Diseases 2

Question 1

What do viruses consist of

Answer 1

Viruses consist of genetic material (DNA or RNA) wrapped in cuspids

Question 2

How do viruses reproduces?

Answer 2

Reproduction of viruses:
-Virus attaches to host cell then passes through the membrane
-Copies itself using the enzymes of the host cells
-Virus particles leave host cells to infect others

Question 3

Antibody structure

Answer 3

Antibody structure:
-Made up of 4 polypeptide chains (2 light/short, 2 heavy/large)
-Antigen binding site
-Hinge region
-Disulfide bridges between polypeptide chains
-Constant region

Question 4

Hinge region of an antibody

Answer 4

The hinge region of an antibody -> flexible -> allows distance between two antigen binding sites to vary

Question 5

Constant region of an antibody

Answer 5

Constant region of an antibody:
Same for every antibody

Question 6

T helper cells

Answer 6

T helper cells has a surface molecule called CD4, which locks onto the MHC molecule on the macrophage

Question 7

Activated T helper cells

Answer 7

Activated T helper cells produce chemicals called interleukins (type of cytokine) -> triggers the activated T helper cells to undergo mitosis + stimulates macrophages to carry out phagocytosis

Question 8

Function of opsonins

Answer 8

Opsonins detect foreign chemicals -> sticks to them ->tagging it as foreign

Question 9

Phagocytosis involving a neutrophil

Answer 9

Phagocytosis involving a neutrophil:
-Neutrophil is attracted by molecules produced by pathogens
-Receptors attach to opsonins + engulfs pathogens (pathogens are now in phagosome vacuole)
-Lysosome move to phagosome and fuses with it to form a phagolysosome
-Lysosome enzymes then break down and destroy the pathogen

Question 10

Phagocytosis involving a macrophage

Answer 10

Phagocytosis involving a macrophage:
-Pathogen engulfed by phagosome
-Lysosome fuses
-Enzymes digest pathogens
-Glycoproteins (called the major histocompatibility complex/MHC) from cytoplasm move to the phagolysosome and bind to antigen molecules
-MHC binds to antigens -> forms an MHC-antigen complex
-Complex moves to cell surface membrane and antigens are presented to the exterior of the cell (this is where we say that the macrophage is acting as an antigen-presenting cell (APC)

Question 11

APC

Answer 11

APC = Antigen presenting cell -> when the MHC-antigen complex is showing on the exterior of the cell

Question 12

Cytokines

Answer 12

Cytokines: signal to phagocytes and other immune cells to move to site of the infection + can also cause inflammation and fevers

Question 13

Process of blood clotting eg in the Arteries when a cut occurs

Answer 13

1) Damaged endothelium (cut skin)
2) Platelets exposed to the proteins outside the endothelium
3) Activates the platelets which triggers blood clotting
4) Forms plug over damaged area and platelets release chemicals (clotting factors including thromboplastin) which then acts on proteins

Question 14

Chain of proteins involved in blood clotting from thromboplastin

Answer 14

Thromboplastin associated with calcium ions -> acts on blood protein prothrombin -> converts prothrombin into active enzyme Thrombin -> Frombin acts on soluble protein Fibronogen -> Forms insoluble protein Fibrin

Question 15

Insoluble fibrin role in blood clotting

Answer 15

Insoluble fibrin forms a mesh which traps red blood cells -> forms blood clot/thrombus

Question 16

Function of activated platelets releasing serotonin in blood clotting formation

Answer 16

Function of activated platelets releasing serotonin in blood clotting formation:
-Serotonin causes smooth muscle cells in blood vessels to contract
-Narrows blood vessel to reduce blood flow to the infected area

Question 17

Why does infected area of skin when cut appear hot and red?

Answer 17

Heat and redness occur due to inflammation when the skin is damaged:
-Damaged tissue activates mast cells
-Activated mast cells release histamine
-Histamine causes nearby blood vessels to dilate (vasolidation) to increase blood supply to infected area which causes redness and heat (heat destroys pathogens)

Question 18

Why do tissue swell (odeama) + feel painful when damaged?

