HEMATOPOEISIS & COMPONENTS OF BLOOD - MLS 113 - HEMA - LECTURE PRELIM

"For the life of the flesh is in the blood, and I have given it to you on the altar to make atonement for your souls; for it is the blood by reason of the life that makes atonement." — Leviticus 17:11 (LSB)

What is the main function of eosinophils?

Defense against parasites and regulation of allergic reactions (2–4% of WBCs).

What percentage of neutrophils is normally found in the blood?

60–70%; they are the first line of defense against bacteria and foreign bodies.

Which cells are responsible for humoral immunity?

Lymphocytes (20–25%), including T cells and B cells.

What is the normal size of a mature erythrocyte?

7–8 μm diameter, 1.5–2.5 μm thick, MCV: 80–100 fL.

What is the central pallor in an RBC?

The lighter area in the center, occupying about 1/3 of the cell due to biconcavity.

What are the main components of plasma?

90–92% water, 7–8% proteins (albumin, globulins, fibrinogen), ~1% other substances.

What is the difference between plasma and serum?

Plasma contains clotting factors; serum is the fluid after blood has clotted (no fibrinogen).

What does hematocrit measure?

The percentage of blood volume made up of RBCs (normal ≈ 50%).

Define MCV, MCH, and MCHC.

MCV: average RBC size; MCH: hemoglobin per RBC; MCHC: hemoglobin concentration in RBCs.

What is a reticulocyte?

An immature RBC with residual RNA, slightly larger and blue-gray; 0.5–2.5% of RBCs.

What distinguishes band neutrophils from segmented neutrophils?

Bands have an unsegmented horseshoe-shaped nucleus; segments have 2–5 lobes connected by thin filaments.

Key staining features of eosinophils?

Large, orange-red granules (acid-loving), MBP (Major Basic Protein) in crystalloid core.

Key staining features of basophils?

Large violet-blue granules that may obscure the nucleus, stain with basic dyes.

Percentage of lymphocytes in blood?

20–44%; small size, round nucleus, minimal cytoplasm.

Distinguishing feature of monocytes?

Kidney-shaped or brain-like nucleus, ground-glass cytoplasm with fine granules.

Normal platelet size and count?

1–4 μm diameter; 150–350 × 10⁹/L.

What is hematopoiesis?

Continuous production, differentiation, and maturation of blood cells from hematopoietic stem cells (HSCs).

Sites of hematopoiesis during development?

Mesoblastic: yolk sac; Hepatic: liver; Myeloid: bone marrow (continues after birth).

What hormone regulates RBC production?

Erythropoietin (EPO) — produced mainly by kidneys in response to hypoxia.

Primary vs secondary lymphoid organs?

Primary: bone marrow, thymus; Secondary: liver, spleen, lymph nodes.

What is the lifespan of a red blood cell?

About 120 days.

What is polycythemia?

Increased RBC count, leading to increased blood viscosity.

What is anemia?

A decrease in oxygen-carrying capacity of blood due to reduced RBC count or hemoglobin concentration.

What is the normal WBC count in adults?

4–11 × 10⁹/L.

What are lysosomes in neutrophils?

Membrane-bound organelles with digestive enzymes that break down pathogens and cell debris.

What is diurnal variation in eosinophil count?

Higher at night, lower in the morning due to cortisol levels.

What are the three major blood cell lineages?

Erythrocytes, leukocytes, thrombocytes.

What is the origin of all blood cells?

Hematopoietic stem cell (HSC) / hemocytoblast in the bone marrow.

What are cytokines in hematopoiesis?

Signalling molecules like interleukins and CSFs that regulate cell proliferation and differentiation.

What are natural killer (NK) cells?

Lymphocytes that destroy infected or cancerous cells without prior sensitization.

What is megakaryopoiesis?

Production and maturation of platelets from megakaryocytes.

What is the role of opsonization in monocyte function?

Coating pathogens with opsonins to enhance phagocytosis.

What is the typical nuclear shape of monocytes?

Kidney-shaped, indented, or brain-like convolutions.

How are platelets estimated in a smear?

Count platelets in 10 oil immersion fields; normal is 7–15 per field.

What is the main function of platelets in hemostasis?

Adhere, aggregate, and provide surface for clotting reactions.

What are the three stages of hematopoiesis in embryonic life?

Mesoblastic (yolk sac), hepatic (liver), myeloid (bone marrow).

What are primary lymphoid organs?

Bone marrow and thymus—sites of initial lymphocyte development.

What are secondary lymphoid organs?

Liver, spleen, lymph nodes—sites of immune cell activation and maturation.

What are digestive vacuoles?

Structures in monocytes/neutrophils that degrade engulfed material.

What is the “packed cell volume” (PCV)?

Another term for hematocrit—percentage of blood composed of RBCs.