Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Guyton And Hall Physiology > Chapter 33 > Flashcards

Chapter 33 Flashcards

1
Q

What is the average life span of a normal red blood cell in the circulation?

A

120 days

Normal red blood cells survive about 120 days before being removed by the spleen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which organ is most responsible for releasing erythropoietin (EPO) in response to hypoxia?

A

Kidney

The kidney’s interstitial fibroblasts are the primary source of erythropoietin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the shape of mature red blood cells?

A

Biconcave discs without nuclei

RBCs lack nuclei and most organelles, maximizing surface area for gas exchange.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the primary function of red blood cells?

A

Transport oxygen and carbon dioxide

RBCs carry oxygen from the lungs to tissues and facilitate carbon dioxide transport back.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Hemoglobin is primarily composed of?

A

Four globin chains and four heme groups

Adult hemoglobin consists of two alpha and two beta globin chains, each with a heme group.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Which form of hemoglobin binds oxygen most readily?

A

Oxyhemoglobin

Oxyhemoglobin is hemoglobin that is bound to oxygen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Iron is absorbed primarily in which part of the gastrointestinal tract?

A

Duodenum

The duodenum is the primary site of iron absorption.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which cell type eventually becomes a mature RBC in the peripheral blood?

A

Reticulocyte

Reticulocytes are immature RBCs that mature into erythrocytes within about 1-2 days.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Erythropoietin production is stimulated by?

A

Low oxygen levels

Hypoxia in the kidney stimulates erythropoietin secretion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The most important regulator of RBC production is?

A

Erythropoietin

Erythropoietin is the key hormone regulating RBC production in the bone marrow.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which nutrient deficiency leads to megaloblastic anemia?

A

Vitamin B12 and folate

Deficiencies in vitamin B12 or folic acid impair DNA synthesis, causing megaloblastic anemia.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the role of transferrin in iron metabolism?

A

Transport of iron in the blood

Transferrin binds and transports iron through the bloodstream to tissues.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The majority of iron in the body is found in?

A

Hemoglobin in RBCs

About two-thirds of the body’s iron is in the heme structure of hemoglobin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

A low reticulocyte count in a patient with anemia suggests?

A

Reduced RBC production

A low reticulocyte count indicates inadequate bone marrow response.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Iron deficiency anemia typically presents as?

A

Microcytic, hypochromic anemia

Iron deficiency leads to smaller RBCs that are paler due to reduced hemoglobin content.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Pernicious anemia is caused by a deficiency of?

A

Intrinsic factor leading to B12 malabsorption

Pernicious anemia results from autoimmune gastritis that reduces intrinsic factor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

The normal red blood cell count in men is approximately?

A

5 million/µL

Normal RBC count for men averages around 5.2 million/µL.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Bilirubin is formed from the breakdown of?

A

The heme portion of hemoglobin

Heme is degraded to biliverdin and then bilirubin when RBCs are destroyed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Polycythemia vera is characterized by?

A

Increased RBC mass due to a myeloproliferative disorder

Polycythemia vera is a bone marrow disorder causing excessive RBC production.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

In response to chronic hypoxia, the body compensates by?

A

Increasing RBC production

Chronic hypoxia stimulates the kidney to produce more EPO, leading to increased RBC production.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

The key regulator of iron absorption from the gut is?

A

Hepcidin

Hepcidin regulates intestinal iron absorption and release from stores.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Aplastic anemia involves?

A

Failure of the bone marrow to produce RBCs

Aplastic anemia results from inadequate hematopoiesis in the bone marrow.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does ferritin do?

A

Stores iron, doesn’t regulate absorption directly

Ferritin is a protein that serves as a storage form of iron in the body.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is aplastic anemia?

A

Failure of the bone marrow to produce RBCs

Aplastic anemia results in insufficient production of all blood cell types, including red blood cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Which substance is crucial for DNA synthesis in RBC precursors?

A

Vitamin B12

Vitamin B12 deficiency can lead to megaloblastic anemia due to impaired RBC maturation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

The oxygen-carrying capacity of blood is directly proportional to:

A

The hemoglobin concentration

More hemoglobin means a greater capacity to carry oxygen in the blood.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Which condition leads to normocytic, normochromic anemia?

