chapter 5 - immunity Flashcards
(54 cards)
1
Q
What is a pathogen ?
A
A microorganism that causes/spreads disease
2
Q
What are the two type of defence mechanism in the body ?
A
- non specific and specific
3
Q
What is non - specific immunity ?
A
- the response is immediate and the same for all pathogens
- e.g physical barriers and phagocytosis
4
Q
What is specific defence ?
A
- the response is slower and specific to each pathogen
- e.g cell mediated and humoral response
5
Q
What are the physical barriers that our body has ?
A
- skin, epithelial cells covered in mucus, hydrochloride acid in the stomach
- also blood clotting ( maybe )
6
Q
How does the skin act as a physical barrier ?
A
- blocks pathogens from entering the body and also produces sebum which is antimicrobial
- by lowering the pH so pathogens cannot grow
7
Q
How do epithelial cells with mucus act as a physical barrier ?
A
- mucus traps pathogens
- cilia transport them to stomach
8
Q
How does hydrochloric acid in the stomach act as a physical barrier ?
A
- it has a low Ph
- so enzymes for most pathogens will denature
- so the pathogen dies
9
Q
What are antigens ?
A
- unique molecules ( proteins )found on the surface of cells
- they can trigger an immune response
- found on the surface of prokaryotic cells, eukaryotic cells and viruses
10
Q
What are the two types of antigen ?
A
- self = found on our boy’s own cells
- non-self = on the surface of pathogens, not from our own body
11
Q
What does the immune system use antigens to detect ?
A
- pathogens
- abnormal ody cells
- toxins
- cells from other organisms of the same species
12
Q
Wha are the 3 types of white blood cells
A
- T lymphocytes, B lymphocytes and phagocytes
13
Q
How do T lymphocytes tell the difference between self antigens and non-self antigens
A
- all T cells each have receptors specific to each antigen
- during foetal development, all T cells that recognise self antigens are destroyed so only the ones that recognise non self antigens are left
- for this to work the foetus cannot be exposed to any pathogens
- the same process occurs in bone marrow after birth
14
Q
What is antigenic variability ?
A
- when the shape of an antigen changes
- because the pathogen has mutated over time
- so any previous immunity to that pathogen lost
15
Q
How does phagocytosis work ?
A
- the pathogen releases chemicals that attract the phagocyte
- when the antigens are recognised as non-self, the phagocyte will bind to the pathogen via receptors
- the phagocyte then engulfs the pathogen
- the pathogen is now in a vesicle called a phagosome
- a lysosomes with lysozymes fuses with the phagosome to form a phagolysosome
- the lysozymes hydrolyse the pathogen
- the phagocyte presents the antigens of the pathogen on its cell surface so is now an APC
- this activates other cells in the immune system
16
Q
Where do T lymphocytes develop and mature
A
- develop in the bone marrow
- mature in the thymus gland
- eventually will move to lymph nodes and spleen where the wait for unsuspecting pathogens
17
Q
Where do B lymphocytes develop and mature ?
A
- develop and mature in the bone marrow
- will eventually move to lymph nodes and spleen to wait for unsuspecting pathogens
18
Q
Which cells are involves in the cellular response ?
A
- T lymphocytes
19
Q
Which cells are involved in the humoural response ?
A
- B lymphocytes
20
Q
How does the cellular response work ?
A
- after engulfing the pathogen , phagocytes become antigen presenting cells (APCs)
- helper T cels with complementary receptors bind to the antigens on the phagocyte
- this stimulates the T cells to divide by mitosis into 4 types of cells
21
Q
What are the 4 types of cells that T cells divide into ?
A
- T helper cells that stimulate phagocytosis
- T cells that stimulate B cells to divide
- Memory cells that are ready to respond to the same pathogen
- Cytotoxic T cells that kill infected cells by releasing peforin which makes holes in the cell surface membrane
22
Q
Which cells are involves in the humoural response ?
A
- B lymphocytes
23
Q
How does the humoural response work ?
A
- B cells with a complementary antibody will bind to the antigens on a pathogen
- it will engulf the pathogen and become and antigen presenting cell
- T helper cells will bind to the B cell which stimulates it to divide via clonal expansion
- B cells will divide into plasma cells and memory cells
- plasma cells create antibodies which are complementary to the pathogen’s antigens
- memory cells circulate around the body fluid and can rapidly divide into plasma cells if infection by the same pathogen happens again
24
Q
Why do the specific immune responses have the names cellular and humoural ?
A
- T cells respond to antigens on body cells so cellular
- B cells produce antibodies found in the body fluids aka humours
25
What is the primary and secondary immune response ?
- primary = when the body is exposed to the pathogen for the first time
- secondary = when the body is exposed to the same pathogen as before
26
What happens during the primary immune response ?
- the production of antibodies is slow
- as there are very few B cells specific to the pathogen’s antigens
- and. It takes time for the B cells to divide into plasma cells to create the correct antibody
- so the person will experience symptoms of the disease
27
What happens during the secondary immune response ?
- the production of antibodies is much quicker
- because memory cells recognise the antigens quickly and quickly divide into plasma cells
- and the plasma cells quickly produces large amounts of antibodies
- so the individual doesn’t experience any symptoms
28
What is the structure of antibodies ?
- y shaped glycoproteins
- 4 polypeptide chains: 2 heavy chains, 2 light chains
- polypeptide chains are held together by disulphide bridges
- constant region
- variable region
- hinge region
29
What is the difference between the constant region and the variable region of antibodies ?
- constant region = the same for all antibodies receptors on cells
- variable region = different to each antibody, the shape is complementary to a specific antigen, binds to antigens
30
What is the name for when an antibody binds to and antigen ?
