Diseases Flashcards
What is a pathogen? Give some examples.
Pathogens are disease-causing organisms.
E.g : Bacteria (E-coli), Protozoa (malaria parasite), Virus (HIV), Fungi (epidermophyton)
Discuss the basic characteristics of bacteria, virus, fungi and protozoa.
Bacteria - They have no real nucleus - Reproduce by splitting in half Virus - Have DNA but no nucleus - They reproduce by attaching to other cells - Cannot be killed by antibiotics Fungi - They do have a nucleus - Reproduce by producing spores - Mushrooms are a kind of fungi Protozoans - They are heterotrophic - Can be symbiotic or parasitic
What are the various ways in which the pathogens can be transmitted?
- Inhaled droplets (influenza virus)
- Direct contact (herpes, varicella)
- Bodily fluids (Strep throat, HIV)
- Animal vectors (rabies, malaria)
- Blood contact (hepatitis B virus)
- Ingested / swallowed (salmonella bacteria)
What are the various ways in which antibodies work?
- DNA replication (bacteriostatics)
- Cell wall and membrane (bacteriocides)
- RNA translation
Why don’t antibiotics work against virus?
- Viruses use host cell metabolism
- They are protected by the host cell structure
- They have different metabolic pathways to bacteria - so antibodies have nothing to target
- Have different structures eg protein coats instead of cell wall
In what way does our body prevent the pathogens from entering our body.
SKIN
- continuous, hard to find an opening
- many layers / tough
- pH, not favourable to pathogens
- lysozyme, enzymes break down pathogens
- natural organisms, competitive exclusion by non-harmful microbes
MUCOUS MEMBRANE
- sticky mucus, traps invader
- pH, not favourable to pathogens
- lysozyme, enzymes break down pathogens
- natural organisms, competitive exclusion by non-harmful microbes
Give the definitions of antigens and antibodies.
Antigens : a substance or molecule found on the cell or virus surface, that causes antibody formation
Antibodies : a globular protein that recognises a specific antigen and binds to it as a part of an immune response
What is the function of B-lymphocytes?
They recognise antigens on the surface of microbes as ‘foreign’ and produce antibodies against them. Antibodies and antigens form immune complexes on surface of microbe, making the microbes clump together.
Describe the process of production of Antibodies.
- Many different lymphocytes exist
- Each type recognises one specific antigen
- When the immune system is challenged by the invasion of a pathogen, the corresponding lymphocytes responds.
- It makes many clones of itself, each of which produces antibodies to the pathogen
- This process is called cloned selection, as the right lymphocyte is selected and then cloned.
- Some of the cloned cells remain as memory cells, ready for the second invasion by the pathogen. This is immunity.
What are the two types of immunity?
ACTIVE IMMUNITY
When the antibodies are produced by our own body
PASSIVE IMMUNITY
When the antibodies are made outside and then introduced in the body
What is the job of the antibodies?
Stick to the antigen and cause the pathogen to become immobile and making the job of phagocytes to engulf pathogens easier.
Describe the process of phagocytosis
- Pseudopodia of neutrophil flow round bacteria, beginning the process of engulfment.
- Engulfment is completed and the encircled microbes are destroyed in the vacuole.
- Neutrophil engulf and destroy bacteria which have been attacked by antibodies.
What is Tissue rejection?
- When a patient is given an organ transplant, the donor is chosen to have similar cell antigens to the patient.
- Donor antigens are never identical to the recipient.
- The recipient’s immune system will recognise the organ as being foreign.
- Antibodies are produced which attack the transplanted organ.
- To prevent rejection drugs may be given to suppress the patient’s immune system.
- These may also reduce the patient’s ability to resist diseases.
What is autoimmune disease?
It is a condition in which your immune system mistakenly attacks your body
