The Immune System Flashcards
What are the 4 main functions of the immune system
Protect, recognise self/ non self , attack and destroy
What are the 2 main arms of the immune system
Innate and acquired arms
What is the innate arm of the immune system
Natural immunity that we are born with and is the same in everyone
What is the acquired arm of the immune system
Immunity recruited over a lifetime that is different between individuals due to different exposures
Which arm of the immune system has a non-specific immune response (attacks the same way every time)
Innate immunity
Which arm of the immune system has a pathogen and antigen specific response
Acquired immunity
Which arm of the immune system has a lag time between exposure and maximal response
Acquired immunity
Which arm of the immune system has no immunological memory
The innate arm
Which arm of the immune system is only found in jawed vertebrates
Acquired
Which arm of the immune system leads to immunological memory
Acquired arm
Why might the innate arm activate the acquired arm of the immune system
As innate response may not be specific enough to overcome infection alone
What are the 2 categories of leukocytes (WBC)
Granuocytes and agranulocytes
What is the difference between agranulocytes and granulocytes
Granulocytes has granules in their cytoplasm, agranulocytes do not
What are the 3 types of granulocytes
Neutrophil, eosinophil and basophil
What are the 2 types of agranulocytes
Lymphocytes and monocytes
What is the main function of neutrophils
Phagocytosis
What % of leukocytes are granulocytes
60-70%
What % of granulocytes are neutrophils
> 90%
What are the 3 main cells of the innate immune system
Neutrophils, monocytes/macrophages, natural killer cells
What percentage of all leukocytes are neutrophils
50-70%
Where are neutrophils found
Mostly in bone marrow, some in circulation and vascular pools
What is the lifespan of neutrophils in blood
5-6 days
What is the lifespan of neutrophils in tissue
2-3 days
Which type of innate immune cell is polymorphonuclear/PMNS (nucleus has multiple lifes)
Neutrophils
What is phagocytosis
The process of ingestion of bacteria, virus or cell debris
Where does phagocytosis occur
In tissues
Describe phagocytosis
Neutrophil moves to antigen, open up and engulfs in vacuole
Describe the killing process following phagocytosis
Granules move to and fuse with vacuole containing antigen/pathogen etc
Degranulation as granules release contents to degrade antigens
respiratory burst
Products of degradation are released as vacuole opens back up
Neutrophils then degrade themselves
What are monocytes/macrophages
Agranulocytes that express pattern recognition receptors (PRR) called Toll-like receptors (TLR) which recognise pathogen associated molecular patterns (PAMPS)
What activates monocytes/macrophages
Binding to TLR (Toll-like receptors)
What are the functions of monocytes/macrophages
Phagocytosis, release of messenger substances (cytokines) to communicate with other cells, APC (antigen presenting cells) for communication with acquired arm
What is the difference between monocytes and macrophages
Monocytes are agranulocytes that circulate the blood and macrophages are agranulocytes once in the tissue (change shape between locations)
What are natural killer cells
Large granular lymphocytes that are intracellular killing cells that destroy a variety of tumour and virus infected cells without the need to recognise the foreign matter to attack
How to natural killer cells destroy infected cells
Bind to surface of infected cells without and release performin which activates apoptosis (cell suicide)
What are the 2 main cells of the acquired immune system
T-lymphocytes and B-lymphocytes
How does the innate arm communicate with the acquired arm of the immune system
Via antigen presenting cells e.g. macrophages/monocytes that display the invading antigen to the acquired arm to activate it
How to APC display antigens
By incorporating the antigen protein into their cell surface and forming a major histocompatibility complex (MCH) II
Which type of lymphocyte mature in the thymus
T-cells
Which type of lymphocyte are part of the humoral (extracellular) response
B cells
Where do B cells mature
Bone marrow
Which type of lymphocyte produce memory cells
Both T and B- cells
Which type of lymphocyte makes up the majority of lymphocytes (60-70%)
T-cells
Which type of lymphocyte has a cell-mediated (intracellular) response
T-cells
What are the 3 subsets of T-cells
T-helper, T-cytotoxic and T-regulatory
What is the function of the T helper subset
Orchestrates and coordinates the immune response by meeting APC and recognising the displayed antigen
What is the function of the T cytotoxic subset
Binds to and kills antigen specific infected cells by releasing perfornin
What is the function of the T regulatory subset
Help to regulate/ switch off the immune response to avoid chronic inflammation (damage to healthy tissue post immune response)
What are the two different responses of T-cells
Type 1 (TH1) and Type 2 T-cells (TH2)
What if the functional difference between Type 1 and 2 T cells
Release different types of cytokines
What does Type 1 T cells promote
Cell-mediated immunity (defence against intracellular pathogens)
What does Type 2 T cells promote
Humoral (antibody) immunity (defence against extracellular pathogens)
What are the 2 types cells produced by B-cells
Plasma cells and memory cells
How are T-cells indirectly involved in the humoral response
T-cells cannot affect pathogens that can survive outside of the cell so instead are part of the initial process by signalling a humoral response is needed
What are plasma cells
Cells that secrete immunoglobulin/antibody specific to an antigen
What are the function of immunoglobins/antibodies
Cannot directly kill the antigen but binding to it to prevent it binding elsewhere and causing further damage
Can also signal to other cells to come and kill or agglutinate to slow cell
What are the 2 response of the acquired immune system
Cell mediated and humoral
What is leukocytosis
Increase in the number of leukocytes circulating blood
Which types of leukocytes predominantly increase during leukocytosis
Neutrophils and lymphocytes
What is leukocytosis a response to
Exercise
What is leukocytosis dependent on during brief exercise (<1 hour)
Intensity
What is delayed leukocytosis
A second increase following exercise 2-4 hours later
Why is the leukocytosis produced by prolonged endurance exercise greater than short term exercise
As delayed leukocytosis occurs whilst exercise is still being performed (super imposed response)
What is the difference between leukocytosis and delayed leukocytosis
Delayed is solely due to an increase in neutrophil number
How can inadequate nutrition directly affect immune function
Altered nutritent availability / co enzyme/ cofactors involved in immune cell energy, metabolism and protein synthesis
How does inadequate nutrition indirectly affect immune function
Altered hormone response/ immune regulatory effects of stress hormones
What can cause low grade chronic inflammation (leading to non communicable diseases)
Positive energy balance
