lymphoid tssues Flashcards
- What is the adaptive immune system compromised of?
- What are the hallmarks of adaptive immunity?
T cells (CD4, CD8, T regulatory cells)
B cells (B lymphocytes and plasma cells) Specificity Memory
- Name the 3 types of lymphocytes
- What is meant by a primary lymphoid organ?
- List 3 primary lymphoid organs
B cells. T cells, NK cells
Organs where lymphocytes are produced - Lymphopoieses Thymus , bone marrow, foetal liver
- What do CD4 (T-helper cells) do?
- What do CD8 (cytotoxic T cells) do?
- What is the primary site of haematopoiesis?
Produce lots of cytokines which guide B cells and other T cell responses
Kill foreign antigen expressing cells
bone marrow
- What are the roles of the red and yellow bone marrows respectively?
- What are immature T cells known as?
- Where do immature T cells migrate from the bone marrow to?
Red - Produces blood cells
Yellow - Fat stores Thymocytes Thymus
- Where do B cells migrate to in the immature stage for differentiation?
- Describe what is meant by ‘repertoire’ in terms of lymphocytes?
- What is thymic involution?
Spleen
The range of **genetically distinct** BCRs or TRCs present in a given host The larger the repertoire, the more threats can be recognised The shrinkage of the thymus with age → associated with a change in structure and a reduced mass
- Where is the thymus?
- What are the 3 steps in the stepwise differentiation of T cells?
On top of heart, above lungs in the thoracic cavity
Positive selection- can the T cells detect our MHC receptors on surrounding cells
Negative selection- If it reacts against self antigen, undergo apoptosis
Final selection and exit
- What is meant by a secondary lymphoid organ?
- List some secondary lymphoid organs
where lymphocytes can interact with antigens and other lymphocytes so they can undergo activation and differentiation
Spleen, lymph nodes, appendix, mucosal associated lymph tissue
- Where in lymph nodes generally are the T cells found relative to B cells?
- What do the words afferent and efferent refer to respectively?
- What is it that makes the spleen so good at filtering antigens from the blood?
T cells - Towards inside (further from the marginal sinus)
B cells - Towards outside (closer to the marginal sinus)
Afferent- into lymphatic vessel
Efferent- out of lymphatic vessel
it is highly attached to the arterial system via the splenic artery
So it can filter blood rapidly in large amounts
- What is the first line of defence against infection?
- What are Peyer’s patches and what do they do?
- Where are they found?
Epithelial barriers
specialised secondary lymphoid tissues
Specialised microfold cells sample antigens directly from lumen and deliver them to antigen presenting cells
below epithelium of ileum
- Define a germinal centre
- Describe how lymphatic drainage occurs at gut associated lymphoid tissue
Anatomically restricted site where B cells undergo maturation and selection to produce high affinity antibodies
intraepithelial lymphocytes enter the villi
these get drained towards mesenteric lymph node
afferent lymphatic vessels at Peyers patches pick these up
follicles are enriched with germinal centres full of B cells
- Why is the intestine so enriched for these germinal centres?
- How do specific T cells become activated by their specific antigen which is in a different part of the body?
microbial products from the microbiota of the intestine provides a high number of antigens
Naïve T cells circulate every 24 hours
lymphatic afferent vessels containing antigens from infected tissue drain towards lymph node
naïve T cell enters lymph node
activated by antigens in lymph node
leave lymph node by efferent lymph vessel
travel to peripheral tissue and inflammation occurs
- What are the 2 steps involved in extravasation of naïve T cells into lymph nodes?
- Define antigen presentation
Selectin binding, integrin binding
The display of peptides in the major histocompatibility complex (MHC) I or II proteins such that the T cell receptor can attempt to bind them
- How do dendritic cells transport antigens from site of inflammation to the secondary lymphocyte tissues?
- How else can the antigens be transported to the secondary lymphatic tissues?
Once dendritic cells have uptaken antigen
migrate out of inflamed tissue
carry antigen to B and T cells
if antigen is in large amounts it can go into lymphatics and be drained by the fluid going through the vessels and taken to secondary lymphoid tissue
what is the Waldeyer ring?
Where is the Thymus
pharyngeal, tubular, palantine and lingual tonsils encircle oral and nasal cavity
specialise in antigen encounter with many germ centres
The thymus gland is in the chest, between the lungs and behind the breastbone (sternum)
where do B and T cells go after they are made in Bone marrow
B cells go to spleen
T cells go to Thymus
