The Lymphoid system Flashcards
(25 cards)
What can APCs be
Macrophages or dendritic cells
What do APCs do
1) phagocytose intruders and remnants of disintegrated cells
2) Fragment ingested proteins and present fragments on MHC molecules on surface
What are the type of T lymphocytes
T helper
Cytotoxic T
Memory T
What are the type of B lymphocytes
Plasma cells
Memory B cells
How are antibodies produced through the action of T cells and B cells
- APC ingests bacteria and digested by lysosomal enzymes into SMALL PEPTIDE FRAGMENTS
- Small peptide fragments loaded onto HMC class 2 proteins
- HMC class 2 proteins are presenters
- T cell and APC talk via cytokines because they are bound
- CLonal multiplication of T cells with identical receptors
- random B cells floating around can also phagocytose and become APC
- T helper cell fits onto B cell and this leads to multiplication of B cells (clonal amplification)
- MAjority of B cells become plasma cells
- Antibodies bind to bateria
- this attracts T cells and other cells that activate the system
Where are APCs found
All exposed surfaces
Also tissues
What are ‘matching venues’
Secondary lymphoid system
What does the secondary lymphoid system include
- lymph follicles
- tonsils
- lymph nodes
- spleen
What do ‘matching venues’ look like in histological stains
As aggregates of thousands of lymphocytes
What are Matching Venues the main site of
Antigen presenting and T and B cell activation and expansion
What are Matching Venues kept in shape by
Reticular fibers that allow lymphocytes and APCs to circulate around them
When are capillaries leaky
Slightly leaky as liquid passed out into interstitial tissue
Where does the ‘leaking’ from capillary go to
-where does this go in turn?
Collected in lymph capillaries with come together to form a larger lymph vessels
Once in larger lymph vessels, where does the liquid go
Ends up in subclavian veins
What are there between subclavian veins and what do these do
Lymph nodes where lymph is checked by APCs
What does the medulla contain
High conc of plasma cells and has macrophages
What surrounds the medulla
Paracortical zone
What happens in the paracortical zone
-What does the paracortical zone contain
Where T cells are proliferated and matured
-Contains the majority of APC in the node
What surrounds the paracortical zone
Cortical zone
What happens in the cortical zone
Where B cells are proliferated and matured
What happens in the adaptive response
1) antigen of pathogen enters body
2) dendritic cells carry the antigen to lymphoid tissue via lymph and goes to closest node
3) cells are activated and proliferation because antigen presented in paracortex
- (B cells picked up antigen in follicle and ingests it then moves to B/T cell interface)
- (activated T and B cells meet at B-T cell face interface and T helper activates the B cell to proliferate and mature
4) Antibodies produced
5) Recirculation to site of infection
In the cortex of a lymph node, what does a germinal centre indicate
An active B cell response
What happens when lymph nodes have a high proliferative activity
Enlarged
How o lymphocytes find their target
Travel in bloodstream
