PART 3- THIRD LEARNING Flashcards
The bone marrow produces
platelets, erythrocytes, granulocytes (neutrophils, eosinophils, and basophils), monocytes and probably the bursa equivalent of B lymphocytes.
The status of the bone marrow cellular activity is reflected in
peripheral blood cell counts
The requirement for direct marrow examination the living animal is not a common practice but needs to be considered when there are:
- Inexplicable peripheral blood changes
- In cases of suspected myeloproliferative disorders
- Inexplicable peripheral blood changes such as:
a. The presence of cells with abnormal or atypical morphology
b. Inappropriate response to an anemia or infection;
c. The development of unexplained anemia and or leukopenia.
Growing animals show active red marrow which is replaced by
replaced by fat tissue as the animal mature
In old animals, active (red) marrow is restricted to the
flat bones and the endosteal area of long bones
Although the marrow respond to heavy demands following infectious insults, in some chronic infectious cases, the spleen, liver, adrenal and other areas where there are foci of primitive mesenchymal cells, production of hematopoietic cells occur at these sites and the process
extramedullary hematopoiesis
hematopoietic cells
Erythroid and myeloid precursors
undergo differentiation and maturation in marrow spaces before their release into vascular sinusoids.
erythroid and myeloid precursors
are entered b hematopoietic cells via diapedesis or proplatelet shearing
vascular sinusoids
structurally support the marrow
trabecular bone
produces trabecular bone
ostoeblasts
sit on a basal lamina and separate the vascular sinusoids lumens from marrow hematopoietic and stroma cells.
endothelial cells
line vascular sinusoids and release cytoplasmic fragments (platelets) into sinusoidal lumens.
megakaryocytes
provide structural and metabolic support to hematopoietic cells
stromal cells
constitute 25% to 75% of the total marrow space. the proportion of adipocytes increases with age.
adipocytes
mechanism of disease in bone marrow and blood cells
BONE MARROW
hypoplasia
hyperplasia
dysplasia
aplasia
neoplasia
myelophthisis (fibrosis, metastatic neoplasia)
necrosis
inflammation
BLOOD CELLS:
increased destruction
hemorrhage (erythrocytes)
consumption
neoplasia
altered distribution
abnormal function
- increased production of various cell lines which occurs frequently in response to demands by, or changes in the other parts of the body.
1) Hyperplasia
is used where the increased production is at the expense of the other cell lines.
MYELOID METAPLASIA
refers to the general reduction in the amount of cells produced in the bone marrow that are in circulation.
2) Pancytopenia
The response is generally that of marrow aplasia and may be caused by such factors
as irradiation, chemical and bacterial toxin and some drugs.
Causes of marrow depression include viral diseases such as
parvovirus, enteric infection of dogs and cats and feline leukemia virus infection, and Erhlichiosis.
is a term used to describe the metastasis of neoplastic cells to the bone marrow
5) MYELOPTHISIS