Lecture 1 Intro to RBCs

Question 1

What is the function of blood?

Answer 1

• Transport gases, nutrients, hormones and metabolic wastes
• Regulates pH, ions, water
• Restricts fluid loss via blood clotting
• Defends against toxins and pathogens
• Regulates body temp

Question 2

What is hematocrit?

Answer 2

% of total blood volume occupied by red blood cells (normal 37-54%)

Question 3

What does plasma consist of?

Answer 3

• Water (92%)
• ions
• organic molecules
• Trace elements and vitamins
• Gases

Question 4

What proteins are found in plasma?

Answer 4

• Albumins (60%) –> osmotic pressure
• Globulins (35%) –> antibodies
• Fibrinogen (4%) –> fibrin -> blood clotting

Question 5

What are the cellular elements in blood?

Answer 5

• Erythrocytes: Red Blood Cells
• Leukocytes: White Blood Cells
• Thrombocytes: Platelets

Question 6

What do RBCs contain?

Answer 6

Hemoglobin and enzymes

Question 7

How many RBCs are there per microliter of blood?

Answer 7

about 5 million

Question 8

Describe the structure of a Hemoglobin Molecule

Answer 8

• 2 alpha chains
• 2 beta chains
• 4 heme structures (one in each chain)
• 4 iron atoms (found in the center of each heme)

Question 9

How many oxygen atoms can each hemoglobin molecule carry?

Answer 9

4 oxygen atoms

Question 10

Describe RBC production and removal

Answer 10

• Produces and removal same rate
• Rate is 2-3 million per second

Question 11

What is Erythropoiesis?

Answer 11

• Production of Erythrocytes from hematopoietic precursor cells in the bone marrow
• Requires iron, Vitamin B12 and folate from diet

Question 12

What is erythropoietin?

Answer 12

• Hormone made in the kidneys which promotes erythropoiesis
• Secreted in response to low oxygen levels
• Secretion leads to an increase in RBC production

Question 13

What happens when Hypoxia Inducible Factor (HIF1alpha) becomes stable?

Answer 13

• Signals low oxygen
• Activates transcription of erythropoietin gene
• Increases RBC production
• Increases Oxygen Circulation

Question 14

In bone marrow, what percent of cells develop into erythrocytes and what percent develop into leukocytes?

Answer 14

• 25% erythrocytes
• 75% leukocytes
  (more erythrocytes in body than leukocytes, however, leukocytes have a higher production rate)

Question 15

How are platelets formed?

Answer 15

• Formed by the breakdown of megakaryocytes in the bone marrow to the blood circulation

Question 16

What is hematopoiesis?

Answer 16

• Process of blood cell formation from occurring in bone marrow
  Development of
• erythrocytes (RBCs)
• Leukocytes (WBCs)
• Thrombocytes (Platelets)

Question 17

What regulates hematopoiesis?

Answer 17

Cytokines

Question 18

What are sites of hematopoiesis?

Answer 18

In Embryo: Yolk sac, Liver, Spleen, Bone marrow
After Birth: Bone marrow
Adults: Pelvis, spine, ribs, cranium, proximal end long bones

Question 19

How are RBCs removed?

Answer 19

• Degraded by Macrophages
• Iron is recycled for new RBCs and transported to bone marrow by Transferrin
• Heme produces Bilirubin and transported to the liver and excreted in bile

Question 20

What are causes of Jaundice (hyperbilirubinemia)

Answer 20

• Large release of hemoglobin from degraded RBCs
• High turnover of RBC
• Liver disease
• Bile duct obstruction (pushing bile back into the liver)

Question 21

What are causes of low RBC production?

Answer 21

• Destruction of stem cells via drugs or radiation
• Inadequate nutrients: iron, folic acid, vitamin B12
• Low erythropoietin (renal)

Question 22

What causes high removal of RBCs?

Answer 22

• Genetic: defect in RBC proteins (hemoglobin)
• Parasitic infections
• drugs
• Autoimmune reactions
• Hemorrhagic (excessive blood loss)

Question 23

What is Polycythemia?

Answer 23

• Hematocrit is too high (too many RBCs)
• Caused by abnormal erythrocyte precursors
• Low oxygen delivery to tissues