Hematology Overview – Blood Basics and Leukocytes

These flashcards review the physical properties, composition, functions, and cell types of blood, as well as hematopoiesis, laboratory tests, and leukocyte biology as discussed in Dr. McVay’s hematology overview.

What characteristics give blood its distinctive appearance and texture?

It is a sticky, opaque fluid with a metallic taste that appears scarlet when oxygen-rich and dark red when oxygen-poor.

What are the normal pH?

Blood pH is 7.35–7.45 and is slightly higher than normal body temperature.

Name the three primary functions of blood.

1) Transport/Distribution, 2) Regulation (temperature, pH, fluid volume), 3) Protection (clotting and immune defenses).

Which formed element percentage is measured by the hematocrit, and what is its normal range?

The hematocrit measures the percentage of red blood cells (RBCs); normal values are about 45 % of total blood volume.

What percentage of whole blood is plasma, and what is its main component?

Plasma makes up ~55 % of whole blood and is 91 % water.

List the four major groups of plasma proteins and their main producer.

Albumin, clotting proteins, alpha and beta globulins, and gamma globulins; all are made in the liver except gamma globulins, which are made by plasma cells.

Why are plasma proteins important for capillary exchange?

Their large size keeps them in the bloodstream, generating colloid osmotic pressure that draws fluid back into capillaries.

Give the normal circulating counts for RBCs, WBCs, and platelets.

RBCs: 4–6 million/µL; WBCs: 5–10 thousand/µL; Platelets: 150–400 thousand/µL.

Define hematopoiesis and state where it occurs in adults.

Hematopoiesis is blood cell formation; it occurs in red bone marrow.

What stem cell is the common precursor to all formed elements?

The hemocytoblast (pluripotent stem cell).

What information does a Complete Blood Count (CBC) provide?

It quickly reports hematocrit, hemoglobin concentration, and counts of RBCs, WBCs, and platelets.

Which test panel measures electrolytes, glucose, lipids, and organ enzymes?

The blood chemistry profile.

Define leukocytosis and give its typical trigger.

Leukocytosis is a WBC count above 11,000/mm³, usually a normal response to inflammation or infection.

Which leukocytes are granulocytes, and what is their shared feature?

Neutrophils, eosinophils, and basophils—each contains cytoplasmic granules and a lobulated nucleus.

State the percentage and primary job of neutrophils.

50–70 % of WBCs; they are phagocytes that attack bacteria.

What is the chief function of eosinophils and their normal percentage?

They secrete toxic substances to kill parasites and perform limited phagocytosis; 1–4 % of WBCs.

Which chemicals are released by basophils and what is their role?

Histamine (vasodilation, attracts WBCs) and heparin (anticoagulant) to promote inflammation; basophils make up 0.5–1 % of WBCs.

Describe monocytes in blood and their fate in tissues.

They are 3–8 % of WBCs, have a horseshoe nucleus, and differentiate into macrophages that perform powerful phagocytosis in tissues.

Which leukocyte type drives the immune response and what is its relative abundance?

Lymphocytes, comprising 20–40 % of WBCs, coordinate adaptive immunity through antibody production and cytotoxic activity.

How does leukemia differ from leukocytosis?

Leukemia is a cancerous overproduction of abnormal WBCs, whereas leukocytosis is a temporary, normal rise in functional WBCs during inflammation.