Defence Against Diseases

Question 1

Skin

Answer 1

. Has flora of microorganisms that outcompete pathogens for space on surface
. Produces sebum, which inhibits pathogen growth

Question 2

Mucous Membranes

Answer 2

. Are lined in airways which secrete sticky mucus

. Traps microorganisms

Question 3

Lysozymes

Answer 3

Destroy bacterial and fungal cell walls

Question 4

Expulsive Reflexes

Answer 4

. Coughs and sneezes eject the pathogen from the gas exchange system
. Vomiting and diarrhoea expels content of gut along with any infective pathogens

Question 5

Blood clotting and wound repairing

Answer 5

. Localised response of pathogens resulting in inflammation at a wound
. Inflammation characterised by pain, heat,redness and swelling of tissue

Question 6

Thromboplastin

Answer 6

. Is a chemical and released when tissue is damaged
. Makes blood vessels dilate causing localised heat and redness. This helps prevent pathogens reproducing
. Makes blood vessel walls leaky so blood plasma is forced out and now is tissue fluid (causes swelling and pain)

Question 7

Cytokines

Answer 7

. Attracts WBC to the cite and dispose of pathogens by phagocytosis

Question 8

Fevers

Answer 8

. Body temperature maintained by hypothalamus in the brain
. When the body gets invaded by a pathogen cytokines stimulates your hypothalamus to rest the thermostat and your body temp goes up
. Is a useful adaptation

Question 9

Phagocytes

Answer 9

. Are a specialised WBC which engulfs and destroys invading pathogens

Question 10

Helpful chemicals

Answer 10

. Opsonins are chemicals that bind onto pathogens and tag them so they can be easily recognised by phagocytes
. Phagocytes have receptors on membranes that bind to opsonins and the phagocytes engulfs the pathogen.