Lecture 2 1/22/24

Question 1

What is hematopoiesis?

Answer 1

the formation of blood cellular components

Question 2

Which components are involved in hematopoiesis?

Answer 2

-stem cells
-cytokines

Question 3

Where does hematopoiesis primarily occur in mammals?

Answer 3

bone marrow

Question 4

What is extramedullary hematopoiesis?

Answer 4

hematopoiesis occurring outside the bone marrow (liver, spleen, lymph nodes) when there is an increased need for cellular blood components

Question 5

What are the characteristics of hematopoietic stem cells?

Answer 5

-mononuclear cells
-long-term self-renewal
-differentiate/commit to cell lines

Question 6

What are the two types of hematopoietic stem cell lines?

Answer 6

-lymphoid
-myeloid

Question 7

Which cell types arise from the lymphoid lineage?

Answer 7

-B cells
-T cells
-NK cells

Question 8

What is the erythron?

Answer 8

total amount of RBCs in the body

Question 9

What are the three pools that make up the erythron?

Answer 9

-marrow
-blood
-spleen

Question 10

What are the cellular steps of RBC maturation?

Answer 10

-rubriblast
-prorubricyte
-rubricyte
-metarubricyte
-reticulocyte
-erythrocyte

Question 11

What happens during RBC maturation?

Answer 11

-decrease in cell size
-decrease in nucleus size
-compaction of chromatin
-cytoplasmic color change

Question 12

How are old erythrocytes removed from circulation?

Answer 12

phagocytosis via macrophages

Question 13

During which step of RBC maturation is the nucleus extruded?

Answer 13

metarubricyte to reticulocyte

Question 14

Which cell type is the best indicator of regeneration?

Answer 14

reticulocytes

Question 15

Which species does not have reticulocytes?

Answer 15

horses

Question 16

What is the cycle involving erythropoietin?

Answer 16

-renal hypoxia stimulates the kidneys to produce erythropoietin
-increased erythropoietin levels stimulate increased RBC production
-result is erythroid hyperplasia

Question 17

What are the three causes of renal hypoxia?

Answer 17

-anemia
-poor oxygenation of blood
-poor renal perfusion

Question 18

How are RBCs broken down extravascularly?

Answer 18

-macrophages phagocytose old RBCs
-RBCs are broken down in the lysosome to produce heme, amino acids, and porphyrin

Question 19

What are the potential fates of heme?

Answer 19

-storage via hemosiderin
-transfer to the bone marrow for erythropoiesis via apotransferrin and transferrin

Question 20

What is the fate of porphyrin?

Answer 20

-converted into biliverdin and eventually unconjugated bilirubin
-sent to the liver for conjugation and bile formation

Question 21

What happens to bile/conjugated bilirubin?

Answer 21

-excreted into the intestine
-converted into urobilinogen

Question 22

What are the fates of urobilinogen?

Answer 22

-excreted in urine
-recirculated to the liver
-converted to stercobilinogen

Question 23

What are the characteristics of thrombopoiesis?

Answer 23

-formation of platelets from megakaryocytes
-platelets delivered into circulation
-mediated by thrombopoietin

Question 24

Which tissues constantly produce thrombopoietin (TPO)?

Answer 24

-hepatocytes
-renal epithelium
-stromal cells in bone marrow

Question 25

Which cell type constantly clears TPO?

Answer 25

platelets/megakaryocytes

Question 26

What is seen with TPO levels in good health?

Answer 26

TPO levels are kept low due to clearance by the normal platelet mass

Question 27

What occurs when an animal has decreased platelet mass?

Answer 27

-increased TPO levels
-increased production of platelets
-megakaryocytic hyperplasia in bone marrow