Comparative anatomy of the haemopoietic system Flashcards
What is the Haemopoietic system?
organs and tissues involved in the production of cellular blood
components
What is Haematopoiesis?
production of blood cells
What is red bone marrow?
has a haematopoietic function, richly vascularised
What kind of bone marrow is found in young mammals?
Red bone Marrow
What is yellow bone marrow predominantly?
Fat, but it has haematopoietic potential
Where does excess fluid drain into?
lymphatic vessels (lymph)
What is the main function of the thoracic duct?
transport lymph back into the circulatory system
where does the thoracic duct drain into?
left branches of the vena cava, e.g subclavian vein, left jugular and brachiocephalic vein
What kind of pressure does lymph flow at?
low pressure as lymphatics are thin walled and can readily collapse
What is the function of Haemal nodes?
to filter blood (they contain blood sinuses and are most common in ruminants)
What is the difference between MALT and lymph nodes?
MALT
: does not have a capsule
: has a closer relationship to the epithelial surface
: positioned at the origin of the lymphatic drainage pathway
where are the majority of peyers patches found?
illeum and jejunum
how can you distinguish peyers patches?
they do not have any villi covering them
Where in the abdomen is the spleen found?
the left cranial part, attached to the greater curvature of the stomach via the gastrosplenic ligament
What artery and vein supplies the spleen?
splenic artery and vein
What is the spleen parenchyma divided into?
red and white pulp
What is the red pulp in the spleen?
venous sinuses
What is the white pulp in the spleen?
lymph nodules
What is the main function of the thymus?
control organ of immune and lymphatic systems (produces large amounts of T cells)
What is the Bursa of Fabricus?
Site of B-Lymphocyte production found only in birds
What are haemal nodes?
Lymph nodes found in blood vessels
What is one difference between lymph nodes and MALT
MALT do not have capsules and they are closer to the epithelial surface
What are the main functions of the spleen?
Blood storage, Blood filtration, Destruction of old RBC’s, and production of lymphocytes
What is the main function of the thymus?
Primary lymphoid organ, produces T cells
What is the species difference of lymph nodes in pigs?
They have central cortical tissue, so the afferent vessels penetrate the capsule near a hilus instead then emerge from the periphery
In what animals are haemal nodes most common?
Sheep and cattle
What are some species differences in the splenic artery and vein?
In dogs and cats, the splenic arteries divide as they approach the organ
In ruminants they pass through undivided and in horses and pigs they branch at intervals
What is the function of the thymus capillaries having a blood-thymus barrier?
Prevents T-cells in the capillaries from being exposed to antigens in the blood
What are primary lymphatic organs?
Where lymphocytes are formed and mature, e.g red bone marrow and the thymus gland
What do primary lymphatic organs provide an environment for?
They provide an environment for Stem cells to divide and mature into B and T cells
What are secondary lymphoid tissues?
They are filters, they monitor the content of extracellular fluids (e.g lymph nodes, the spleen and MALT)
What animal has a bursa of fabricius as a primary lymphoid organ
Birds
What secondary lymphoid organs do birds have?
Spleen, Bone marrow and intestinal lymphoid tissue
What birds have lymph nodes and where are they?
ducks and geese, they have 2 primitive pairs near the thyroid gland and the kidneys
What does the bursa of fabricius look like?
Contains folds of lymphoid tissue, it is thick walled in domestic fowl, thin and saclike in budgies, canaries etc.
What does the spleen look like in birds?
It is found in the right coelom, quite small and can be oval/triangular or elongated
What is a lymph heart and what animals have it?
A lymph heart is an organ that pumps lymph around the body, it is found in reptiles
What organ in the fish is a haematopoietic organ?
The cephalic/ cranial kidney
Where do reptiles have their paired thymus glands?
Either side of the neck in lizards and just cranial to the heart in snakes
What animals lack lymph nodes?
Amphibians
What animals have a functioning thymus throughout their whole life?
Amphibians
What is another name for a lymph nodule?
germinal centre
What does the thymus look like in birds?
3-8 pale lobes near the jugular vein
What is the purpose of the thoracic ducts either side of the spine?
They drain the lymph from the hindlimb and abdominal vessels then deliver it into the jugular veins at the base of the neck
What is the morphology of the spleen like in different species?
- Dumbbell-shape in dog and cat
- Strap-like in pig
- Broad oblong in cattle
- Hooked in horse
What are some species differences of Reptiles?
They lack lymph nodes so they have lymph hearts
Thymus is present throughout their entire life however it does get smaller over time
The lymph system is associated with the blood system so you may get lymph when sampling blood
What type of animals have GALT?
Amphibians