A

Acute blood loss

Acute hemorrhage initially presents as normocytic, normochromic anemia before compensatory changes occur.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Hemolytic anemias are characterized by:

A

Increased RBC destruction

Hemolytic anemia involves the premature destruction of RBCs, leading to elevated bilirubin levels.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Carbonic anhydrase in RBCs facilitates:

A

Conversion of CO2 and H2O into H2CO3

This reaction aids in the transport of carbon dioxide in the blood.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

The normal hematocrit for a healthy adult male is approximately:

A

45%

Normal male hematocrit is around 40-50%, with 45% being a common value.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

In iron deficiency anemia, serum ferritin levels are typically:

A

Low

Ferritin levels drop in iron deficiency as it reflects body iron stores.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Excessive RBC destruction often leads to:

A

Jaundice (increased bilirubin)

Hemolysis increases free bilirubin load in the body, which can cause jaundice.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Hemoglobin F (fetal hemoglobin) differs from adult hemoglobin (HbA) because it:

A

Has a higher affinity for oxygen

This higher affinity facilitates oxygen transfer from maternal to fetal blood.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

The final step in heme synthesis occurs in the:

A

Mitochondria of RBC precursors

Heme synthesis begins in the mitochondria, moves to the cytosol, and ends back in the mitochondria.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Iron overload (hemochromatosis) can damage organs due to:

A

Iron-mediated oxidative stress

Excess iron can lead to the formation of free radicals, causing tissue damage.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

The normal mean corpuscular volume (MCV) for RBCs is approximately:

A

80-100 fL

Normal MCV indicates the average size of RBCs; values outside this range suggest microcytosis or macrocytosis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Chronic renal failure often leads to anemia because:

A

The kidneys produce inadequate EPO

Damaged kidneys do not produce sufficient erythropoietin (EPO), reducing RBC production.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

A key characteristic of sickle cell anemia is:

A

RBCs that form sickle shapes under low-oxygen conditions

Sickle cell anemia is caused by abnormal hemoglobin that polymerizes under low oxygen tension.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Which of the following can cause secondary polycythemia?

A

High altitude living conditions

Chronic hypoxia from high altitude increases EPO production, leading to more RBCs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

The majority of RBC energy (ATP) is generated via:

A

Glycolysis in the cytoplasm

RBCs lack mitochondria and rely on anaerobic glycolysis for ATP.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Which protein in RBC membranes maintains their biconcave shape?

A

Spectrin

Spectrin is a cytoskeletal protein essential for RBC membrane elasticity and shape.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

In the absence of adequate iron, the RBCs formed will have:

A

Reduced hemoglobin content

Iron is required for hemoglobin synthesis; without it, RBCs are hypochromic and microcytic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

When RBCs are destroyed, the iron released from hemoglobin is:

A

Stored as ferritin or hemosiderin for reuse

The body efficiently recycles iron, storing it for future hemoglobin synthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

The primary stimulus for increased RBC production in secondary polycythemia is:

A

Low partial pressure of oxygen in tissues

Chronic hypoxia triggers increased EPO secretion, leading to more RBCs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

In macrocytic anemias, RBCs are larger because of:

A

Impaired DNA synthesis leading to delayed nuclear maturation

Macrocytosis arises from deficiencies in folate or B12, causing slow nuclear maturation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

The term ‘hematopoiesis’ refers to:

A

Production of blood cells

Hematopoiesis involves the formation and development of all blood cell types.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What does the term ‘hematopoiesis’ refer to?

A

Production of blood cells

Hematopoiesis means formation and development of all blood cell types.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

In the early embryo, where are the first RBCs formed?

A

Yolk sac

Primitive erythropoiesis begins in the yolk sac during early embryonic life.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Which cells secrete the intrinsic factor necessary for vitamin B12 absorption?

A

Parietal cells of the stomach

Parietal cells secrete intrinsic factor, required for B12 absorption in the ileum.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Hematopoietic stem cells in the bone marrow give rise to which types of blood cells?

A

RBCs, WBCs, and platelets

Hematopoietic stem cells are multipotent and can differentiate into all blood cell lineages.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Why can’t RBCs repair themselves?

A

They have no DNA or nucleus

Mature RBCs lack a nucleus and organelles, preventing protein synthesis or damage repair.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Which condition results in RBCs that are abnormally fragile and prone to rupture?

A

Hereditary spherocytosis

Caused by defects in RBC cytoskeleton proteins, leading to spherical, fragile RBCs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

A patient with high RBC count and low EPO levels most likely has what condition?

A

Polycythemia vera

A primary polycythemia where RBCs proliferate independently, often with low EPO due to negative feedback.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Which glycolytic intermediate regulates oxygen release from hemoglobin?

A

2,3-Bisphosphoglycerate (2,3-BPG)

2,3-BPG binds to deoxyhemoglobin, stabilizing it and facilitating oxygen release to tissues.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Which RBC membrane protein is crucial for anchoring the spectrin-actin cytoskeleton?

A

Ankyrin

Ankyrin links spectrin to band 3 proteins in the RBC membrane, maintaining RBC shape and deformability.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Which index measures the variation in RBC size?

A

RDW (Red Cell Distribution Width)

RDW indicates the variation in RBC size; a high RDW suggests a wide range of cell sizes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What is the earliest recognizable precursor of the RBC lineage in the bone marrow?

A

Proerythroblast

The proerythroblast is the first morphologically identifiable RBC precursor in the marrow.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What does poikilocytosis refer to?

