Lymphoid tissues

Question 1

What is the function of non-immune cell swithin body tissue?

Answer 1

• They present antigens to patrolling activated adaptive immune cells
• They also release cytokines to warm off infection

Question 2

What are some examples of circulating immune cells?

Answer 2

Innate cells (such as neutrophils)
Adaptive cells (such as T and B cells)

Question 3

What is the function of the lymphatic system?

Answer 3

• It drains tissues and links lymphatic organs
• Helps to remove debris from tissues

Question 4

Complete the sentence…
The lymphatic system cannot be …(1)… and it runs at a …(2)…, …(3)… speed.

Answer 4

• Closed
• Slow
• Inconsistent

Question 5

What is lymph made of?

Answer 5

Filtered tissue fluid along with various leukocytes

Question 6

How does the lymphatic system contribute to immune response?

Answer 6

• It samples the tissues for debris and antigens
• It maximises the chance of specific lymphocyte activation during an infection

Question 7

What sentinel cells are already present in most body tissues?

Answer 7

Macrophages and dendritic cells

Question 8

What is the purpose of these sentinel cells?

Answer 8

• Detect pathogens or damage associated proteins
• Act as APCs which then travel to the lymph node

Question 9

What is the difference between a primary and secondary lymphoid organ?

Answer 9

Primary = where lymphocytes are formed and mature
Secondary = Where lymphocytes are activated

Question 10

What are the 3 primary lymphoid organs?

Answer 10

• Bone marrow
• Thymus
• Bursa of fabricus

Question 11

What happens in the bone marrow?

Answer 11

• B cells develop and selection (B cells that produce antibodies against self-cells are filtered out and destroyed)
• Innate immune cells such as neutrophils, monocytes and eosinophils develop here
• T cells originate here (but mature in the thymus)

Question 12

Where is the thymus situated?

Answer 12

Cranial to the heart

Question 13

What is the function of the thymus?

Answer 13

It helps to screen out potential auto-reactive T cells before they reach circulation. T cells develop here.

Question 14

What is the function of the bursa of fabricus?

Answer 14

It is the site of B cell development

Question 15

Lymph notes are the secondary lymphoid organs, what are the 9 key lymphoids/ lymph nodes?

Answer 15

1) Submandibular
2) Parotid
3) Retropharyngeal
4) Prescapular
5) Axillary
6) Bronchial
7) Mesenteric
8) Superficial inguinal
9) Popliteal

Question 16

What enters lymph nodes?

Answer 16

• Blood (containing lymphocytes)
• Lymph (containing antigens and APCs)

Question 17

How do lymphocytes travel through lymph nodes?

Answer 17

• Naive lymphocytes are constantly re-circulating throughout the lymph node
• Lymphocytes enter the lymph node through blood and leave via efferent lymphatic vessels

Question 18

What is the overall function of lymph nodes?

Answer 18

They act as a highly organised environment evolved for the activation, proliferation and differentiation of lymphocytes.

Question 19

In which areas of a lymph node are T cells, B cells and APCs found?

Answer 19

• B cells found primary lymphoid follicle
• T cells found in the paracortical area
• APCs found in the medullary cords

Question 20

What happens inside a lymph node?

Answer 20

1) APCs present antigens to activate T and B cells
2) Activated T cells interact and activate B cells
3) Germinal centres form proliferating B cells which generate high affinity antibodies

Question 21

What is lymphadenopathy and what could it indicate?

Answer 21

• Enlarged lymph nodes
• Could indicate infection or neoplasia (cancer)

Question 22

What is the purpose of lymph node aspirations?

Answer 22

It can enable you to look at cell type, cell morphology and pathogen presence and possibly help identify cancer

Question 23

What do birds and reptiles have instead of lymph nodes?

Answer 23

Lymphoid nodules

Question 24

What is different about the lymph nodes of a pig?

Answer 24

Pigs have inverted lymph nodes

Question 25

Where is the spleen located in dogs?

Answer 25

In the left, cranial quadrant of the abdomen near the end of the rib cage

Question 26

What is the difference between red and white pulp in the spleen?

Answer 26

- Red pulp has haematological functions - White pulp has immunological functions

Question 27

What is the function of red pulp?

Answer 27

- Removes particulate matter from the blood stream - Causes destruction of old RBCs - Storage of RBCs and platelets

Question 28

What is the function of white pulp?

Answer 28

Filters microbes, antigens and antigen-antibody complexes out of the blood

Question 29

How does the spleen help to activate lymphocytes?

Answer 29

- Mature dendritic cells and macrophages migrate from tissues to the spleen via the blood. - They then reside in the marginal zone and help to activate lymphocytes

Question 30

What are the 3 different types of MALT? (mucosa associated lymphoid tissues)

Answer 30

GALT = Gut Associated Lymphoid Tissues NALT = Nasal Associated Lymphoid Tissues BALT = Bronchus Associated Lymphoid Tissues

Question 31

Complete the sentence... There are more ...(1)... in MALTs than in the rest of the body

Answer 31

(1) Lymphocytes

Question 32

What is the main GALT and where is it found?

Answer 32

Peyer's patches Found in the ileum and at the ileocaecal junction

Question 33

What type of cell is found on the surface of Peyer's patches?

Answer 33

Specialised antigen-sampling M cells

Question 34

What cells are contained within each of the Peyer's patches?

Answer 34

- Dendritic cells - Macrophages - B cells - T cells

Question 35

What is the function of Peyer's patches?

Answer 35

- Activation of lymphocytes - Germinal centre formation - Prevention of inappropriate activation

Question 36

What would be an example of inappropriate activation?

Answer 36

Food allergies and inflammatory bowel disease