Communicable diseases Flashcards
3 communicable diseases caused by Bacteria?
Bacterial meningitis, TB, Ring rot
3 communicable diseases caused by Viruses?
HIV, Influenza, Tobacco mosaic virus
3 communicable diseases caused by Fungi?
Ringworm, Athlete’s foot, Black Sigatoka
2 communicable diseases caused by Protoctist?
Malaria, Potato blight
Name 3 animal barriers to infection
- Skin
- Mucous membranes
- Blood clotting/ wound repair
Name 4 passive physical plant barriers against infection
- Waxy cuticle
- Cellulose Cell walls
- Callose
- Tylose formation
How does Callose work regarding actually stopping pathogens entering the individual cells?
Deposited between cell walls and plasma membranes and makes it harder for pathogens to enter cells
2 plant chemicals that defend against pathogens
Saponins - Destroy fungi etc cell membranes
Phytoalexins - Inhibit growth of fungi etc
Outline the process of clonal expansion
- Antigens bind to B cells antibodies
- Interleukins/Helper T-cells activate B-cells
- B-cells reproduce and produce plasma cells
- The plasma cells bear antibodies with the identical antigen specificity as the antigen receptors of the activated B cells.
- The antibodies are released and circulate through the body, binding to antigens.
- B cells produce memory cells. Memory cells provide future immunity.
Outline the process of clonal selection
- Receptors on T-cells bind to antigens presented by APC’s
- This activates the T-cell, this is Clonal Selection
- Then T-cell divides to produce clones (Clonal expansion) Into the 4 types of T-Cell
What is the function of T-Helper cells?
Release substances to activate B-Lymphocytes
What is the function of T-Killer cells?
These attach to antigens on a pathogen and kill the cell
What is the function of T-Regulator cells?
They suppress the immune system from other WBC’s to stop self-cells mistakenly attacking the host body’s cells
How do Antigens stimulate an Immune Response?
Antigens on the cell surface are identified as foreign which activates cells in the immune system
Outline Phagocytosis
- Phagocyte recognises antigen on pathogen
- Phagocyte binds to opsonin attached to the antigen
- Cytoplasm of phagocyte moves round pathogen and engulfs it by endocytosis, forming phagosome
- Lysosomes fuse to phagosome forming Phagolysosome and release digestive enzyme
- Enzymes break down pathogen, harmless products absorbed into cell
- Phagocyte then presents pathogen’s antigens on its surface (APC)to activate other immune system cells
Describe what plasma cells are and do
-Plasma cells are identical clones of the B lymphocyte
-They secrete lots of the antibody specific to the antigen,
into the blood
- These antibodies bind to the antigens on the surface of the pathogen to form lots of A-A complexes
Describe the structure of an Antibody
- Variable region (complementary to specific antigen)
- Hinge region (allows flexibility when binding)
- Constant region (Same in all antibodies)
- Disulphide bridges (Hold polypeptide chains together)
Why is a secondary response faster?
- Clonal selection happens faster as memory B lymphocytes are activated and divide into plasma cells that produce the right antibody to the antigen
- the secondary response gets rid of the pathogen before you begin to show any symptoms
What is Active Natural immunity?
When you become immune after catching a disease eg. measles as a child meaning you never have it again
What is Active Artificial immunity?
When you become immune after having been given a vaccination
What is Active immunity in general?
Type of immunity you get when immune system makes its own bodies after being stimulated by an antigen
What is Passive immunity in general?
Type of immunity you get from being given antibodies made by a different organism
What is Passive Natural immunity?
When a baby becomes immune due to the antibodies it receives from its mother through placenta + breast milk
What is Passive Artificial immunity?
When you become immune by being injected with antibodies from someone else
Give 2 Autoimmune diseases?
- Lupus
- Rheumatoid arthritis
Why do autoimmune diseases occur?
- Organisms immune system isn’t able to recognise self-antigens
- When this happens the immune system launches immune response against organisms own tissues
What is herd immunity?
Using a vaccine to provide immunity to all or almost all of the population at risk
What do vaccinations do?
They contain antigens that cause your body to produce memory cells against a particular pathogen. You become immune without getting any symptoms