Lymphoid tissues

Question 1

What enzyme adds further diversity to the variable regions

Answer 1

Deoxynucleotidyl transferase

Question 2

Where is the d chain located

Answer 2

Only on the heavy chain

Question 3

Additional ways in which B cells can alter the specificity of the antibody that they produce

Answer 3

When B cell meets an antigen that it recognises, B cell can undergo somatic hypermutation. Here an enzyme called action induced cytidine deaminase (AID) makes random mutations in the antibody variable region genes . Results in antibody binding more strongly.

Question 4

Primary lymphoid organs

Answer 4

Organs where lymphocytes are produced

Thymus, bone marrow and foetal liver

Question 5

Bon marrow haematopoeisis

Answer 5

In foetus: haematopoiesis occurs in all bones, liver and spleen; marrow very cellular
In adults: haematopoiesis occurs mostly in flat bones, vertebrae, iliac bones, ribs, and ends of long limb bones.

Question 6

Immature T cells migrate from the bone marrow to the

Answer 6

Thymus

Question 7

Selection process of T lymphocytes

Answer 7

• Stepwise differentiation
• Positive selection – can the T cell receptor signal (does it do what it is meant to)
• Negative selection – does it react against our own body (does it do things it isn’t meant to)
• Final selection and exit

Question 8

Thymic involution

Answer 8

the shrinking of the thymus with age. Associated with a change in structure and a reduced mass.

Question 9

Secondary lymphoid organs

Answer 9

Spleen, lymph nodes, appendix and mucosal associated lymphoid tissue ( MALT)

Can be discrete organs (e.g. lymph nodes/adenoids) or distinct regions within a tissue (e.g. spleen)

Question 10

Epithelial barriers

Answer 10

• First line of defence against infection
  
  • Physical barrier
  • Extensive lymphatic network which drains the antigens

Question 11

Gut associated lymphoid tissue

Answer 11

• Specialized secondary lymphoid tissues called Peyer’s patches
• Found below the epithelium of the ileum of the small intestine.

• The follicle in highly enriched with B cells, and contains a high frequency of germinal centres.

There are high amounts of antigen produced from microbial products here due to gut micro biome

Question 12

Germinal centr

Answer 12

anatomically restricted site where B cells undergo mutation and selection to generate high affinity antibodies (affinity maturation)

Question 13

Tonsils

Answer 13

• Pharyngeal, tubular, palantine and lingual tonsils encircle the oral and nasal cavity – form the Waldeyer ring
Contains lymphocytes

Question 14

Extravasation of naive T cells into lymph nodes

Answer 14

A lot like that of neutrophils

CCL21 and CCL7 provide chemotactic signals

Question 15

Where do the dendritic cells go

Answer 15

Migrate via afferent lymph to the lymph nodes