DISEASE AND THE IMMUNE SYSTEM

Question 1

what is a disease

Answer 1

a condition that impairs the normal functioning of an organism

Question 2

pathogen

Answer 2

organism that causes disease

Question 3

types of disease

Answer 3

bacteria
virus
fungi
protoctista

Question 4

communicable disease

Answer 4

a disease that can spread between organisms

Question 5

bacterium disease

Answer 5

bacterial meningitis- humans
tuberculosis- animals and humans
ring rot- potatoes and tomatoes

Question 6

virus disease

Answer 6

HIV/AIDs- humans
influenza- animals and humans
tobacco mosaic virus- plants

Question 7

fungus disease

Answer 7

athlete’s foot- humans
ringworm- cattle
black sigatoka- banana plants

Question 8

protoctist disease

Answer 8

malaria- humans and animals

potato/tomato late blight- potatoes and tomatoes

Question 9

direct transmission

Answer 9

directly from one organism to another
droplet infection (coughing or sneezing)
sexual intercourse
touch
HIV
athlete’s foot

Question 10

indirect transmission

Answer 10

transmitted via an intermediate (air, water, food, vector)
potato/tomato late blight- spores carries between plants in air then in water
malaria- vector

Question 11

overcrowding

Answer 11

TB- droplet infection
indirectly also as it remains in the air for long periods of time
risk increased when lots of people in the same area

Question 12

climate

Answer 12

potato/tomato late blight common during wet summers because spores need water to spread
malaria common in tropical countries which are humid and hot

Question 13

social factors

Answer 13

limited access to good healthcare- people less likely to be diagnosed and treated
no healthcare education to inform how disease is transmitted and how to be avoided

Question 14

skin as a barrier

Answer 14

blocks entrance of pathogens

chemical barrier by producing chemicals that are antimicrobial and lower the pH which inhibits the growth of pathogens

Question 15

mucous membranes as barriers

Answer 15

protect body openings which are exposed to the environment

some secrete mucus which traps pathogens and contains antimicrobial enzymes

Question 16

blood clotting as a barrier

Answer 16

blood clot= mesh of protein fibres which plug wounds to prevent pathogen entry and blood loss
formed by a series of chemical reactions that take place when platelets are exposed to damaged blood vessels

Question 17

inflammation as a barrier

Answer 17

swelling, pain, heat, redness
triggered by tissue damage- releases molecules which increase the permeability of the blood vessels so they release fluid into the surrounding area
isolated surrounding pathogens, the molecules also cause vasodilation which increase blood flow- white blood cells reach the surface

Question 18

wound repair as a barrier

Answer 18

skin can reform a barrier
surface repaired by the outer layer of the skin cells dividing and migrating to the edges
tissue below contracts and brings the edges of the wound together
repaired using collagen fibres and produces a scar

Question 19

repulsive reflexes as a barrier

Answer 19

coughing and sneezing
a sneeze happens when the mucous membranes in nostrils are irritated by dust or dirt
cough stems from irritation of the respiratory tract
automatic

Question 20

2 plants physical barriers

Answer 20

wait cuticle- prevents water collecting on the leaf

cell walls

Question 21

callose

Answer 21

production of the polysaccharide callose which gets deposited between plant cell walls and plasma membranes during times of stress making it harder for pathogens to enter cells
callose deposition at the plasmodesmata may limit the spread of viruses between cells

Question 22

antimicrobial chemicals that kill pathogens and inhibit their growth

Answer 22

saponins- destroy fungi cell membranes

phytoalexins- inhibit the growth of fungi

Question 23

4 stages of the immune response

Answer 23

phagocytosis
activations of T lymphocytes
activation of B lymphocytes
plasma cells made

Question 24

phagocytosis

Answer 24

phagocyte recognises antigens on pathogen
cytoplasm of phagocyte moves around the pathogen and engulfs it
osponins attach to the foreign antigens and aid phagocytosis
pathogen now in phagosome
lysosomes fuses with phagosome which breaks down the pathogen
phagocyte presents the antigens of the pathogen and sticks them on the surface to trigger immune system cells and by doing this- acts as a antigen presenting cell (APC)

Question 25

activation of T lymphocytes

Answer 25

type of white blood cell with a surface covered in receptors receptors binds to antigen presenting cells (APC) when receptors of T lymphocyte meets a complementary antigen it binds to it so each lymphocyte binds to a different antigen activates the T lymphocyte- clonal selection lymphocyte undergoes clonal expansion where it divides to produce clones of itself

