Unit 3: Blood Part C

Question 1

Hematopoiesis

Answer 1

Production of formed elements (blood cells) from pluripotent hematopoietic stem cells found in
bone marrow

Question 2

Pluripotent hematopoietic stem cells

Answer 2

develop into many diff. cell types
as they specialize, they narrow their possible fates

1st - become UNCOMMITTED STEM CELLS

2nd - then PROGENITOR CELLS that are committed to developing into RBC’s, lymphocytes, other WBC’s, & megakaryocytes (parent cells of platelets)

Question 3

Bone marrow

Answer 3

a soft tissue that fills the hollow center of bones

Question 4

Red marrow

Answer 4

active hematopoiesis (25% of overall production = RBCs, 75% = WBCs)

Question 5

Yellow marrow

Answer 5

= adipose cells, inactive hematopoiesis

Question 6

List the formed element of blood

Answer 6

1. Erythrocytes (Red Blood Cells or RBCs)
2. Leukocytes (White Blood Cells or WBCs)
   a. Lymphocytes – produced directly from Pluripotent stem cell.
   b. Monocytes
   c. Neutrophils
   d. Eosinophils
   e. Basophils (in tissues = mast cells)
3. Platelets (formed from megakaryocytes)

Question 7

What are the 5 types of mature Leukocytes (WBC’s)?

Answer 7

a. Lymphocytes
b. Monocytes
c. Neutrophils
d. Eosinophils
e. Basophils

Question 8

Erythrocytes (Red Blood Cells or RBCs)

Answer 8

• have LOST their nuclei by the time they enter the bloodstream
• key role in transporting O2 from lungs to tissues, & CO2 from tissues to lungs

Question 9

Leukocytes (White Blood Cells or WBC’s)

Answer 9

• ONLY functional cells in the circulation
• key role in body’s immune response, defending the body against foreign invaders (parasites, bacteria, & viruses etc.)
• most circulate through the body in the blood, but their work is usually carried out in the tissues rather than in the circulatory system

Question 10

Platelets

Answer 10

cell fragments that split off a large parent cell known as a megakaryocyte

primary function is hemostasis

Question 11

Lymphocytes

Answer 11

responsible for acquired immune response
sometimes called immunocytes

Question 12

Monocytes

Answer 12

phagocytes; after migrating into tissues, they develop into MACROPHAGES

Question 13

Neutrophils

Answer 13

mobile phagocytes that ingest foreign substances & pathogens release cytokines

Question 14

Eosinophils

Answer 14

produce toxic compounds directed against invading pathogens
allergic reactions

Question 15

Basophils

Answer 15

tissue basophils are also called MAST CELLS
release histamine, heparin

Question 16

What is collectively known as Phagocytes? Why?

Answer 16

Monocytes, Macrophages (what monocytes dev. into), & Neutrophils

b/c they can engulf & ingest foreign particles such as bacteria (phagocytosis)

Question 17

What controls the production and development of blood cells?

Answer 17

cytokines: peptides or proteins released from one cell that affect the growth or activity of another cell

Question 18

List the 4 different types of cytokines:

Answer 18

1. Interleukins
2. Erythropoietin
3. colony stimulating factors
4. thrombopoietin

Question 19

Interleukins

Answer 19

variety of functions including stimulation of uncommitted stem cells to form committed progenitor cells.

Produced and released by WBCs to act on other WBCs

Question 20

Erythropoietin (EPO

Answer 20

Ø stimulates erythropoiesis (red blood cell production)

Ø produced and released by the kidneys in response to low
oxygen levels (hypoxia)
People who are adapted to live at
high altitude have a higher hematocrit as a result.

Ø Erythroblasts (nucleated) –> Reticulocyte—> Erythrocyte (anucleate

Question 21

Colony Stimulating Factors (CSFs)

Answer 21

Ø stimulate leukopoiesis (white blood cell production)

ØSecreted by endothelial cells and fibroblasts in bone marrow, and by other leukocytes.

ØResponds to need. (e.g. during bacterial infection, CSFs stimulate production of neutrophils and monocytes.; viral infections cause increase in proportion of lymphocytes).

Question 22

Thrombopoietin (TPO)

Answer 22

Ø regulates growth and development of megakaryocytes (and
therefore platelet production).

ØProduced and secreted by the liver