Chapter 18, Lesson 2: Erythrocytes

Flashcards from Chapter 18, Lesson 2 of McGraw Hill Anatomy and Physiology, Ninth Edition, by Kenneth S. Saladin.

Erythrocytes

Also called red blood cells, they transport oxygen and carbon dioxide

Erythrocyte structure

Discoid with a biconcave shape and no organelles with anaerobic fermentation for ATP and no protein synthesis or mitosis

Hemoglobin

Particle that makes up 33% of an erythrocyte’s cytoplasm; gives a red pigment and aids in oxygen and carbon dioxide transport

Glycolipids

Particles on the outer surface of an erythrocyte for blood typing

Hemoglobin structure

4 proteins consisting of a heme group with iron to carry oxygen and globins binding with carbon dioxide

Hematocrit (packed cell volume)

The percentage of whole volume composed of red blood cells; typical values for men are 42-52% and women are 37-48%

Hemoglobin concentration

How much hemoglobin is in a whole blood sample; typical values for men are 13 to 18 g/dL and women 12 to 16 g/dL

Red blood cell count

Blood cells in a sample; men have 4.6 to 6.2 million per microliter and women have 4.2 to 5.4 million per microliter

Gender erythrocyte differences

Women have lower values due to androgens, periodic menstrual losses, and hematocrit being inversely proportional to body fat

Erythropoiesis

Erythrocyte production; occurs at a rate of 3 to 5 days at 1 million per second for a lifespan of 120 days

Erythrocyte production

• Stem cell forms colony-forming units

• Hemoglobin is synthesized as nucleus is discarded

• Polyribosomes disintegrate, creating erythrocytes

Reticulocytes

Immature erythrocytes with polyribosomes

Erythrocyte homeostasis

Maintained through a negative feedback loop; lower counts can result in hypoxemia (oxygen deficiency) but is replaced in 3 to 4 days by kidneys to increase counts in blood loss, high altitudes, exercise, or emphysema

Iron

Used heavily for erythropoiesis but lost through daily life with low absorption

Vitamin B₁₂ and folic acid

Used for rapid cell division and DNA synthesis

Vitamin C and copper

Cofactors for enzymes synthesizing hemoglobin

Erythrocyte death

• Membrane proteins deteriorate

• Cell ruptures in spleen and liver

• Macrophages digest and separate particles; heme becomes biliverdin

Primary polycythemia

Erythrocyte excess with cancer in bone marrow

Secondary polycythemia

Polycythemia from all other causes

Anemia

The deficiency of erythrocytes or hemoglobin, could cause hypoxia or reduced viscosity:

• hemmorhagic (bleeding)

• hemolytic (destroyed)

• insufficient synthesis

Sickle-cell disease

A hereditary hemoglobin effect prominent in Africa, the Middle East, and India where cells are sickle-shaped and cannot carry oxygen as well