2.4 Immunology

Question 1

pathogen

Answer 1

a micro-organism that has the potential to cause disease

Question 2

ways that pathogens can cause disease

Answer 2

kill body cells
releasing toxins that damage cells

Question 3

what is an antigen made from

Answer 3

proteins

Question 4

antigen

Answer 4

a molecule (protein) which causes an immune response resulting in the prodcution of specific antibody

Question 5

self antigen

Answer 5

a molecule (protein) found in the cell surface membrane of your own body cells which allows immune system to recognise the cell as itself

Question 6

four types of pathogen

Answer 6

bacteria
viruses
fungi
protozoa

Question 7

non specific immune response

Answer 7

phagocytosis

Question 8

steps of phagocytosis

Answer 8

1. phagocyte engulfs pathogen
2. pathogen in vesicle (phagosome)
3. lysosome containg hydrolytic enzymes fuses with vesicle (phagolysosome)
4. pathogen hydrolysed and digested
   5.waste released and antigens presented on cell surface

Question 9

specific immune responses

Answer 9

• cell mediated response (producing T-lympocytes)
• humoral response (B lymphocytes)

Question 10

T lymphocytes

Answer 10

associated with cell mediated immmunity (immunity involving body cells)

Question 11

B lymphocytes

Answer 11

associated with humoral response and produce antibodies

Question 12

roles of T cells

Answer 12

stimulate cytotoxic T cells to divide
stimultae further phagocytosis
stimulate B cells to divide
develop into memory T cells to prevent future infection

Question 13

cytotoxic T cells

Answer 13

seek out antigens on suface of antigen presenting cells
they bind to the invaded cell and secrete toxic substance to kill cell

Question 14

antigen presenting cells (APC’s)

Answer 14

either phagocytes or cells that have been invaded
once phagocytosis has happened pathogens antigens are presented on cell membrane of phagocyte
T cells then respond to the cell which is presenting the antigens

Question 15

cell mediated immunity steps

Answer 15

1. pathogens invade body cells or are taken in by phagocytosis
2. APC’s present pathogens antigen on its own cell surface
3. T helper cells have receptors which fit to presented antigens this stimulates t cells to divide by mitosis
4. T cells either:
   - stimulate cytotoxic T cells
   - stimulate further phagocytosis
   - stimulate B cells to divide
   - develop into memory T cells to prevent future infection

Question 16

steps of humoral response

Answer 16

1. T helper cellls activate the complementary B cels
2. B cells divide by mitosis
3. makes memory cells for future infections
4. makes plasma cells which make antibodies
5. antibodies bind to antigen on pathogen to destroy them

Question 17

passive immunity

Answer 17

immunity from being given antibodies made by a different organism

Question 18

natural passive immunity

Answer 18

a baby becomes immmune to antibodies it recieves from mother through placenta and breast milk

Question 19

artifical passive immunity

Answer 19

when given antibodies from someone else eg blood donation

Question 20

active immunity

Answer 20

immunity you get from your own immune system making its own antibodies aftre being stimulated by an antigen

Question 21

natural active immunity

Answer 21

when you become immune after catching a disease

Question 22

artificial active immunity

Answer 22

when you become immune after being given a vaccination

Question 23

what is antigenetic variability

Answer 23

antigens can mutate and change shape
memory cells therefore cannot recognise the pathogen
antibodies no longer complementary to receptors and a secondary response cannot be initiated

Question 24

monoclonal antibodies

Answer 24

made from the same B cell
all the same
and all complemenary to the same antigen

Question 25

what is a vaccination

Answer 25

an injection of a dead or weakend pathogen which initiated an immune response and produces memory cells

Question 26

what does HIV do

Answer 26

attacks the bodies immune system.

Question 27

what is AIDS

Answer 27

a person is considered to have AIDS when the immune system is so weak it can no longer fight off diseases