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immunity Flashcards

1
Q

what is a lymphocyte

A

white blood cell involved in immune responses

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2
Q

what is self antigen

A

a molecule on the cell surface membrane of a body cell that does not usually trigger an immune response

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3
Q

what is immunity

A

the means by which the body protects itself from infection

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4
Q

what is a foreign antigen

A

a molecule on the cell surface membrane of a foreign cell that triggers an immune response

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5
Q

what is a pathogen

A

a disease causing microorganism

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6
Q

what is a non specific defence mechanism
give examples

A

response is immediate and the same for all pathogens
skin
phagocytosis

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7
Q

what is a specific defence mechanism
give examples

A

response is slower and specific
cell mediated response - t cells
humoral response - b cell

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8
Q

how is skin a non specific mechanism

A

has a flat outer layer of dead cells consisting of keratin protein which makes a tough barrier

keratin is a fibrous protein which has a;
repetitive primary structure sequence
errors have less impact on function
few tertiary bonds

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9
Q

how is cilia a non specific structure

A

they are in your nose and covered in mucus produced by goblet cells
cilia waft pathogens trapped in the mucus up the throat to be swallowed

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10
Q

how is stomach acid a non specific structure

A

kills pathogens by denaturing proteins in bacterial cell wall or outer layer of virus

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11
Q

how is lysosomes a non specific structure

A

in your tears
enzyme which digests the cell wall of bacteria

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12
Q

what is a phagocyte and what types can it be

A

phagocyte is a special type of leukocyte which can engulf pathogens
they travel via bloodstream but can migrate to other tissue

it can be a macrophages - patrols around the body and lasts a long time
or
neutrophil - lasts 7 days

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13
Q

what is histamine and what does it do

A

chemical which is released by damaged tissues (cuts)
this causes the blood vessel to dilate and helps to speed up arrival of phagocytes to the area

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14
Q

what is an antibody

A

protein synthesised by plasma cells with a specific tertiary structure that is complementary to an antigen so they can bind to form an antigen antibody complex

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14
Q

describe phagocytosis

A

1.cytokines produced by pathogen attract phagocyte towards pathogen
2.phagocytes attach themselves to the surface of the pathogen
3. phagocytes engulf the pathogen to form a vesicle called a phagosome
4.lysosomes containing hydrolytic enzymes fuse with phagosome
5.enzymes hydrolyses phagosome and digests it
6.soluble products from the hydrolysed pathogen are absorbed into the phagocyte
7. antigens are presented on the cell membrane
8. inflammation occurs because histamine in the area has puss made of dead and digested pathogens and phagocytes

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15
Q

where does a t lymphocyte mature
what does it do

A

thymus gland
it does cell mediated responses and does NOT secrete antibodies

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16
Q

where does a b lymphocyte mature
what does it do

A

bone marrow
humoral response does secrete antibodies

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17
Q

why does your body not fight its own cells

A

they have highly specific tertiary structure proteins which lymphocytes will recognise

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18
Q

what are the two types of leukocyte

A

phagocyte and lymphocyte

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19
Q

what are the two types of lymphocyte

A

T and B

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20
Q

what does a phagocyte do

A

phagocytosis

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21
Q

what does a B lymphocyte make

A

B memory cells and plasma cell

22
Q

what does a B memory cell do

A

remember antigens for next time

23
Q

what does a T memory cell do

A

remember antigens for next time

24
Q

what do T lymphocytes make

A

T suppressor cells
T helper cells
T memory cells
T cytotoxic cells

25
Q

what does a T suppressor cell do

A

stops an immune reaction

25
Q

what does a T helper cell do

A

produces cytokynes to attract other cells and activate phagocytosis and activate clonal selection and expansion

26
Q

what does a T cytotoxic cell do

A

kill infected host cells by perforating the membrane so osmosis can happen

27
Q

what is clonal selection and expansion

A

selection - looking for the right cells complementary to antigen
expansion - relevant cells divide by mitosis

28
Q

describe the steps of a humoral response

A

1.pathogens circulate the blood stream and phagocytosis occurs
2. pathogen antigens also circulate the blood stream
3. specific B lymphocytes engulf pathogenic antigens
4. foreign pathogen are displayed on surface of the B lymphocytes
5. activated T helper cells bind to presented foreign antigen
6. activated T helper cells activate one B lymphocyte to divide via mitosis
7.the clones differentiate to form plasma B cells and B memory cells
8. plasma cells produce antibodies
9. the antibodies bind with antigens on invading pathogens
10. memory B cells remain for next time

