Lymphatics Flashcards
Name the components of lymphatic nodes
Afferent lymphatics, cortex with germinal centres (b lymphocytes) surrounded by T cells, lymph accumulates in subscapular sinuses, macrophages are surrounded throughout, capsule is elastic and smooth mm, blends with fine fibrous trabeculae, medullary sinuses lined by antibody secreting mature B cells ‘plasma cells’
What are the exceptions to the lymph nodes
In the pig everything is reversed and turned inside out
Describe the lymphatic development
Develop later than blood vessels, 6 sacs (outgrowths of veins), plexi of vessels grow from these
Development of lymphatics in embryo
Jugular vein, 2 jugular sacs, 2 interconnecting throacic ducts > final duct formed from caudal Right and cranial Left, 1 retroperitoneal, 1 cisterna chyli, 2 iliac sacs, common iliac vein, caudal vena cava
What drains into the right lymphatic duct next to right jugular vein
Right head, neck, forelimb and thorax
Cisterna
Irregular cavity between caudal vena cava, aorta and spine
Describe the lymphatic system
Drains and filters interstitial fluid called lymph
Drains fatty acids from intestine via lacteals chyle
Transports and houses immune cells: lymphocytes and monocytes/macrophages
Contains lymphatic aggregations including MALT = mucosa-associated lymphoid tissue
What are the lymphatic vessels
2 forces in blood capillaries: HP driving water into intersittum, OP drives water into capillaries
Pressure out is greater at arterial but less at venous end
Describe lymphatic capillaries
Blind ending, endothelium lined, permeable collecting chambers. Permeability is greater than in blood capillaries due to overlapping anchoring filaments,
Describe lymphatic vessels
Not present in CNS, bone marrow, cartilage, epidermis, alveoli or placenta. Thinner walled than veins but contain more valves.
Describe the transport of lymphatic vessels
Skeletal muscle pump, nearby arterial pulsing, intrinsic smooth muscle contractility (sympathetic innervation, constriction if BP decreases)
What is the pathology
Inadequate lymph drainage may lead to oedema
Rupture of thoracic duct > chylothorax (cavity filled with milky fluid, duct eventually heals)
Describe lymph nodes
All lymph passes through one or more lymphocytes, often located where interference is minimal with other organs
Name three infectious spreads associated with the nodes
Lymphadenitis, lymphoma, secondary tumours
What are mononuclear phagocytes
Reticuloendothelial system, present as macrophages in connective tissue around the body, liver kupfer cells, CNS miroglia and in the spleen, phagocyte pathogens/debris/blood cells store fe
