L1 - The Role of The Immune System and the Threat to the Body

Question 1

Immunology: what is it and how significant is it in mortality?

Answer 1

The study of the body’s defence system

• Leading cause of death in those <50 years of age
• Second to cardiovascular disease in those >50 years of age

Question 2

What conditions are caused by immune deficiency due to age?

Answer 2

• Cancer
• Atherosclerosis (heart attack, stroke)
• Alzheimer’s
• Parkinson’s
• Obesity

Question 3

Stages of infection

Answer 3

• Entry into the body (infection)
• Replication and spread
• Disease
• Exit from the body (infect others)

Question 4

Barriers to infection - the primary barriers against entry (M,C,M)

Answer 4

Mechanical:
* Epithelial cells joined by tight junctions (in skin/gut/lungs/ENT)
* Longitudinal flow of air/fluid (in skin/gut)
* Movement of mucus by cilia (lungs)
* Tears/nasal cilia (in ENT)

Chemical:
* Fatty acids and β-defensins, Lamellar bodies, Cathecilidin (skin)
* Low pH, enzymes (pepsin), α-defensins (cryptidins), RegIII (lectidins), and Cathelicidin (gut)
* Pulmonary surfactant, α-defensins, and Cathelicidin (lungs)
* Enzymes in tears and saliva (lysozyme) and histatins and β-defensins (ENT)

Microbiological:
* Normal microbiota

Question 5

Specific chemicals and their location of operation as primary defence barriers to infection

Answer 5

α-defensins - gut, lungs
β-defensins - skin, ENT
Cathecilidin - skin, gut, lungs

Question 6

Progenitors of hematocytes

Answer 6

BM - Pluripotent stem cell:
* Common lymphoid progenitor
* Common myeloid progenitor

BM - Common lymphoid progenitor:
* B-cell -> LN - B-cell -> plasma cell in tissue
* T-cell -> LN - T-cell -> activated t-cell in tissue
* NK cell -> LN - NK cell ->activated NK cell in tissue

BM - Common myeloid progenitor:
* Granulocytre/macrophage progentior
* Megakaryocyte/erythrocyte progenito

BM - Megakaryocyte/erthryocyte progenitor:
* Megakaryocyte (BM) -> platelets (blood)
* Erythroblast (BM) -> erythrocyte (blood)

BM - Graniulocyte/macropharge progenitor:
* Granulocytes in blood (neutro, eosino, and basophils, UPoMC, and monocytes)
* Unknown precursor of mast cells (blood) -> mast cells (blood)
* Monocyte (blood) -> macrophage (tissue)

IMMATURE DENDRITIC CELL (tissue) -> MATURE DENDRITIC CELL (Lymph Nodes)

Question 7

Macrophage: what are they part of and what do they do?

Answer 7

Innate immunity

Phagocytosis, activation of bactericidal mechanisms and antigen presentation (for adap/immun)

Question 8

PMNs: what are they

Answer 8

Polymorphonuclear leukocyte - neutrophil, the largest and first phagocytic defence

Question 9

Monocyte

Answer 9

In blood - it can enter the tissue and differentiate into macrophages

Question 10

General pathway of defence against a pathogen all the way to adaptive immunity

Answer 10

• Pathogen binding to epithelia
• Epithelial penetration
• Detection by the local immune system
• Immune response
• Adaptive immunity

Question 11

Phagocytes: what are they, what is their function, and what cells are they?

Answer 11

White blood cells and tissue-dwelling cells able to ingest (engulf) and kill particles

• Tissue macrophages
• Monocytes in the blood
• Neutrophils Polymorphonuclear (PMN) leukocytes in blood