Erythrocytes Flashcards
hepcidin
regulates intestinal absorption and cellular release of Fe. Binds to ferroportin to limit absorption and release
Synthesized primarily by hepatocytes
When hepciding binds to membrane ferroportin on the basolateral membranes of small intestinal villus enterocytes…
ferroportin is internalized and the cell loses its ability to export Fe from the cell to the circulation. Accumulated intracellular Fe inhibits the expression of divalent metal transporter 1 and ferric reductase (duodenal cytochrome b) on the brush border, so Fe absorption into the cell is also decreased
Synthesis of hepcidin is influenced by…
hypoxia, Fe availability, IL-6
hepcidin and inflammation
During inflammation, cytokines are released, including IL-6, which promotes synthesis of hepcidin –> binds to ferroportin which is then internalized. Thus the amount of ferroportin available for the export of Fe from cells (including macrophages) is reduced. This process tends to sequester Fe in macrophages –> less available for erythropoiesis and infectious agents.
hepcidin and hypoxia
When hepatocytes detect hypoxia, decreased formation of hepcidin –> ↓ hepcidin concentration –> ↑ availability of Fe for erythropoiesis; that is, the ↑ movement of Fe from enterocytes to plasma and ↑ release of Fe from macrophages to plasma
Describe Anaplasma marginale and associated pathogenic processes
marginal body is a small, dark staining coccus ~0.5 µm diameter on the internal margin of erythrocytes; typically one organism per cell but may be multiple.
Immune hemolysis, possibly others
Describe Anaplasma centrale and associated pathogenic processes
small dark-staining coccus ~0.5µm diameter within erythrocytes; typically one organisms per cell but may be multiple
immune hemolysis, possibly others
Describe Babesia spp and associated pathogenic processes
intracellular oval to teardrop or pyriform trophozoites (piroplasms); B. gibsoni and other small babeisa are <2µm, others are 2-4µm long; typically pale blue with a darker outer membrane and a reddish purple eccentric nucleus
Several theories, including immune mechanisms, protease activity, decreased cell pliability, oxidative damage
Describe Cytauxzoon felis and associated pathogenic processes
intracellular oval structures (0.1-2.0µm) with out thin rim and eccentric nuclei; may resemble signet ring or safety pin; one to several piroplasms per cell
Pathogenesis of anemia may be multifaceted (inflammation, marrow damage, possibly hemolysis in some cases)
Describe distemper in dogs and associated pathogenic processes
round or variably shaped, pale blue or pink homogenous inclusions, variable sizes; also in leukocytes
Indicates active distemper infection
Describe Mycoplasma species of cattle and associated pathogenic processes
rings, rods, or cocci on surface of erythrocytes; 0.3-1.0µm
Immune hemolysis
Describe Mycoplasma haemocanis and associated pathogenic processes
typically thin chains of cocci on membrane that may form pleomorphic pattterns (violin bow, oval, cross)
Immune hemolysis
Describe Mycoplasma haemofelis and associated pathogenic processes
Typically cocci (individual or in short chains) and small rings or doughnuts (<1µm) on erythrocyte surface, stain blue-grey to pale purple Immune hemolysis
Describe Candidatus Mycoplasma haemominutum and associated pathogenic processes
typically cocci (0.1-0.2 µm), individual or in short chains Immune hemolysis, but low virulence
Describe Theileria species and associated pathogenic processes
highly pleomorphic piroplasms including cocci, rings, rods, pears, Maltese crosses
Several theories, including immune mechanisms, protease activity, decreased cell pliability, oxidative damage
