Deck 3: The Red Blood Cell: Structure and Function

Question 1

A loss of RBC membrane deformity may be associated with which of the following?

A) Increase in membrane calcium
B) Loss of ATP
C) Decrease in the phosphorylation of spectrin
D) All of the above
E) None of the above

Answer 1

All of the above

Question 2

The RBC membrane is relatively impermeable to which of the following?

A) Na⁺
B) K⁺
C) Ca²⁺
D) All of the above
E) None of the above

Answer 2

All of the above

Question 3

Normal hemoglobin production is dependent upon which of the following processes?

A) Adequate globin synthesis
B) Adequate iron delivery and supply
C) Adequate synthesis of protoporphyrins
D) All of the above
E) None of the above

Answer 3

All of the above

Question 4

Proteins that extend from the outer surface and traverse the entire RBC membrane to the inner cytoplasmic side are termed __________ membrane proteins.

A) Integral
B) Peripheral
C) Cytoplasmic
D) All of the above
E) None of the above

Question 5

Which integral membrane protein contains approximately 60% carbohydrate and accounts for most of the membrane sialic acid that gives the RBC its negative charge?

A) Spectrin
B) Actin
C) Glycophorin
D) Ankyrin
E) None of the above

Question 6

Which of the following is the RBC intracellular-to-extracellular ratio for potassium?

A) 25:1
B) 1:12
C) 12:1
D) 1:25
E) None of the above

Question 7

Which principal peripheral protein represents approximately 75% of the peripheral RBC membrane protein and 25% of the total membrane protein?

A) Spectrin
B) Actin
C) Glycophorin
D) Ankyrin
E) None of the above

Question 8

The majority of which of these proteins carry RBC antigens and are receptors?

A) Spectrin
B) Actin
C) Glycophorin
D) Ankyrin
E) None of the above

Question 9

What is the normal lifespan of the RBC in circulation?

A) 60 days
B) 12 days
C) 120 days
D) 80 days
E) None of the above

Question 10

RBC membrane proteins that are limited to the cytoplasmic surface of the membrane are called __________ proteins.

A) Integral
B) Peripheral
C) Cytoplasmic
D) All of the above
E) None of the above

Question 11

Hemoglobin F (fetal hemoglobin) is defined biochemically as:

A) (₂₂)
B) (₂₂)
C) (₂₂)
D) (₂₂)
E) None of the above

Question 12

Which of the following abnormal RBC morphologies is associated with abetalipoproteinemia?

A) Schistocytes
B) Target cells
C) Spherocytes
D) Acanthocytes
E) None of the above

Question 13

Which of the following is the RBC intracellular-to-extracellular ratio for sodium?

A) 25:1
B) 1:12
C) 12:1
D) 1:25
E) None of the above

Question 14

A loss of RBC membrane results in the formation of which abnormal RBC morphology which represents a reduced surface-to-volume ratio?

A) Target cells
B) Spherocytes
C) Acanthocytes
D) Sickle cells
E) None of the above

Question 15

The RBCs generate their energy (ATP) almost exclusively through which metabolic pathway?

A) Krebs cycle
B) Glycolytic pathway
C) Phosphogluconate pathway
D) Luebering-Rapaport pathway
E) None of the above

Question 16

Normal adult hemoglobin A consists of:

A) Two alpha chains
B) Two beta chains
C) Four heme groups
D) All of the above
E) None of the above

Question 17

The RBC membrane is freely permeable to which of the following?

A) Na⁺
B) HCO₃^-
C) H₂O
D) Ca²⁺
E) K⁺

Question 18

Which membrane protein is principally responsible for the skeleton of microfilaments on the inner surface of the RBC membrane?

A) Spectrin
B) Actin
C) Glycophorin
D) Ankyrin
E) None of the above

Question 19

Which of the following abnormal RBC morphologies is associated with liver disease?

A) Schistocytes
B) Target cells
C) Spherocytes
D) Acanthocytes
E) None of the above

Question 20

Hemoglobin A₂ is defined biochemically as:

A) (₂₂)
B) (₂₂)
C) (₂₂)
D) (₂₂)
E) None of the above

Question 21

Which of the following represents embryonic hemoglobin?

A) (₂₂)
B) (₂₂)
C) (₂₂)
D) (₂₂)
E) None of the above

Question 22

A ringed sideroblast in the bone marrow is diagnostic for what defect?

A) Deficient iron absorption
B) Deficient globin synthesis
C) Deficient RBC metabolic pathways
D) Deficient protoporphyrin synthesis
E) None of the above

Question 23

The storage form of iron is termed:

A) Haptoglobin
B) Ferritin
C) Transferrin
D) Hemopexin
E) None of the above

Question 24

Which of the following stains iron in the bone marrow?

