What are pathogens?
Any microorganism that causes harm
What are examples of pathogens?
What is self tolerence?
The bodies immune defences not attacking tissue that carry a self marker
What is the first form of immunological defence?
What are examples of physical barriers?
Mucosal barrier (reproductory, respiratory, digestive tract)
What produces mucus?
What does mucus do?
Prevents the attachment of pathogens
What does mucus contain?
Antimicrobial enzymes that destroy pathogens
What are examples of the enzyme contained in mucus that destroys pathogens?
What does mucus contain other than enzymes?
Immunoglobins (Ab) which help to destroy pathogens
What are the two components of the immune system?
Innate immune system
Adaptive immune system
What are some properties of the innate immune system?
Exists from birth
First to respond
Same response every time, no immunological memory
What are some properties of the adaptive immune system?
When is the adaptive immune system called?
When the innate immune system cannot deal with the threat on its own
What is the cellular and chemical barrier of the innate immune system?
What is the blood protein of the innate immune system?
What cells are involved in the innate immune system?
Phagocytes (macrophages, neutrophils)
Natural killer cells
What are the cellular and chemical barriers of the adaptive immune system?
What is the blood protein of the adaptive immune system?
What cells are involved in the adaptive immune system?
How does the innate and adaptive immune system work together?
- Dendritic cells mature and carries microbial antigen to local lymph node (innate)
- Becoming an antigen presenting cell (innate)
- Activates T cells to respond (adaptive)
- T cells go to the site of infection (adaptive)
What does the innate immune system cause an influx of at the site of infection?
Macrophages which perform phagocytosis
What is the process of phagocytosis?
- Engulfs bacterium
- Forming a phagosome
- Fuses with a lysosome which contains enzymes that kill the bacteria
- Discharge of waste material
Where do immune cells develop?
What are the 4 effector T cells?
What does Th1 target?
What does Th2 target?
What does Th12 target?
What does Tfh target?
What do effector T cells do to their targets?
Activate their targets
What is the relationship between manocytes and macrophages?
Manocytes are in the blood, once they enter connective tissue they differentiate into macrophages
What do macrophases do?
Give of chemical messanges which:
Restrict blood flow away from the site
Cause swelling to allow more immune cells to help
Produce cytokines to alert other cells and induce travel to the site
What do neutrophiles do?
Only perform phagocytosis, being activated when they enter the tissue
How long do neutrophils survive for in the blood and in the tissue?
6 hours in the blood
5 days in the tissue
What happens at the end of a neutrophils life?
They undergo apoptosis
What do eosinophiles do?
Combat pathogens with granules of enzymes
What kind of infection do eosinophiles usually combat?
What kind of immune cells controls the mechanisms associated with asthma and allergies?
Where are eusinophiles found?
Lower GI tract
Where are eusinophiles not found?
What do mast cells do?
Contain granules which have active chemicals that it dumps into the parasit and kills it
What could mast cells cause to the host?
An allergic reaction
What is the function of barophil?
Unknown, but they are found in parasitic infection
They contains granules of histamine
What are the two ways natural killer cells can kill?
Make hole in target and secrete enzymes into pore inducing suicide
Interact with Fas on the target cells creating a suicide signal
Where are natural killer cells found?
In the spleen and the bloodstream
What can natural killer cells kill?
Virus infected cells
How do natural killer cells decide to kill or not?
By binding to inhibitory (MHC1) receptor or activating receptor
What inhibitory receptor tells natural killer cells not to kill?
Can natural killer cells kill viruses?
No, they replicate to quickly for natural killer cells to keep up
What are some non-specific humoral factors within body fluids with protective functions?
What does the compliment system bridge the gap between?
The innate and adaptive immune systems
How many proteins is the compliment system composed of?
What are the 3 activation pathways of the compliment system?
Which of the 3 compliment mechanisms are innate and adaptive?
Alternative and lectin are effecter mechanisms of the innate system and classical is of the adaptive immune system
What is the process of the compliment system?
- Binding of compliment protein to microbial cells or antibody
- Formation of C3 complex
- Cleavage of C3
- Formation of C5 convertase
What is the central event in the compliment pathway?
Proteolysis of protein C3 which is the most abundent compliment protein
What are the safeguards in place to stop the compliment system from attacking our own cells?
Protein on surface of cells Decay Accerleration Factor (DAF) accerlerates the breakdown of C3bBb
C3b clipped to an inactive form by protein in the blood
What are functions of the compliment system?
Induce lysis of microbes (MAC)
Promotes phagocystosis of microbes (opsonisation)
Stimulates inflammation (activates amst cells and neutrophils)
Stimulates attraction of B cells and antibody production
What are cytokines?
Chemical messengers used by cells to communicate with other cells
What are the different kinds of cytokine actions?
Autocine (on self)
Paracrine (nearby cells)
Endocrine (distant cells)
When does the inflammatory response happen?
When tissues are injured
Why does the inflammatory response happen?
Damaged cells release chemicals that cause blood veseels to leak into tissues
What are the classifications of the inflammatory response?
What is acute inflammation?
Initial response to harmful stimuli
What is chronic inflammation?
Progressive shift in type of cells at site of inflammation, simutanous destruction and healing of tissue