Lymphoid tissues 2 Flashcards
What 2 things is the lymphatic system comprised of?
Lymphatic vessels and secondary lymphoid tissue
What is lymphoid tissue comprised of?
Primary, secondary, tertiary
What happens in primary lymphoid organs?
Lymphopoiesis
What are 3 primary lymphoid organ?
Thymus
Bone marrow
Fetal liver
What are the 3 lymphocytes?
B cells
T cells
Natural Killer cells
What cells is the adaptive immune response comprised of?
B and T cells
What are the 2 hallmarks of the adaptive immune response and describe them?
Specificity – provided by a vast range of unique T cell and B cell receptors
Memory – rapid expansion in response to secondary encounter
What bones does hematopoiesis most occur in in adults?
Flat bones, but also vertebrae and ends of long limb bones
What does repertoire mean?
The range of genetically distinct BCRs or TCRs present in a given host
Where do B cells undergo final differentiation (repertoire generated)?
Bone marrow
Where does final maturation of B cells occur?
The periphery
Where are immature T cells produced?
Bone marrow
Where do T cells mature?
The thymus
What are the 2 types of selection T cells undergo?
Positive and negative selection
What is positive selection?
T cell is asked whether it can recognise an antigen
What is negative selection?
Tests if it reacts against our own body
What happens to T cells that fail the selection?
Apoptosis
What is thymic involution?
The shrinking of the thymus with age
What is thymic involution associated with?
Change in structure and reduced mass
Does T cell output increase or decrease with age?
Decrease
Does thymus get more or less fatty with age?
More fatty
How many TCR sequences per T Cell?
1
How many TCR sequences do genes allow for?
10^15- 10^20
How many T cells do we have?
3.75x10^11
What happens at secondary lymphoid tissues?
Lymphocytes interact with antigens and other lymphocytes
Name 4 secondary lymphoid organs
Spleen
Lymph nodes
Appendix
Mucosa-associated lymphoid tissue
How are lymphoid tissues interconnected?
Via lymphatic system and the blood
Why are lymphoid tissues beneficial?
Bring cells in close proximity to antigen
Do lymph nodes have distinct regions for B and T cells?
Yes
What are the 2 categories of lymphatic vessels in lymphatic tissue?
Afferent and efferent
What is the first line of defence against infection
Epithelial barriers
What type of barrier is an epithelial barrier?
A physical barrier
What type of lymphoid tissue is located in the gut and what is it called?
Specialized secondary lymphoid tissues called Peyer’s patches
Where exactly are Peyer’s pathes found?
Below the epithelium of the ileum of the small intestine.
What are Peyer’s patches enriched with?
Germinal centres
What are the 4 types of tonsils?
Pharyngeal, tubular, palantine and lingual
What ring do the 4 types of tonsil create?
Waldeyer ring
How often does each naïve T cell recirculate?
Once every 24 hrs
What is the purpose of dendritic cells?
Antigen presentation
What are the two types of dendritic cells in relation to movement?
Tissue resident and migratory
How do DC migrate into lymph nodes?
Via the afferent lymph into lymph nodes
