma, in which various cells and substances are suspended. The composition and functions of blood are as follows:

Composition of Blood:

Plasma: This is the liquid component of blood, making up about 55% of its total volume. Plasma is a pale yellow fluid that contains water, electrolytes, proteins, hormones, waste products, and gases.

Formed Elements: These are the cellular components suspended in the plasma. The formed elements include:

Red Blood Cells (RBCs or erythrocytes): These cells are responsible for transporting oxygen from the lungs to the body tissues and carbon dioxide from the tissues back to the lungs. They contain the protein hemoglobin, which gives blood its red color.
White Blood Cells (WBCs or leukocytes): These cells are part of the immune system and play a crucial role in defending the body against infections. There are different types of white blood cells with specific functions.
Platelets (thrombocytes): These are small cell fragments involved in blood clotting. They help in the formation of blood clots to prevent excessive bleeding.
Functions of Blood:

Transportation: Blood carries oxygen from the lungs to the body tissues and organs and transports carbon dioxide from the tissues back to the lungs for elimination. It also transports nutrients, hormones, waste products, and heat throughout the body.

Immune Defense: White blood cells, antibodies, and other immune system components in the blood help defend the body against pathogens such as bacteria, viruses, and other foreign invaders.

Clotting: Platelets in the blood are essential for blood clotting. They help seal wounds and prevent excessive bleeding when blood vessels are injured.

Regulation of pH and Electrolyte Balance: Blood helps maintain the body's pH within a narrow range, ensuring optimal conditions for enzymatic activity. It also helps regulate electrolyte balance, which is crucial for various physiological processes.

Temperature Regulation: Blood helps regulate body temperature by redistributing heat generated by metabolic processes throughout the body.

Fluid Balance: Blood helps maintain fluid balance in the body by distributing water to various tissues and organs.

In summary, blood is a complex fluid that serves a variety of essential functions, including transportation, immune defense, blood clotting, pH regulation, temperature regulation, and fluid balance. Its composition and cellular elements work together to support the overall health and homeostasis of the body.