4.1 Disease and immunity Flashcards
What is a pathogen?
An organism that causes disease. The four types are bacterium, virus, fungi, and protoctista
What are three types of bacterial diseases and what do they infect?
Tuberculosis - Typically humans and cattle
Meningitis - Humans
Ring rot - Potatoes and tomatoes
What are three types of viral diseases and what do they infect?
HIV/AIDS - Humans
Influenza - Typically humans
Tobacco mosaic virus - Plants
What are three types of fungal diseases and what do they infect?
Black sigatoka - Banana plants
Ringworm - Cattle
Athlete’s foot - Humans
What are three types of protoctist diseases and what do they infect?
Potato blight/tomato late blight - Potatoes and tomatoes
Malaria - Typically humans
What are the three types of direct transmission in animals?
Direct contact - Touching, kissing, contact with cuts, and sexual contact
Inoculation - Animal bites, sharing needles, and cuts in skin
Ingestion - Drinking and eating contaminated water/food.
What are the three types of indirect transmission in animals?
Vectors - Usually animals that pass the pathogen on to humans
Droplets - Pathogens transmitted in drops of water
Fomites - Inanimate objects that transmit pathogens
What is direct transmission in plants?
Direct contact - Between infected plants
What are the two types of indirect transmission in animals?
Contaminated soil - Pathogens and their spores can remain in the soil and infect roots of nearby plants
Vectors - Wind, water, animals, and humans can carry pathogens and spores from one plant to another
What living conditions can affect modes of transmission?
Hot climates - Increased heat provides more kinetic energy for chemical reactions and reproduction
Social factors - Could result in poorer sewage infrastructure, a lack of fresh water and food, poorer sanitation, and overcrowded living quarters
How have plants adapted to respond to pathogens?
Barriers to prevent entry, such as bark or waxy cuticles
Antibacterial chemicals and proteins
Produce callose to stop pathogens spreading between their cells
What are the non-specific responses in animals?
Skin (primary) - physical barrier which stops pathogens
Blood clots (secondary)- temporary barrier formed at the site of a cut
Mucous membranes (primary) - line many body tracts and traps pathogens
Lysozymes (primary)- hydrolytic enzymes that digest pathogens
Reflexes (primary)- sneezing/coughing/vomiting
Inflammation (secondary)- occurs in localised areas, triggers the release of histamines and cytokines
Histamines (secondary)- cause blood vessels to dilate, make wall of blood vessel more permeable
Cytokines (secondary)- attract phagocytes
Phagocytosis (secondary)- phagocytes travel in the blood and engulf and digest pathogens
What is the process of phagocytosis?
Damaged cells and pathogens release cell-signalling chemicals that attract the phagocytes.
Pathogen attaches to phagocytes to by antibodies and surface receptors
Pathogen is engulfed by phagocyte by endocytosis
Invagination of plasma cell membrane to form a phagosome
Lysosomes fuse to the phagosome
H2O2 and HCl are released into the phagosomes
The pathogen is digested and harmless products are either removed or used by phagocyte
The phagocytes displays antigenic components on their external surfaces of the plasma membrane (antigen presenting cell)
What is the specific/immune response in animals?
Antibodies - immunoglobulin produced in response to antigens during the immune response. They work in three ways; agglutination, marking, and anti-toxins.
What is agglutination?
Clumping together of pathogens to make it easier for phagocytes to locate and engulf them
What is the marking of pathogens?
Antibodies act as an opsonin when an antibody-antigen complex has been formed. The antibodies are marking the antigen making them more susceptible to phagocytosis
What happens when antibodies act as anti-toxins?
Antibodies can bind to toxins, preventing them from entering cells and causing harm
What are the two types of passive immunity?
Natural - transfer of maternal antibodies to foetus via milk or placenta
Artificial - administration of pre-formed antibodies
What are the two types of active immunity?
Natural - infection
Artificial - vaccination
What is the process of cell signalling response?
Pathogens engulfed by cells from the immune system
Removal of antigens from pathogens
Antigens presented on surface of engulfing cells (ACP)
Selection of correct T cells (clonal selection)
What happens after the clonal expansion of T Killer cells (cell signalling)
T killer cells search for infected cells
Attach to infected cells
Secrete toxic substances into infected cells to kill the cell and the pathogens it contains
What happens after the clonal expansion of T helper cells (cell signalling)
Interleukins are released
B cells are activated
Clonal expansion of B cells
Some B cell clones differentiate into plasma cells which manufacture antibodies
The other B cells differentiate into B memory cells which circulate in the body providing immunological memory
What are the different types of vaccinations?
Living attenuated microbes - microbes that have lost the ability to produce dangerous clinical disease
Dead microbes - cultures of the pathogenic microbial strains are killed in such a way that they retain their ability to stimulate the body to produce an immunological response
Component - consisting of substances isolated from the virulent strains. No whole organism, living or dead, are present.
Toxoid - made by treating toxins produced by pathogens with heat or chemicals.
Edible - through common foods. Genes that make an antigen effective against a microbe are cloned into a common food.
DNA - consisting of DNA fragments that can be transformed into host tissue. Once in the host tissue, the DNA is transcribed and translated and the protein produced is seen by the specific immune system as foreign material and an immune response is induced.
What is herd vaccination?
vaccinates most/all people. Stops infection spreading within the population.
