05 Spleen

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Lymphoid Organs

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• Cortex: white, contains follicle

• Paracortex: T cells

• Medulla with cords and sinus

• Afferent lymph goes through the 3 layers, exit at 1 efferent vessel

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• APC process free antigens

Cortex

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• dendritic cell like velcro picking up antigens that allow B cell to react

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• 4: follicle

• 3: white, germinal center, thus secondary follicle

Paracortex

[_](Paracortex contains what cells. Classic disorder. How does it respond during infection. What's so special about the venules)..

• HEV: spaces between endothelium to allow B and T from blood to enter lymph

Medulla

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Spleen

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• not lymph filter

• filters blood

• everything in blood enters spleen

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• first from artery to white pulp (white)

• then blood moves through red section, red pulp

• eventually back to splenic vein

White Pulp

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Red Pulp

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• endothelium with barrel hoop membrane. Still large enough for blood to pass through

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• less complement activity because needs IgG and IgM for binding Fc

• antibody binding leads to MAC and c3b formation

• macrophage binds to antibody and c3b, phagocytosis

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• malaria/babesia: infected RBC can't be cleared

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• ITP: low platelets. Take out spleen to increase platelet

• spherocytosis: take spleen out, less destruction of anemia

• Sickle cell: so many abnormal RBC that damages spleen when removed

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• target cells usually cleared by spleen