Chapter 8: The Immune System Flashcards
Plasma Cells
Form from B-cells exposed to antigen and produce antibodies.
Memory B-cell
Form from B-cells exposed to antigen and lie in wait for a second exposure to a given antigen to mount a rapid, robust response.
Helper T-cell
Coordinate and strengthen immune responses by secreting a repertoire of cytokines depending on the specific infection or disease.
Cytotoxic T-cell (Killer T Cell)
Directly kill virally infected cells and respond to antigen bound MHC-I.
Suppressor (regulatory) T-cell
End the immune system response after a pathogen has been cleared and promote self-tolerance.
Memory T-cell
Like memory B-cells, lie in wait until a second exposure to a pathogen to mount a rapid, robust response.
Allowing the body to “remember” the infection so that it can mount a quicker, stronger immune response should the pathogen reappear
What are the three main effects circulating antibodies can have on a pathogen?
- Circulating antibodies can mark a pathogen for destruction by phagocytic cells (opsonization).
- Can cause agglutination of the pathogen into insoluble complexes that can be taken by phagocytic cells.
- Neutralize the pathogen by preventing it from invading tissues.
How do antibodies become specific for a given antigen
B-cells originally mature in the bone marrow and have some specificity at that point; however, antibodies that can respond to a given antigen undergo hypermutation, or rapid mutation of their antigen-binding sites. Only those B-cells that have the highest affinity for the antigen survive and proliferate, increasing the specificity for the antigen over time.
A T-cell appropriately passes through positive selection, but then inappropriately passes through negative selection. What will this T-cell be reactive towards.
Positive selection occurs when T-cells in the thymus that are able to respond to antigen presented on MHC are allowed to survive (those that do not respond under apoptosis). Negative selection occurs when T-cells that respond to self antigens undergo apoptosis before leaving the thymus. A T-cell that appropriately passes through positive selection, but then inappropriately passes through negative selection will be reactive to self-antigens.
Which cells account for the fact that the secondary response to a pathogen is much more rapid and robust than the primary response?
Memory cells allow the immune system to carry out a much more rapid and robust secondary response
What is the difference between active immunity and passive immunity?
Active Immunity: refers to the stimulation of the immune system to produce antigens against a pathogen. Passive Immunity: refers to the transfer of antibodies to prevent infection, without stimulation of the plasma cells that produces these antibodies.
B-cells mature in the ____
Bone marrow
T- cells mature in the ____
Thymus
Active Immunity
The immune sysem is stimulated to produce antibodies against a specific pathogen. Which means one is exposed to a pathogen naturally or artficially.
Ex: you get infected and develop antibodies or given a vaccine that artfivially affects you then you develop the antibodies.
Passive Immunity
Results from the transfer of antivodies to an individual.
Ex: mom gives baby antibodies through breastfeeding
Red Blood Cell
(Erythrocytes)
Deliver oxygen and nutrients to the whole body
Platelets
Platelets heal scrapes and wounds around the body by establishing a plug around broken areas of the endothelium (blood vessel walls) and releasing substances to initiate the clotting process.
White Blood Cells
(Leukocytes)
The first white blood cells to arrive at the infected site, they phagocytose and degrade pathogens.
Monocytes and Macrophages
Monocytes, slightly larger than neutrophils. They circulate in the blood, but when they enter an infected site they transform into macrophages. Macrophages serve a variety of roles, mainly phagocytosing and degrading pathogens, foreign substances, damaged tissue and dead neutrophils. They also release proteins called cytokines to coordinate the activities of other cells and parts of the body and present antigens to maintain adaptive immune responses.
Dendritic Cells
Dendritic cells are mononuclear cells best characterised by the numerous dendrites emerging from the centre. Located in many organs around the body such as the gut and lungs, they survey the blood and external environment for pathogens. Should it detect a pathogen, the dendritic cell will digest it and present a piece of the pathogen (an epitope) to a T cell to initiate adaptive immune responses.
Eosinophil
Eosinophil granules mostly contain MBP (Major Basic Protein) which immobilise and kill parasites, positioning eosinophils as protectors of parasitic infection. Eosinophil granules also contain histaminase and arylsulfatase that break down histamine and leukotrienes respectively to dampen inflammation and allergy
Basophil
Basophils respond to infections, particularly those against large parasites such as ticks and worms. Their granules contain a lot of histamine that when released dilate blood vessels and increase permeability, allowing cells and proteins to move from blood to tissue. Histamine from basophils and mast cells is also involved in the development of allergies.
Mast Cell
Mast cells are similar in appearance to basophils. Unlike basophils; however, mast cells reside in tissue. Their granules contain enzymes that are released during infection to initiate inflammation by damaging tissue. Mast cells also release histamine to dilate blood vessels and increase their permeability, easing access of white blood cells to the infected site
NK cell
NK cells are unique in that even though they have a similar morphology to lymphocytes, they function as innate immune cells. Similar to killer T cells, they kill infected or tumour cells caused by different diseases. However, their method of activation is different to those of a killer T cell
