PRELIM: RBC Morphology

Transport of oxygen and carbon dioxide

What is the primary function of red blood cells (RBCs)?

25 trillion

Approximately how many RBCs circulate in the body of an adult according to the notes?

Red bone marrow

Where are RBCs primarily produced?

Hematopoietic stem cell → BFU-E → CFU-E → proerythroblast → basophilic erythroblast → polychromatophilic erythroblast → orthochromatic erythroblast → reticulocyte → mature erythrocyte

Which sequence correctly represents erythrocyte development?

Erythropoietin

What does EPO stand for in the context of RBC production?

Kidneys

Which organ produces most erythropoietin (EPO)?

Hypoxia

What condition primarily stimulates increased erythropoietin production?

2 days

A reticulocyte remains in the bone marrow for approximately how long before entering circulation?

1 day

Once reticulocytes enter peripheral blood, approximately how long do they circulate before becoming mature erythrocytes?

Residual ribosomal RNA

Which substance is still present in reticulocytes but absent from mature erythrocytes?

120 days

What is the average lifespan of a normal RBC?

Spleen, liver, and bone marrow

Which group correctly identifies major sites where aged RBCs are destroyed by macrophages?

It is recycled

During RBC destruction, what happens to the iron?

Bilirubin

During RBC breakdown, heme is converted into:

• Oxygen transport

• Carbon dioxide transport

• Acid-base balance

Which of the following are listed as a function of RBCs in the notes?

Acid-base balance

Which RBC function is directly related to maintaining the body's acid-base balance?

Nitric oxide

Which additional substance is transported by RBCs according to the notes?

Biconcave, anucleate, and approximately 7–8 μm

Which description best represents a normal erythrocyte?

7–8 μm

What is the normal diameter of an RBC?

2 μm

What is the approximate thickness of an RBC at its edge?

One-third

The central pallor of a normal RBC occupies approximately what proportion of its diameter?

Pink-orange

What is the normal color of an RBC with Wright stain?

It has neither a nucleus nor organelles

Which statement about a mature normal RBC is correct?

Spectrin

Which membrane component is specifically listed as part of the RBC membrane skeleton?

Spectrin, ankyrin, actin, Band 3 protein, protein 4.1

Which combination contains only RBC membrane components listed in the notes?

They maintain cell shape, flexibility, and deformability

What is the main importance of the RBC membrane proteins described in the lecture?

Hereditary spherocytosis and hereditary elliptocytosis

A defect in the RBC membrane skeleton may result in which disorders?

Large surface area

Which feature of the biconcave shape provides an advantage for oxygen diffusion?

Their membrane provides high flexibility and deformability

Why can normal RBCs pass through capillaries smaller than their own diameter?

Size, color, shape, distribution, inclusions, and arrangement

Which set represents the major characteristics evaluated during RBC morphologic examination?