3.2.4 Cell Recognition + The Immune System

Question 1

What are pathogens

Answer 1

Micro-organisms that cause disease

Question 2

What are the 2 types of pathogens and how do they cause disease

Answer 2

Virus - invade cells, take over + burst them (kill body cells)
Bacteria - release toxins that make you ill

Question 3

Why do many pathogens not harm us

Answer 3

As were resistant to them not having the needed conditions

Question 4

5 examples of defences we have for pathogens that do harm us

Answer 4

Tears
Ear wax
Skin
Mucus
Sweat
Cilia
Anus
Urine

Question 5

What antibacterial enzymes do tears contain

Answer 5

Lysozymes

Question 6

How do earwax and skin work as defences

Answer 6

Earwax - has antiseptic properties

Skin - barrier

Question 7

How do mucus and sweat work as defences

Answer 7

Mucus - traps bacteria in airways

Sweat - has antiseptic properties

Question 8

What does cilia do to mucus as a defence

Answer 8

Traps and sweeps mucus up

Question 9

What does the harmless bacteria in the anus do to pathogens

Answer 9

Outcompetes them

Question 10

How does urine work as a defence

Answer 10

It’s antiseptic and so flushed bacteria out of urethra

Question 11

What are antigens

4 things they identify

Answer 11

Markers on the cell surface that allow the immune system to identify:
pathogens
cells from other organisms of same species
Abnormal body cells -> mutated
Toxins

Question 12

4 things antigens can be made from

Answer 12

Proteins
Carbohydrates
Glycoproteins
DNA

Question 13

What are non-self antigens detected by

Answer 13

White blood cells

Question 14

What are the 2 types of immune response

Answer 14

Non-specific immune response

Specific immune response

Question 15

What’s a non-specific immune response launched against

Answer 15

Anything (to any non-self antigen) bacteria that doesn’t belong to you

Question 16

Advantage and disadvantage of non-specific immune repsinse

Answer 16

Fast response to possible infection

Only temporary, doesn’t give long lasting immunity

Question 17

What are the 3 types of non-specific immune response

Answer 17

Fever
Inflammation
Phagocytosis

Question 18

How do pathogens cause a fever

Answer 18

They cause the hypothalamus in the brain to change the body’s thermostat

Question 19

What does a fever do do the pathogen more so than the body cells
What’s the temperature for this

Answer 19

Increased temperature damages pathogen more than body cells

37*c + can denature pathogen

Question 20

What inflammation a build up of

4 symptoms of it

Answer 20

Build up of fluid

Redness
Swelling
Pain
Heat

Question 21

What becomes more permeable when there’s inflammation

Therefore what can escape the blood and enter tissue fluid easier (3)

Answer 21

Capillaries

White blood cells
Antibodies
Compliment proteins

Question 22

What do compliment proteins do

Answer 22

Trigger a series of events that leads to lysis of bacteria

Question 23

What are the 2 phagocytes

Answer 23

Macrophages (most useful)

Neutrophils

Question 24

What do phagocytes target

Answer 24

Anything that doesn’t belong to you (non-self antigens)

Question 25

What’s phagocytosis

Answer 25

Ingestion + digestion of microbes by phagocytes (type of WBC)

Question 26

Describe the process of phagocytosis (6)

Answer 26

1. Damaged tissue by infection released mediators 2. Chemotaxis occurs + phagocytes engulf pathogen 3. Once engulfed, the pathogen is stored in a phagosome vesicle 4. Lysosomes in phagocyte migrate to phagosome and fuse with membrane, secreting lysozyme enzymes 5. The enzymes digest the pathogen 6. Pathogens remains (debris) is absorbed and can be used again by cell

Question 27

What are mediators

Answer 27

Chemicals that attract macrophages (released by damaged tissue)

Question 28

What’s chemotaxis

Answer 28

Movement in direction of a chemical

Question 29

How to phagocytes engulf a pathogen

Answer 29

By extending , wrapping membranes around + engulfing

Question 30

What’s the vesicle called that a pathogen is enclosed and stored in

Answer 30

Phagosome

Question 31

What do lysosomes secrete and what do they do

Answer 31

Lysozyme enzymes that digest the pathogen

Question 32

What are the 2 types of WBCs used

Answer 32

Phagocytes | Lymphocytes

Question 33

What responses are lymphocytes involved in

Answer 33

Specific immune response

Question 34

What part of the body is protected from infections by lymphocytes

Answer 34

Foetus

Question 35

Adv + disadvantage of specific immune response

Answer 35

Slower | But longer lasting

Question 36

2 types of specific immune response

Answer 36

Humoral (antibody mediated response) | Cell mediated response

Question 37

What particular type of lymphocyte does cell mediated immunity involve

Answer 37

T-cell

Question 38

How many types of lymphocytes are there

Answer 38

10 million

Question 39

What are T-cells called this

Answer 39

T - matured in thymus gland (centre of chest)

