Immunology Flashcards
Where is the immune system located?
It’s scattered throughout the body
What is the role of the immune system? Describe two situations where it is necessary.
Its role is to protect the entire body at all times
1. From pathogens (bacteria, virus, parasite)
2. From altered body cells (cancer)
Describe two situations in which the immune system can “turn on us”.
The body will misrecognize cells as foreign in
1. autoimmune disorders
2. If tissues are tranplanted
What are the two components of the immune system?
- non-specific/ innate system
- Specific/ Adaptive
Of the two major components of the immune system, we are born with […]
both
Name two differences between innate immunity and adaptive immunity.
Non-specific:
Does not need to recognize a pathogen
Same response every time it sees the pathogen
Specific:
Requires to recognize the pathogen
Has a faster response the second time it sees the same pathogen
Explain the origin of vaccination
Smallpox disease led to lesions, which left behind scars called “pox”. Dr. Edward Jenner noticed that no milkmaids, who had gotten cowpox, had the marks of smallpox, leading him to assume that one protected the individual from the other. He took pus from a smallpox pustule and put it other the skin of another individual to inoculate them against smallpox and it worked.
What are the two categories of lymphoid organs? Explain the difference between them.
PRIMARY lymphoid organs
- Where the stem cells divide
- Where immune cells develop
SECONDARY lymphoid organs
- Sites where most immune responses occur
Immune cells are also known as..
leukocytes
Name the two primary lymphoid organs.
Bone marrow
Thymus
What is the immune function of the bone marrow?
It produces blood cells: B-cells and immature T-cells
It’s also where B-cells mature
What is the bursa and what is it homologous to in humans?
It’s homologue to the bone marrow since it also produces the B-cells
What is the immune function of the thymus?
It contains T-cells, dendritic cells, epithelial calls and macrophages
It’s also where T-cells mature
What happens to the thymus as we age?
it atrophies and can be almost gone with old age
Name the three secondary lymphoid organs.
Lymph nodes
Spleen
Lymphoid nodules
Where are lymph nodes found?
about 600 scattered throughout the body
What is the immune function of lymph nodes?
It filters the microbes before draining the lymphatic fluid into larger blood vessels
The macrophages inside the nodes phagocytize the microbes that enter the lymph
What is the immune function of the spleen?
Remove microbes and old erythrocytes
What is the immune function of lymphoid nodules?
Provide immunity in the mucosal-associated tissues
Give 3 examples of lymphoid nodules.
Tonsils
Appendix
Peyer’s patches
What are the two major categories of leukocytes?
Originating from the lymphoid or Myeloid committed cells
Name the 3 major types of lymphocytes.
T cells
B cells
NK cells
Where do each of the 3 lymphocyte types mature?
B cells in bone marrow
T cells in tymus
NK cells i’m not sure
Name the three types of T cells.
Cytotoxic
Helper
Regulatory
Myeloid leukocytes are divided into two major categories, […] and […]
granulocyte and agranulocyte
Name all the granulocytes and their function.
Eosinophils: destroy parasite
Basophils: release chemicals and histamine
Mast cells: release chemicals and histamine
Neutrophils: Phagocytes
Name all the monocytes and their function.
Macrophages and dendritic cells are there for phagocytosis
In innate immunity, what qualifies as the first and second line of defense?
FIRST: physical barriers
SECOND: cellular and humoral factors
Explain the first line of defense in innate immunity.
They are barriers to entry and can also creat an unpleasant environment for the microorganisms to live in
Name 5 physical barriers leading to innate immunity in the skin.
Tight junctions of the epithelia
Longitudinal flow of air or fluids
Fatty acids
Antibacterial peptides
Normal flora
Name 6 physical barriers leading to innate immunity in the gut.
Tight junctions of the epithelia
Longitudinal flow of air or fluids
Low pH
Enzymes
Antibacterial peptides
Normal flora
Name 3 physical barriers leading to innate immunity in the lungs.
Tight junctions of the epithelia
Movement of mucus by cilia
Antibacterial peptides
Name 2 physical barriers leading to innate immunity in the eyes and nose.
Tight junctions of the epithelia
Salivary enzymes –> lysozyme
When is the second line of defense in innate immunity needed?
When the foreign body goes through the physical barriers (first line), the second line of immunity is activated
Name 3 humoral factors in the second line of defence.
Inflammation and fever
Antimicrobial substances (complement)
Interferons
Name 3 cellular factors in the second line of defense.
Phagocytic cells
Cells with inflammatory mediators
NK cells
What are the 4 distinct signs and symptoms of inflammation and what are they caused by?
Redness: increased blood flow
Heat: increased blood flow
Pain: factors following injury
Swelling: humeral factors moving into the tissues
What are the first stage of inflammation?
