introduction the the immune system Flashcards
what is the immune system?
a network of specialised cells, tissues and soluble factors that operate to kill and eliminate pathogens
what happens when the immune system doesn’t function properly
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
what are immuno-suppressive and anti-inflammatory drugs
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.
what is cancer immunotherapy
immunotherapy enables the immune system to recognize, target, and eliminate cancer cells, making it a potential “universal answer” to cancer
what does t cell immunotherapy involve
it involves a patients own cells to recognize a protein present in cancer cells, enabling them to seek out and destroy the cancer
what are the two types of immunity
innate immunity
adaptive immunity
explain innate immunity
the first line of defense
immediate
non specific
no memory
explain adaptive immunity
secondary
needs time (days)
specific
has a memory
what are the points of entry in the body for a pathogen and their routes of attack
digestive system
respiratory system
urogenital system
skin damage
routes of attack: circulatory system and lymphatic system
what are the protective physical and chemical mechanisms to stop pathogens
-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
what are the phagocytic cells and what do they do
neutrophils, monocytes, and macrophages. Dendritic cells
they orchestrate the initiation of the response. they recognise, ingest and kill bacteria and yeasts
what are the degranulating cells and what do they do
mast cells, eosinophils and basophils
they orchestrate initiation of response, they damage and kill multicellular parasites and viruses
what are the secreted proteins
complement (induced)
chemokines
cytokines
what happens if there are pathogens on the skin and the skin barrier breaks
the pathogens invade and the innate immune response is initiated
how do Tissue-resident innate immune cells recognise pathogens as ‘non-self’ and dangerous
Pathogens express PAMPs (Pathogen Associated Molecular Patterns)
* PAMPs are recognised by specific Pattern Recognition Receptors (PRRs) thatare expressed by immune cell
what are the steps of macrophages ingesting extracellular bacteria
- Macrophages express a set of ‘PRRs’
- Receptor binding to ‘PAMPs’ signals the formation of the phagocytic cup
- Cup extends around the target and pinches off, forming a phagosome
- Fusion with lysosomes to form a phagolysosome –killing of pathogens and degradation of contents(acidification, lysosomal hydrolases)
- Debris (including antigens) is released into the extracellular fluid
- Pathogen-derived peptides are expressed on special cell surface receptors (MHC-II molecules)
- Pro-inflammatory mediators are released (e.g. TNFα
what is degranulation
release of pre-formed pro-inflammatory substances (e.g. histamine)
gene expression
production of new pro-inflammatory substances
explain acute inflammation
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
what are the three pathways of the complement system
Classical pathway
lectin pathway
alternative pathway (positive feedback loop)
what is the classical pathway
This pathway is activated by the binding of antibodies to pathogens or other foreign materials
what is the lectin pathway
This pathway is activated by the presence of foreign materials that directly interact with complement proteins.
what is the alternative pathway
This pathway is activated by the binding of specific proteins called lectins to carbohydrates on the surface of pathogens.
what is opsonization
the coating of pathogens by humoral (soluble) factors
what engulfs opsonized bacteria
phagocytes
what are chemokines
signaling proteins secreted by cells that induce directional movement of leukocytes
what does inflammation promote
-vascular changes
-recruitment and activation of neutrophils (transendothelial migration)
-bacteria produce chemicals that attract neutrophils to the site of infection
