Disease and the immune system Module 4

Question 1

What’s a pathogen and 4 types?

Answer 1

An organism which causes disease, fungi, bacteria, virus and protoctista

Question 2

What’s a communicable disease?

Answer 2

A disease that can spread between organisms

Question 3

Tuberculosis affects? and is caused by?

Answer 3

Animals (mainly human and cattle), bacterium

Question 4

Bacterial meningitis affects? and is caused by?

Answer 4

Humans, bacterium

Question 5

Ring Rot affects? and is caused by?

Answer 5

Potatoes, tomatoes, caused by bacterium

Question 6

HIV/AIDS affects? and is caused by?

Answer 6

Humans, virus

Question 7

Influenza affects? and is caused by?

Answer 7

All animals, virus

Question 8

Tobacco mosaic virus affects? and is caused by?

Answer 8

Plants, virus

Question 9

Black sigatoka affects? and is caused by?

Answer 9

Banna plants, fungus

Question 10

Ringworm affects? and is caused by?

Answer 10

Cattle, fungus

Question 11

Athlete’s foot affects? and is caused by?`

Answer 11

Humans, fungus

Question 12

Potato and tomato late blight affects? and is caused by?

Answer 12

Potatoes and tomatoes, protoctisa

Question 13

Malaria affects? and is caused by?

Answer 13

All animals, protoctisa

Question 14

What’s direct transmission and 2 examples of it?

Answer 14

When a disease is directly transmitted from one organism to another
eg sexual intercourse passing on HIV and Athelte’s foot can be spread via touch

Question 15

What’s indirect transmission and 2 examples of it?

Answer 15

When a disease is transmitted from one organism to another via an intermediate

Eg. Potato/tomato late blight is spread when spores are carried between plant via air and then water

Malria is spread between humans via mosquitos

Question 16

3 factors which affect the transmission of disease?

Answer 16

Overcrowding
Climate
Social factors

Question 17

How does the skin prevent infection?

Answer 17

Acts as a physical barrier, blocking pathogens from entering the body
Acts as a chemical barrier, by producing chemicals that are antimicrobial and can lower pH, inhibiting the growth of pathogens

Question 18

How do mucous membranes prevent infection?

Answer 18

These protect body openings that are exposed to the environment, eg. nostrils mouth
Secrete mucus, that traps pathogens, and contains antimicrobial enzymes

Question 19

How does blood clotting prevent infection?

Answer 19

Mesh of protein caused by platelets, which plugs wounds to prevent pathogen entry, and blood loss

Question 20

How does inflammation prevent infection?

Answer 20

Triggered by tissue damage, which releases molecules which increase the permeability of the blood vessels causing them to leak fluid into the surrounding area. This causes swelling, and helps to isolate any pathogens which may have entered the damaged tissue
Vasodilation occurs, which increases blood flow to the affected area and brings white blood cells to the affected area and makes it hotter which fights the pathogens

Question 21

How do expulsive relfexes prevent infection?

Answer 21

Sneeze occurs when the mucous membranes in the nostrils are irritated by things such as dust and dirt
Coughing occurs when there’s irritation in the respiratory tract
Both expel foreign objects from the body, including pathogens from the body

Question 22

Describe the Physical defences plants have against pathogens?

Answer 22

Waxy cuticle prevents water entering, and staying on there which pathogens could grow in

Plant cells are surrounded by cell walls, which act as protection

Produce a polysaccharide called callose, which gets deposited between plant cell walls and the plasma membrane. It is deposited in times of pathogen invasion, and prevents pathogens entering cells, and can block plasmodesmate, preventing spreading

Question 23

What chemical defences do plants have?

Answer 23

Produce antimicrobial chemicals, which kill pathogens or inhibit their growth

Produce chemicals which are toxic to insects, reducing insect feeding, and chance of infection via an insect vector

Question 24

What’s an antigen?

