Module 7: Infectious Diseases Flashcards

Question

What are macroscopic parasites?

Answer 1

Multicellular pathogens that can be seen with the naked eye. Examples are tapeworm, ticks and fleas, all of which suck human blood for nutrients.

Answer 2

Ebola is a viral disease that is spread through direct contact with the body fluids of an infected person.

Answer 3

Spread through intermediates, which allow the disease to spread on a larger scale.

Answer 4

Extracellular substance that aid pathogens in invading the host's body. They break down host defences and facilitate the growth and spread of the pathogen. There are spreading factors, enzymes which impact the strucutre of tissue matrices and spaces between cells. There are clotting factors, enzymes which induce clotting, converting fibrinogen to fibrin, disguising pathogens and protecting it from phagocytes. There are enzymes that disrupt cell membranes, facilitating pathogen entry into cells. However, some pathogens are able to bypass the cell membrane through passive entry.

Answer 5

Pili and fimbriae help the pathogen stick to the glycolipids of the cell membrane. Cell surface adhesion molecules have shapes that bind to the proteins found on the cell membrane.

Answer 6

1. Identify the pathogen Done through clinical observation and laboratory confirmation 2. Environmental Management - to reduce contact with pathogen Cleansing water supplies Creating sanitary conditions like removing waste from public areas and building sealed sewage systems 3. Quarantine

Answer 7

- Proved Bacilus anthracis is the cause of anthrax. Done by extracting the bacterium from a sheep which had died from anthrax, grew it and injected a mouse with it, and showed that the mouse had developed the disease as well. - His postulates - Created advanced staining and culture techniques Used methyl violet dye to show up the bacteria causing septicaemia, significantly helping our ability to see bacteria under a microscope. Also, by solidifying broth with gelatine and agar, Koch created a medium to culture bacteria which easier to handle than the liquids Pasteur used. - His pure culture techniques allowed him to identify the causative agents of tuberculosis and cholera, and helped the future identification of the pathogens responsible for typhus, tetanus and the plague.

Answer 8

Intense farming, various techniques that are performed to yield greater output, such as planting crops in higher density, increasing direct contact between individuals and thus, risk of infectious disease. To combat this, farmers employ intensive use of medicine and antibiotics, yet this creates more risk as overuse of medicine can promote resistance among pathogens. For example, in the UK 1990s, there was an outbreak of Mad Cow Disease, a fatal neurological condition in cows caused by a prion. This was due to farmers using the leftovers of previous animals, such as their cartilage, organs and bones to create food for their living farm animals. This intensification allowed farmers to save resources, yet in doing so, caused the prion causing Mad Cow Disease to spread throughout the cattle population in the UK.

Answer 9

Foot and Mouth disease - Originated from the importation of viral infected lamb from Argentina and Chile, while costed the agricultural industry over 14 billion dollars. These diseases are combatted by border control measures like intense screening and inspection processes at airports and docks.

Answer 10

Non-Specific (or innate defence) repels all pathogens equally. You are born with all of your non-specific defence mechanisms. Includes barriers to infection and innate immune system. Specific defence targets specific pathogens, which develops and adapts in response to pathogens which the body encounters over time. Involves the adaptive immune system.

Answer 11

- Barriers to infection - Innate immune system - Adaptive immune system

Answer 12

A molecule capable of triggering an immune response. The body distinguises all antigens as either self antigens, or non-self, attacking the non-self antigens. Examples of self antigens are cells, proteins or chemicals made by your own body. Examples of non-self antigens are pathogens, chemicals in venom, proteins in food or transplanted organs and blood.

Answer 13

First line of defence, which stops pathogens from entering the body, and is non-specific.

Answer 14

Activated when the pathogen breaks through the first line of defence, attempts to stop the pathogen from establishing itself within the body and spreading. - Phagocytosis - Inflammation

Answer 15

The third line of defence, which is specific. It activates as soon as the pathogen enters the body, but takes a while to work. When a pathogen enters the body for the first time, the adaptive immune system identifies its weakness in order to remove the pathogen. Adaptive immune system creates memory cells, which allows the body to quickly recognise and respond to antigens if re-exposed.

Answer 16

- Physical Physically block the pathogen from entering the body. For example, skin, mucus and cilia. Cilia sweeps mucus containing pathogens along to respiratory tract to be coughed, sneezed or swallowed. - Chemical Make body surfaces inhospitable for pathogens. Lysozymes are enzymes that break down the cell walls of bacteria, and is found in tears, saliva and mucus. Acidic secretions such as toxic metabolites, are found in the ear canal, vagina and stomach and contain degradative enzymes like lysozyme. - Microbiological Microflora are microorganisms in our body that don't cause harm, found on mouth, skin and intestines. They compete with pathogens for space and nutrients, and produce antimicrobial chemicals, which prevent the growth of other organisms.

