Lymphoid Organs Flashcards
Primary lymphoid organs?
Thymus - t cell production ( cell mediated immune response)
Bone marrow - b cell production (proliferate, plasma cells, humoral response & pre-t cell production)
6 lympoid organs
Bone marrow (hematopoietic process) Spleen Thymus ( t cell production ) Lymph nodes Tonsils Peyers patches
Secondary lymphoid organs ?
Spleen, lymph nodes (peripheral organs) - surrounded by CT capsule
- find antigens -> immune reponse
Where lymphatic nodules contain no capsule?
Digestive system, respiratory system.
Where are peyers patches? (4)
Small intestine - Ileum.
Resemble tonsils in structure.
Capture and destroy bacteria
Therefore can distinguish ileum from duodenum.
Which is the only lymphoid organ not to fight antigen?
Thymus
Diffuse lymphatic tissue. 3 main located and Where located within these. Specific characteristic….
GALT digestive tract BALT respiratory tract Genital urinal tract Located in lamina propria No capsule
Maturation of lymphocytes? (7)
Bone marrow, pluripotent lymph cells, thymus, t-cells, maturation, leave via blood or lymph nodes, circulate in blood or pop. 2nd lymphoid organs
Thymus structure (3)
Connective capsule, 2 lobes, cortex and medulla (lobules)
Cortex - close packed, dark basophilic
Medulla - less dense, less close cells.
Thymus medulla differs from cortex (3)
Less closely packed, hassal corpuscle, dendritic cells
Hassal corpuscle (3) and which type of cell and what stain color with h and e?
Formed by epithelioreticular cells (type 6)
Production of factors - regulate maturation of t cells
H and e - pink
Thymus cells in cortex?
Epithelioreticular (type 1 under capsule, type 2 in cortex), thymocytes, macrophages
Thymus cells in medulla?
Epithelioreticular cells (5, 6 around hassal corpuscle)
Dendritic cells,
Macrophages,
Thymocytes
Blood-x barrier (3)
Brain - astrocytes (CNS) - perivascular feet
Thymus (4) - epithelioreticular cells, macrophages, capillary endothelium and basal lamina
Testis - occluding junctions - prevent exposure of immune response cells and testosterone to spermatogonia.
Importance of blood thymus barrier?
Prevent antigen into thymus.
Therefore protect immature t cells from immunocompetent lymphocytes
Thymus - cortex medulla boundary contain?
Type 3&4 epithelioreticular cells - selection of lymphocytes with specific receptors - pass thru barrier
Thymus and lymphatic follicles?
Contains none, found in spleen and lymph nodes.
Where are lymph nodes located?
Purpose?
And 2 types of defence cells in lymph and function?
In terms of lymphocytes competancy?
Along lymphatic vessels
Filter lymph - returned to blood
Macrophages - engulf and destroy foreign substances
Lymphocytes - immune response to antigens.
Lymphocytes maturation and competency organs
Regional lymph nodes? (5)
Axillary, inguinal, neck, abdomen, mediastinum
4 cell types in lymph nodes?
Macrophages, lymphocytes, dendritic cells, reticular cells (type 3 collagen production - provide structural framework for organ)
What is lymph?
Similar to blood plasma, no proteins.
Seeps out of blood from peripheral capillaries.
What is purpose to lymphatic vessels?
Convey fluid from peripheral capillaries to veins
Lymph nodes structure?
Capsule, sub-capsular sinus ( specific to lymph node, contain lymph from lymphatic vessels).
Cortex - b cells, primary and secondary follicles ( germinal + mantle)
Para cortex - mainly t cells
Medullary cords - macrophages and plasma cells
Medullary sinus
Hilum(artery and vein)
Lymph nodes follicles?
Primary - lymphocytes not stimulated by antigen
Secondary - lymphocytes stimulated - proliferation of cells
- mainly b cells
- germinal - lymphocytes recognised antigen.
Spleen dimensions and weight? Which artery connects and how effects?
L - 12-15cm, W - 4-8cm, Thickness 3/4cm
Weight 120-140g, Dark red
Splenic artery - important branching - influences structure of spleen,
Functions of spleen (4)
Blood reservoir,
hemocatalysis,
hemopoiesis (2nd trimester of birth),
activation of b and t lymphocytes
If organ dark strain - contain lymphocytes….
Spleen, lymph nodes, thymus - contain lymphocytes
Structure of spleen? 2 area of arteries
Connective capsule - thick trabeculae
Arteries - central and penicillar aterioles
Malpighian corpuscle - accumulation of lymphocytes, cover central artery, lymphatic nodules, specific to spleen
Sheated capillaries - by macrophages
Splenic sinus - net of capillaries connect to venules - splenic vein - exit organ.
Spleen white pulp?
20% White - immune response - Malpighian corpuscles encircle branches of splenic artery (central arteries).
Spleen red pulp
80% red pulp - hemocatalysis, blood reservoir - macrophages and blood cells - red pulp sinus (wide sinusoids)
Thymus (2) peak and endocrine function
Peak during childhood. Adult converted into white adipose tissue. Produce hormones (thymosin) program lymphocytes
Where are lymph nodules located? And lined by?
Lamina propria of mucosa
lined by epithelium
Tonsils, where, 4 locations which form………ring
Lymphoid nodules mouth.
Entrance to respiratory and digestive system.
Contain crypts - increase SA.
Tubaric, pharyngeal, lingual, palatine form “weldeyer ring”
