Lecture 1 8/22/24 Flashcards
What changes do erythrocytes undergo during maturation?
-become progressively smaller
-nucleus becomes progressively condensed
What stage of the RBC is released from the bone marrow in the majority of species when in health?
reticulocytes
How do mature erythrocytes appear on blood smear?
-red-orange stain
-round and biconcave
-central pallor
How do reticulocytes appear on blood smear?
-blue-purple stain
-slightly larger than mature erythrocytes
-more visible central pallor
Which state of iron is required for hemoglobin production?
ferrous state (Fe2+)
How is bilirubin produced?
breakdown of the porphyrin ring in heme
How do enterocytes function in iron metabolism?
absorption and storage of dietary iron
How do macrophages function in iron metabolism?
degradation of aged RBCs and recycling and storage of iron
How do hepatocytes function in iron metabolism?
storage of iron
What is ferritin?
a storage protein for iron that can enter circulation in small amounts
Why is measuring ferritin useful?
provides an estimate of the storage iron in an animal’s body
What is transferrin?
protein that transports iron in the blood
How does inflammation impact iron storage and export?
inflammatory mediator hepcidin degrades the channel that releases iron from the cell into the bloodstream, trapping iron in its storage sites
What are the characteristics of iron-restricted erythropoiesis?
-occurs when there are inadequate amounts of iron for normal hemoglobin production
-can lead to anemia
What are the two most common causes of iron-restricted erythropoiesis?
-depleted iron stores/absolute iron deficiency
-iron sequestration due to inflammation
What is extravascular hemolysis?
removal of RBCs from the blood and degradation of RBCs within macrophages adjacent to the blood vessels
What is intravascular hemolysis?
RBCs rupture within the blood vessel, releasing free hemoglobin into the plasma
Which form of hemolysis clears the majority of aged RBCs?
extravascular hemolysis
What are the two potential causes of increased bilirubin?
-hemolysis
-liver dysfunction
What are the two hallmark features of intravascular hemolysis?
-hemoglobinemia
-hemoglobinuria
What leads to the red discoloration of urine and plasma in hemoglobinemia and hemoglobinuria?
large amounts of free hemoglobin entering the plasma and urine
Which components of the erythrogram are indicators of RBC mass?
-hematocrit/packed cell volume
-RBC count
-hemoglobin concentration
What are the characteristics of the indicators of RBC mass as a group?
-typically increase/decrease together
-decrease indicates anemia
-increase indicates erythrocytosis
What is indicated by HCT and PCV?
percentage of total blood volume occupied by RBCs
What is indicated by RBC count?
number of RBCs in a microliter of whole blood
What is indicated by HGB concentration?
grams of hemoglobin in each deciliter of whole blood
What is HGB concentration proportional to?
total mass of RBCs in the blood
Which components of the erythrogram are considered RBC indices?
-mean cell volume
-mean cell hemoglobin concentration
-red cell distribution width
What information does MCV provide?
average size of the RBCs
What information does MCHC provide?
average concentration of hemoglobin in each RBC
What information does RDW provide?
variation in RBC size
What are the descriptors for MCV?
-normocytic/within ref. interval
-microcytic/below ref.
-macrocytic/above ref.
What are the descriptors for MCHC?
-normochromic/within ref. interval
-hypochromic/below ref.
-hyperchromic/above ref.
What causes increased MCHC to appear on a CBC?
-falsely increased HGB
-falsely decreased HCT
-MCHC is always artifact and falsely high
What is anisocytosis?
variability in cell size
What does an increased RDW indicate?
an increased number of smaller and/or larger RBCs
What is the importance of the absolute reticulocyte count?
allows for the determination between regenerative and non-regenerative anemia
What are the characteristics of the CHr measurement?
-measures amount of hemoglobin present in reticulocytes
-used when evaluating for iron deficiency
