TURGEON (5TH ED. | ERYTHROCYTE MATURATION, PHYSIOLOGY, AND LIFECYCLE

Question 1

What are the (4) characteristics of a mature erythrocyte?

Answer 1

1) Biconcave disc
2) Has a central pallor (1/3 of the cell)
3) Soft
4) Pliable

Question 2

The central pallor of a mature erythrocyte occupies what size of the cell?

Answer 2

1/3

Question 3

In a mature erythrocyte, what are the (2) components that perform the function of oxygen-carbon dioxide transport?

Answer 3

1) Respiratory protein
2) Hgb

Question 4

What is the average life span of a mature erythrocyte?

Answer 4

120 days

Question 5

What is the purpose of a mature erythrocyte being pliable?

Answer 5

For it to move w/ ease through the tissue capillaries and splenic circulation

Question 6

What happens as RBCs ages?

Answer 6

Cytoplasmic enzymes are catabolized -> increased membrane rigidity (density), phagocytosis, and destruction

Question 7

What is the process of erythrocyte production?

Answer 7

Erythropoiesis

Question 8

What is erythropoiesis?

Answer 8

Differentiation from the HSC to mature erythrocyte

Epitomizes highly specialized cellular differentiation and gene expression

Question 9

True or False

As cells progress through the stages of erythropoiesis, their potential to differentiate into lymphoid or other cell types is restricted

Answer 9

True

Question 10

What comprises 95% of the total cellular protein of erythrocytes?

Answer 10

Hgb

Question 11

Erythropoiesis is regulated by combined actions of what (2) components?

Answer 11

1) Cytokine signaling pathways
2) Transcription factors

Question 12

TRUE OR FALSE

Molecular regulators of erythropoiesis can be categorized as those committing pluripotent precursors to an erythroid fate and those regulating the differentiation of erythroid progenitors into erythrocytes

Answer 12

True

Question 13

What are molecular chaperones?

Answer 13

1) A diverse group of proteins
2) Important in red cell maturation

Question 14

Molecular chaperones influence all aspects of normal cellular function including what (4) components?

Answer 14

1) Signaling
2) Transcription
3) Cell division
4) Apoptosis

Question 15

What is the process of hematopoiesis?

Answer 15

Begins w/ the development of primitive erythrocytes in the embryonic yolk sac -> continues in extramedullary organs such as the liver in the developing fetus -> ultimately located in the red bone marrow during late fetal development, childhood, and adult life

Question 16

What are the (2) functions of heme?

Answer 16

1. Transport of oxygen to the tissues
2. Transport of carbon dioxide from the tissues

Question 17

What is heme?

Answer 17

A pigment in hgb

Question 18

When is heme synthesized?

Answer 18

It is synthesized as the erythrocyte matures

Question 19

What are the (8) basic substances needed for normal erythrocyte and hgb production?

Answer 19

1. Amino acids (proteins)
2. Iron
3. Vitamin B₁₂
4. Vitamin B₆
5. Folic acid
6. Trace minerals
   i. Cobalt
   ii. Nickel

Question 20

What is a member of the vitamin B₂ complex?

Answer 20

Folic acid

Question 21

In adult humans, how many mg of elemental iron are needed for the daily production of > 200 billion erythrocytes?

Answer 21

> 20 mg elemental iron

Question 22

> 20 mg of elemental iron are required for the daily production of > 200 billion erythrocytes, where does the majority of this iron came from?

Answer 22

From the recycling of senescent erythrocytes by macrophages of the mononuclear phagocytic system

Question 23

Where does the 1 - 2 mg of daily iron supply come from (for the daily production of erythrocytes)?

Answer 23

They are derived from the intestinal absorption (which at steady state is sufficient only to replace iron lost by epithelial cell sloughing and functional and dysfunctional bleeding)

Question 24

In what countries is defective erythropoiesis frequently seen?

Answer 24

Underdeveloped countries (where protein deficiencies are common)

Question 25

Other types of anemias can be caused by deficiencies in what (3) components?

Answer 25

1. Vitamin B₁₂
2. Folic acid
3. Iron

Question 26

Erythropoietin is primarily produced by what?

Answer 26

Kidneys

Question 27

At what site in the kidneys is erythropoietin produced?

Answer 27

Peritubular cells

Question 28

Aside from the kidneys, what is the extrarenal organ that also produces erythropoietin?

Answer 28

Liver

Question 29

How many percent of erythropoietin production occurs in the liver?

Answer 29

10 - 15%

Question 30

What is the primary source of erythropoietin in the unborn?

Answer 30

10 - 15% production in the liver

Question 31

What are the (2) characteristics of erythropoietin?

Answer 31

1. Glycoprotein hormone
2. MW = 46,000

Question 32

What are the (2) actions / functions of erythropoietin?

Answer 32

1. Stimulates erythropoiesis
2. Can cross the placental barrier between mother and fetus

Question 33

What was the first human hematopoietic factor to be identified?

Answer 33

Erythropoietin

Question 34

The gene for erythropoietin is located in what chromosome?

Answer 34

7

Question 35

TRUE OR FALSE

Blood levels of erythropoietin are directly related to tissue oxygenation

Answer 35

False, blood levels of erythropoietin are inversely relatead to tissue oxygenation

Question 36

What are the (2) situations where blood levels of erythropoietin can increase up to 20,000 mU/mL?

Answer 36

In response to:
1. Anemia
2. Arterial hypoxemia

Question 37

TRUE OR FALSE

Erythropoietin is detectable in the serum

Answer 37

False, erythropoietin is detectable in the plasma

Question 38

What is the normal concentration of erythropoietin in the plasma?

Answer 38

Up to 20 mU/mL