Blood Physiology

Blood is a connective tissue, a vital fluid circulating throughout the body. It's crucial for delivering oxygen and nutrients while removing waste products.

Arterial blood is rich in oxygen, pumped from the heart to the body tissues.

Venous blood is deoxygenated, returning to the heart after circulating through the body.

The average blood volume in an adult is around 5 liters.

Blood is slightly alkaline with a pH of 7.4.

Blood is thicker than water due to the presence of red blood cells and proteins.

The liquid component of blood, containing proteins, water, hormones, and nutrients.

The solid components of blood, made of red blood cells (RBC), white blood cells(WBC), and platelets.

White blood cells, which are crucial for immune defense against infection and disease.

Red blood cells, responsible for oxygen transport throughout the body.

Platelets, which help blood clot and stop bleeding.

A pigment found in RBCs, responsible for the red color of blood. It binds to oxygen and carbon dioxide.

The normal value of RBC in blood is between 4.5 million and 5.5 million per microliter (cubic millimeter).

The normal value of RBC in blood for adult males is around 5.0 million per microliter.

The normal value of RBC in blood for adult females is around 4.5 million per microliter.

RBCs have a flattened disk shape, concave on both sides.

The central portion of an RBC is thinner than the outer rim.

The biconcave shape allows efficient diffusion of oxygen and other substances, increases surface area for absorption and removal, minimizes tension on the membrane, and allows RBCs to squeeze through capillaries without damage.

RBCs lack a nucleus, mitochondria, and Golgi apparatus. They have a lifespan of 120 days and make up 45% of blood volume.

The process of production, development, and maturation of red blood cells.

Erythropoiesis begins in the yolk sac during the first two months of fetal development.

Erythropoiesis shifts primarily to the liver during the third month of fetal development, with some occurring in the spleen and lymphoid tissues.

Erythropoiesis starts occurring in the bone marrow and liver during the fourth month of fetal development.

Erythropoiesis occurs in the bone marrow of long and flat bones during the first two decades of life.

Erythropoiesis largely occurs in the vertebrae, sternum, ribs, scapula, iliac bones, and skull bones after the age of 20.

Hematopoietic stem cells (HSCs) are primary cells capable of self-renewal and differentiation into various specialized blood cells.

PHSCs can give rise to all types of blood cells.

Committed PHSCs are HSCs that have decided what type of blood cell they will produce.

There are two types of committed PHSCs: lymphoid stem cells (LSCs) and colony-forming unit (CFU) cells.

LSCs produce lymphocytes and natural killer (NK) cells.

CFUs produce myeloid cells, which include the various types of white blood cells, excluding lymphocytes.

Myeloid cells are blood cells other than lymphocytes. They include basophils, eosinophils, and neutrophils.

CFU-erythrocytes (CFU-E) develop into erythrocytes (red blood cells).

CFU-granulocytes/monocytes develop into granulocytes (basophils, eosinophils, neutrophils) and monocytes.

CFU-megakaryocytes (CFU-M) develop into platelets.

The stages of erythropoiesis include proerythroblast, early normoblast, intermediate normoblast, late normoblast, reticulocyte, and matured erythrocytes.

The factors necessary for erythropoiesis include general factors, maturation factors, and factors necessary for hemoglobin formation.

General factors include erythropoietin, thyroxine, hemopoietic growth factors, and vitamins B, C, D, and E.

Maturation factors include vitamin B12 (cyanocobalamin) and intrinsic factor of Castle, which is essential for the absorption of vitamin B12.

Vitamin B12 is essential for the maturation of red blood cells.

Intrinsic factor of Castle is essential for the absorption of vitamin B12 from the intestines.

Deficiency in vitamin B12 can lead to pernicious anemia, a condition marked by red blood cell deficiency.

Vitamin B12 is also called an anti-pernicious factor due to its role in preventing pernicious anemia.

Erythrocyte sedimentation rate (ESR) is the rate at which red blood cells settle down in a vertical tube.

Erythrocyte sedimentation rate (ESR) is also known as sedimentation rate, sed rate, and Biernacki reaction.

The buffy coat is a thin, white layer located between the plasma and the red blood cells. It consists of white blood cells and platelets, making up less than 1% of the blood volume.

Red blood cells have several important functions, including transport of respiratory gases, buffering action, and blood group determination.

Oxygen binds to hemoglobin in red blood cells, forming oxyhemoglobin for oxygen transport. Carbon dioxide also binds to hemoglobin, forming carbhemoglobin.

The presence of antigens A, antigens B, and Rh factors on the surface of red blood cells determines an individual's blood group.