There is vasodilatation to bring more blood resources (blood cells and plasma proteins) into the lesion. By doing that, the vessels are stretched and create more space between the cells of the vessels. That way, the vessels are more permeable and allow substances to go to the damaged site.
Give 3 examples of humoral antimicrobial substances.
Interferons
Complement
Iron binding proteins
Explain the function of interferons in the immune system.
a virus uses the infected cell to reproduce itself
Once a virus infects a cell, it will release interferons. Those are going to link to the interferon receptors on the uninfected cells. They will then be able to produce antiviral proteins before getting infected. When the cell IS INFECTED, it already had protein to prevent the replication of the virus.
What is a complement?
Plasma proteins with multiple functions to participate in fighting infections
Name the two main complement pathways and whether they belong to innate immunity or adaptive immunity.
The alternative pathway (innate)
The classical pathway (adaptive)
Explain how the alternative complement pathway works in innate immunity.
When there is an injury, the plasma protein moves into the tissue and attaches to the pathogen’s surface. The complement is then activated and opsonizes the pathogen (preparing it to be phagocyted)
Explain the function of complement C3b as an opsonin.
It sticks to the bacteria and makes the bacteria more recognizable to phagocytes since they have Cb3 receptors on their surface.
Given an example a humoral substance that is an iron-binding protein and explain its function.
Transferrin
When a bacteria is infecting an organism, it needs iron to replicate itself. However, once the body has identified a bacteria, it will produce more transferrin so it can pick up any additional iron. That way the bacteria can’t use it to replicate itself.
Give 2 examples of autoimmune diseases.
HIV AIDS and SCID
What are the two components of the second line of defense of the innate immune system?
The humoral and cellular factors
The major cellular factors in the second line of innate immune defense are […]
NK cells
Phagocytic cells
Cells with inflammatory mediators
What are NK cells? How do they act
They are cells that target virus-infected and cancer cells
Are NK cells antigen-specific?
No
NK cells kill infected cells by […]
They attack and kill the target cell by releasing a first molecule that punctures the infected cell and a second molecule that goes into the cell to kill it
Explain how the NK cell knows which cells to kill.
Normal body cells express a MHC 1 protein (cancels the other ligand). When the NK cells are not able to recognize that protein on a cell, it knows it’s foreign and knows to kill it
What is the function of phagocytes?
Non-specifically engulf microbial invaders
What are the two types of phagocytes? Explain the major difference between them.
Macrophages and dendritic cells are already in the tissue where there could be an injury
On the other hand, Neutrophils travel in the circulation and are going to be recruited at the site of injury.
Name the four steps of phagocytosis and intracellular destruction of a microbe.
Adherence (endocytosis)
Ingestion (phagosome)
Digestion (lysosome)
Killing (phagolysosome)
Explain the process of phagocytosis and intracellular destruction of a microbe.
The microbe in the ISF is brought in by endocytosis into the phagocyte. It’s kept in a phagosome so it doesn’t spread in the cytoplasm, and lysosomes are brought to from a phagolysosome. At that point. the bacteria is killed, and produces debris and/or a signal to send to other immune cells.
How do phagocytes recognize microbes?
They recognize structures that are not necessary from body cells and so are unique to microbial physiology. They are called Pathogen-Associated Molecular Patterns (PAMPs)
Macrophages recognize PAMPs using […]
Pattern Recognition Receptors (PRR) on their surface. They are Toll-Like Receptors (TLRs)
What are toll-like receptors?
They are transmembrane receptors with an extracellular domain that recognizes pathogens and an intracellular domain for signalling what was identified.
They are essential for microbial recognition via PAMPs by macrophages.
When toll-like receptors detect […], this starts the process of […]
PAMPs
Inflammation
Explain what happens when PAMPs get detected by toll-like receptors.
The macrophage is activated and signals are sent out to the body to active the inflammation process and recruit more immune cells to the site of injury, including neutrophils.
The first cell to be recruited once the process of inflammation has begun is […]
the neutrophil
The recruitment of neutrophils corresponds to the […] stage of inflammation
emigration of phagocytes [after vasodilatation]
Explain the first step in the emigration of phagocytes to the injured site.
The first step is chemotaxis. Once the toll-like receptors have detected PAMPs, they send out chemoattractants, which attract phagocytes (neutrophils) to the injured site.
Explain the second step in the emigration of phagocytes to the injured site.
Margination. The neutrophils stick to the surface of the blood vessels
Explain the third step in the emigration of phagocytes to the injured site.
Diapedesis. The neutrophils move across the capillary wall to act on the injury site.
Once the neutrophils have arrived at the injury site, explain what their function is.
They attack the bacteria and die in the process. By dying, they form NETs. Those slow down the bacteria and keep them stuck in some sort of glue-ish net.
NETs are made of […]
cytoplasmic proteins that come from the lysed neutrophil