Hematology Flashcards
What is extra medullary hematopoiesis and when does it occur?
hematopoiesis occuring outside of the medullary cavity.
This can occur during fetal development where hematopoiesis will occur in the liver or spleen.
This can also occur during pathological process such as myelofibrosis where fibrosis occurring in the bone marrow forces hematopoeitic cells out of the marrow into the spleen or liver.
Comment on the difference between young and old animals bone marrow…
Young: Have red, active marrow producing many RBC’s (the need for new RBC’s is high)
Old: Limited parts of the marrow are producing cells. Active marrow is usually at the end of the long bones. They contain yellow marrow in the region of the diaphysis which consists of fat and supporting cells. This area does have the ability for active marrow to infiltrate.
What is the first recognizable cell seen in erythropoiesis?
rubriblast.
What is the first cell seen in bone marrow aspirates? What is a unique feature of this cell.
Erythroblast. Round Nucleus. Very blue.
What is a unique characteristic of Normoblasts?
They have a condensed, shiny black nucleus poking out of the side of the cell and eventually it will get rid of the nucleus.
What are reticulocytes?
They are immature, anucleated, red blood cells that develop and mature in the red bone marrow. They circulate for about a day or two before maturing into an RBC.
Splenic Sequestration
This occurs in dogs and horses. During times of stress or nervousness will get a splenic contraction (spleen is a reservoir for RBC’s) which will cause an increase in circulating RBC’s however this is a transient situation. Circulation numbers will return to normal. Keep this in mind when sampling to not confuse with blood disorder.
Describe the progression of Granulopoiesis.
- Multipotential stem cell
- Unipotential stem cell
- Myeloblast (first recognizable cell)
- Promyeloctye
- Myelocyte
- Metamyelocyte
- Band Neutrophils
- Mature Neutrophils/ segmenters ( wait in the bone marrow for stimulus to allow release)
A higher than normal number of circulating reticulocytes could indicate what?
- Bleeding
- Hemolytic Anemia
- Increase production of EPO in the kidneys
What stain can be used to test for increased/ decreased reticulocytes in the blood sample?
When immature red blood cells are stained with a supravital dye, the cytoplasmic RNA is precipitated into a reticulum-like network.
Describe the lifecycle of an erythrocyte beginning in the bone marrow.
- Matures in the bone marrow from a multi potential stem cell to a reticulocyte over a 5 day period.
- The reticulocyte is released into circulation and circulates for ~48 hours until it matures into a RBC.
- Depending on the species, the RBC will circulate for “x” amount of days until is aged enough to be phagocytosed my macrophages primarily in the spleen but possibly in the liver and bone marrow as well.
- When becoming phagocytosed, the macrophages break down the RBC into bilirubin, Fe, and protein.
- The bilirubin is then transported to the liver via the plasma protein albumin. The Liver will conjugate bilirubin into a H20 soluble product allowing it to be come excreted.
- The Fe will be transported and recycled back into the bone marrow for further use.
What is the RBC life span of:
a. Horse
b. Cow
c. Dog.
d. Cat.
e. Mice
A. 145 B. 130 C. 120 D. 70 E. 43
What is EPO, what is its purpose, and where is it produced?
Erythopoietin is a hormone produced by the kidneys in response to HYPOXIA. It will enter the circulation, travel to the marrow, and stimulates the proliferation of erythroid progenitors (undifferentiated stem cells in the bone marrow)
Describe the life cycle of a neutrophil beginning the bone marrow..
Multi potential stem cells mature in Neutrophils after ~6 days in the bone marrow. Neutrophils enter the circulation for ~ 7-14 days and then can either be
- Circulating neutrophils where the stay in the
in the central axis of the blood stream. OR
- Marginating neutrophils that creep along the walls of the endothelium waiting to move into tissues in response to inflammation/ infection.
When taking a blood sample you will sample the circulating neutrophils.
Once neutrophils have entered the tissues they will not re enter back into circulation. They will either be lost from the body or phagocytosed by macrophages.
Describe the life span of eosinophils…
Eosinophils take 2-6 days to mature in the bone marrow. They will enter the circulation and circulate for 1-24 hours before entering tissues (skin, GI, resp). They will last in the tissues for as shorts as 2 days and as long as 2 weeks.