Answer 18

-Histamine produced by activated mast cells makes vessel wall more permeable
-Allows more blood plasma to leave blood and form tissue fluid
-Nearby tissues swell and feel painful

Question 19

Specific immune responses

Answer 19

The two specific immune responses:
-The cellular/cell-mediated response involves the highly specialised cells that targets pathogens inside cells
-The humoral or antibody-mediated response targest pathogens in body fluids with antibodies

Question 20

Agglutination of antibodies

Answer 20

Agglutination: One antibody binds to two pathogens, causing them to clump together. This makes pathogens more easily engulfed by phagocytosis

Question 21

Neutralisation of pathogens and toxins

Answer 21

Antibodies can act as antitoxins, binding with toxins produced by pathogens

Question 22

Cell-mediated immunity response

Answer 22

Cell-mediated immunity response:
1). Macrophages engulf and digest pathogens by phagocytosis. They present the antigens on their surface (becoming antigen-presenting cells)
2). Specific T helper cell with receptor that fits the antigen on the macrophage will bind. The T helper cell will produce interleukins which stimulate more T cell to be produced
3). Cloned T cells may become more T helper cells (to produce more interleukins)/ Killer T cells / T memory cells to destroy infected pathogens

Question 23

T killer cells

Answer 23

T killer cells kill pathogens by producing a chemical called perforin, which makes holes in pathogens cell plasma membranes

Question 24

T memory cells

Answer 24

T memory cells act as the immunological memory, as they remain the blood for long periods of time. When a second infection occurs, they divide rapidly to form many killer T cells

Question 25

T regulator cells

Answer 25

T regulator cells prevent an autoimmune response by repressing the immune system after all the pathogens have been destroyed

Question 26

Humoral immunity response

Answer 26

Humoral immunity response:
1). T helper cells bind to the antigens on the presenting B cells (clonal selection)
2). Interleukins produced by the T helper cells activate the B cells
3). The B cells divide rapidly by mitosis to produce many different B cells (plasma and memory cells) (clonal expansion)
4). These cloned plasma cells produce specific complementary antibodies to bind to the pathogens antigen, disabling them, or causing agglutination or neutralisation

Question 27

Plasma cells as a B lymphocyte

Answer 27

Plasma cells produce specific antibodies to an invading antigen, only live for few days but reproduce rapidly

Question 28

B effector cells

Answer 28

B effector cells divide to form plasma cell clones

Question 29

B memory cells

Answer 29

B memory cells remain in blood for long periods of time, providing immunological memory

Question 30

Autoimmune response

Answer 30

Autoimmune response refers to when the immune system stops recognising ‘self’ antigens and attach healthy body tissues, some causing chronic inflammation to complete breakdown of tissues, immunosupressant drugs used

Question 31

What does vaccines involve?

Answer 31

Vaccines involve:
-Dead pathogens injected into bloodstream
-B memory cells remain in bloodstream and remember the antigen
-Vaccines involve clonal selection and expanision
-Lymphocytes release antibodies more quickly and efficiently

Question 32

Role of opsonins

Answer 32

Opsonins bind to pathogens and tag them, so to encourage phagocytosis

Question 33

Immunisation

Answer 33

Immunisation is the process of developing immunity

Question 34

How to find the volume of a neutrophil?

Answer 34

Volume of a neutrophil = 4/3 x pi x radius (cubed)

Question 35

Why are antibodies specific to nuclear proteins not made?

Answer 35

Antibodies specific to nuclear proteins are not made because proteins are normally hidden in the nucleus

Question 36

Natural sources of medicine

Answer 36

Natural sources of medicine: plants + microorganisms

Question 37

Type of immunity for vaccination of antibodies and vaccination of inactive pathogens

Answer 37

-Vaccination of antibodies = artificial passive immunity
-Vaccination of inactive pathogens = artificial active immunity

Question 38

Process that leads to the production of antibodies

Answer 38

Process that leads to the production of antibodies:
-Lymphocytes detect antigen on pathogen cell surface membrane
-Becomes activated and selected B cells divide by mitosis and differentiate into plasma cells
-Plasma cells release antibodies specific to antigen

Question 39

Role of T helper cells

Answer 39

T helper cells = stimulated by APCs -> releases cytokines/interleukins -> then stimulates B cell -> causes mitosis/clonal expansio

Question 40

Role of B memory cells

Answer 40

B memory cells: remain in the bloodstream after a primary infection in order to rapidly respond to a secondary infection as clonal selection is faster

Question 41

Neutrophil specialisations

Answer 41

Neutrophil specialisations:
-Well-developed cytoskeletons
-Many lysosomes
-Many mitochondria
-Lobed nucleus

Question 42

What is meant by ‘immunologically distinct toxins’?

Answer 42

Immunologically distinct toxins:
-Toxins produced by each strain different
-Each toxin has own 3D shape
-Toxins act as antigens to immune system
-Immune response occurs

Question 43

Example of primary defence mechanism against pathogens

Answer 43

Primary defence mechanism = immune system -> skin, tears, mucus, blood clotting

Question 44

Differences between humoral immune response and the cell-mediated immune response

Answer 44

Humoral immune response = involves B-lymphocytes, of which are activated by T cells that are attached to APC, stimulates B cells to divide into plasma cells

Cell-mediated response = involves T-lymphocytes, of which binds to receptor cells and activates other T cells to divide (eg into T killer cells, T regulator cells or T helper cells)