key terms Flashcards
cellular v non cellular
Influenza is non cellular pathogen. It is nonliving, has no metabolic activity and cannot reproduce independently in the cell. Contains only RNA
transmission
coughing/ sneezing
inhaling infected droplets
breathed in through nose and mouth into the throat past the mucosal membrane
detecting self and non self
influenza is a non self forge in pathogen
the influenza infected cell invades the host cell and then begins to replicate inside of it by changing the rna synthesised cap and guides host cells to reproduce the influenza virus. they then leave the host cell and invade another one and repeat
the lymphatic system
Primary lymph tissue is where white blood cells are produced and mature includes bone marrow of the long bones
Secondary lymph tissue is where B and T cells gather and attach to foreign antigens. Includes the lymph nodes, vessels and everywhere else in the body.
The humoral response occurs primarily in the lymph nodes
The Lymph is tissue fluid, lymph nodes are spongy.
Influenza travels through the lymphatic system, attaching to b and t cells in the lymph nodes.
first line of defence
Influenza’s main entry points are through the nose and throat into the ducts of the respiratory system or through the mouth into the digestive tract.
The mouth cavity has a mucus membrane that traps microorganisms such as influenza. The mouth is then cleaned by saliva
The nasal cavity has hairs and and mucus used to trap microorganisms and keep them out.
The mucous membrane secretes a thick gelatinous fluid called mucus that can trap particular matter including pathogens. The mucous membrane is washed constantly with the constant flow of saliva. This prevents pathogens from becoming established
stages of phagocytosis
The pathogenic identified as being non self by the macrophage and is engulfed by the outer foldings of the plasma cell membrane of the macrophage.
The pathogen is the completely enclosed in a vesicle known as a phagosome
Lysosomes fuse with the phagosome and release toxic chemicals that attack the pathogen
The pathogen then undergoes digestion from this combined chemical attack
Indigestible material is discharged from the phagocytic cell via exocytosis.
interferons
Interferons are important in the innate immunity response to virus infections. The name of these proteins reflects the fact that they ‘interfere’ with viral replication. Because viral infections can occur quickly, interferons are critical in the body’s initial responses.
Once a body cell is infected with viruses, the cell secretes interferons
The interferons that it secretes into its surroundings act as warning signals to nearby cells so that they can prepare in advance for a possible virus infection.
Interferons activate immune cells such as NK cells that eliminate virus infected cells
the inflammatory response
Mast cells are primarily involved
Mast cells are white blood cells that start off in the blood but mature and settle in the connective tissues of the body.
When mast cells detect damage to cells around them in near by tissues, they respond by releasing histamines. These leave the cell and cause responses in tissues around them including:
Dilation of blood vessels: more blood comes into the area it becomes red and warm. This allows blood vessels to open up and let more phagocytes get into the area and engulf the pathogen
Blood vessels leak: they become permeable to plasma / leukocytes can leave the bloodstream and get in-between cells outside the bloodstream (this allows phagocytes to get out)
Constriction of the airways
Attraction of phagocytes
Escape of immune cells from capillaries: The expansion of the capillary bed enables neutrophils to squeeze between the endothelial cells that line the capillaries (see figure 7.27).
Migration of neutrophils to infection site: Neutrophils are the first immune cells to arrive at the infection site, attracted by cytokines released by damaged cells. Other immune cells, including macrophages from nearby tissues, follow. These cells release signals, such as histamine and more cytokines, that attract more phagocytic cells to the infection site.
Phagocyte attack on bacteria: Both neutrophils and macrophages attack bacterial pathogens by engulfing them in a process called phagocytosis (refer back to Cells of the innate immune system). Phagocytic cells also remove cell debris from the infection site by a similar process. Pus consists mainly of dead phagocytic cells and other immune cells, and also contains living cells and cell debris.
the third line of defence
The third line of defence is
Specific- able to recognise and respond to self antigens and non self antigens
Adaptive - able to learn how to respond to a specific target
Acquired - the organism is not born with this knowledge, the must gain adaptive immunity through exposure to antigens. This info is no passed through onto the next generation
Has two pathways, the humoral response and the cell mediated response
T cell lymphocytes
Mature in the thymus and then migrate to the lymph node
Has one antigen binding site
Each t cell has many surface receptors that recognise one specific antigen
They are activated by exposure to antigens presented to them on the surface of other cells
Types of T cells
Cytotoxic T cells: activated cells eliminate infected and abornmal cells
Activated helper T cells: activated by interleukin 1, send signals that stimulate B cells to secrete specific antibodies (releases interleukin 2)
Memory T cells: retain a ‘memory’ of antigens met previously. Stay in the lymph node
the beginning of the third line of defense
(applies for the humoral and the cell mediated)
Macrophages/dendritic cells (ANTIGEN PRESENTING CELLS) carry a specific antigen (influenza) they’ve engulfed to the lymph node. Here they bind with a Helper T cell with a complementary receptor. Interleukin one is released which activates the help T cell. The helper T cell then is activated and releases interleukin 2. and makes thousands of copies of itself.
Now there is millions of T cells with the same complementary receptor to the pathogen
cell mediated response
response involves T lymphocytes (VIRUS INTRACELLULAR)
A unique Cytotoxic t cells bind with the virus’ MCH class 1 protein presented on the antigen (the macrophages or dendritic cells (APC’s)). They are able to bind because they have complementary receptor and are specific to the antigen
This activates the cytotoxic T cell to proliferate to form clones of cells each with complementary receptors specific to the antigen
The cytotoxic T cells migrates to the site of infection and can now encounter and eliminate other cells infected with the virus.
The infected body cells present the antigen on the outside of their surface on the class 1 MHC marker. Cytotoxic T cells since they have a complementary receptor are able to identify these as non self and bind. The cytotoxic T cell is then stimulated to release molecules known as perforin. Perforin kills the target cell causing the cell to lyse.
The increase in inflammation then stimulates the macrophages to come and clean uptake debris of the pathogen
B cell lymphocytes
Involved in the humoral response
Unlike T cells, B cells have 2 antigen binding sites.
the humoral response
B lymphocytes encounter an antigen and breaks it down using lysomes. The b lymphocyte then presents the antibody on their surface (MHC 2 MARKER). The helper T cell then recognises the B cell with the MHC 2 maker and secretes cytokines (interleukin) via paracrine signalling. This stimulates the B cell to proliferate
The B cell then makes lots of copies of itself including B memory cells which remain inactive in our system and give us lasting immunity against the immunity
The proliferated B cells now known as B plasma cells are essentially antibody factories that that mass produce and release antibodies into the host body. This is known as clonal expansion
The antibodies attack the specific pathogen and neutralise it
This then stimulates phagocytes to clean up via phagocytosis
parts of an antibody
variable region
constant region
light and heavy chains
disulphide bond
