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Lymphatic System - Coggle Diagram
Lymphatic System
Immune System
Lymphocytes
T Lymphocytes (See Bone Marrow)
- bone marrow --> thymus to mature
- proliferate, rearrange TCR genes
acquire surface receptors
- If react with self-antigens, apoptose
- Mature T populate secondary lymphoid
organs and circulate via bloodstream
to search for antigens
B Lymphocytes
-
- precursors in bone marrow
- most mature into plasma cells,
synthesize antibody
- undergoes division after activation
- produces clone of cells able to synthesize
Ig with that specificity (clonal expansion)
Primary and Secondary Response
- Primary immune response (1st time)
- few cells from same clone mature
become memory B cells
- Antibody production in a secondary
immune response much quicker and greater
- 25% of leukocytes, densely stained
round dumptruck nucleus
- Circulate between red bone
marrow, lymphoid tissues, and other tissues
- B, T, and NK cells (5%)
- few months to several years
First Line of Defense
- non specific
- epithelial coverings (int/ext)
- some secretion, pH, and bact
Second Line of Defense
- Innate/cell-mediated/natural
- non specific, complement system
- plasma prot, bind to complement
receptors on phagocytes
- macrophages/neutrophuls phagocytosis
- NK kill some foreign cells
Third Line of Defense
- T, B, and Antigen Presenting cells
Immune Response
1. Lymphocytes circulate in blood, lymph
and other EC fluids
2. They pause in Lymphoid tissues
3. come in contact with antigen
4. It binds to surface receptors and activates
the lymphocyte
5. Very tightly regulated cause we don't
want response to anything in the body
General Features
- dense population of lymphocytes
- reticular connective tissue, macrophages
and plasma cells
Lymphoid Organs
Primary (bone marrow and thymus)
- Lymphocytes proliferate
and differentiate into mature
immunocompetent cells
Secondary (spleen, nodes, nodules,
diffuse lymphatic tissue, tonsils)
- where lymphocytes come in
contact with foreign antigens
Lymphoid Organs
Primary
Thymus
General
- Flattened Lymphoid organ
- under sternum slowly undergoes involution
after childhood
- Multiple lobules merge
- Epithelium sponge like
- reticular fiber, mesh like network
- Capsule with invaginations, surrounds
every lobule (little septae)
- Blood Thymus Barrier
Functions
-
Epithelial cells provide mechanical support
for lymphocytes and promote T cell diff and
proliferation, and secrete polypeptides with
hormonal characteristics for that purpose (thymus and lymphoid tissue) they hidden by T cells, need special stain
-
Cortex
- highly cellular (T cells) darker
- T cells migrate and move into
sub capsular area to begin maturation
- If fail, apoptose and phagocytosed
Medulla
- less cellular, lighter
- mature T cells migrate there,Self-Tolerance
- Epithelial cells pale staining nuclei
and eosinophilic cytoplasm
- End of Journey, T cells enter blood vessels
Hassall Corpuscules
- appear in fetal life, increase
in size and number after
- balls of dermis, keratinized
epithelial cells
Selection
- Hematopoeitic stem cells (for T cells)
- Double negative *no CD4 or CD8)
- Double positive
- mature to single positive (helper4 or killer8)
- 98% die during dev by failing pos or neg selection
-
Secondary
Lymph Nodes
-
- at junctions of major lymphatic vessels
- T and B interact with antigens and APC
- Lymphocytes activation and division
- Purpose to filter, almost like checkpoint
- tiny to massive, very organized, minimum 450
- Very cellular, lots of lymphocytes
- very commonly found in adipose tissue
Lymph Flow
- afferent vessels from subcapsular
sinus area (cancer first) , to trabecular sinuses,
and medullary sinuses (Outside to inside)
- Leaves at hilum
- different from blood bc afferent and efferent
from Hilum but lymph outside to inside to hilum
MALT
- tonsils (very defined) and adenoids (oropharynx)
- Peyer's patches and lymphoid aggregates
in large intestine
- Diffuse pop of lymphos and plasma cells in
mucosal of GI, respiratory, and GU tracts
- GALT, BALT
Spleen
Look and Location
- Left Upper Quadrant Abdomen
- HUGE artery, like pig's tail
- grossly dark red, v vascular
- white little nodules
- splenic vein into hepatic portal system
Function
- SUPER VASCULAR, filtering blood
- T and B cells interact with
blood borne antigens and undergo
stimulation and division
- slows down blood flow, RBC graveyard
- fetus, hematopoiesis
- recycle iron
- lymph node equivalent for blood
Pulp
Red
- sinus cavities
- blood and macrophages
- Filtering blood, Recycle Fe
White
- lymphatic portion
- T and B cells
- B cell reservoir
- mount adaptive immune response
- darker histologically (purple)
Clinical Correlations
Angioma
- benign tumor
- cells from vascular/lymphatic
vessel walls
- usually asymptomatic,
discovered incidentally
Splenic Rupture
- massive hemorrhage
- can bleed out pretty quickly
- splenectomy