Erythrocyte Physiology

Question 1

How is hematocrit level determined?

Answer 1

Height of RBCs/Total height of sample in tube

Question 2

What are the 3 primary functions of erythrocytes?

Answer 2

Carry O2 from lungs to body
Carry CO2 from body to lungs
Acid/base buffering

Question 3

What aspects of erythrocytes contribute to increased surface area for efficient gas exchange?

Answer 3

Biconcavity

Question 4

Erythropoiesis occurs on erythroblastic islands of ______ ________.

__________ mature into erythrocytes upon entering circulation

Answer 4

Bone marrow

Reticulocytes

Question 5

At what point in erythropoeisis does EPO become necessary to continue the maturation process?

Answer 5

CFU-E (EPO bidns to EPOR on the cell)

Question 6

At what stage of erythropoiesis does enucleation occur?

Answer 6

Between orthoerythroblast and reticulocyte

Question 7

At what stage of erythropoiesis does degradation of residual organelles and microvesicle exocytosis occur?

Answer 7

Between reticulocyte and mature RBC

Question 8

___________ is the principle regulator of erythropoiesis

Answer 8

Erythropoieitin

Question 9

A genetic deletion in Hypoxia Inducible Factor may result in what condition?

Answer 9

Anemia

Question 10

Impaired regulation of HIF would result in what pathologic condition?

Answer 10

Erythrocytosis

Question 11

Mutations in HIF may lead to what pathologic condition?

Answer 11

Polycythemia

Question 12

What happens to EPO-producing renal cells under hypoxic conditions?

Answer 12

Increases

Question 13

What 3 conditions stimulate EPO production to increase in the kidneys?

Answer 13

Anemia
Decreased renal blood flow
Central hypoxia

Question 14

What 2 factors are necessary in order to get from a normoblast to a reticuocyte?

Answer 14

B12 and folate

Question 15

Why is it beneficial that tissue oxygenation operates on a negative feedback mech. in response to hypoxia?

Answer 15

Prevents increase in blood viscosity

Question 16

True or false: folate is the same as folic acid

Answer 16

False

Question 17

Requirements for erythropoiesis include:

Adequate _______

_______ availability

Vitamin ____ and Vitamin ______ for DNA synthesis

Answer 17

Nutrition; iron; B12; B9

Question 18

__________ or _________ Deficiency results in megaloblastic macrocytic anemia

Answer 18

Folate; B12

Question 19

Poor B12 absorption due to an autoimmune disorder results in ___________ anemia

Answer 19

Pernicious

Question 20

What type of anemia is iron-deficient?

Answer 20

Microcytic anemia - most common cause of anemia worldwide

Question 21

Iron circulates in plasma as _____________

Answer 21

Transferrin

Question 22

___________ anemia results from deficient transport of transferrin to developing erythroblasts

Answer 22

Hypochromic

Question 23

Iron absorption is enhanced by ___________

Answer 23

Ascorbate (vit. C)

Question 24

What compounds impair iron absorption?

Answer 24

Hepcidin
Phytates
Tannins
ANTACIDS

Question 25

Iron overload

Answer 25

Hemochromatosis

Question 26

What are the 3 types of hemochromatosis

Answer 26

Primary (genetic) Secondary (multiple blood transfusions, ineffective erythropoiesis, increased iron intake) Neonatal (develops in utero, unknown cause)

Question 27

What are 3 complications to hemochromatosis?

Answer 27

Liver cirrhosis, skin pigmentation, and DM

Question 28

What is the normal Hgb content in adults?

Answer 28

14 g/dL in females 15.5 g/dL in males

Question 29

There are four types of Hgb chains: alpha, beta, delta, and gamma. What does the type of chain indicate?

Answer 29

Binding affinity

Question 30

Each gram of Hgb combines with ______ mL oxygen The average male contains _____ Hgb per 1 dL blood. How many mL of O2 can be carried in 1 dL of blood? What about at 97% saturation (avg)?

Answer 30

1.34 15 20. 1 19. 5

Question 31

What effect does anemia have on oxygen carrying capacity and percent saturation?

Answer 31

Decreases O2 carrying capacity, but not necessarily percent saturation

Question 32

Oxygen ____________ = max amount of oxygen that can be carried by hemoglobin in blood

Answer 32

Capacity (20.1 mL/dL)

Question 33

Oxygen ___________ = how much oxygen is actually being carried by the blood

Answer 33

Content (19.5 mL/dL)

Question 34

Oxygen __________ = spots occupied by oxygen as a percentage of total available spots

Answer 34

Saturation

Question 35

What effect does ATP generated by glycolysis have on RBCs?

Answer 35

Improves membrane flexibility, ion transport, prevents oxidative damage, and maintains iron in Fe2+ form [If iron is in Fe3+ state it impacts the ability to bind O2]

Question 36

The erythrocyte life cycle ends when they rupture in the ________; the released Hgb is ingested by __________ immediately Heme is converted to ________ Peptides go to ________ Iron goes to ________

Answer 36

Spleen (red pulp); monocytes/macrophages Bilirubin (liver) Amino acid metabolism Transferrin (recycling)

Question 37

Anemia results from a reduction of the total circulating red cell mass below normal limits -- often identified as reduced _________ and _________ concentration

Answer 37

Hematocrit; Hgb

Question 38

What are some characteristics of primary polycythemia?

Answer 38

``` Genetic (low EPO) Extra RBCs Increased total blood volume Increased blood viscosity Normal cardiac output ```

Question 39

What are some characteristics of secondary polycythemia?

Answer 39

Hypoxia (high EPO) Extra RBCs Cardiac output may be abnormal

Question 40

What are some characteristics of physiologic polycythemia?

Answer 40

High altitude adaptation Extra RBCs Normal cardiac output

Question 41

Which form of polycythemia may manifest with an abnormal cardiac output?

Answer 41

Secondary

Question 42

Which type of polycythemia affects blood volume and viscosity?

Answer 42

Primary

Question 43

What condition is characterized by iron remaining in ferric form, resulting in decreased O2 availability to tissues and chocolate-colored blood?

Answer 43

Methemoglobinemia (increased methemoblobin)