29
Q

what is agglutination

A

binding antigens together so that phagocytosis can happen quicker ( so they can be engulfed easier)

30
Q

what is opsonisation

A

antibodies binds to antigens and receptor on the surface of pathogen

31
Q

describe the structure of an antigen

A

Y shaped protein secreted by plasma b cell
made of 4 polypeptide chains - 2 heavy , 2 light
variable region is specific to antibody

32
Q

describe how a monoclonal antibody test works

A

antigen is attached to the well of a dish
sample of blood is added ( if antibodies are present they will bind )
wash out the well
add a second antibody and enzyme which binds to specific antibody
wash out well
add a solution which will make the enzyme a colour to show if antibodies are present

33
Q

how can monoclonal antibodies be used for cancer treatment

A

bind to cancer and block chemical signals which stimulate uncontrollable growth
radioactive substances can be attached to antibodies and delivered to specific site

34
Q

What diseases can monoclonal antibodies be used to diagnose

A

influenza
hepatitis
chlamydia

35
Q

how can monoclonal antibodies be used for pregnancy tests

A

allows early detection at home
rely on placenta producing HCG which is detected in urine which moves along the stick until antigens catch on antibodies making a white line

36
Q

how are monoclonal antibodies made

A

mouse if exposed to something causing antibodies to be made by the B cells
these are collected and mixed with a tumor cell to make them reproduce rapidly
detergent is added to break down cell surface membrane so they fuse together making hybridoma cell
the cells are then separated and any clone producing the antibody are made on a large scale
antibodies are then extracted

37
Q

ethical issues with monoclonal antibodies

A

deliberately stimulating tumor cells in mice

38
Q

how does the quantity and speed of antibody production change after 2 injections

A

primary response produces less antibodies at a slower rate because clonal selection and expansion is slower
secondary response is quicker and produces more antibodies because memory cells speed up clonal selection

39
Q

what is a vaccine

A

injection of antigens or attenuated microorganisms that have been treated in some way to make them harmless
stimulates the formation of memory cells

40
Q

how does a vaccine stimulate the formation of memory cells

A

macrophage engulf the pathogens and present it as an antigen presenting cell
then the cell goes through clonal selection where T helper cells release cytokines to attract complementary B cells
the correct B cells then go through clonal expansion via mitosis and then differentiate to produce memory cells

41
Q

what is passive immunity

A

injection of antibodies
short lived
antibodies not replaced by the person’s immune system

42
Q

what is active immunity

A

injection of antigens
produces antibodies actively
long lasting immunity
antibodies replaced by person’s immune system

43
Q

what is herd immunity

A

when a sufficiently large proportion of the population has been vaccinated against a disease making it difficult for a pathogen to spread

44
Q

5 reasons why vaccines rarely eliminate disease

A

people with defective immune systems fail to induce immunity
people can develop the disease immediately after the vaccine and infect people
pathogens mutate frequently
different varieties of disease
objections to individuals

45
Q

ethics of injections

A

risk to the individual who is having the vaccine
should expensive vaccine programs be carried out if disease is almost eradicated
is it fair to test new vaccines with unknown health risks only in a country where the target disease is common
animals involvement in vaccine development
should they be compulsory

46
Q

describe how HIV replicates

A

1.HIV is in the blood
2.attachment proteins bind to CD4 on T helper cell
3. capsid fuses with cell membrane RNA and reverse transcriptase enter
4. DNA made from RNA using reverse transcriptase
5. DNA moves into nucleus via pores
6. virus DNA transcribed to MRNA
7. MRNA diffuses out of the nucleus
8. protein synthesis occurs to make HIV proteins
9. HIV particles break off
exocytosis releases it into the blood

47
Q

why are people with HIV at greater risk from infectious diseases

A

it damages their T helper cells which means the patient is unable to produce cytokines , activate phagocytosis and clonal selection/ expansion

48
Q

explain why AIDS leads to death

A

patients are more at risk from other diseases especially influenza , cold and TB
they don’t have enough T helper cells so the pathogens damage the cells , tissues and organs and release toxins

49
Q

how is HIV treated and controlled

A

no cure
meds can slow the spread around the body by stopping the pathogen replicating so quickly

50
Q

how is HIV transmitted

A

unprotected sex
sharing needles between intravenous drug users
infected mothers across the placenta
blood transfusions

51
Q

why are antibiotics ineffective against viruses

A

they inhibit enzymes making mirin in the cell walls - viruses don’t have cell walls

they inhibit DNA replication- viruses don’t have DNA

52
Q
A

biology (18 decks)

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