Answer 24

Proteins or polysaccharides found on the surface of cells

Question 25

What happens when a pathogen invades the body as it’s got a foreign antibody?

Answer 25

Antibody is recognised as foreign, causing an immune response which has non specific and specific stages

Question 26

What are the 4 stages in the immune response?

Answer 26

Phagocytes engulf pathogens
Phagocytes activate T lymphocytes
T lymphocytes Activate B lymphocytes which divide into plasma cells
Plasma cells make more antibodies to a specific antigen

Question 27

Describe the first step of the immune response, phagocytes englufing pathogens?

Answer 27

A phagocyte recognises the antigens on a pathogen

The cytoplasm of the phagocyte moves round the pathogen engulfing it

The pathogen is now contained in a phagosome in the cytoplasm of the phagocyte

A lysosome fuses with the phagosome, enzymes digest the pathogen

The phagocyte then presents the pathogens antigens. It sticks the antigens on it’s surface to activate other immune system cells

This is a antigen-presenting cell (APC’s)

Question 28

What are nuetrophils?

Answer 28

Type of phagocyte, they are the first white blood cell to respond to a pathogen inside the body, and are attracted to cytokines released at the wound

Question 29

Describe the second step in the immune response, phagoyctes activate T lymphocytes?

Answer 29

A T lymphocyte is another type of white blood cell
Their surface is covered with receptors
The receptors bind to antigens, presented by APC’s
Each T lymphocyte has a different receptor on it’s surface
When the receptor on the surface of a T lymphocyte meets a complementary antigen, it binds to it - so each T lymphocyte will bind to a different anitgen
This activates the T lymphocytes - known as clonal selection
It then undergoes clonal expansion - divides to produce clones of itself

Question 30

What do T helper cells do?

Answer 30

Release substances to activate B lymphocytes and T killer cells

Question 31

What do T killer cells do?

Answer 31

Attach to and kill cells that are infected with a virus

Question 32

What do T regulatory cells do?

Answer 32

Suppress the immune system from other white blood cells

So the hosts own cells aren’t damaged

Question 33

Describe the 3rd step in the immune response of T lymphocytes activating B lymphocytes which divide into plasma cells?

Answer 33

B lymphocytes are another type of white blood cell, and are covered with proteins called anitbodies

Antibodies bind to complementary antigens to form an antigen-anitbody complex

Each B lymphocyte has a different shaped antibody on it’s surface

This together with other substances from T helper cells, activates the B lymphocyte, causing clonal selection

The activated B lymphocyte then divides by mitosis into plasma cells and memory cells = clonal expansion

Question 34

Describe the 4th step in the immune response of plasma cells making more antibodies to a specific antigen?

Answer 34

Plasma cells are clones of the B lymphocyte

They secrete lots of the antibody, specific to the antigen into the blood

These antibodies will bind to the antigens on the surface of the pathogen, to form lots of antigen-antibody complexes

Question 35

Describe the structure of an antibody?

Answer 35

Y shaped

Variable regions at the top, the variable region is complementary to a particular antigen, therefore the region will vary in different antibodies

Hinge region at the bend allows flexibility when the antibody binds to the antigen

The constant regions at the bottom, allow binding to receptors on immune system cells

Disulphide bonds hold the poly peptide chains of the protein together (imagine the Y has been split horizontally down the centre)

Question 36

3 ways antibodies help to clear an infection?

Answer 36

agglunitating pathogens- each antibody has 2 binding sites, so an antigen can bind to 2 pathogens at the same time, the pathogens become clumped together. Phagocytes then bind to the antibodies and and phagocytose a lot pathogens at once

Neutralising toxins - Antibodies called anti-toxins can bind to the toxins produced by pathogens. Preventing the toxins from harming body cells

Prevent the pathogen binding to human cells - when antibodies bind to the antigens on pathogens, they may block the cell surface receptors that the pathogen needs to bind to the hosts cells. Meaning the pathogen can no longer infect

Question 37

What is the primary response?