A

Variation in RBC shape

Poikilocytosis is abnormal variation in RBC shape.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

During early fetal life, the primary site of hematopoiesis transitions from the yolk sac to the:

A

Liver

After initial hematopoiesis in the yolk sac, the fetal liver becomes the main site of RBC production.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Which RBC enzyme pathway provides NADPH to maintain reduced glutathione?

A

Hexose monophosphate (pentose phosphate) shunt

This pathway generates NADPH to keep glutathione reduced, protecting RBCs from oxidative damage.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What triggers macrophages in the spleen to phagocytose aged RBCs?

A

Changes in RBC membrane carbohydrates and exposure of phosphatidylserine

Aging RBCs show altered membrane patterns, signaling splenic macrophages for removal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

How do RBCs assist in acid-base balance?

A

Carbonic anhydrase converting CO2 to bicarbonate and H+

This reaction facilitates CO2 transport and buffering in the blood.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

Relative polycythemia can occur due to:

A

Dehydration reducing plasma volume

This results in an apparent increase in RBC count due to decreased plasma volume.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

Which RBC index reflects the concentration of hemoglobin in a given volume of RBCs?

A

MCHC (Mean Corpuscular Hemoglobin Concentration)

MCHC measures the concentration of hemoglobin per unit volume of RBCs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

One of the key characteristics of extravascular hemolysis is:

A

RBC destruction primarily by macrophages in the spleen and liver

Extravascular hemolysis occurs within macrophages, not free in the bloodstream.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

In intravascular hemolysis, free hemoglobin released into blood is bound by:

A

Haptoglobin

Haptoglobin binds free hemoglobin in plasma, preventing kidney damage and iron loss.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

Lead poisoning affects RBCs by inhibiting which process?

A

Heme synthesis enzymes, leading to basophilic stippling

Lead inhibits enzymes like ferrochelatase and ALA dehydratase, causing abnormal RBCs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

The reticulocyte production index (RPI) adjusts the reticulocyte count for:

A

Degree of anemia and RBC lifespan

RPI corrects the reticulocyte percentage to account for the severity of anemia.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

Which abnormal RBC form is characteristically seen in hereditary spherocytosis?

A

Spherocytes

Hereditary spherocytosis is due to membrane skeletal protein defects leading to spherical RBCs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

What causes hereditary spherocytosis?

A

Defects in membrane skeletal proteins leading to spherical RBCs

Hereditary spherocytosis results in a characteristic shape change in red blood cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

What happens to stored RBCs in blood banks over time?

A

Decreased ATP and 2,3-BPG levels, reducing O2 delivery capacity

Stored RBCs lose energy and their ability to efficiently release oxygen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

An elevated RDW (Red Cell Distribution Width) is commonly associated with what?

A

A mixed population of microcytic and normocytic RBCs

High RDW indicates variability in red blood cell sizes, often seen during treatment for iron deficiency.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

A high MCHC (Mean Corpuscular Hemoglobin Concentration) is most commonly seen in which condition?

A

Hereditary spherocytosis

Higher MCHC occurs due to the spherical shape and reduced volume of RBCs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

The presence of target cells (codocytes) is associated with which conditions?

A

Liver disease, thalassemia, and hemoglobinopathies

Target cells can be seen in various conditions affecting hemoglobin and cell morphology.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

Basophilic stippling of RBCs is commonly observed in what?

A

Lead poisoning and thalassemia

This stippling indicates impaired maturation of red blood cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

What is the key effect of increasing RBC 2,3-BPG levels at high altitude?

A

Increased oxygen delivery to tissues

Elevated 2,3-BPG reduces hemoglobin’s affinity for oxygen, promoting better oxygen release.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

In the embryo, the very first RBCs formed in the yolk sac are characterized by what?

A

Primitive nucleated erythrocytes with embryonic hemoglobins

These early RBCs are different from adult hemoglobins and are involved in early oxygen transport.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

RBC deformability is critical for what function?

A

Allowing RBCs to pass through narrow capillaries

Deformability is essential for effective oxygen delivery in the microcirculation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

When RBCs are destroyed intravascularly, what is a possible clinical sign?

A

Hemoglobinuria and hemosiderinuria

Free hemoglobin released into plasma and urine indicates intravascular hemolysis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

Which condition is characterized by defective synthesis of globin chains leading to microcytosis?

A

Thalassemia

Thalassemia results in microcytic anemia due to impaired globin chain production.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

Iron overload can lead to what physiological response?

A

Increased hepcidin levels to limit iron absorption

Hepcidin regulates iron homeostasis, especially during overload conditions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

RBC aging is often marked by a decrease in what?

A

Enzyme activity and ATP levels

Aging RBCs lose functionality and signaling for removal as energy levels drop.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

Which organ primarily monitors and removes aged RBCs from circulation?

A

Spleen (red pulp macrophages)

The spleen plays a crucial role in filtering and phagocytosing senescent red blood cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

In anemia of chronic disease, increased hepcidin traps iron in storage sites, which reduces what?

