How The Body Respond To Infection

Question 1

What are the primary lymphoid organs?

Answer 1

Bone marrow and thymus

Question 2

What are the secondary lymphoid organs?

Answer 2

Tonsils, adenoids, lymph nodes, peyer’s patches, bronchus associated lymphoid tissues, lamina propria, appendix

Question 3

Explain the lymphocyte recirculation.

Answer 3

After being produced in primary lymphoid organs, lymphocytes gets into the blood stream. They then cross the walls of the vessels to get to the secondary lymphoid organs, where they stay for a couple of days b4 going back to circulation.
80-90% of the lymphocytes in the lymph nodes come from the circulation, the others come from afferent lymphatics (derived from tissues fluid that contain lymphocytes).

Question 4

What is the significance of the thoracic duct?

Answer 4

The thoracic duct is the junction between blood circulation and lymphatics

Question 5

What are infectious agents?

Answer 5

Bacteria
Viruses
Protozoa
Fungi
Works

Question 6

What are the cellular mediators of immunity?

Answer 6

Myeloid: neutrophils, basophils, eosinophils,mast cells, monocytes/macrophages
Lymphoid: B lymphocytes, T( CD4+ and CD8+) lymphocytes, dendritic cells, NK cells

Question 7

What cellular mediators are found in tissues?

Answer 7

Mast cells
Plasma cells
Macrophages

Question 8

What are the secreted mediators of immunity?

Answer 8

Anti-microbial: antibodies, pentraxins ( CRP), collectins, complement proteins, defensive, lytic enzymes, interferons, cytotoxicity (preforms, granzymes)

Regulatory/inflammatory: cytokines (interleukins, TNF, interferons), chemokines, histamines, PGs and leukotrienes

Question 9

What are the properties of innate immunity?

Answer 9

Quick
Stays same on repeated exposure 
Moderate efficiency
General response 
Made by recognition of PAMPs (bacterial lipopolysaccharides, viral double stranded RNA) by PRRs (toll-like receptors)

Question 10

What are the characteristics of adaptive immunity?

Answer 10

Slowly activated
Improve on repeated exposure
High efficiency 
Response tailored to specific microbes 
Made of recognition of antigen specific to the microbe by antigen specific receptors of the lymphocytes

Question 11

What are the 4 stages of primary immune response?

Answer 11

1. Epithelial barrier
2. Immediate local response (complement proteins, macrophages)
3. Early induced response (secretion of inflammatory mediators to make vessels leaky and attract leukocytes at site of infection)
4. Later adaptive response (APC carry antigen to lymphocytes)

Question 12

What are the categories of infection?

Answer 12

Extra-cellular infection (infiltrate tissue but stay outside of cells, dealt with by complement proteins, phagocytes and antibodies)
Intra-cellular vesicular infection (microbe get engulfed by phagocyte and stays in it because phagocyte cannot digest it so it gets hyper stimulated by T helper cells) e.g.:TB, leprosy
Intra-cellular cytosolic infection ( microbe present in cytosol of cell, E.g.: all viruses)

Question 13

Give examples of immunopathologies.

Answer 13

Allergy (contact dermatitis, allergic rhinitis)
Autoimmunity (thyroiditis, rheumatoid arthritis)
Transplant rejection
Lymphoproliferative disease