Lymphoid tissues Flashcards
(34 cards)
What are primary lymphoid tissues?
Where lymphocytes are produced?
What are lymphocytes?
B-cells
T-cells
Natural Killer cells
What are the primary lymphoid organs?
Thymus
Bone marrow
Foetal liver
What do T-cells and B-cell comprise?
The adaptive immune response
Very specific
Memory for secondary encounter
Where is the primary site of haematopoiesis?
Bone marrow
When does white cell production increase?
During infection
What is Repertoire?
The range of the genetically distinct b-cell receptors and t-cell receptors that any given person has
Larger repertoire- more threats can be recognised
What happens in the thymus?
Immature T-cells migrate to the thymus where they undergo a step wise differentiation process
What is positive selection?
Whether the T-cell receptor that the cell expresses is functionally correct.
What is negative selection?
Will it react against our own body? If yes, undergoes apoptosis
What is meant by self?
Anything recognised by immune system as part of your normal molecular make-up
What is meant by non-self?
Anything recognised by the immune system as foreign
What is thymus involution?
The shrinking of the thymus with age
Associate with a change in structure and a reduced mass
How many T-cell in the blood roughly?
3.75x10^11
How many antigens can our body recognise?
10^15-10^20
How does a small population of cells (e.g 1) find a foreign protein in a human body?
Secondary lymphoid organs are where
Name some secondary lymphoid organs
Lymph node
Spleen
Appenix
Mucosal associated lymphoid tissue
How are the lymphoid organs connected?
Lymphatic system and the blood
What are the two types of lymphoid tissue?
Discrete organs e.g lymph nodes/adenoids
Distinct regions with a tissue e.g spleen
What are the main features of lymph nodes and the spleen?
Distinct T and B cell zones
Afferent (in) and efferent (out)
Arterial and venous connection
What are epithelial barriers?
First line of defence against infection
Physical barrier
Extensive lymphatic network
What are gut associated lymphoid tissue?
Specialised secondary lymphoid tissues called Peyer’s patches
Found below the epithelium of the ileum of the small intestine
Follicle is highly enriched with B-cells and contains a high frequency of germinal centres
What is a germinal centre?
Anatomically restricted site where B cells undergo mutation and selection generate high affinity antibodies
What are tonsils?
Pharyngeal, tubular, palatine and lingual tonsils encircle the oral and nasal cavity- form the Waldeyer ring
