Anatomy and Physiology / Unit 8: The Cardiovascular and Lymphatic Systems
8.2 Red Blood Cells, White Blood Cells and Platelets
Notes
- Erythrocytes: biconcave discs with no nucleus, packed with hemoglobin (iron-containing protein that carries oxygen). About 4.5 to 6 million per microliter. Lifespan about 120 days; old cells are broken down in the spleen and liver. Production is stimulated by erythropoietin (EPO) from the kidneys when oxygen is low.
- Anemia: reduced oxygen-carrying capacity (iron deficiency, B12 deficiency, blood loss). Polycythemia: too many red cells.
- Leukocytes (5,000 to 10,000 per microliter) defend the body: neutrophils (most common, engulf bacteria), lymphocytes (B and T cells, immunity), monocytes (become macrophages), eosinophils (parasites and allergies), basophils (release histamine). Remember: Never Let Monkeys Eat Bananas.
- Platelets are cell fragments (from megakaryocytes) needed for clotting.
- Leukemia is cancer of white blood cell producing tissue.
Practice
Which cell type is the most abundant white blood cell and first to respond to bacterial infection?
Neutrophils engulf bacteria and are usually 50 to 70% of white blood cells.
A person has pale skin, fatigue and low hemoglobin due to a lack of dietary iron. This condition is:
Iron is needed to make hemoglobin; deficiency reduces oxygen transport.
A patient moves to a high mountain location. Over several weeks, the number of RBCs rises. The stimulus is:
EPO stimulates red marrow to make more red blood cells.
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