Answer 37

When a pathogen enters the body for the first time, and it’s antigens on it’s surface activate the immune system

Question 38

Why is the primary response slow and what does this mean?

Answer 38

There aren’t many B lymphocytes that can make the antibody needed to bind to it, eventually there will be enough but during that time the person will show symptoms of the disease

Question 39

What occurs in the primary response that makes the secondary response much faster?

Answer 39

After being exposed to an antigen, both T and B lymphocytes produce memory cells, which will remain in the body for a long time. So the person is now immune

Question 40

What occurs in the secondary response and why is it so fast?

Answer 40

When the same pathogen enters the body again

Clonal selection is much faster, memory B lymphocytes are activated, and divide into plasma cells that produce the right antibody for the pathogens antigen

Memory T lymphocytes are activated, and divide into the correct type of T lymphocytes to kill the cell carrying the antigen

Normally gets rid of disease before showing symptoms

Question 41

How do you spot red blood cells on a smear?

Answer 41

No nucleus, and there is lots of them

Question 42

How do you spot neutrophils on a smear?

Answer 42

White blood cell, 3 interconnected blobs and cytoplasm is grainy

Question 43

How do you spot a lymphocyte on a smear?

Answer 43

Smaller than a neutrophil, and the whole cell is nearly taken up by the nucleus

Question 44

How do you spot a monocyte on a smear?

Answer 44

Type of phagocyte, and it has a kidney bean shaped nucleus, and doesn’t have a grainy cytoplasm

Question 45

What’s active immunity?

Answer 45

When your immune system makes it’s own antibodies after being stimulated by an antigen

Question 46

What’s Natural active immunity?

Answer 46

When you become immune after catching a disease

Question 47

What’s Artificial active immunity?

Answer 47

When you’ve become immune, after you’ve been given a vaccination

Question 48

What’s passive immunity?

Answer 48

When your given antibodies by a different organism

Question 49

What’s natural passive immunity?

Answer 49

When a baby becomes immune due to the antibodies it receives from it’s mother , through the placenta, and in breast milk

Question 50

What’s artificial passive immunity?

Answer 50

When you become immune, after being injected with antibodies from someone else

Question 51

Differences between active and passive immunity?

Answer 51

Active requires exposure to the antigen, passive does not

In active immunity it takes a while for protection to develop, in passive it’s immediate

In active immunity it’s long term, in passive it’s short term

In active memory cells are produced, but in passive they are not

Question 52

What’s an autoimmune disease?

Answer 52

When an organism’s immune system, can’t recognise self antigens on it’s own cells, so an immune response is launched on it’s own tissues

Question 53

What does a vaccination do?

Answer 53

Contains antigens, that causes your body to produce memory cells against a particular pathogen, without the pathogen causing disease. So become immune without experiencing any symptoms

Question 54

What’s herd immunity?

Answer 54

When the disease won’t spread as most of the population has been vaccinated

Question 55

Why does a new vaccine need to be made every for the influenza virus?

Answer 55

Because it changes every year so will have new antigens, that the old memory cells won’t recognise

Question 56

What do antibiotics do?

Answer 56

Treat bacterial infections, without damaging the human body cells

Question 57

What is antibiotic resistance and why is it a big problem?

Answer 57

When genetic mutations make a bacteria immune to an antibiotic, so it will live and reproduce more passing the allele on to the next generation

The more we use antibiotics, the more superbugs will be created

Question 58

Example of antibiotic resistant bacteria?

Answer 58

MRSA- causes serious wound infections, and is resistant to methicillin

Question 59

Why do we need to preserve animals plants and microorganisms in terms of medicine?

Answer 59

They can provide many cures

Question 60

2 new technologies coming to medicine?

Answer 60

Personalised medicine- doctors will prescribe a medicine tailored to your DNA

Synthetic biology- can make artificial proteins and cells