3.5- non specific body defences

Question 1

what is a pathogen?

Answer 1

an organism such as a bacterium or virus that causes disease

Question 2

2 ways immunity is effective

Answer 2

resist infection by a pathogen

destroy the organism if it succeeds in invading and infecting the body

Question 3

what are the 3 lines of defences?

Answer 3

first two are non-specific

third is specific

Question 4

how do non-specific lines of defence work?

Answer 4

work against any type of disease causing agent

Question 5

how do specific lines of defence work?

Answer 5

components each work against a particular pathogen

Question 6

2 ways physical barriers are used

Answer 6

closely packed epithelial cells in the skin protect against bacteria and viruses

epithelial cells make up the mucous membranes lining the body’s digestive and respiratory tracts

Question 7

1 use of a chemical barrier

Answer 7

skin and mucous membranes fight against potential pathogens

Question 8

4 chemical secretions produced against invading pathogens

Answer 8

tears

saliva

mucus

stomach acid

Question 9

function of sweat

Answer 9

keeps the skin at a low pH where most organisms cant thrive

Question 10

function of tears/saliva

Answer 10

tears/saliva contain enzyme lysozyme that digests cell wall of bacteria

Question 11

function of mucus

Answer 11

traps micro organisms and cilia can remove the mucus

Question 12

function of stomach acid

Answer 12

destroys many of the microbes that have been swallowed

Question 13

what is the inflammatory response?

Answer 13

the inflammatory response is a localised defence mechanism that is used when the body suffers physical injury

Question 14

3 steps of the inflammatory response

Answer 14

following injury, mast cells become activated and release large quantities of histamine

histamine results in blood vessels of injured area undergoing vasodilation and capillaries becoming more permeable

additional supply of blood leads to the injured area becoming red and inflamed, the accumulation of phagocytes and clotting elements at the site of infection

Question 15

2 things that cause the body to use the inflammatory response

Answer 15

invasion by microorganisms

cut

Question 16

where are mast cells found?

Answer 16

mast cells are found in connective tissue throughout the body

Question 17

what do mast cells possess and what do those things contain?

Answer 17

possess many granules

granules contain histamine

Question 18

what are mast cells closely related to?

Answer 18

white blood cells

Question 19

4 steps of how phagocytes destroy pathogens during phagocytosis

Answer 19

phagocytes detect chemicals released by pathogens

move towards the pathogen

phagocyte engulfs invader by infolding the cell membrane

this is pinched off to form a vacuole

Question 20

what does a phagocytes cytoplasm have a rich supply of and what do they contain?

Answer 20

phagocytes cytoplasm has a rich supply of lysosomes

contain digestive enzymes

Question 21

function of some lysosomes

Answer 21

some lysosomes fuse with vacuole and release their enzymes into it digesting the bacterium

breakdown products are absorbed by the phagocyte

Question 22

what does the phagocyte release after digestion of the microorganism and what do they do?

Answer 22

after digestion of microorganisms, phagocyte releases cytokines

these attract more phagocytes to the site of infection

Question 23

what may build up at the infected site and as what?

Answer 23

dead bacteria and phagocytes may build up at infected site

pus

Question 24

what are cytokines and what do they come from?

Answer 24

cytokines are cell signalling protein molecules

secreted by white blood cells that arrived at the site of injury or infection

Question 25

function of **cytokines**

Answer 25

function of cytokines is to act as a signal to other specific white blood cells making them accumulate at site of infection