A) Wright stain
B) Giemsa stain
C) Prussian blue
D) Hematoxylin and eosin
E) None of the above

Question 25

The dissociation and binding of oxygen by hemoglobin is not directly proportional to the pO₂ of its environment but instead exhibits a sigmoid-curve relationship termed:

A) The Embden-Meyerhof pathway
B) The phosphogluconate pathway
C) The hemoglobin oxygen dissociation curve
D) The Luebering-Rapaport pathway
E) None of the above

Question 26

Two thirds of the total body iron is bound to __________ in the hemoglobin molecule.

A) Globin
B) Transferrin
C) Heme
D) Hemopexin
E) None of the above

Question 27

The function of hemoglobin is to:

A) Deliver oxygen to the tissues
B) Consume oxygen
C) Deliver carbon dioxide to the tissues
D) All of the above
E) None of the above

Question 28

Free metheme of the oxidized disassembled hemoglobin molecule during excessive intravascular hemolysis is carried by what transport protein?

A) Haptoglobin
B) Ferritin
C) Transferrin
D) Hemopexin
E) None of the above

Question 29

Which of the following is the protein carrier for the alpha-beta dimers of the dissociated hemoglobin molecule during intravascular hemolysis?

A) Haptoglobin
B) Ferritin
C) Transferrin
D) Hemopexin
E) None of the above

Question 30

Normal hemoglobin production is dependent on which of the following?

A) Adequate iron delivery and supply
B) Adequate synthesis of protoporphyrin
C) Adequate globin synthesis
D) All of the above
E) None of the above

Question 31

Which of the following can shift the hemoglobin-oxygen dissociation curve to the left?

A) Increases in 2,3-diphosphoglycerate (2,3-DPG)
B) Acidosis
C) Increase in body temperature (fever)
D) All of the above
E) None of the above

Question 32

RBCs contain which of the following genes?

A) Four alpha ()
B) Two beta ()
C) Two delta ()
D) Four gamma ()
E) All of the above

Question 33

Which of the following types of hemoglobin is (are) found in adult RBCs?

A) 95-97% HbA
B) 2-3% HbA₂
C) 2% or less HbF
D) All of the above
E) None of the above

Question 34

Which of the following is the transport protein for iron?

A) Haptoglobin
B) Ferritin
C) Transferrin
D) Hemopexin
E) None of the above

Question 35

Which of the following can shift the hemoglobin-oxygen dissociation curve to the right?

A) Alkalosis
B) Abnormal Hb (methemoglobin and carboxyhemoglobin)
C) Decreases in 2,3-DPG
D) All of the above
E) None of the above

Question 36

Protoporphyrin synthesis begins in the mitochondria with the formation of __________ from glycine and succinyl CoA, which is the major rate-limiting step in heme synthesis.

A) Porphobilinogen (PBG)
B) Uroporphyrinogen (UPG)
C) Delta aminolevulinic acid (D-ALA)
D) Coproporphyrinogen (CPG)
E) None of the above

Question 37

Which of the following are abnormal hemoglobins that cannot transport or deliver oxygen?

A) Carboxyhemoglobin
B) Methemoglobin
C) Sulfhemoglobin
D) All of the above
E) None of the above

Question 38

Which of the following is a rare inherited congenital disorder that results in large amounts of UPG I accumulating in the RBCs, bone marrow, and urine of these patients due to an abnormal pathway for the synthesis of protoporphyrin?

A) Ringed sideroblastic anemia
B) Erythropoietic porphyria
C) Hepatic porphyria
D) Thalassemia
E) None of the above

Question 39

In the fetus, the majority of the hemoglobin is __________.

A) HbA
B) HbA₂
C) HbF
D) None of the above
E) All of the above

Question 40

The formation of which abnormal hemoglobin can occur in a number of conditions, such as in chronic heavy smokers, and result in the binding of the abnormal molecule to heme 200 times tighter than the binding of oxygen to heme?

A) Carboxyhemoglobin
B) Methemoglobin
C) Sulfhemoglobin
D) All of the above
E) None of the above

Question 41

Which of the following RBC metabolic pathways produces the pyridine nucleotide NADPH from NADP⁺ along with reduced glutathione to provide the main line of defense against oxidative injury?

A) Embden-Meyerhof
B) Hexose monophosphate (phosphogluconate)
C) Methemoglobin reductase
D) Luebering-Rapaport
E) None of the above

Question 42

What percentage of ATP needed by the RBC is generated by the Embden-Meyerhof glycolytic pathway?

A) 10%
B) 50%
C) 5%
D) 90%
E) None of the above

Question 43

Aggregates that form in the RBC as a result of oxidation, denaturation, and precipitation of globin are called __________.

A) Siderotic granules
B) Pappenheimer bodies
C) Howell-Jolly bodies
D) Heinz bodies
E) None of the above

Question 44

At what level of increased circulating carboxyhemoglobin may cyanosis, anemia, and death occur due to a tissue oxygen deficit related to the increased concentration of this abnormal hemoglobin?

