Composition of Blood and Erythrocytes

Study Notes

Composition of Blood

Blood is a complex fluid connective tissue.
It comprises plasma, a yellowish liquid, and formed elements (cells and cell fragments).
Plasma accounts for about 55% of blood volume.
Plasma is mostly water (90-92%), with dissolved proteins (albumin, globulins, fibrinogen), electrolytes (e.g., sodium, potassium, calcium), nutrients, waste products, and hormones.
Formed elements include erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes (platelets).
Erythrocytes are the most numerous blood cells and are responsible for oxygen transport.
Leukocytes are involved in the immune response and defense mechanisms.
Thrombocytes are essential for blood clotting.

Erythrocytes (Red Blood Cells)

Erythrocytes are biconcave discs, lacking a nucleus in mammals.
They are filled with hemoglobin, a protein that binds oxygen.
Hemoglobin gives blood its red color.
Function primarily in oxygen transport from the lungs to the body tissues and carbon dioxide transport from tissues to the lungs.
Erythrocytes have a lifespan of about 120 days.
Their breakdown occurs in the spleen and liver.

Leukocytes (White Blood Cells)

Leukocytes are crucial components of the immune system.
They defend the body against pathogens and foreign substances.
Leukocytes are classified into granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes).
Granulocytes have granules in their cytoplasm, while agranulocytes do not.
Neutrophils are phagocytic cells that engulf and destroy microorganisms.
Eosinophils combat parasitic infections and allergic reactions.
Basophils release histamine and heparin, playing a role in inflammation.
Lymphocytes (T cells and B cells) are key players in adaptive immunity, mediating specific responses to antigens.
Monocytes differentiate into macrophages, which engulf cellular debris and pathogens.

Thrombocytes (Platelets)

Thrombocytes are small cell fragments derived from megakaryocytes.
They play a vital role in blood clotting (hemostasis).
Platelets release clotting factors and promote the formation of a platelet plug at the site of injury.
They participate in the coagulation cascade, leading to the conversion of fibrinogen to fibrin, forming a stable clot.

Blood Types

Blood is categorized into different types based on the presence or absence of specific antigens on the surface of red blood cells.
The most common blood typing system is the ABO system (A, B, AB, O) and the Rh system (positive or negative).
Blood transfusions must be carefully matched to prevent a harmful immune response, an important consideration in healthcare.

Blood Functions

Blood plays an essential transport role, delivering oxygen and nutrients to tissues and removing waste products.
Blood also regulates body temperature, pH, and fluid balance.
Blood protects the body by carrying antibodies and cells involved in the immune response.
The clotting mechanism protects the body from excessive blood loss.

Description

Explore the fascinating composition of blood, including plasma and formed elements. Learn about the vital roles of erythrocytes in oxygen transport and the importance of leukocytes and thrombocytes in immune response and clotting.