- antigen-antibody complex
31
What are the ways that antibodies can destroy pathogens?
- agglutination
- neutralisation of toxins
- preventing pathogens from binding
32
Describe agglutination of pathogens by antibodies
- clumping pathogens together to enable easier phagocytosis
- because antibodies act as agglutinins
33
Describe how antibodies neutralise toxins
- when antibodies bind to toxins to inactivate them
- the bindings neutralises the toxins so no damage can be done
34
Describe when antibodies prevent pathogens from binding
- when antibodies bind to pathogens to stop them from infecting body cells
- because the antigens they would use to bind to host cells are blocked by the antibodies
35
What are monoclonal antibodies ?
- antibodies produced from a single lone of plasma cells
36
What are the uses of monoclonal antibodies ?
- diagnosing disease = mca bind to specific cell types to identify infected cells
- treating disease = mca bind to specific cells bringing therapeutic drug to them
- pregnancy testing = mca bind to the pregnancy hormone in pregnancy test kits, usually have a dye attached to it
- detecting cancers = mca can bind to specific antigens to identify specific cancers
- all of these involve mca being specific to an antigen
37
Describe how monoclonal antibodies are used in director treatment of cancer
- mca complementary to antigens on cancer cells are given to patient
- the mca bind to the cancer cells
- this prevent chemicals that cause uncontrolled cell division from binding to cancer cells
- and as mca are specific to cancer cells they don’t damage any other cells
38
Describe indirect monoclonal antibody therapy for cancer
- mca complementary to cancer cells are given to patient
- the mca have drugs attached
- so cancer drugs are directly delivered to cancer cells and can kill them
- this reduces the harmful side effects that chemotherapy can cause
39
Describe the ELISA test
- add a sample containing the target antigen to a beaker
- wash to remove any unbound test sample
- add the antibody that is specific to the target antigen, they will bind together
- wash the beaker to remove any unbound antibodies
- add a second antibody that is complementary t the first antibody and will bind to it , the second antibody antibody has an enzyme attached to it
- wash the beaker to remove any unbound second antibody
- add a solution contains a substrate to the beaker, the solution is colourless but when the enzyme acts on the substrate a colour change is present
- if there is a colour change , the antigen is present
- the intensity of the colour shows the quantity of the antigen present
40
What is passive immunity ?
- when antibodies come from outside the body, this gives immediate immunity but its short term as no memory cells are produced
- natural examples = antibodies from mother to baby through breastmilk
- artificial example = antibodies injected into an individual
41
What is active immunity ?
When the immune system develops its own antibodies
- this gives long term protection although it takes a while for the person to become immune to the disease
- natural example = being exposed to a pathogen and making your own antibodies
- artificial example = taking a vaccine and the body making its own antibodies as a response
42
What are vaccines ?
- a dead or weakened form of a pathogen which is injected into the bloodstream
- they may contain just the antigen proteins, the whole pathogen or lots of different antigens for pathogens that have antigenic variation
43
What do vaccines do to the body ?
- they cause a primary immune response and produce memory b cells, so if the person is comes across the pathogen again, their body will have a very quick response to it
44
What is herd immunity ?
- when most of the population has been vaccinated
- so an individual that cannot be vaccinated will not come in contact with that pathogen as no one around them can pass it to them because they are immune
45
What is antigenic variation ?
- when the genes in a pathogen mutate causing the shape of their antigens to change
- meaning memory cells that come from a pathogen will not work on the new mutated strain
- and the person has to go through the primary immune response again
46
What challenges do antigenic variation create ?
- it make it difficult to develop a vaccine
- as vaccine may contain tha antigen of the pathogen before it was mutated
- and so the vaccination will not work on the mutated pathogen
47
What is HIV and what does it do ?
- a deadly virus
- that works by destroying t helper cells
- meaning no t helper cells to stimulate phagocytosis or b cells or to act as cytotoxic cells
- so they practically have no immunity
- it doesn’t directly kill the patient
48
What is AIDS ?
- when a persons with HIV has a very low t helper cell count
- meaning their immune system has weakened again
- so they can die from opportunistic infections ( ones that aren’t actually meant to kill you )
- because they have no immune defence
49
What is the structure of HIV ?
- it has a core of RNA, integase and reverse transcriptase , this is surrounded by a capsid
- an outer layer called the liquid envelope surrounds all of this
- the liquid envelope has attachment protein embedded into it
50
How does HIV pass from person to person
- by the exchange of bodily fluids
51
Describe how HIV causes infection in the body ?
- once in the bloodstream, HIV will uses its attachment proteins to attach to t helper cells
- this releases the capsid into the cell
- the capsid breaks apart leaving the rna ans the enzymes
- reverser transcriptase is used to convert the rna into dna
- intergase is used to intergrate the dna of the virus in the t helper cell’s dna so no the T cell will produce the viral proteins
- viral mRNA in also formed
- these then come to the edge of the cell and rip the t helper cells membrane to act as their own membrane
- this destroys the T cells and now there are more HIV molecules to infect other cells
52
How do antibiotics work ?
- they interfere with the production of bacteria cell walls or ribosomes of the bacteria
- this prevents enzyme and dna replication
53
Why do antibiotics not work on viruses or our won body cells?
- viruses do not have ribosomes to cell walls
- human body cells do not have cell walls and the ribosomes in our cells are a lot bigger than the ribosomes in bacteria
54
What are some ethical objections to vaccines a monoclonal antibodies ?
- some believe its unethical to use animals to create monoclonal antibodies