A) 5.0 g/dL
B) 1.5 g/dL
C) 0.5 g/dL
D) 0.1 g/dL

Question 45

In hemoglobinuria, methemoglobin predominates in acidic urine and gives it what color?

A) Purple
B) Red
C) Brown
D) None of the above
E) All of the above

Question 46

Circulating methemalbumin gives the plasma or blood what color?

A) Purple
B) Red
C) Brown
D) None of the above
E) All of the above

Question 47

What is the normal level of plasma haptoglobin?

A) 50-200 mg/dL
B) 5 g/L
C) 2-5 mg/dL
D) 50-100 mg/dL
E) None of the above

Question 48

At what level of increased circulating sulfhemoglobin may cyanosis, anemia, and death occur due to a tissue oxygen deficit related to the increased concentration of this abnormal hemoglobin?

A) 5.0 g/dL
B) 1.5 g/dL
C) 0.5 g/dL
D) 0.1 g/dL

Question 49

Each day, what percentage of old RBCs in circulation is taken out by a system of fixed macrophages in the body known as the reticuloendothelial system (RES)?

A) 1%
B) 20%
C) 50%
D) 80%
E) None of the above

Question 50

This abnormal hemoglobin can form as a result of chronic constipation and represents an irreversible change to the hemoglobin molecule which cannot carry oxygen and will persist until the RBCs carrying this abnormal hemoglobin are removed from the circulation.

A) Carboxyhemoglobin
B) Methemoglobin
C) Sulfhemoglobin
D) All of the above
E) None of the above

Question 51

In hemoglobinuria, oxyhemoglobin predominates in alkaline urine and gives it what color?

A) Purple
B) Red
C) Brown
D) None of the above
E) All of the above

Question 52

Which of the following RBC metabolic pathways is responsible for the production of the organic phosphate 2,3-DPG, which is important in delivering oxygen to the tissues?

A) Embden-Meyerhof
B) Hexose monophosphate (phosphogluconate)
C) Methemoglobin reductase
D) Luebering-Rapaport
E) None of the above

Question 53

What percentage of normal RBC destruction occurs through the process of intravascular hemolysis?

A) 90%
B) 50%
C) 5-10%
D) 25%
E) None of the above

Question 54

What is the normal level of plasma hemoglobin?

A) 50-200 mg/dL
B) 5 g/L
C) 2-5 mg/dL
D) 50-100 mg/dL
E) None of the above

Question 55

What percentage of the destruction of senescent (old) RBCs occurs by the processing of extravascular hemolysis?

A) 90%
B) 50%
C) 5-10%
D) 25%
E) None of the above

Question 56

Adequate ATP levels are crucial to RBC survival and function by maintaining which of the following?

A) Hemoglobin function
B) Membrane integrity and deformity
C) RBC volume
D) Adequate amounts of reduced pyridine nucleotides
E) All of the above

Question 57

This abnormal hemoglobin forms when the iron is oxidized to the ferric (Fe³⁺) state, and normally, less than 1% of the total circulatory hemoglobin is in this form in the normal individual.

A) Carboxyhemoglobin
B) Methemoglobin
C) Sulfhemoglobin
D) All of the above
E) None of the above

Question 58

What is the normal level of plasma hemopexin?

A) 50-200 mg/dL
B) 5 g/L
C) 2-5 mg/dL
D) 50-100 mg/dL
E) None of the above

Question 59

Which of the following RBC metabolic pathways is important in maintaining the heme iron in the reduced (Fe²⁺, ferrous) functional state?

A) Embden-Meyerhof
B) Hexose monophosphate (phosphogluconate)
C) Methemoglobin reductase
D) Luebering-Rapaport
E) None of the above

Question 60

At what level of increased circulating methemoglobin may cyanosis, anemia, and death occur due to a tissue oxygen deficit related to the increased concentration of this abnormal hemoglobin?

A) 5.0 g/dL
B) 1.5 g/dL
C) 0.5 g/dL
D) 0.1 g/dL

Question 61

What change(s) is/are associated with the aging of the RBC?

A) Increased spheroidal shape
B) Decreased mean corpuscular volume (MCV)
C) Increased oxygen affinity
D) All of the above
E) None of the above

Question 62

Which of the following abnormal RBC morphology result as an accumulation of cholesterol in the cell membrane?

A) Stomatocytes
B) Bite cells
C) Spherocytes
D) Target cells
E) All of the above

Question 63

A shift to the right of the hemoglobin oxygen dissociation curve can occur as a result of _____________________.

A) Hypoxia
B) Alkalosis
C) Increase quantity of methemoglobin
D) Increase quantity of hemoglobin F
E) None of the above

Question 64

Decreased cellular deformability leads to:

A) Increased RBC survival
B) No change in RBC survival
C) Decreased RBC survival
D) Normal RBC survival
E) None of the above