Immunity Topic 6

Question 1

what is the definintion of an antigen?

Answer 1

Marker molecules that can be detected by antibodies and trigger an immune response.

Question 2

what happens when a non self cell is detected

Answer 2

• triggers an immune response

Question 3

what can be identified by different surface molecules?

Answer 3

• pathogens
• toxins
  *

Question 4

Describe how macrophages ingest the bacteria

Answer 4

• macrophage phagocytoses bacteria / engulfs
• bacterium is held inside a vesicle

Question 5

Explain how a person can develop artificial active immunity following vaccination.

Answer 5

• dead bacterium injected into person in vaccine
• stimulation of a specific immune response
• t-helper cells stimulated
• b cell activation
• t killer cells activated
• b memory cells activated to provide long term protection agaisnt infection.

Question 6

State two characteristic features of antibodies.

Answer 6

• glycoprotein
• y shape
• light and heavy regions
• constant region
• variable region
  *

Question 7

suggest how scientists could develop a means of producing active immunity against a HIV infection using a synthetic glycoprotein

Answer 7

• use of synthestic glycoprotein in a vaccine
• active artificial immunity
• stimulation of specific immune response
• t helper cells produce cytokines stimulating B cells
• b memory cells produced
• antibodies can be produced faster and in greater concentration

Question 8

what are the three ways a non specific immune response occurs?

Answer 8

• inflammation
• phagocytosis
• interferons

Question 9

what is the surface of the skin covered by to help protect agaisnt bacteria? (4)

Answer 9

• surface covered by oily sebum secreted by the sebacaeous glands
• provides a slightly acidic layer preventing the growth of harmful bacteria
• covered with harmless microorganisms
• they reduce the growth of pathogens by competing for rescources

Question 10

what are the respiritory organs lined with the prevent pathogen entry?

Answer 10

mucusmembranes which secrete mucus that traps microorganisms which can then be destroyed by phagocytes

Question 11

what white blood cells are in the non specific immune response?

Answer 11

phagocytes
- macrophages
- neutrophils

Question 12

what happens when a neutrophil engulfs a bacterium? (3)

Answer 12

• it goes to a type of vacuole called a phagosome
• lysosomes move towards this forming a phagolysosome
• lysosomal enzymes break down the pathogen and destroy it

Question 13

what can macrophages do that neutrophils cannot?

Answer 13

they can presnt antigens of enulfed bacteria (APC)

Question 14

decribe the process of a macrophage becoming an APC in the non specific immune response (6)

Answer 14

• macrophage engulfs pathogen to form a phagosome
• lysosomes join to form a phagolysosome
• lysosomal enzymes digest the pathogen
• MHC binds to the antigens of the pathogen forming an MHC antigen complex
• the MHC antigen complex moves to the cell surface membrane and antigens are presented
• chemicals released called cytokines triggering cells to move to infected area

Question 15

what is the role of the inflammatory response?

Answer 15

to bring WBCs to the site of infection to dispose of bacteria by phagocytosis

Question 16

explain how white blood cells swarm to accumulate at the site of inflammation (4)

Answer 16

• histamine is released
• vasodilation then occurs at the arterioles
• increased blood flow to site of inflammation
• increased permeability of capillaries
• allowing WBC (blood plasma) moves from blood to tissue space

Question 17

what is the role of the interferon?

Answer 17

• inhibit the production of viral proteins
• activate white blood cells that destroy infected cells
• increase the non specific response

Question 18

explain why the symptoms of HIV occur when t cells are destroyed

Answer 18

• less cytokine production
• decreased activation of B cells
• decreased antibody production
• increased risk of opportunist infections such as TB

Question 19

Explain how HIV invades t helper cells

Answer 19

• gp120 glycoproteins on the surface of HIV
• bind to CD4 receptors on the t helper cell
• viral envelope fuses with t cell membrane
• viral RNA enters cell

Question 20

describe the specific response to an infection

Answer 20

• bacterium engulfed by macrophage
• antigens displayed on the MHC and Macrophage becomes an APC
• CD4 receptor on T cell binds to antigen
• T helper cell divides via mitosis into T memory, T helper and T killer cells
• T cell binds to APC releasing cytokines
• this stimulates division of B cells into B effector and B memory cells
• B effector cells differentiate into plasma cells
• plasma cells kill bacterium
• t killer cells secrete chemicals that cause pores to form in bacterium and cell lysis occurs

Question 21

describe the ways plasma destroys antibodies.

Answer 21

• agglutination - microbes clump together making them easier to be dogested via phagocytosis
• lysis - causes microbes to burst
• oponisation - antibodies coat bacteria to mark for phagocytes
• neutralisation - neutralise harmful toxins

Question 22

describe what happens in the secondary reponse

Answer 22

• antibodies are produces faster and in greater numbers
• lag time to produce active lymphocytes is reduced