Question 26

types of T lymphocytes

Answer 26

T helper cells- releases interleukins to activate B lymphocytes and T killer cells T killer cells- attach and kill cells affected with a virus T regulatory cells- suppresses the immune response from other white blood cells which helps to stop the immune system cells from mistakenly attacking the host’s body cells T memory cells

Question 27

activation of B lymphocytes

Answer 27

B lymphocytes are covered in antibodies which bind to form an antigen-antibody complex when antibody on the surface of a B lymphocyte meets a complementary shaped antigen it binds T helper cells release interleukins which activate a B lymphocyte- clonal selection activated B lymphocyte divides by mitosis into plasma cells and memory cells- clonal expansion cell signalling important here

Question 28

plasma cells made

Answer 28

clones of B lymphocyte secrete loads of the antibody which are specific to the antigen into the blood these antibodies bind to antigens on the surface of the pathogen to form lots of antigen-antibody complexes

Question 29

what does an antigen-antibody consist of

Answer 29

``` variable region constant region disulphide bridge antigen attached light chain heavy chain ```

Question 30

3 ways of clearing infection

Answer 30

agglutinating proteins- each antibody has 2 binding sites so it can bind to 2 pathogens at the same time and they become clumped together. phagocytes then bind to the antibodies and phagocytise a lot of the pathogens all at once neutralising toxins- antitoxins bind to toxins produced by pathogens which prevents the toxins from affecting human cells. the toxins are phagocytosed prevent pathogen binding to human cells- antibodies binding to the antigens on pathogens block the cell surface receptor that the pathogens need to bind to the host cells

Question 31

primary response

Answer 31

slow with no B lymphocytes eventually enough antibodies will be made and the symptoms will show both T and B lymphocytes produce memory cells memory T lymphocytes and B lymphocytes produce memory cells memory T lymphocytes remember the specific antigen and will recognise it memory B lymphocytes record the specific antibodies needed person now immune

Question 32

secondary response

Answer 32

quicker stronger response clonal selection will happen faster memory B lymphocytes are activated and divide into plasma cell that produces the right antibody memory T lymphocytes are activated and divide into the correct type of T lymphocyte to kill the cell carrying the antigen gets rid of pathogen before you show any symptoms

Question 33

types of blood cells

Answer 33

monocyte- biggest white blood cell, kidney bean shaped nucleus and non grainy cytoplasm lymphocyte- nucleus takes up most of the cell neutrophil- nucleus looks like three interconnected blobs (multilobed) and the cytoplasm is grainy

Question 34

active immunity

Answer 34

``` immune system makes its own antibodies after being stimulated by an antigen exposure to antigen takes a while for protection protection= long term memory cells produced ```

Question 35

passive immunity

Answer 35

being given antibodies made by a different organism protection is immediate protection= short term no memory cells produced

Question 36

natural immunity

Answer 36

active- become immune after catching a disease | passive- immune after being given antibodies

Question 37

artificial immunity

Answer 37

active- immune after vaccination | passive- immune after being injected with antibodies from someone else

Question 38

autoimmune disease

Answer 38

immune system doesn’t recognise its self antigens and treats them as foreign antigens and launches an immune response against the organisms tissues chronic and treated but not cured

Question 39

examples of autoimmune disease

Answer 39

lupus- immune system attacks connective tissues causing inflammation, can affect the skin, joints, heart and the lungs rheumatoid arthritis- immune system attacks the joints and causes pain and inflammation

Question 40

vaccines

Answer 40

the administration of antigens into the body contains antigens that cause your body to produce memory cells against a particular pathogen contain antigens- free or attached to a dead or weaken pathogen booster vaccines MMR meningitis C vaccine

Question 41

herd immunity

Answer 41

most people in a community are vaccinated | prevents epidemics

Question 42

immunation

Answer 42

the process where immunity is developed | vaccination causes immunity

Question 43

antibiotics

Answer 43

chemicals that kill or inhibit the growth of bacteria target bacterial cells without damaging human cells penicillin- first antibiotic to be isolated (Alexander Flemming) can cause side effects

Question 44

antibiotic resistance

Answer 44

genetic mutations cause some bacteria to be naturally resistant can survive and reproduce- carrying on the allele for antibiotic resistance to the offspring (natural selection) MRSA- causes serious wound infection- immune to meticulous

Question 45

overcoming antibiotic resistance

Answer 45

developing new antibiotics modifying old antibiotics reduce use of antibiotics take full course of antibiotics

Question 46

future of medicine

Answer 46

personalised- medicines tailored for person’s DNA synthetic- uses technology to design and make things like artificial proteins, cells and microorganisms. engineering bacteria