A

Availability for RBC production

This mechanism contributes to anemia by limiting iron necessary for erythropoiesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

A ‘shift to the right’ in the oxygen-hemoglobin dissociation curve is facilitated by what?

A

RBCs release 2,3-BPG, decreasing Hb’s oxygen affinity

This shift enhances oxygen release to tissues, especially under hypoxic conditions.

86
Q

In sickle cell disease, the mutation in the beta-globin chain replaces which amino acid?

A

Glutamic acid with valine

This specific mutation leads to the sickling of red blood cells under low oxygen conditions.

87
Q

In sideroblastic anemia, ringed sideroblasts form because?

A

Iron cannot be incorporated into heme properly

This defect leads to abnormal erythroblast maturation and iron accumulation.

88
Q

RBC lifespan in circulation is maintained despite no nucleus by what?

A

Stable enzyme systems and membrane maintenance pathways

RBCs rely on long-lived enzymes for functionality throughout their lifespan.

89
Q

The pentose phosphate pathway in RBCs mainly serves to produce what?

A

NADPH to maintain reduced glutathione

This function protects RBCs from oxidative damage.

90
Q

Erythropoiesis-stimulating agents (ESAs) can cause what?

A

Increased RBC mass and possibly elevated blood viscosity

ESAs stimulate RBC production, which may lead to increased hematocrit.

91
Q

What is the normal adult hemoglobin (HbA) composition?

A

α2β2

This composition is essential for normal oxygen transport in the blood.

92
Q

In anemia of chronic disease, iron is sequestered in storage sites due to what?

A

Increased hepcidin levels

Hepcidin’s role is crucial in regulating iron availability for erythropoiesis.

93
Q

In anemia of chronic disease, iron is sequestered in storage sites due to?

A

Increased hepcidin levels

Hepcidin blocks iron release from macrophages and enterocytes, leading to sequestration.

94
Q

In polycythemia vera, the mutation often found is in?

A

The JAK2 tyrosine kinase

Polycythemia vera frequently involves a JAK2 mutation, leading to erythrocytosis independent of EPO.

95
Q

RBC fragility tests measure?

A

The strength of RBC membranes under hypotonic conditions

Osmotic fragility tests assess RBC membrane stability in hypotonic solutions.

96
Q

RBC sedimentation rate (ESR) increases when?

A

Plasma fibrinogen and globulins increase, reducing RBC repulsion

Increased fibrinogen and other acute-phase reactants cause RBCs to stack (rouleaux), increasing ESR.

97
Q

The RBC’s unique biconcave shape helps by?

A

Increasing surface-to-volume ratio for efficient gas exchange

The biconcave shape increases surface area relative to volume, aiding rapid gas diffusion.

98
Q

Carbon monoxide (CO) interferes with RBC function by?

A

Displacing O2 from hemoglobin with higher affinity

CO binds hemoglobin with much greater affinity than O2, impairing O2 delivery.

99
Q

A decrease in plasma volume (as in dehydration) without a change in RBC mass results in?

A

Relative polycythemia

Reduced plasma volume elevates hematocrit, appearing as polycythemia but RBC mass is unchanged.

100
Q

The body’s inability to excrete excess iron easily leads to?

A

Iron loading in tissues (hemochromatosis)

With no regulated excretion route, excess iron accumulates, causing tissue damage.

101
Q

The hormone EPO acts on which cells in the bone marrow?

A

Progenitor and precursor cells in the erythroid lineage

EPO stimulates erythroid progenitors (CFU-E) and precursors to proliferate and differentiate.

102
Q

In G6PD deficiency, RBCs are more susceptible to oxidative stress because?

A

They have reduced glutathione levels due to less NADPH

G6PD deficiency impairs the pentose phosphate pathway, reducing NADPH and thus glutathione, increasing oxidative damage risk.

103
Q

In anemia of chronic disease, serum iron is often low because?

A

Hepcidin blocks iron release from macrophages and intestinal cells

Hepcidin sequesters iron in storage sites, reducing serum iron despite adequate stores.

104
Q

The lifespan of stored RBCs after transfusion is?

A

Often reduced due to storage lesion-related damage

Storage lesions cause reduced RBC deformability and shortened post-transfusion survival.

105
Q

Effective erythropoiesis ensures that?

A

Iron, vitamin B12, and folate availability match RBC production needs

Successful erythropoiesis depends on adequate supplies of iron, B12, and folate, as well as appropriate hormone regulation.

106
Q

What is the average life span of a normal red blood cell in the circulation?

A

120 days

Normal red blood cells survive about 120 days before being removed by the spleen.

107
Q

Which organ is most responsible for releasing erythropoietin (EPO) in response to hypoxia?

A

Kidney

The kidney’s interstitial fibroblasts are the primary source of erythropoietin.

108
Q

What is the shape of mature red blood cells?

A

Biconcave discs without nuclei

RBCs lack nuclei and most organelles, maximizing surface area for gas exchange.

