Chapter 8: Immunity

Question 1

Nonspecific immunity:

Answer 1

• natural or innate
• Reacts in same way to all infectious disease
• physical and chemical barriers to infection
• has no memory of prior infection

Question 2

Specific immunity:

Answer 2

• production of specialised cells and antibodies
• acts against particular infection
• has a memory so that increased response is obtained upon reinfection

Question 3

First line of defence; includes

Answer 3

• best action is to prevent their entry into the body altogether.
• takes place at the body surfaces:
• skin
• mucous membranes
• Natural secretions
• natural flora

Question 4

Mucous membranes:

Answer 4

• in respiratory tract, it traps bacteria which is then swept back up the throat and removed via cough, sneeze, etc.
• lining digestive tract forms protective barrier

Question 5

Natural secretions:

Answer 5

• many contain bactericidal agents. Tears and saliva contain lysozyme (causes bacteria to lyse or burst.

Question 6

Natural flora:

Answer 6

• “good bacteria” prevents growth of pathogenic bacteria in the places it grows.
• they compete more successfully for space and nutrients that are available.

Question 7

Second line of defence:

Answer 7

If the first line of defence fails, a second line of defence has a number of parts.

Question 8

Phagocytes:

Answer 8

• white blood cells that engulf and destroy micro-organisms and other foreign materials that enter the body.
• neutrophils and monocytes are phagocytes.

Question 9

Monocytes:

Answer 9

• turn into macrophage since they leave the blood stream.

- particularly active against micro-organisms that can live inside the cells of the person they infect.

Question 10

Natural killer cells:

Answer 10

• white blood cells that kill virus infected body cells.

Question 11

Complement proteins:

Answer 11

• many different kinds of complement proteins.

- activation of one kind, results in a cascade effect where each activated complement protein then activates another.

Question 12

Roles of complement proteins;

Answer 12

• some stick to invading microorganisms, which then become more identifiable to phagocytes as foreign
• stimulate phagocytes to become more active
• attract phagocytes to site of infection
• Destroy membranes of invading micro-organisms.

Question 13

Interferon:

Answer 13

• proteins
• secreted by some cells when they’re infected by virus particles.
• act on uninfected cells making them more resistant to the virus.
• interfere with viral replication
• relies on interferons for defence when antibodies have not yet been made.

Question 14

Cytokines:

Answer 14

• protein molecules that act as messengers between cells.
• produced by almost all cells in immune system, particularly by certain T cells.
• like hormones for immune system.

Question 15

Inflammation:

Answer 15

• reaction to infection
• arteriolar in the area around cut dilate resulting in an increased blood supply to the area.
• phagocytes already at scene release chemicals such as histamine that attract more phagocytes to the infection.

Question 16

Cells of third line of defence:

Answer 16

lymphocytes

• B lymphocytes (B cells)
• T lymphocytes (T cells)

Question 17

Identifying foreign material:

Answer 17

• major histocompatibility complex (MHC); proteins produced are called markers.
• all cells have MHC markers, class 1 markers found on all except red blood cells ,class 2 markers found on b and T cells and some macrophages.
• they have receptor sites, some for self others for non self, so that they can identify when cells are foreign to immune system, so immune response can occur.

Question 18

Antigen:

Answer 18

Material (or marker) that triggers a response from a B cell or a T cell

Question 19

Kinds of B cells:

Answer 19

• b memory cells

- plasma cells

Question 20

Immunoglobulins:

Answer 20

Proteins that identify antigens. On the surface of B cells. Also called antibodies.

Question 21

Plasma cells:

Answer 21

• produce antibodies and release them into bodily fluids.

- only survive for a few days.

Question 22

Clonal selection theory:

Answer 22

• when coming into contact with a particular antigen, the B cell reproduces rapidly to give rise to a number of identical clone cells.
• this is called clinal expansion
• they then differentiate into either plasma cells or b memory cells.

Question 23

Structure of an antibody:

Answer 23

• four polypeptide chains
  (Two long heavy chains and two shorter light chains joined together)
• antigen binding sites differ in different antibodies.
• can bind to two antigens.

Question 24

Different kinds of antibody;

Answer 24

• IgM and IgG activate macrophages and the complement system, and are particularly active against bacteria and their toxins.
• IgE- activate mast cells
• IgA- present in saliva, tears, the lungs and along the lining of the gut.

Question 25

T- cells:

Answer 25

• don’t make antibodies

- mature in thymus

Question 26

Helper T-cells:

Answer 26

• recognise foreign antigens and stimulate B cells to form plasma cells.
• activated by presence of foreign antigens displayed on macrophages
• produce cytokines that activate B-cells displaying appropriate antibodies.
• bond between the macrophage and the appropriate b-cells causing the latter to differentiate into a plasma cell that produces the appropriate antibodies.

Question 27

Cytotoxic T cells:

Answer 27

• white blood cells that destroy virus infected cells.

- they can kill the virus only when it is inside a cell.

Question 28

T and B cells travel around the body:

Answer 28

• circulate in lymph in particular.

Question 29

Acquired specific immunity:

Answer 29

• when antibodies are acquired through different methods.

Question 30

Active immunity:

Answer 30

• production of antibodies within a person in response to exposure to a particular antigen.
• B memory cells and T cells are produced and react quickly if another encounter occurs.

Question 31

Natural active immunity:

Answer 31

• exposure to pathogen, antibodies produced.

- immune system in infected individual has made antibodies and continues to do so.

Question 32

Induced active immunity:

Answer 32

• vaccines, which contain dead or treated living microorganisms are used to activate the immune system to produce the antibodies against disease-causing organisms without actually causing the disease.
• attenuated: causing disease capability removed.

Question 33

Passive immunity:

Answer 33

• antibodies have not been made by the user.

Question 34

Natural passive immunity:

Answer 34

• a developing Cetus received maternal antibodies across placenta and through mothers milk.

Question 35

Induced passive immunity:

Answer 35

• if a member of your family develops hepatitis a, you are at risk. If immediately receive an injection of antibodies specific to hepatitis a, then infection may be avoided.
• injection of antibodies.

Question 36

What does vaccination do in the case of tetanus?

Answer 36

• results in the production of b memory cells that are capable of producing the tetanus antibodies.
• when the tetanus bacteria enter the wound the appropriate B memory cells are activated and can quickly differentiate into plasma cells producing antibodies against tetanus bacteria before they can cause tetanus.

Question 37

B memory cells

Answer 37

• same antibody-antigen specificity as the parent B cell.
• can survive for several years and in some cases life.
• if a second infection of the same pathogen occurs, these cells react more vigorously than the initial b-cell reaction to the first infection.