Pathology of the Hemopoietic System

Flashcards covering the pathology of the hemopoietic system, including hematopoiesis, RBC/WBC disorders, platelet kinetics, and diseases of the bone marrow, spleen, and lymphatic organs.

What is the process through which blood cells are produced, and what is its etymology?

Hematopoiesis or Hemopoiesis; from the Greek words "haima" (blood) and "poiein" (to make).

Where is the site of hematopoiesis in an embryo versus an adult mammal?

In the embryo, it occurs in the yolk sac; in adults, it occurs in the bone marrow of all regions of flat bones and the extremities of long bones.

What are the common sites for Extramedullary hematopoiesis (EMH) during fetal development and in response to need?

Yolk sac, liver, spleen, thymus, and lymph nodes.

What is the primary regulator of erythropoiesis and where is it synthesized?

Erythropoietin ($Epo$), which is synthesized in the Kidney in response to Hypoxia.

How is the "Erythron" defined?

The mass of circulating erythrocytes plus the erythropoietic tissue of the bone marrow, consisting of erythrocyte precursors, blood erythrocytes, and splenic erythrocytes.

What are the two types of Absolute Erythrocytosis?

Primary Erythrocytosis (proliferation of marrow precursors independent of $Epo$) and Secondary Absolute Erythrocytosis (excessive production of $Epo$ commonly caused by hypoxia).

What are the clinical manifestations of increased blood viscosity in Absolute Erythrocytosis?

Cyanotic oral mucus membranes, marked depression, impaired blood flow inducing cyanosis, and a tendency for thrombosis.

How is anemia classified based on cell size?

Normocytic Anemia (normal size), Microcytic Anemia (small cells), and Macrocytic Anemia (large cells).

What constitutes the hallmark clinical findings of Regenerative Anemia?

Polychromasia and Reticulocytosis; other findings include Anisocytosis, Howell-jolly bodies, and nucleated RBCs.

Explain the difference between intravascular and extravascular hemolysis.

Intravascular hemolysis occurs within blood vessels, causing hemoglobinemia and hemoglobinuria; extravascular hemolysis occurs outside the vascular system (via macrophages) and does not typically show hemoglobinemia or hemoglobinuria.

What are the histological findings in Toxic Aplastic Anemia?

The bone marrow appears acellular and hypoplastic.

Define Poikilocytosis and list four specific examples of abnormally shaped RBCs.

Poikilocytosis is the presence of variable-shaped RBCs. Examples include Acanthocytes (with spicules), Dacryocytes (teardrop), Codocytes (target cell), and Schizocytes (fragmented).

What are Heinz bodies as seen in erythrocyte inclusions?

Clumps of precipitated hemoglobin usually visualized by Wright-stained smears or special stains like New methylene blue.

Into what two broad groups are leukocytes divided?

The Phagocytes (Granulocytes: neutrophils, eosinophils, basophils; and Monocytes) and the Immunocytes (Lymphocytes, their precursors, and plasma cells).

What characterizes a "Shift to the Left" in the leukocyte response?

The presence of immature neutrophils in the blood, such as band neutrophils, metamyelocytes, or myelocytes.

What are the giant cells in the bone marrow that produce platelets, and what is their approximate diameter?

Megakaryocytes, which have a diameter of $35-160\,\mu\text{m}$.

What are the three interrelated pathways of the coagulation system?

The Intrinsic pathway, the Extrinsic pathway, and the Common pathway.

What clinical signs are indicative of Thrombocytopenia?

Petechiation (mucosa and ocular sclerae), mucosal bleeding (gingival margin and intestine), epistaxis, and severe hemorrhage post-surgery or trauma.

What are the preferred sites for collecting bone marrow samples in Cattle and Horses?

In Cattle, the proximal ribs; in Horses, the sternum.

What is the largest component of the reticuloendothelial system and what are its functions?

The Spleen; it performs hematopoiesis, iron metabolism, filtration/phagocytosis of RBCs, blood reservoir, and immunologic functions.

What are the common anatomical and viral causes of Lymphoma/Lymphosarcoma?

It can be sporadic, hereditary (porcine), or viral (FeLV in cats, BLV in cattle).

What is the clinical significance of Von Willebrand's Factor (vWF)?

It is an adhesive protein synthesized by vascular endothelial cells and megakaryocytes that contributes to platelet adhesion.

What is Serous atrophy of fat in the bone marrow?

A gelatinous transformation of fat within the marrow often caused by cachexia.

How does the thymus change as an animal ages?

It reaches maximum development at birth and undergoes progressive involution as the animal ages, though it remains important for T-cell maturation.