109
Q

What is the primary function of red blood cells?

A

Transport oxygen and carbon dioxide

RBCs carry oxygen from the lungs to tissues and facilitate carbon dioxide transport back.

110
Q

Hemoglobin is primarily composed of?

A

Four globin chains and four heme groups

Adult hemoglobin consists of two alpha and two beta globin chains, each with a heme group.

111
Q

Which form of hemoglobin binds oxygen most readily?

A

Oxyhemoglobin

Oxyhemoglobin is hemoglobin that is bound to oxygen.

112
Q

Iron is absorbed primarily in which part of the gastrointestinal tract?

A

Duodenum

The duodenum is the primary site of iron absorption.

113
Q

Which cell type eventually becomes a mature RBC in the peripheral blood?

A

Reticulocyte

Reticulocytes are immature RBCs that mature into erythrocytes within about 1-2 days.

114
Q

Erythropoietin production is stimulated by?

A

Low oxygen levels

Hypoxia in the kidney stimulates erythropoietin secretion.

115
Q

The most important regulator of RBC production is?

A

Erythropoietin

Erythropoietin is the key hormone regulating RBC production in the bone marrow.

116
Q

Which nutrient deficiency leads to megaloblastic anemia?

A

Vitamin B12 and folate

Deficiencies in vitamin B12 or folic acid impair DNA synthesis, causing megaloblastic anemia.

117
Q

What is the role of transferrin in iron metabolism?

A

Transport of iron in the blood

Transferrin binds and transports iron through the bloodstream to tissues.

118
Q

The majority of iron in the body is found in?

A

Hemoglobin in RBCs

About two-thirds of the body’s iron is in the heme structure of hemoglobin.

119
Q

A low reticulocyte count in a patient with anemia suggests?

A

Reduced RBC production

A low reticulocyte count indicates inadequate bone marrow response.

120
Q

Iron deficiency anemia typically presents as?

A

Microcytic, hypochromic anemia

Iron deficiency leads to smaller RBCs that are paler due to reduced hemoglobin content.

121
Q

Pernicious anemia is caused by a deficiency of?

A

Intrinsic factor leading to B12 malabsorption

Pernicious anemia results from autoimmune gastritis that reduces intrinsic factor.

122
Q

The normal red blood cell count in men is approximately?

A

5 million/µL

Normal RBC count for men averages around 5.2 million/µL.

123
Q

Bilirubin is formed from the breakdown of?

A

The heme portion of hemoglobin

Heme is degraded to biliverdin and then bilirubin when RBCs are destroyed.

124
Q

Polycythemia vera is characterized by?

A

Increased RBC mass due to a myeloproliferative disorder

Polycythemia vera is a bone marrow disorder causing excessive RBC production.

125
Q

In response to chronic hypoxia, the body compensates by?

A

Increasing RBC production

Chronic hypoxia stimulates the kidney to produce more EPO, leading to increased RBC production.

126
Q

The key regulator of iron absorption from the gut is?

A

Hepcidin

Hepcidin regulates intestinal iron absorption and release from stores.

127
Q

Aplastic anemia involves?

A

Failure of the bone marrow to produce RBCs

Aplastic anemia results from inadequate hematopoiesis in the bone marrow.

128
Q

What does ferritin do?

A

Stores iron, doesn’t regulate absorption directly

Ferritin is a protein that serves as a storage form of iron in the body.

129
Q

What is aplastic anemia?

A

Failure of the bone marrow to produce RBCs

Aplastic anemia results in insufficient production of all blood cell types, including red blood cells.

130
Q

Which substance is crucial for DNA synthesis in RBC precursors?

A

Vitamin B12

Vitamin B12 deficiency can lead to megaloblastic anemia due to impaired RBC maturation.

131
Q

The oxygen-carrying capacity of blood is directly proportional to:

A

The hemoglobin concentration

More hemoglobin means a greater capacity to carry oxygen in the blood.

132
Q

Which condition leads to normocytic, normochromic anemia?

A

Acute blood loss

Acute hemorrhage initially presents as normocytic, normochromic anemia before compensatory changes occur.

133
Q

Hemolytic anemias are characterized by:

A

Increased RBC destruction

Hemolytic anemia involves the premature destruction of RBCs, leading to elevated bilirubin levels.

134
Q

Carbonic anhydrase in RBCs facilitates:

A

Conversion of CO2 and H2O into H2CO3

This reaction aids in the transport of carbon dioxide in the blood.

135
Q

The normal hematocrit for a healthy adult male is approximately:

A

45%

Normal male hematocrit is around 40-50%, with 45% being a common value.

136
Q

In iron deficiency anemia, serum ferritin levels are typically:

A

Low

Ferritin levels drop in iron deficiency as it reflects body iron stores.

137
Q

Excessive RBC destruction often leads to:

A

Jaundice (increased bilirubin)

Hemolysis increases free bilirubin load in the body, which can cause jaundice.