Answer 17

Process by which phagocytes (a type of WBC or leukocyte) engulf and destroy foregin or unwanted material. It occurs in 4 steps. 1. Phagocyte englufs foreign material, forming a phagosome 2. A lysosome fuses with the phagosome, forming a phagolysosome 3. The enzymes within the lysosome break down the foreign material. 4. Small waste fragments are expelled by exocytosis

Answer 18

Cells which are important in defence against virus-infected or cancerous cells. They release cytotoxic chemicals such as perforin, which can kill cells directly.

Answer 19

Accumulation of fluid, plasmid proteins and WBC at a site where tissue is damaged or infected. Characterised by redness, heat, swelling and loss of function in area. Steps of the inflammatory response: 1. Pathogen successfully makes it through the first line of defence, or tissues are damaged. 2. Injured cells release chemokines, which attract neutrophils and make mast cells release histamine, which dilates blood vessels, and allowing antimicrobial factors to pass into the affected area. Important: The increased temperature slows the growth and replication of pathogens in the inflamed area, as enzymes denature outside of their optimal temperature. Also, it enhances the activity of WBCs,

Answer 20

A set of more than 30 proteins that float around in blood, no cells. When a pathogen breaks through, the proteins rapidly bind to it, leading to a cascade of reactions on its surface. For example, it can punch holes in the cell membrane, promote inflammation, and opsonisation, meaning flagging the antigens for removal.

Answer 21

Phagocytes (ingesting unwanted material) - Neutrophils - Macrophages - Mast Cells Lymphocytes (Specialised for adaptive immune responses) - B cells - T cells

Answer 22

Neutrophils are the most abundant, able to quickly enter tissues and engulf pathogens in acute infections. Also release antimicrobial compounds like hydrogen peroxide, disrupting bacterial and fungal cell membranes. Macrophages live longer than other phagocytes, and thus assist in chronic infections. Play a role in activating the adaptive immune system, by acting as antigen-presenting cells. This allows T cells to recognise the antigens of the pathogens invading the body. Dendritic cells have a similar role to macrophages. All release cytokines, which attract other immune cells to the site and promote inflammation.

Answer 23

Antibody mediated immunity Cell mediated immunity

Answer 24

B cells are a type of WBC, produced in bone marrow. Once matured they are released into bloodstream, where they accumulate in the lymphoid tissues. When a B cell comes into contact with a specific antigen, it becomes activated. It begins to proliferate to form millions of clones. These daughter cells become either plasma cells or memory B cells. Plasma cells produce antibodies, which are proteins with specific shapes that bind to antigens.

Answer 25

Neutralisation - deactivating a pathogen or toxin by blocking its active site Precipiation - antibodies bind to soluble antigens to form insoluble antigens, which assists in phagocytosis Agglutination - antibodies bind to antigens on the surface of cells to form clumps of cells Activating complement system

Answer 26

Remain in lymph tissue and provide immunological memory. If an animal is re-exposed to the same antigen, memory cells recognise it and divide to produce plasma cells. Creates a faster and stronger immune response.

Answer 27

Involves T cells. Produced in bone marrow but mature in the thymus gland. Once matured, they are released into the blood until they come into contact with their specific antigen. It will then proliferate into one of four types.

Answer 28

Cytotoxic - 'Killer' Cells kill foreign, infected and abnormal cells, including our own body cells. To kill, they secrete or inject toxic chemcials into the target pathogen. Helper - Help promote the activites of other immune responses, but secreting cytokines. Suppressor - Deactivates immune system once antigen has been destroyed. Memory - Same as B cell, and if body is re-exposed, divides into cytotoxic and helper T Cells.

Answer 29

Active Occurs when immune system makes its own B cells, T cells and antibodies in response to an antigen. Natural active immunity is when you become immune after catching a disease, as the pathogen introduces the anitgen that triggers the adaptive immune system. Artifical active immunity involves vaccines, where a controlled dose of antigenic material is introduced to the body.

Answer 30

When antibodies are transferred to an unimmunised person, providing them with temporary protection. Natural passive immunity involves babies who become immune due to antibodies it receives from its mother through the placenta and breast milk. Artificial passive immunity is when your body is injected with another individual's antibodies.

