Red Blood Cell Physiology and Disorders Flashcards

Flashcards testing red blood cell physiology, lab indices, blood typing, transfusion reactions, anemias, polycythemia, and neonatal hematology.

What two primary morphologic advantages does the biconcave shape of mature erythrocytes provide?

It provides a larger surface area for oxygen diffusion compared to a spherical cell of equal volume, and its thin membrane allows oxygen to diffuse rapidly into the innermost regions of the cell.

Which two fibrous proteins form a complex network on the inner RBC membrane surface to maintain flexibility and elasticity?

Spectrin and ankyrin.

How does fetal hemoglobin ($\text{HbF}$) structural composition differ from adult hemoglobin ($\text{HbA}$), and what functional advantage does it provide?

$\text{HbF}$ contains a pair of gamma ($\gamma$) chains instead of beta ($\beta$) chains, giving it a higher affinity for oxygen that facilitates oxygen transfer across the placenta from maternal blood.

How do the kidneys respond to decreased tissue oxygen levels to stimulate erythropoiesis?

The kidneys sense decreased oxygen levels and produce erythropoietin, which travels to the bone marrow to stimulate RBC production.

What is the metabolic function of $2,3\text{-diphosphoglycerate (2,3-DPG)}$ produced during RBC anaerobic glycolysis?

It binds to hemoglobin and reduces its affinity for oxygen, facilitating the release of oxygen at the tissue level.

What is the lifespan of a mature red blood cell, and where are aging cells destroyed?

The lifespan is approximately $120\,\text{days}$. Aging cells are destroyed by phagocytic cells in the spleen, liver, bone marrow, and lymph nodes.

How is absorbed iron transported in the plasma and stored in body tissues?

Absorbed iron combines with apotransferrin to form transferrin for transport in the plasma, and it is stored in tissues (liver, marrow, spleen) as ferritin.

How is insoluble unconjugated bilirubin processed by the body for elimination?

Unconjugated bilirubin attaches to plasma proteins (albumin) for transport to the liver, where it is conjugated with glucuronide to make it water-soluble (conjugated bilirubin), and is then excreted in bile.

What are the normal adult reference ranges for RBC count and Reticulocytes?

RBC Count: Men $4.2\text{--}5.4 \times 10^6/\mu\text{L}$, Women $3.6\text{--}5.0 \times 10^6/\mu\text{L}$; Reticulocytes: $1.0\%\text{--}1.5\%$ of total RBC.

What are the normal adult reference ranges for Hemoglobin, Hematocrit, MCV, and MCHC?

Hemoglobin: Men $14\text{--}16.5\,\text{g/dL}$, Women $12\text{--}15\,\text{g/dL}$; Hematocrit: Men $40\%\text{--}50\%$, Women $37\%\text{--}47\%$; MCV: $85\text{--}100\,\text{fL}$; MCHC: $31\text{--}35\,\text{g/dL}$.

What antibodies are found in the serum of individuals with Type A, Type B, Type AB, and Type O blood?

Type A: Anti-B; Type B: Anti-A; Type AB: None; Type O: Anti-A and Anti-B.

Which specific antigen determines Rh-positive status, and how does Rh antibody development differ from ABO antibody development?

The D antigen determines Rh-positive status. Unlike ABO antibodies, Rh antibodies do not occur naturally and only develop after exposure through pregnancy or blood transfusion.

How do Transfusion-Related Acute Lung Injury (TRALI) and Transfusion-Associated Circulatory Overload (TACO) differ in mechanism?

TRALI involves pulmonary edema, hypotension, and hypoxemia within $6\,\text{hours}$ due to lung injury, whereas TACO is caused by fluid overload leading to respiratory distress, particularly in patients with heart or renal disease.

What is the RBC morphology, etiology, and key clinical manifestations of Hereditary Spherocytosis?

RBC Morphology: Spherical (spherocytes); Etiology: Defect in spectrin/ankyrin leading to loss of membrane surface; Key Manifestations: Splenomegaly, jaundice, and bilirubin stones.

What genetic mutation causes Sickle Cell Disease, and what are its key clinical manifestations?

A point mutation substituting valine for glutamic acid in the beta chain; key manifestations include pain crises, organ infarction, and acute chest syndrome.

What is the RBC morphology, underlying cause, and key clinical manifestations of Iron Deficiency Anemia?

RBC Morphology: Microcytic, hypochromic; Cause: Chronic blood loss or dietary deficiency; Key Manifestations: Pica, koilonychia (spoon nails), and smooth tongue.

What is the cause and clinical presentation of Aplastic Anemia?

Cause: Bone marrow failure producing pancytopenia due to toxins or radiation; Clinical Presentation: Bleeding due to low platelets and infection due to low WBCs (with normocytic, normochromic RBCs).

How do Relative Polycythemia, Primary Polycythemia, and Secondary Polycythemia differ in their causes?

Relative Polycythemia (Gaisböck Syndrome) is caused by fluid/plasma volume loss (dehydration); Primary Polycythemia (Polycythemia Vera) is a neoplastic disease of marrow stem cells; Secondary Polycythemia is a compensatory increase in erythropoietin from chronic hypoxia.

What is Physiologic Anemia of the Newborn, and when does it occur?

It is a natural decline in hemoglobin occurring around $2\,\text{months}$ of age in infants due to reduced RBC production and plasma dilution.

What causes Hemolytic Disease of the Newborn (Erythroblastosis Fetalis), and how is it prevented?

Pathogenesis: An Rh-negative mother sensitized by Rh-positive fetal blood produces maternal anti-Rh antibodies that cross the placenta in subsequent Rh-positive pregnancies; Prevention: Administration of Rh immune globulin (RhoGAM) at $28\,\text{weeks}$ gestation and within $72\,\text{hours}$ of delivery.

Why can unconjugated bilirubin cause kernicterus in neonates while conjugated bilirubin cannot?

Unconjugated bilirubin is lipid-soluble and can cross the blood-brain barrier to damage basal ganglia, whereas conjugated bilirubin is water-soluble and cannot cross the blood-brain barrier.

Why do patients with chronic renal failure frequently develop anemia?

The kidneys produce $90\%$ of the body's erythropoietin; damaged kidneys secrete inadequate amounts to stimulate RBC production, and uremic toxins further shorten RBC survival.

What age-related changes affect red blood cell production and response to acute stress in older adults?

Marrow reserve declines and shifts to the axial skeleton, hemoglobin levels decrease after middle age (lowest in those $>85$), and older adults cannot replace RBCs as promptly as younger adults during acute stress like hemorrhage.