138
Q

Hemoglobin F (fetal hemoglobin) differs from adult hemoglobin (HbA) because it:

A

Has a higher affinity for oxygen

This higher affinity facilitates oxygen transfer from maternal to fetal blood.

139
Q

The final step in heme synthesis occurs in the:

A

Mitochondria of RBC precursors

Heme synthesis begins in the mitochondria, moves to the cytosol, and ends back in the mitochondria.

140
Q

Iron overload (hemochromatosis) can damage organs due to:

A

Iron-mediated oxidative stress

Excess iron can lead to the formation of free radicals, causing tissue damage.

141
Q

The normal mean corpuscular volume (MCV) for RBCs is approximately:

A

80-100 fL

Normal MCV indicates the average size of RBCs; values outside this range suggest microcytosis or macrocytosis.

142
Q

Chronic renal failure often leads to anemia because:

A

The kidneys produce inadequate EPO

Damaged kidneys do not produce sufficient erythropoietin (EPO), reducing RBC production.

143
Q

A key characteristic of sickle cell anemia is:

A

RBCs that form sickle shapes under low-oxygen conditions

Sickle cell anemia is caused by abnormal hemoglobin that polymerizes under low oxygen tension.

144
Q

Which of the following can cause secondary polycythemia?

A

High altitude living conditions

Chronic hypoxia from high altitude increases EPO production, leading to more RBCs.

145
Q

The majority of RBC energy (ATP) is generated via:

A

Glycolysis in the cytoplasm

RBCs lack mitochondria and rely on anaerobic glycolysis for ATP.

146
Q

Which protein in RBC membranes maintains their biconcave shape?

A

Spectrin

Spectrin is a cytoskeletal protein essential for RBC membrane elasticity and shape.

147
Q

In the absence of adequate iron, the RBCs formed will have:

A

Reduced hemoglobin content

Iron is required for hemoglobin synthesis; without it, RBCs are hypochromic and microcytic.

148
Q

When RBCs are destroyed, the iron released from hemoglobin is:

A

Stored as ferritin or hemosiderin for reuse

The body efficiently recycles iron, storing it for future hemoglobin synthesis.

149
Q

The primary stimulus for increased RBC production in secondary polycythemia is:

A

Low partial pressure of oxygen in tissues

Chronic hypoxia triggers increased EPO secretion, leading to more RBCs.

150
Q

In macrocytic anemias, RBCs are larger because of:

A

Impaired DNA synthesis leading to delayed nuclear maturation

Macrocytosis arises from deficiencies in folate or B12, causing slow nuclear maturation.

151
Q

The term ‘hematopoiesis’ refers to:

A

Production of blood cells

Hematopoiesis involves the formation and development of all blood cell types.

152
Q

What does the term ‘hematopoiesis’ refer to?

A

Production of blood cells

Hematopoiesis means formation and development of all blood cell types.

153
Q

In the early embryo, where are the first RBCs formed?

A

Yolk sac

Primitive erythropoiesis begins in the yolk sac during early embryonic life.

154
Q

Which cells secrete the intrinsic factor necessary for vitamin B12 absorption?

A

Parietal cells of the stomach

Parietal cells secrete intrinsic factor, required for B12 absorption in the ileum.

155
Q

Hematopoietic stem cells in the bone marrow give rise to which types of blood cells?

A

RBCs, WBCs, and platelets

Hematopoietic stem cells are multipotent and can differentiate into all blood cell lineages.

156
Q

Why can’t RBCs repair themselves?

A

They have no DNA or nucleus

Mature RBCs lack a nucleus and organelles, preventing protein synthesis or damage repair.

157
Q

Which condition results in RBCs that are abnormally fragile and prone to rupture?

A

Hereditary spherocytosis

Caused by defects in RBC cytoskeleton proteins, leading to spherical, fragile RBCs.

158
Q

A patient with high RBC count and low EPO levels most likely has what condition?

A

Polycythemia vera

A primary polycythemia where RBCs proliferate independently, often with low EPO due to negative feedback.

159
Q

Which glycolytic intermediate regulates oxygen release from hemoglobin?

A

2,3-Bisphosphoglycerate (2,3-BPG)

2,3-BPG binds to deoxyhemoglobin, stabilizing it and facilitating oxygen release to tissues.

160
Q

Which RBC membrane protein is crucial for anchoring the spectrin-actin cytoskeleton?

A

Ankyrin

Ankyrin links spectrin to band 3 proteins in the RBC membrane, maintaining RBC shape and deformability.

161
Q

Which index measures the variation in RBC size?

A

RDW (Red Cell Distribution Width)

RDW indicates the variation in RBC size; a high RDW suggests a wide range of cell sizes.

162
Q

What is the earliest recognizable precursor of the RBC lineage in the bone marrow?

A

Proerythroblast

The proerythroblast is the first morphologically identifiable RBC precursor in the marrow.

163
Q

What does poikilocytosis refer to?

