Immunology Two Flashcards
What is the role of the immune system?
Protect body from harmful substances, germs and cells that can make someone ill
What makes up the immune system?
Organs
Tissues
Cells
What can the immune system do?
Identify threat
Mediate attack
Eliminate pathogen
In some cases, remember pathogen in case attack happens again
What does a prolonged immune response lead to?
Chronic inflammation
What are the two branches of the immune system?
Innate
Adaptive/acquired
What are features of the innate immune system?
Immediate
Non-specific
No memory
What are features of the adaptive immune system?
Takes days to weeks
Highly specific
Has a memory
What does it mean to say the innate immune system is non-specific?
Can distinguish a human cell from an invader but cannot distinguish an invader from another invader
What is the first line of defence in the innate immune system?
Physical barriers
Cells lining the skin, cilia in airways, mucous membrane
What is the second line of defence in the innate immune system?
Physiological barriers
Saliva, flushing action of sweat and tears
What do the physical and physiological barriers do?
Stop infection from entering the body
What immune system is the complement system a part of?
The innate immune system
What is the complement system?
The complement system is made up plasma proteins that induce a series of inflammatory responses to fight infection.
What are the 11 steps in the complement system?
- Pathogen with antibodies enters the system
- Antibodies recognise antigens and bind to them. Antigen-antibody complex formed.
- C1 binds to antigen-antibody complex.
- C1 activation causes C2 and C4 to split.
- Part of C2 and C4 come together to form C3 convertase.
- C3 convertase splits into a small and larger section - C3a and C3b.
- C3a will fan out and attract more lymphocytes to the area.
- C3b will bind to the surface of the pathogen, marking it for destruction.
- C3b causes C5 to split into C5a and C5b
- C5b joins with C6-9 to from membrane attachment complex which attaches to membrane of pathogen, forming a hole in it.
- Water gushes into pathogen, forcing it to break apart.
What does it mean to say the adaptive immune system is specific?
The cells of adaptive immune system have receptors that differentiate one pathogen from another by their unique ports called antigens.
What does it mean to say that the adaptive immune system is diverse?
Can recognise an infinite amount of specific antigens and make a specific response against each of them
What is the advantage of the adaptive immune system?
Has a memory
Whats is the disadvantage of the adaptive immune system?
Takes days to weeks to work
How does the adaptive immune system have memory?
Each time the adaptive immune system sees a pathogen, they massively proliferate.
When that adaptive immune system sees the same pathogen, they massively proliferate again, resulting in a faster and greater response.
Most of these cells are deleted, but the ones that stay are memory cells.
What do multipotent hematopoietic stem cells branch into?
Myeloid progenitor cells
Lymphoid progenitor cell
What do myeloid cells become?
Cells of the innate immune system
What are the cells of the innate immune system?
Mast cell
Dendritic cells
Macrophages
Monocytes
Granulocytes:
Basophil
Eosinophil
Neutrophil
Natural Killer cells
What cells are phagocytic?
Neutrophils
Macrophages
Natural killer cells
What are basophils, eosinophils and mast cells all involved in?
Response to allergic reactions
What cell initiates allergic reactions?
Basophils
What cells cause inflammation in allergic reactions?
Mast cells
What cells are known for fighting parasites?
Eosinophils
What is the role of neutrophils?
One of the first immune cells to respond.
Travel to infection and destroy microorganisms via phagocytosis.
What does a rise in neutrophils indicate?
Bacterial infection
What does a rise in lymphocytes indicate?
Viral infection
What cells release cytokines?
Monocytes
Dendritic
Macrophage
What is the role of cytokines?
Stimulate, recruit, and proliferate immune cells
Where do monocytes circulate?
In the blood
Where do macrophages circulate?
Only in tissues
What do monocytes become?
Macrophages
What is the prototypical antigen presenting cell?
Dendritic cell
Where are dendritic cells found?
In sites that are in contact w/ external antigens ie skin epithelium
What cells are good at phagocytosis when they are immature?
Dendritic cells
What do mature dendritic cells do?
Breaks up pathogens into small amino acid chains
Go to nearest lymph node
Perform antigen presentation
What is antigen presentation?
Present amino acid chains - antigens - to the T cells
What connects the innate and adaptive immune system?
Antigen presentation
What cells can do antigen presentation?
The antigen presenting cells:
Dendritic cells
Macrophages
Monocytes
Why are dendritic cells the best at antigen presenting?
They are the only cells that live where pathogens enter and traffic from those tissues to lymph nodes
What does MHC stand for?
Major histocompatability complex
What is the role of the MHC?
Bind peptide fragments from pathogens & display them on the cell surface for recognition by T cells, for the right T cell to bind to it.
What do lymphoid cells produce?
B cells
T cells
Natural killer cells
What immune response are B and T cells a part of?
Adaptive immune system
Where do B cells and Natural Killer cells complete their development?
Bone marrow
Where do T cells complete their development?
Thymus
Where can lymphocytes travel?
In and out out tissue and blood stream
What are the features of natual killer cells?
Large
Has granules
What cells do natural killer cells target?
Cells infected with intracellular organisms - viruses
Cells that pose a threat - cancer cells
How do natural killer cells kill harmful substances?
Releasing cytotoxic granules
Punch hole’s in target cell’s membranes by binding to the phospholipid & creating pores
Target cells undergo apoptosis
What is the main difference between B and T cells?
B cells do not need antigens to be presented to them using a MHC - can bind directly
What does a T cell do upon activation?
Helps B cell mature into a plasma cell
Plasma cell can secrete lots of antibodies
Antibodies have same specificity as B cell they came from
Where do antibodies circulate and what can they do?
Circulate in plasma
Attach to pathogens, tagging them for destruction
What is B-cell immunity also called and why?
Humoural immunity
Because antibodies aren’t bound to cells and float freely in the blood
What is another name for T-cell immunity and why?
Cell mediated immunity
Antigen specific but cannot secrete their antigen receptor
What are the different types of T cells?
CD4 - helper cells, helps kill bacteria and helps B cells make antibodies
CD8 - cytotoxic T cells, directly cell killing, can destroy cancer or virus
What does CD stand for in reference to T cells?
Cluster of differentiation
What do CD4+ do?
Secrete cytokines that coordinate macrophages and B cells
Help activate cytotoxic T cells to kill infected target cells
How can CD4+ see their antigen?
If it is presented on a MHC II molecule
What are CD8+ T cells also known as?
Cytotoxic T cells
What do CD8+ T cells do?
Kills cells with specific antigen on MHC I molecule by secreting cytokines