Answer 31

Basal Resistance - The plant immediately fortifies itself against infection by becoming impenetrable, closing the stomata of the leaves. There is also callose deposition, which limits the spread of disease between cells by blocking off access to other cells. Also releases various chemicals, such as sopoins which destroy the pathogen membrane. Phytoalexins attack the pathogens by impairing their growth.

Answer 32

- Physical Exterior barrier is a waxy cuticle made up of lignin and cutin. Many plants are also covered in bark, an exeternal layer of dead cells. Plant's cell wall physically prevents the pathogens to penetrate the cell. Thorns, hairs and trichomes and drooping leaves deters contact with insects that may carry disease. Leaf shape prevents water from pooling, and giving rise to waterborne diseases. - Chemical Plants possess antimicrobial chemicals, such as antibiotics. They also have toxins that target insects that feed on plants.

Answer 33

Concept that dictates that a plant will only succeed in resisting a pathogen if it contains a specific resistance gene against the pathogen. Simiarly, the pathogen must contain a specific avirulence gene, or in other words, not contain the virulence gene that makes it pathogenic. Only through this resistance gene can plants destroy the pathogen.

Answer 34

Activated in the plant following exposure to a pathogen, where the plant is able to mount a faster and quicker attack for subsequent re-exposures.

Answer 35

Limits the pathogen access to just the host plant, involvinf apoptosis by the host plant to restrict the pathogen to its infected site, ands save the rest of the plant.

Answer 36

Pathogen's ability to: - Survive Dictates how far the pathogen is able to travel, and opportunity to affect. - Growth How quickly and easily the pathogen can replicate - Persistence Allows them to replicate over a long period of time. The most persistent pathogens are those that can effectively evade the immune system. These factors affect how a pathogen is spread, whether through direct or indirect contact.

Answer 37

When a certain subtance accumulates in the body tissues of organisms in increasing amounts the higher trophic level, e.g. pesticides

Answer 38

Used to be used to prevent the spread of malaria, killing anopheles mosquitoes which act as vectors for the transmission of malaria. However, use of pesticides acts as a selection pressure on the targeted population, developing resistance to DDT, which is now no longer used for these reasons.

Answer 39

Drugs that help treat bacterial infections. They either kill the bacteria, or slow the growth so the immune system has a greater chance of removing them. For them to be effective, they can't damage theh host organism, so they specifically target biological pathways and molecules that are unique to prokaryotic bacteria, such as cell wall synthesis and nucleic acid synthesis. Penicllin was the first antibiotic ever discovered, which was purified directly from a type of fungus, and prevents bacterial cell walls from developing properly by inhibiting the synthesis of peptidoglycan. This prevents the bacterial cell wall from remaining osmotically balanced, resulting in the death of the cell as water moves in.

Answer 40

Vaccines contain the antigens of pathogens, which are either weakened or dead. By mimicking the disease, our body is able to develop immunity to the disease by producing memory cells.

Answer 41

Pros: They aren't specific, they can be used to kill a wide range of bacteria. Cons: For this reason, they often kill bacteria that aids our body. Antibiotic resistance, which arises through spontaneous mutation, and is often due to the failure to complete an antibiotic course, enabling resistant bacteria to survive and replicate.

Answer 42

Drugs that treat viral infections. They minimise the viral load by reducing the number of viruses produced in the host. The simple structure of viruses, as they are non cellular, can make it difficult to specifically target it with medicine.

Answer 43

1. Preventing viruses entering host cells by binding to receptors, blocking viruses from entering the cell. 2. Inhibiting enzymes which catalyse the reproduction of the viral genome. 3. Blocking transcription and translation of viral proteins, which need the host cell's ribosomes to replicate. 4. Preventing the virus from leaving the cell. 5. Grabbing the virus while outside the cell by targeting capsid proteins.

Answer 44

Pros: Allow for treatment of viral infections Cons: Antivirals are difficult to develop, thus taking time to develop. Some conditions also have so many viral strains that it is impossible to create a corresponding antiviral, such as the common cold, which is created by over 200 viruses.

Answer 45

Acyclovir is an antiviral that treats against herpes. It blocks the production of Herpes' DNA polymerase, so it cannot replicate. HIV is a type of RNA virus and retrovirus, meaning it uses reverse transcriptase to produce DNA from RNA. It also relies on integrase to integrate the retroviral DNA into the host chromosome, which is permanent.

Module 7: Infectious Diseases Flashcards

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