22.3:
Composition of Blood
Whole blood consists of the blood plasma, a fluid extracellular matrix, and formed elements, including cells and cell fragments.
Blood plasma, which makes up about 55% of total blood volume, is a yellowish fluid. It is predominantly water dissolved with vital substances, such as electrolytes and proteins.
It also acts as a medium for carrying nutrients, enzymes, antibodies, hormones, gasses, and blood cells.
Red blood cells, white blood cells, and platelets, collectively known as the formed elements, make up 45% of the blood's volume.
The red blood cells or erythrocytes comprise about 99% of the formed elements; their percentage in the total volume of a blood sample is known as the hematocrit.
The mature erythrocytes are anucleated and contain hemoglobin — a specialized protein that binds and transports oxygen and carbon dioxide between lungs and tissues.
The white blood cells or leukocytes are a group of nucleated cells involved in immune responses.
Lastly, platelets are enucleated cell fragments essential for clotting and repairing damaged blood vessels.
22.3:
Composition of Blood
The blood in our bodies comprises three major components: blood plasma, formed elements, and the extracellular matrix. Blood plasma is a yellowish fluid that constitutes 55% of the total blood volume. It is primarily made up of water and essential substances such as electrolytes and proteins. Blood plasma serves as a medium for transporting blood cells and also contains nutrients, enzymes, hormones, antibodies, and gases.
Formed elements constitute the remaining 45% of the blood volume. These elements include red cells, white cells, and platelets. Red cells, or erythrocytes, account for about 99% of the formed elements. The proportion of erythrocytes in a blood sample's total volume is known as the hematocrit. Mature erythrocytes are anucleated and contain hemoglobin, a specialized protein that binds and transports oxygen and carbon dioxide between the lungs and tissues.
White cells, or leukocytes, are nucleated cells involved in immune responses and play a crucial role in defending the body against infections.
Lastly, platelets, small enucleated cell fragments, are essential for clotting and repairing damaged blood vessels.