2.2.1 Infectious Disease Flashcards
define non-infectious disease
- a disease that cannot be passed between people, caused by a problem in the bod or a lifestyle issue
- eg. cardiovascular diseases, cancer, genetic diseases
define infectious diseases
- diseases caused by an infectious agents called pathogens. This is anything that is able to infect a host and can be transmitted from one host to another
- eg. bacteria, fungi, parasites, prions, viruses
define bacteria
- able to survive in a wide range of environments, meaning they make us ill
- no set pattern for who can be infected and the severity
eg. to know: - coccus
- ros/bacillus
- spirochetes
- spirilla
define fungi
- spore producing structures
- e.g. athletes foot, ringworm
define parasites
3 types
- Protists: called protozoa in humans
- eg. malaria - Helminths: wormy creatures
- eg. tapeworm - ectoparasites: found on the outside of the body
- lice
define prions
- the smallest of all pathogenic molecules
- do not contain genetic material (eg. protein structures)
- triggers normal proteins in the brain to fold abnormally
- eg. mad cow disease
define virus
- non-living infective agent made of: protein, DNA, receptors
- very small
How do viruses work?
- take over the host cell
- make more of themselves
- spread to other cells
Describe adhesion factors and how it aids viral pathogens
- the ability to adhere to host cells and resist physical movement
- bacteria can resist physical removal by producing pili
Describe invasion factors and how it aids viral pathogens
- the ability of a pathogen to enter a host’s tissues, multiply and spread to other tissues
- pathogens may secrete enzymes such as collagenase to break down collagen
Describe capsules and how it aids viral pathogens
- capsules allow pathogens to resist host immune defense by preventing phagocytes from adhering to them
Describe toxins and how it aids viral pathogens
- pathogens can damage host tissues by either endotoxins or exotoxins
Describe lifestyle changes and how it aids viral pathogens
- viruses can move between different lifecycles
- lytic cycle
1. virus attaches itself to a specific host cell
2. the genetic material from the virus is injected into the cell
3. The virus uses proteins and enzymes in the host to make lots of copies of itself
4. The causes the cell to split open to release the new virus - lysogenic cycle
1. the virus attaches itself to a specific host cell
2. the genetic material from the virus is incorporated, this time, into the DNA of the cell
3. the host cell divides normally and, as it does so ,it replicates the viral genetic material. However, the virus remains dormant and no new viruses are made.
4. Eventually a trigger (chemical or environment change) causes the viral genetic material to leave the genome and enter the lytic pathway.
Describe the innate immune system in vertebrates
Physical barriers
- skin, hair, cilia
- mucus membranes
- chemical secretions
- digestive enzymes in mouth
- stomach acid
Internal defenses
- inflammatory response
- complement proteins
- phagocytic cells
- natural killer (NK) cells
Describe the inflammatory response and the role of the complement system
The inflammatory response (inflammation) occurs when tissues are injured. The damaged cells release chemicals including histamine and prostaglandins. These cause vasodilation and increase blood vessel permeability, allowing increased blood flow to the area and chemotaxis (a chemical signal to summon more white blood cells such as phagocytes and NK cells).
