– Blood is a vital fluid that performs many functions in the human body. It is composed of four main components: plasma, red blood cells, white blood cells, and platelets. Each component has a specific role and function in blood. Here is a summary of the components of blood and their functions and uses:
Plasma
– Plasma is the liquid part of blood that makes up about 55% of total blood volume. It is mostly water (92%), but also contains proteins, electrolytes, hormones, antibodies, and other substances.
Plasma has several functions, such as:
• Transporting gases (oxygen, carbon dioxide, nitrogen), nutrients, and hormones throughout the body.
• Helping with the maintenance of acid-base homeostasis by buffering pH and osmotic balance.
• Regulating body temperature by balancing heat loss and heat gain.
• Providing clotting factors and immunoglobulins for coagulation and immunity.
Red blood cells
– Red blood cells, or erythrocytes, are specialized cells that circulate through the body and deliver oxygen to tissues. They make up about 45% of total blood volume. They are small and biconcave (thinnest in the center) and do not contain a nucleus or mitochondria when mature.
Red blood cells have several functions, such as:
• Carrying oxygen bound to their hemoglobin molecules (a protein that contains iron) from the lungs to the tissues.
• Carrying carbon dioxide bound to their hemoglobin molecules or dissolved in plasma from the tissues to the lungs.
• Participating in acid-base balance by exchanging hydrogen ions and bicarbonate ions with plasma.
White blood cells
– White blood cells, or leukocytes, are part of the immune system and function in immune response. They make up about 1% of total blood volume. They are larger than red blood cells and have a nucleus and organelles.
There are five types of white blood cells, each with a different function and appearance. They are:
🔅 Neutrophils: They are the most abundant type of white blood cells (50-70%) and have a multilobed nucleus and granules in their cytoplasm. They are involved in phagocytosis (ingestion) of bacteria and other foreign particles.
🔅 Eosinophils: They are less abundant than neutrophils (1-4%) and have a bilobed nucleus and red granules in their cytoplasm. They are involved in allergic reactions and parasitic infections.
🔅 Basophils: They are the least abundant type of white blood cells (<1%) and have a lobed nucleus and blue granules in their cytoplasm. They are involved in inflammatory responses and release histamine (a chemical that causes vasodilation and increased permeability of blood vessels) and heparin (an anticoagulant).
🔅 Lymphocytes: They are the second most abundant type of white blood cells (20-40%) and have a large round nucleus and little cytoplasm. They are involved in specific immune responses and can be divided into two types: B lymphocytes (B cells) and T lymphocytes (T cells). B cells produce antibodies that bind to antigens (foreign substances) and mark them for destruction. T cells recognize antigens presented by other cells and either kill them directly or activate other immune cells.
🔅 Monocytes: They are less abundant than lymphocytes (2-8%) and have a kidney-shaped nucleus and abundant cytoplasm. They are involved in phagocytosis of bacteria, viruses, dead cells, and debris. They can also differentiate into macrophages (large phagocytic cells) or dendritic cells (antigen-presenting cells) in tissues.
Platelets
– Platelets, or thrombocytes, are cell fragments that are responsible for hemostasis (prevention of blood loss). They make up about 0.1% of total blood volume. They are derived from megakaryocytes (large bone marrow cells) and do not have a nucleus but contain granules with clotting factors and other substances. Platelets have several functions, such as:
• Adhering to damaged blood vessels and forming a platelet plug to stop bleeding.
• Releasing clotting factors that activate a cascade of reactions that result in the formation of fibrin (a protein that forms a mesh-like structure that traps red blood cells and forms a clot).
• Releasing growth factors that promote healing of injured tissues.
Blood is essential for life as it performs many vital functions in the body. It is important to understand the components of blood and their functions and uses for health and disease prevention.
