CHATPER 5: IMMUNITY Flashcards
1
Q
what are diseases
A
- a disease is a condition that interferes with the normal functioning of an organism; usually with specific symptoms.
- can be infectious or noninfectious
2
Q
what are pathogens
A
- most microbes are harmless (non-pathogenic) - only about 1% can cause disease
- most pathogens are species-specific and tissue-specific
- pathogens are agents that cause diseases in their hosts
- can be extracellular → pathogen in the body but not in the cells yet (innate response)
- can be intracellular → pathogens in the cells (adaptive response)
3
Q
cellular vs non-cellular pathogens
A
- cellular: made of cells and can reproduce independently
- bacteria, parasites (worms), fungi, protozoa
- non-cellular: not made of cells and cannot reproduce independently → need the cells of the host to reproduce (hijack)
- viruses, prions
4
Q
what are antigens
A
antigens are substances that cause/stimulate an immune response
5
Q
self vs non-self antigens
A
- Self-antigens: antigens on cells that are recognised by self-receptors as being part of the same body
- tolerated by the immune system
- Non-self antigens: antigens that do not belong to the body’s own cells
- attacked by immune system
6
Q
distinguishing self from non-self
A
- plasma membrane of this immune cells carries:
- self-antigens that identify this immune cell as ‘self’
- cell surface receptors for self-antigens so that this cell can identify and not attack other body cells
- cell surface receptors for foreign antigens so that the immune cell can identify foreign material and signal other immune cells to eliminate it
7
Q
1.
MHC I vs MHC II markers
A
- both are located on the outside of cells, anchored to the cell membrane and are specific to individuals.
- MHC-I markers are present on all nucleated cells
(not red blood cells) of the body and present the peptide fragments from inside the cells- they signify if a cell is ‘self’ or ‘non-self’
- if the correct MHC-I marker is not detected, immune cells will cause it to undergo apoptosis.
- MHC-II markers are only found on specific cells in the immune system such as macrophages, dendritic cells, and B lymphocytes
- all involved in antigen presentation → present the antigens from outside the cell.
8
Q
bacteria
A
- prokaryotic microbes and their genetic material is double-stranded DNA
- If bacteria multiply in areas they are not normally found they can cause disease
- Intracellular and extracellular
- Symptoms of bacterial infection are often caused by the toxins the bacterium produces
- Bacteria can cause disease in humans if:
1. They can enter a person who can act as a host.
2. They have the capacity to reproduce within the host.
3. They act adversely on tissues in their host (exotoxins, adverse enzyme production)
9
Q
protozoans
A
- single-celled, eukaryotes
- infection by ingestion of cysts by sexual transmission or insect vectors
- able to multiply in humans, enabling them to survive in a human host while causing disease.
- symptoms: blood, gut and lymphatic system
- Eg. Malaria – bites of mosquitos
- Ingesting contaminated food
10
Q
fungi
A
- eukaryotes
- grow from the tips of filaments (hyphae) that make up the bodies of the organisms (mycelia)
- opportunistic pathogens - immune system is weak
- usually external or skin infections
- Eg. Candida albicans - Thrush (oral
candidiasis) - Athletes food – tinea (Trichophyton spp.)
- Eg. Candida albicans - Thrush (oral
11
Q
parasites (worms)
A
- (not microbes) can be seen with the naked eye
- transmitted via soil contaminated with human faeces that contains eggs of those worms
- Eg. hookworm, roundworms, whipworms
12
Q
viruses
A
- comprise of nucleic acid (DNA or RNA) surrounded by one or more coats of protein.
- replicate only within host cell
- viruses cause disease by killing body cells
- to make more viruses, a virus takes over a host cell and uses it as a ‘factory’
- release of viral particles from an infected cell may be by budding or by cell lysis
- infected host cell ‘explodes’ as its plasma membrane disintegrates and viral particles are released into the extracellular fluid from where they can infect other cells.
13
Q
what is the immune system
A
the body system that helps resist infections and disease through specialised cells
14
Q
3 levels of the immune system
A
INNATE - present from birth, no immunological memory, not acquired
- the first line of defence
- innate
- non-specific
- skin, stomach acid, etc.
- the second line of defence (hasn’t infected cells yet)
- innate
- non-specific
- macrophages, inflammation, complement proteins
- the non-specific cellular and molecular responses to pathogens that have breached the first line of defence and have entered the body.
- The innate immune response is nonadaptable, and does not change during an individual’s lifetime.
ADAPTIVE - more targeted to a specific pathogen
- third line of defence
- acquired (learns and has memory)
- specific
- B cells, T cells, antibodies
- takes time to develop
15
Q
first line of defence
A
- physical barriers act to prevent the entry of pathogens
- chemical barriers act to inhibit the growth or development of pathogens and/or act to destroy pathogens
- microbiota barriers act to prevent the growth or colonisation of microorganisms that may be pathogenic.