A

Variation in RBC shape

Poikilocytosis is abnormal variation in RBC shape.

164
Q

During early fetal life, the primary site of hematopoiesis transitions from the yolk sac to the:

A

Liver

After initial hematopoiesis in the yolk sac, the fetal liver becomes the main site of RBC production.

165
Q

Which RBC enzyme pathway provides NADPH to maintain reduced glutathione?

A

Hexose monophosphate (pentose phosphate) shunt

This pathway generates NADPH to keep glutathione reduced, protecting RBCs from oxidative damage.

166
Q

What triggers macrophages in the spleen to phagocytose aged RBCs?

A

Changes in RBC membrane carbohydrates and exposure of phosphatidylserine

Aging RBCs show altered membrane patterns, signaling splenic macrophages for removal.

167
Q

How do RBCs assist in acid-base balance?

A

Carbonic anhydrase converting CO2 to bicarbonate and H+

This reaction facilitates CO2 transport and buffering in the blood.

168
Q

Relative polycythemia can occur due to:

A

Dehydration reducing plasma volume

This results in an apparent increase in RBC count due to decreased plasma volume.

169
Q

Which RBC index reflects the concentration of hemoglobin in a given volume of RBCs?

A

MCHC (Mean Corpuscular Hemoglobin Concentration)

MCHC measures the concentration of hemoglobin per unit volume of RBCs.

170
Q

One of the key characteristics of extravascular hemolysis is:

A

RBC destruction primarily by macrophages in the spleen and liver

Extravascular hemolysis occurs within macrophages, not free in the bloodstream.

171
Q

In intravascular hemolysis, free hemoglobin released into blood is bound by:

A

Haptoglobin

Haptoglobin binds free hemoglobin in plasma, preventing kidney damage and iron loss.

172
Q

Lead poisoning affects RBCs by inhibiting which process?

A

Heme synthesis enzymes, leading to basophilic stippling

Lead inhibits enzymes like ferrochelatase and ALA dehydratase, causing abnormal RBCs.

173
Q

The reticulocyte production index (RPI) adjusts the reticulocyte count for:

A

Degree of anemia and RBC lifespan

RPI corrects the reticulocyte percentage to account for the severity of anemia.

174
Q

Which abnormal RBC form is characteristically seen in hereditary spherocytosis?

A

Spherocytes

Hereditary spherocytosis is due to membrane skeletal protein defects leading to spherical RBCs.

175
Q

What causes hereditary spherocytosis?

A

Defects in membrane skeletal proteins leading to spherical RBCs

Hereditary spherocytosis results in a characteristic shape change in red blood cells.

176
Q

What happens to stored RBCs in blood banks over time?

A

Decreased ATP and 2,3-BPG levels, reducing O2 delivery capacity

Stored RBCs lose energy and their ability to efficiently release oxygen.

177
Q

An elevated RDW (Red Cell Distribution Width) is commonly associated with what?

A

A mixed population of microcytic and normocytic RBCs

High RDW indicates variability in red blood cell sizes, often seen during treatment for iron deficiency.

178
Q

A high MCHC (Mean Corpuscular Hemoglobin Concentration) is most commonly seen in which condition?

A

Hereditary spherocytosis

Higher MCHC occurs due to the spherical shape and reduced volume of RBCs.

179
Q

The presence of target cells (codocytes) is associated with which conditions?

A

Liver disease, thalassemia, and hemoglobinopathies

Target cells can be seen in various conditions affecting hemoglobin and cell morphology.

180
Q

Basophilic stippling of RBCs is commonly observed in what?

A

Lead poisoning and thalassemia

This stippling indicates impaired maturation of red blood cells.

181
Q

What is the key effect of increasing RBC 2,3-BPG levels at high altitude?

A

Increased oxygen delivery to tissues

Elevated 2,3-BPG reduces hemoglobin’s affinity for oxygen, promoting better oxygen release.

182
Q

In the embryo, the very first RBCs formed in the yolk sac are characterized by what?

A

Primitive nucleated erythrocytes with embryonic hemoglobins

These early RBCs are different from adult hemoglobins and are involved in early oxygen transport.

183
Q

RBC deformability is critical for what function?

A

Allowing RBCs to pass through narrow capillaries

Deformability is essential for effective oxygen delivery in the microcirculation.

184
Q

When RBCs are destroyed intravascularly, what is a possible clinical sign?

A

Hemoglobinuria and hemosiderinuria

Free hemoglobin released into plasma and urine indicates intravascular hemolysis.

185
Q

Which condition is characterized by defective synthesis of globin chains leading to microcytosis?

A

Thalassemia

Thalassemia results in microcytic anemia due to impaired globin chain production.

186
Q

Iron overload can lead to what physiological response?

A

Increased hepcidin levels to limit iron absorption

Hepcidin regulates iron homeostasis, especially during overload conditions.

187
Q

RBC aging is often marked by a decrease in what?

