Diseases - 4.1 Flashcards
What is a pathogen?
A microorganism that causes disease
What is a communicable disease
A disease that can be transmitted from one organism to another
What diseases are caused by bacteria?
- Tuberculosis (A)
-Meningitis(A)
-Ring rot (P)
What diseases are caused by viruses?
-HIV (A)
-Influenza (A)
-Corona virus (A)
-Tobacco mosaic virus (P)
What diseases are caused by protostists?
-Malaria (A)
-Blight (P)
What diseases are caused by fungi?
-Athletes foot (A)
-Ringworm (A)
-Black sigatoka (P)
What is an antibiotic?
A drug that slows bacteria growth or kills bacteria
What are the primary reasons for the development of antibiotic resistance?
-Over prescription of antibiotics
-Patients not completing the course of antibiotics
-Routinely using antibiotics in farming
How are pathogens transmitted?
- Direct physical contact (reduce by hand washing, cleaning surfaces, etc)
- Faecal - oral transmission usually by eating food or water contaminated by the pathogen, eg cholera (reduce by washing fresh food and treatment of drinking water)
- Droplet infection ( reduce by covering mouth when coughing, etc)
- Transmission by spores - they can be carried in the air or in soil (reduce by washing hands after contact with soil)
What is a vector?
An organism that carries a pathogen from one host to another. This is indirect transmission- eg the plasmodium that causes malaria enters a host via a bite from a mosquito
What is the role of T helper cells?
Release cytokines that stimulates B cells to develop and stimulates phagocytosis by phagocytes
What is the role of T killer cells?
Attack and kill host body cells that display the foreign antigen
What is the role of T memory cells?
Provide long term immunity
What is the role of T regulator cells?
Shut down the immune response after the pathogen has been successfully removed. Also involved in preventing autoimmunity
What is the role of plasma cells?
Circulate in the blood to manufacture and release antibodies
What is the role of B memory cells?
Remain in the body for years and act as the immunological memory
What happens in clonal selection in the specific immune response?
The specific antigens on the pathogen are detected by T and B lymphocytes that carry a specific receptor molecule on their plasma membrane that is complimentary to the shape of the antigen. This is where a T helper cell is clonally selected
What happens in clonal expansion in the specific immune response?
Once the correct lymphocytes have been activated they must increase in number to become effective so divide by mitosis. The T helper cells also secretary cytokines which attract B cells
What happens during differentiation during the specific immune response?
T and B lymphocytes develop into a range of useful cells
What are the three main groups of antibodies?
-Agglutinins
-Opsonins
-Antitoxins
How do Opsonins work?
Bind to the antigens in a pathogen which acts as a binding site for phagocytic cells so they can bind more easily to destroy the pathogen
How do agglutinins work?
It cross links pathogens by binding an antigen in one pathogen with one binding site and then an antigen in another pathogen with its other binding site. This clumps together the pathogens which impedes them from carrying out some of their functions and makes it easier for them to be engulfed by phagocytosis
How do antitoxins work?
Directly bind to toxin molecules decreased by pathogen to neutralise them and prevent damage to cells
State three factors that would affect the speed of transmission in plants
-climate change
-wind
-overcrowding of crops
-warm humid conditions