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
How does antibiotic resistance occur?
- There is a genetic mutation in a population of bacteria
- Making some bacteria naturally resistant to an antibiotic
- Bacteria that are resistant are likely to survive so it lives longer and reproduces more times
- Leading to an antibiotic resistance being passed on to lots of offspring
Name 2 examples of antibiotic resistant bacteria?
MRSA and C. difficile
Name 3 Active Physical defences in plants
- Leaves sense pathogen presence, and prioritise use of energy in secreting harmful chemicals
- Cellulose produced to further fortify the cell walls
- Oxidative bursts: produce harmful oxygen molecules to target the pathogen
What are Opsonins?
A protein molecule that attaches to the antigens on the surface of a pathogen. They are a type of antibody.
What is the function of Opsonin?
To enhance the ability of Phagocytic cells to bind and engulf the pathogen
What are Agglutins and what do they do?
Antibodies that cause pathogens to stick together and thus are easier to be detected by phagocytes
What are Cytokines?
Hormone-like molecules used in cell signalling to stimulate the immune response
What are Interleukins?
Signalling molecules that are used to communicate between different white blood cells
Why do Fungi cause redness and irritation, in animals?
Due to Hyphae released from the fungus
The most common means of transmission can be identified as five groups, what are they?
- Droplet Transmission
- Physical contact
- Faecal-oral transmission
- Transmission by spores
- Vector transmission
Name a bacteria that is spread through Faecal-oral transmission, a type of direct transmission
E. coli
Give an example of droplet transmission
E.g. through sneezing - pathogen is contained within mucus
Give an example of a disease that is spread by physical contact, a type of direct transmission
E.g. Ringworm, a fungal skin disease in cattle, spread by an infected animal brushing against an uninfected animal
Give an example of transmission by spores, a type of direct transmission
E.g. Anthrax
What are spores?
A resistant form of a pathogen
What makes spores particularly harmful/dangerous?
The fact they can resist extremes of temp, pH, and even strong disinfectants
Give an example of a disease spread by Vector transmission, a type of indirect transmission
E.g. Malaria
In what 2 ways can can the environmental factor ‘Climate’ contribute to the spread of disease and INCREASE it?
- Some vectors only live in hot climates, E.g. Mosquitoes
- Many viruses, protoctists, and bacteria survive better in hot weather
- Very cold climates can kill pathogens
In what way can can the environmental factor ‘Climate’ contribute to the spread of disease and DECREASE it?
- Very cold climates can kill pathogens
In what 2 ways can a particular environment help increase the spread of disease?
- Cramped and crowded environments are conducive to spread of disease
- Dirty environments harbour pathogens
How do cramped and crowded environments conduce the spread of disease? (2)
- Droplet infection rate likely to be higher
- Contact infection also likely to be higher
How do dirty environments harbouring pathogens contribute to the increased spread of disease? (2)
Through E.g. the use of human sewage to fertile crops in some parts of the world
- This is likely to cause FAECAL-ORAL pathogen spread
There are two types of passive defence against pathogens in plants, what are they?
Physical and chemical
What is Callose, and what does it do?
- Large polysaccharide deposited into sieve tubes, around the sieve plates, in the phloem
- blocks flow in sieve tube
- Prevents spread of Pathogen around a plant
What is Tylose and what does it do?
- Balloon-like swelling in xylem
- Blocks xylem and stops pathogens from travelling this way around the plant
What are Tannins a type of, and what do they do?
- Its a type of Phenol, the defensive chemical
- Found in bark, they inhibit attack by insects
Name the 4 chemicals produced in plants as a (usually) active defence against pathogens
- Terpenoids
- Phenols
- Alkaloids
- Hydrolytic enzymes
What are primary defences?
Those that prevent pathogens from entering the body
What are secondary defences?
Those that prevent pathogens from harming the body once it has infected the host
Describe the process of the mucus-cough reflex and the cells involved
- Goblet cells in trachea secrete mucus
- Mucus traps pathogens
- Cilia cells lining respiratory tract waft mucus towards back of throat
- Cough reflex expels mucus and clears the airway
How are Sebaceous glands secreting lactic acid and fatty acids a defence against pathogens by the skin?
Forms an acidic environment and this disrupts the bacterial processes
How does the clotting process start/get triggered?
Clotting factors are released from platelets and damaged tissue, which activate an enzyme cascade.
What chemicals are involved in the inflammation process?
HISTAMINES
- Damaged/Mast cells release them
- Cause the capillaries to dilate and become more permeable to WBCs and Phagocytic WBCs
CYTOKINES
- Damaged cells release Cytokines which attract Phagocytes
Describe the Nucleus of a Neutrophil?
- It is Multi-lobed to enhance flexibility of cell
Where are Both Neutrophils and Macrophages manufactured?
In the bone marrow
Why are neutrophils released in large numbers?
Because they are short lived
Where to Macrophages tend to settle?
In organs, particularly in Lymph Nodes
What do macrophages travel in the blood as, and where do they go to mature in to Macrophages?
Monocytes
Dendritic cells - a type of macrophage - are found where?
In the more peripheral tissues
What happens to a pathogen when it is engulfed by a Macrophage as opposed to a neutrophil?
- Not fully digested
- Antigen from its surface is saved and moved to a special protein complex on the surface of the macrophage
- Cell is now and Antigen-presenting cell (APC)
Give the three type of Antibodies
Antitoxins
Opsonins
Agglutinins
What is supposed to happen to lymphocytes that are programmed to attack “self” during a pathogenic infection?
During clonal selection they are normally/meant to be destroyed before entering the bloodstream