A

Enzyme activity and ATP levels

Aging RBCs lose functionality and signaling for removal as energy levels drop.

188
Q

Which organ primarily monitors and removes aged RBCs from circulation?

A

Spleen (red pulp macrophages)

The spleen plays a crucial role in filtering and phagocytosing senescent red blood cells.

189
Q

In anemia of chronic disease, increased hepcidin traps iron in storage sites, which reduces what?

A

Availability for RBC production

This mechanism contributes to anemia by limiting iron necessary for erythropoiesis.

190
Q

A ‘shift to the right’ in the oxygen-hemoglobin dissociation curve is facilitated by what?

A

RBCs release 2,3-BPG, decreasing Hb’s oxygen affinity

This shift enhances oxygen release to tissues, especially under hypoxic conditions.

191
Q

In sickle cell disease, the mutation in the beta-globin chain replaces which amino acid?

A

Glutamic acid with valine

This specific mutation leads to the sickling of red blood cells under low oxygen conditions.

192
Q

In sideroblastic anemia, ringed sideroblasts form because?

A

Iron cannot be incorporated into heme properly

This defect leads to abnormal erythroblast maturation and iron accumulation.

193
Q

RBC lifespan in circulation is maintained despite no nucleus by what?

A

Stable enzyme systems and membrane maintenance pathways

RBCs rely on long-lived enzymes for functionality throughout their lifespan.

194
Q

The pentose phosphate pathway in RBCs mainly serves to produce what?

A

NADPH to maintain reduced glutathione

This function protects RBCs from oxidative damage.

195
Q

Erythropoiesis-stimulating agents (ESAs) can cause what?

A

Increased RBC mass and possibly elevated blood viscosity

ESAs stimulate RBC production, which may lead to increased hematocrit.

196
Q

What is the normal adult hemoglobin (HbA) composition?

A

α2β2

This composition is essential for normal oxygen transport in the blood.

197
Q

In anemia of chronic disease, iron is sequestered in storage sites due to what?

A

Increased hepcidin levels

Hepcidin’s role is crucial in regulating iron availability for erythropoiesis.

198
Q

In anemia of chronic disease, iron is sequestered in storage sites due to?

A

Increased hepcidin levels

Hepcidin blocks iron release from macrophages and enterocytes, leading to sequestration.

199
Q

In polycythemia vera, the mutation often found is in?

A

The JAK2 tyrosine kinase

Polycythemia vera frequently involves a JAK2 mutation, leading to erythrocytosis independent of EPO.

200
Q

RBC fragility tests measure?

A

The strength of RBC membranes under hypotonic conditions

Osmotic fragility tests assess RBC membrane stability in hypotonic solutions.

201
Q

RBC sedimentation rate (ESR) increases when?

A

Plasma fibrinogen and globulins increase, reducing RBC repulsion

Increased fibrinogen and other acute-phase reactants cause RBCs to stack (rouleaux), increasing ESR.

202
Q

The RBC’s unique biconcave shape helps by?

A

Increasing surface-to-volume ratio for efficient gas exchange

The biconcave shape increases surface area relative to volume, aiding rapid gas diffusion.

203
Q

Carbon monoxide (CO) interferes with RBC function by?

A

Displacing O2 from hemoglobin with higher affinity

CO binds hemoglobin with much greater affinity than O2, impairing O2 delivery.

204
Q

A decrease in plasma volume (as in dehydration) without a change in RBC mass results in?

A

Relative polycythemia

Reduced plasma volume elevates hematocrit, appearing as polycythemia but RBC mass is unchanged.

205
Q

The body’s inability to excrete excess iron easily leads to?

A

Iron loading in tissues (hemochromatosis)

With no regulated excretion route, excess iron accumulates, causing tissue damage.

206
Q

The hormone EPO acts on which cells in the bone marrow?

A

Progenitor and precursor cells in the erythroid lineage

EPO stimulates erythroid progenitors (CFU-E) and precursors to proliferate and differentiate.

207
Q

In G6PD deficiency, RBCs are more susceptible to oxidative stress because?

A

They have reduced glutathione levels due to less NADPH

G6PD deficiency impairs the pentose phosphate pathway, reducing NADPH and thus glutathione, increasing oxidative damage risk.

208
Q

In anemia of chronic disease, serum iron is often low because?

A

Hepcidin blocks iron release from macrophages and intestinal cells

Hepcidin sequesters iron in storage sites, reducing serum iron despite adequate stores.

209
Q

The lifespan of stored RBCs after transfusion is?

A

Often reduced due to storage lesion-related damage

Storage lesions cause reduced RBC deformability and shortened post-transfusion survival.

210
Q

Effective erythropoiesis ensures that?

A

Iron, vitamin B12, and folate availability match RBC production needs

Successful erythropoiesis depends on adequate supplies of iron, B12, and folate, as well as appropriate hormone regulation.

Guyton And Hall Physiology (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions