Human Blood Composition

What percentage of the body weight is approximately equal to the normal blood volume?

What is the approximate life span of WBCs in the blood?

What is the primary function of platelets in the blood?

What is the approximate percentage of WBCs in the blood that are myeloid cells?

What is the approximate ratio of RBCs to WBCs in the blood?

What is the approximate percentage of platelets that are stored in the spleen?

What is the primary function of erythrocytes in the circulation?

What is the typical lifespan of an erythrocyte in the circulation?

What is the term for the percentage of blood volume occupied by erythrocytes?

What is the molecular weight of hemoglobin?

What is the name of the glycoprotein chain that differs by 10 amino acids in HbA2 compared to HbA?

What is the term for the process by which glucose attaches to the terminal valine in the beta chain of hemoglobin?

What is the name of the complex formed when hemoglobin binds to oxygen?

What is the stimulus for the production of erythrocytes in the bone marrow?

Blood Composition

Blood consists of 55% plasma and 45% cellular elements
Plasma is composed of proteins, minerals, and water
Cellular elements include RBCs, WBCs, and platelets

Blood Volume

Normal blood volume is approximately 8% of body weight
For a 70kg person, blood volume is approximately 5.6L

Plasma and Cellular Elements Volumes

Plasma volume is approximately 3.08L (55% of 5.6L)
Cellular elements volume is approximately 2.52L (45% of 5.6L)

Bone Marrow (BM)

BM is a large organ and is highly active
BM size is comparable to liver size
BM weight is comparable to liver weight
BM stem cells differentiate into WBCs (75% myeloid and 25% maturing RBCs)

Red Blood Cells (RBCs)

There are approximately 5 million RBCs for every 10,000 WBCs
RBCs have a lifespan of 120 days
RBCs are produced in the red bone marrow
Immature RBCs have a nucleus, which is lost in mature RBCs
Normal RBC count is 5.4 million/uL in males and 4.8 million/uL in females
Hematocrit is the volume of blood occupied by RBCs
RBCs have a diameter of 7.5um and a thickness of 2um
Each RBC contains approximately 29pg of Hb

White Blood Cells (WBCs)

WBCs have a lifespan of hours
Monocytes differentiate into tissue macrophages (e.g., Kupffer cells, osteoclasts, mast cells, dendritic cells, and Langerhans cells)

Platelets

Platelets are produced from megakaryocytes through fragmentation
Platelets have a lifespan of 4 days
Normal platelet count is approximately 300,000/uL
60-70% of platelets circulate in the blood, while 30-40% are stored in the spleen
Splenectomy increases platelet count due to the release of stored platelets

Hemoglobin (Hb)

Hb is a protein that carries oxygen in the blood
Hb has a molecular weight of 6445D
Hb is composed of four subunits, each consisting of a heme group and a polypeptide chain
Adult Hb is 97.5% of type A (α2β2) and 2.5% of type A2 (α2δ2)
HbA1c is a glycated form of Hb that indicates poor glucose control in diabetes mellitus

This quiz covers the composition of human blood, including the proportions of plasma and cellular elements, and the characteristics of blood marrow. It also discusses the relative numbers of red blood cells and white blood cells.