Question 40

What are the many different types of T cell each capable of

Answer 40

Recognising a different antigen

Question 41

What does each T-cell have in its surface

Answer 41

A different type of receptor - complimentary to 1 specific antigen (only 1 t-cell for each disease)

Question 42

Why does cell mediate response take a long time

Answer 42

As there’s only 1 individual T-lymphocyte that matches 9tsk4s dats to come into contact)

Question 43

What does every pathogen have that different

Answer 43

Different antigen

Question 44

What happens to a t-cell if a t-cell receptor binds to an antigen

Answer 44

The T-cell multiplies rapidly via mitosis (activated)

Question 45

Once bound to a non-self antigen, what are the T cells known as

Answer 45

T helper cells

Question 46

What 4 things do t helper cells cause to happen once bound to a non-self antigen

Answer 46

1. Memory cells form 2. Further phagocytosis 3. B lymphocytes to divide 4. Activate cytotoxic T cells

Question 47

What do memory cells enable

Answer 47

Quick responses to secondary infection

Question 48

What does further phagocytosis activate more of

Answer 48

Macrophages

Question 49

How are cytotoxic T cells activated

Answer 49

By release of chemicals (cytokines)

Question 50

What are cytotoxic T cells also known as

Answer 50

Killer T cells

Question 51

What do lots of cytotoxic T cells do (2)

Answer 51

All bind do antigens and either: 1. Release chemicals (perforins) that cause holes in pathogens membrane so it’s permeable and will die 2. Coat the cell in chemicals so it’s a target for phagocytosis (chemotaxis)

Question 52

What are the chemicals called that cytotoxic T cells release causing holes in pathogens membrane

Answer 52

Perforins

Question 53

What happens to the pathogen once perforins make it permeable

Answer 53

It will die as it can fill with water and explode

Question 54

What type of antigens on body cells can T cells specifically recognise

Answer 54

Foreign antigens

Question 55

Where is an antigen fragment associated with an MHC molecule transported to and what recognises this combination

Answer 55

Transported to the cell’s surface. Where the combination is recognised by a T cell, alerting it to the infection

Question 56

Describe the cell mediated immune response (3)

Answer 56

1. The T cells secrete cytokines (chemicals) 2. The cytokines cause the division of killer T cells by mitosis 3. The killer T cells divide into killer cells + memory cells

Question 57

What’s the process of stimulating the production of active killer T cells called

Answer 57

Colonial expansion/selection

Question 58

What types of cells do killer T cells terminate

Answer 58

Cancer cells | Cell infected by a virus/bacterium

Question 59

What is cell mediated response protection from (6)

Answer 59

``` Viruses Bacteria Cancerous cells Transplanted tissue Fungi Parasitic worms ```

Question 60

What do B cells attack | What do T cells attack

Answer 60

B cells -> attack invaders outside cells | T cells -> attack invaders inside cells

Question 61

What are antibodies a type of | What’s this specific type called

Answer 61

Proteins (amino acids held by polypeptide bonds) Specific type of protein called immunoglobulins

Question 62

What shape are antibodies and what are they made up of | What’s the type of structure

Answer 62

Y shaped Made up of 4 polypeptide chains Quaternary structure

Question 63

What are the 2 types of chains on an antibody

Answer 63

``` Light chain (short) Heavy chain (long) ```

Question 64

What bit of an antibody is the variable region (differs), bit that binds to antigen

Answer 64

Top of light chain (short)

Question 65

How many binding sites does an antibody have | What does it form when it binds to antigen

Answer 65

2 binding sites so can bind to 2 antigens Forms an antibody antigen complex

Question 66

What are antibodies produced by

Answer 66

White blood cells called b-lymphocytes (b cells)

Question 67

When do b lymphocytes develop Where to they remain inactive until infection will activate them (3)

Answer 67

Develop before/just after birth Remain inactive in lymph nodes/ liver/ spleen

Question 68

What does the B cell do once an antigen binds to its receptor

Answer 68

Antigen is absorbed into B cell and displayed on B cells membrane

Question 69

What cells attach to the presented antigen on the B cell that causes mitosis

Answer 69

T-helper cells

Question 70

What 2 things can B-cells become after mitosis

Answer 70

Plasma cell | Memory cell

Question 71

What 2 components are plasma cells filled with and why

Answer 71

RER -> to make proteins | Mitochondria -> for energy

Question 72

What’s the life span of plasma cells and what do they do | What type of response involves plasma cells

Answer 72

Life span of a few days and they secrete antibodies into the blood This is a primary immune response

Question 73

What’s the life span of memory cells and what do they do What type of response involves memory cells

Answer 73

Can live for decades in blood/tissue fluid They retain information on antibody production and can divide if the correct antigen is present Type of secondary immune response