introduction the the immune system

Question 1

what is the immune system?

Answer 1

a network of specialised cells, tissues and soluble factors that operate to kill and eliminate pathogens

Question 2

what happens when the immune system doesn’t function properly

Answer 2

These problems include immunodeficiency diseases. If you have an immunodeficiency disease, you get sick more often. Your infections may last longer and can be more serious and harder to treat

Question 3

what are immuno-suppressive and anti-inflammatory drugs

Answer 3

they are essential for the treatment of autoimmune diseases, allergic diseases, asthma, and cancer

they are key to preventing the rejection of donor tissues in transplant recipients.

Question 4

what is cancer immunotherapy

Answer 4

immunotherapy enables the immune system to recognize, target, and eliminate cancer cells, making it a potential “universal answer” to cancer

Question 5

what does t cell immunotherapy involve

Answer 5

it involves a patients own cells to recognize a protein present in cancer cells, enabling them to seek out and destroy the cancer

Question 6

what are the two types of immunity

Answer 6

innate immunity
adaptive immunity

Question 7

explain innate immunity

Answer 7

the first line of defense
immediate
non specific
no memory

Question 8

explain adaptive immunity

Answer 8

secondary
needs time (days)
specific
has a memory

Question 9

what are the points of entry in the body for a pathogen and their routes of attack

Answer 9

digestive system
respiratory system
urogenital system
skin damage

routes of attack: circulatory system and lymphatic system

Question 10

what are the protective physical and chemical mechanisms to stop pathogens

Answer 10

-an outer surface membrane that is tough and impermeable to micro-organisms
-an inner surface bathed continuously in moving secretion such as mucous and acid

Question 11

what are the phagocytic cells and what do they do

Answer 11

neutrophils, monocytes, and macrophages. Dendritic cells

they orchestrate the initiation of the response. they recognise, ingest and kill bacteria and yeasts

Question 12

what are the degranulating cells and what do they do

Answer 12

mast cells, eosinophils and basophils

they orchestrate initiation of response, they damage and kill multicellular parasites and viruses

Question 13

what are the secreted proteins

Answer 13

complement (induced)
chemokines
cytokines

Question 14

what happens if there are pathogens on the skin and the skin barrier breaks

Answer 14

the pathogens invade and the innate immune response is initiated

Question 15

how do Tissue-resident innate immune cells recognise pathogens as ‘non-self’ and dangerous

Answer 15

Pathogens express PAMPs (Pathogen Associated Molecular Patterns)
* PAMPs are recognised by specific Pattern Recognition Receptors (PRRs) thatare expressed by immune cell

Question 16

what are the steps of macrophages ingesting extracellular bacteria

Answer 16

1. Macrophages express a set of ‘PRRs’
2. Receptor binding to ‘PAMPs’ signals the formation of the phagocytic cup
3. Cup extends around the target and pinches off, forming a phagosome
4. Fusion with lysosomes to form a phagolysosome –killing of pathogens and degradation of contents(acidification, lysosomal hydrolases)
5. Debris (including antigens) is released into the extracellular fluid
6. Pathogen-derived peptides are expressed on special cell surface receptors (MHC-II molecules)
7. Pro-inflammatory mediators are released (e.g. TNFα

Question 17

what is degranulation

Answer 17

release of pre-formed pro-inflammatory substances (e.g. histamine)

Question 18

gene expression

Answer 18

production of new pro-inflammatory substances

Question 19

explain acute inflammation

Answer 19

bacteria trigger macrophages to release cytokines and chemokines
vasodilation and increased vascular permeability cause redness, heat, and swelling
Inflammatory cells migrate into the tissue, releasing inflammatory mediators that cause pain

Question 20

what are the three pathways of the complement system

Answer 20

Classical pathway
lectin pathway
alternative pathway (positive feedback loop)

Question 21

what is the classical pathway

Answer 21

This pathway is activated by the binding of antibodies to pathogens or other foreign materials

Question 22

what is the lectin pathway

Answer 22

This pathway is activated by the presence of foreign materials that directly interact with complement proteins.

Question 23

what is the alternative pathway

Answer 23

This pathway is activated by the binding of specific proteins called lectins to carbohydrates on the surface of pathogens.

Question 24

what is opsonization

Answer 24

the coating of pathogens by humoral (soluble) factors

Question 25

what engulfs opsonized bacteria

Answer 25

phagocytes

Question 26

what are chemokines

Answer 26

signaling proteins secreted by cells that induce directional movement of leukocytes

Question 27

what does inflammation promote

Answer 27

-vascular changes
-recruitment and activation of neutrophils (transendothelial migration)
-bacteria produce chemicals that attract neutrophils to the site of infection