body defence mechanisms

Question 1

what 4 things do the immune system allow pathogens to identify

Answer 1

• pathogens
• cells from other organism of the same species
• abnormal body cells
  (e.g: cancer cells)
• toxins

Question 2

define pathogen

Answer 2

microorganism that causes disease

Question 3

define antigen

Answer 3

proteins on the cell surface membrane that stimulate an immune response

Question 4

define disease

Answer 4

anything that causes damage to body cells

Question 5

what is the biological importance of antigens

Answer 5

• these things are all potentially harmful: pathogens, cells from other organism of the same species, abnormal body cells (e.g: cancer cells), toxins
• if the immune system can recognise and differentiate between self (normal healthy body cells) and non self body cells then a quick response to destroy non self cells can be produced

which decreases the risk of harm

Question 6

list 2 potential problems with antigens

Answer 6

• transplants

(to prevent rejection you need to use immunosuppressant drugs)

• blood transfusions

Question 7

define antigenic variability

Answer 7

antigens can change due to genetic mutations

Question 8

why is antigenic variability a problem for the immune system

Answer 8

• surface receptors on lymphocytes and memory cells that produce antibodies are complementary to only one specific antigen
• if the shape of the antigen changes the antibody is no longer complementary which causes reinfection

Question 9

name the cells of the immune system

Answer 9

phagocytes

t- lymphocytes

b - lymphocytes

Question 10

what process are phagocytes involved

Answer 10

phagocytosis

NON SPECIFIC

Question 11

are lymphocytes specific or non specific

Answer 11

specific

Question 12

what are the 2 types of T - lymphocytes

Answer 12

Th cells (helper)

Tc cells (cytotoxic)

Question 13

what are the 2 types of B - lymphocyte

Answer 13

plasma cells

memory cells

Question 14

define non specific defence mechanisms

Answer 14

response is immediate and same for all pathogens

Question 15

give an example of a non specific defence mechanism

Answer 15

• physical barrier … skin
• phagocytosis

Question 16

define specific defence mechanisms

Answer 16

response is slower and specific to each pathogen

Question 17

give an example of a specific defence mechanism

Answer 17

cell mediated response: T lymphocytes

humoural response : B lymphocytes

Question 18

how do lymphocytes recognise self body cells in fetuses

Answer 18

in fetuses lymphocytes are constantly colliding with each other

lymphocytes only collide with the self

some of the lymphocytes will have receptors that fit some of the body own cells

these lymphocytes die or are suppressed

only lymphocytes that fit and therefore respond to foreign material remain

Question 19

how do lymphocytes recognise self body cells in adults

NEED TO CHECK IN TEXTBOOK

Answer 19

lymphocytes in bone marrow initially encounter self antigens

any lymphocytes that show an immune response to self cells undergo apoptosis before they differentiate into mature lymphocytes so only those who might respond to non self antigens remain