secondary non-specific defences

Question 1

what are secondary defences used for ?

Answer 1

• used to combat pathogens that have entered the body

Question 2

what happens when a pathogen enters the body ?

Answer 2

-it’s recognised as foreign by the chemical markers on its outer membrane

Question 3

define antigen

Answer 3

a molecule, usually a protein or glycoprotein, that is recognized by the immune system and can trigger an immune response

Question 4

draw and label an antigen

Answer 4

found somewhere :)

Question 5

where are antigens found ?

Answer 5

• proteins or glycoproteins intrinsic to the plasma membrane

Question 6

what do diseased cells also have and for ?

Answer 6

• such as cancer cells
  –> also have antigens on their surface which trigger the body’s defence system

Question 7

what are antigens ?

Answer 7

• are molecules that trigger an immune response
• found on the surface of pathogens
• help the immune system distinguish between self + non-self cells
• contains epitopes which are recognised by B-cell and T-cell receptors
• stimulate antibody production by B lymphocytes or activate T- lymphocytes
  -play a key role in vaccination, inducing immunity without causing disease

Question 8

what are antigens ?

Answer 8

• specific to the organism

Question 9

what do our own cells have and they ..?

Answer 9

• antigens
  –> recognised as our own and do not produce a response

Question 10

define antigen-presenting cell

Answer 10

• a cell that isolates the antigen from a pathogen and places it on the plasma membrane so that it can be recognised by other cells in the immune system

Question 11

define opsonins

Answer 11

• proteins bind to the antigen on a pathogen then allow phagocytes to bind

Question 12

how does opsonins work ?

Answer 12

• stick to antigens on the surface of a pathogen
• this makes the pathogens more recognisable to phagocytes (like macrophages )
• the phagocyte binds to the opsonin and engulfs the pathogens more easily (phagocytosis)

Question 13

why is it important this process is carried out with opsonins ?

Answer 13

• opsonins help the immune system work faster by tagging harmful microbes for destruction
• examples include antibodies (IgG) and complement proteins (C3b)

Question 14

what are opsonins a type of ?

Answer 14

antibody

Question 15

what are opsonins not and therefore..

Answer 15

aren’t very specific
–> so they can attach to a variety of pathogenic cells

Question 16

what is the role of opsonin ?

Answer 16

• enhance the ability to phagocytic cells to bind and engulf the pathogens