Anemia Flashcards
Healthy Erythron
12-15 g/dL
Normal structure
Circulate for 120 days
Kidneys respond to RBC need with erythropoeitin
RBC precursors normal with enough iron and vitamin cofactors
Senescent RBCs cleared by spleen
Normal RBCs
Pliable, elastic, anucleate
Membrane is selectively permeable
Large SA to V ration permites RBC to squeeze through capillaries and resume shape
Normal RBC cytoplasm content
Hemoglobin A for transport of oxygen to tissues
RBC membrane structure
Phospholipid bilayer and cholesterol Internal spectrin cytoskeleton Transmembrane proteins Glycopeptides and glycolipids (outer) GPI-linked proteins (outer) Absorbed plasma substances (outer)
Interactions of RBC membrane determine
Shape, metabolism, trasnport, and survival
Definition of anemia
Reduction in RBC mass, numbers, or hemoglobin concentration with corresponding decrease in oxygen carrying capacity of the blood
Compensatory mechs to anemia
Circulatory - increase HR, dilation of arterioles to increase tissue perfusion
Biochem - increase 2,3-DPG in RBCs…decreases hemoglobin affinity to increase delivery to tissues
Bone marrow - hyperplasia due to increase in erythropoetin…increase in reticulocytes
When compensation fails (clinical features of anemia)
Pallor Weakness Malaise Headaches Dyspnea (on exertion at firt)
Later consequences of anemia with resulting hypoxia
Angina pectoris and heart failure
Fatty change in liver
Compensatory bone marrow hyperplasia
How do we classify anemia?
By RBC morphology
RBC morphology (size, color, appearance)
Size - normocytic, microcytic, macrocytic
Color - normochromic, hypochromic
Appearance - spherocytes, target cells, schistocytes, cytoplasmic inclusions
Color reflects
Degree of hemoglobinization
Hypochromic microcytic anemia
Could be due to iron deficiency
Small red cells contain narrow rim of peripheral hemoglobin
Megaloblastic anemia
Enlarged oval RBCs
Spherocyte
Membrane loss…loss of SA relative to volume
Loss of central pallor
Typical of extravascular hemolysis
Not all affected
Target cell
Membrane excess…def of cytoplasm
Cause might be thalassemias (reduces Intracell Hb but not membrane surface area)
Schistocytes
RBCs mechanically fractured in circulation
Cytoplasmic inclusions
Could see precipitate of denatured globin in supravital staining
Think G6PD deficiency
Bite cells will be produced as macrophages pluck out
Reticulocytes
Larger size with blue tint
Percentage reflects both demand and effective of erythropoiesis
If large, increases MCV
Polychromasia
Many reticulocytes
Mechs of anemias
Blood loss
Impaired RBC production (nutrient def or marrow disorder)
Increased RBC destruction (hemolytic anemias)
Acute blood loss symptoms depend on
Rate of hemorrhage and site of bleeding (int vs ext)
Severe blood loss can
Lead to cardiovascular collapse, shock, and death
Acute blood loss compensatory
Shift of fluid from extraascular space ot cirulcation—–leads to hemodilution and decreased hematocrit…**hemocrit and hemoglobin values may not reflect magnitude of blood loss because this takes some time