communicable diseases c:

Question 1

What are some non-specific defences that keep the pathogens out?

Answer 1

• Skin covers the body to prevent the entry of pathogens, healthy microorganisms that outcompete the pathogens and sebum is produced that inhibit pathogen growth
• Mucous membranes secrete sticky substances that trap microorganisms and contain lysozymes that destroy bacteria and fungal cell walls
• Lysozymes in tears and urine, and acid in the stomach prevent pathogen entry
• Expulsive reflexes such as coughs, sneezes, vomiting and diarrhoea expel unwanted pathogen content

Question 2

How does blood clotting and wound repair prevent pathogen entry?

Answer 2

Thromboplastin is an enzyme that trigger a cascade of reactions for blood clotting.
Serotonin will make the smooth muscles contract to narrow blood supply to that area.

Platelets meet collagen in skin, adhere and begin secreting thromboplastin and serotonin.

Epidermal cells will grow below a scab to seal the wound. Collagen fibres then give tissue strength and scab falls off.

Question 3

What does the inflammatory response consist of?

Answer 3

Mast cells activate and release chemicals called histamines and cytokines,

Histamines cause blood vessel dilation for raised temperature to prevent pathogen reproduction and make the blood vessels more leaky.
Cytokines attract phagocytes to dispose o pathogens by phagocytosis.

Question 4

What do fevers do?

Answer 4

Cytokines stimulates hypothalamus to raise temperature above 37* which will inhibit pathogen reproduction and make the specific immune system work faster,

Question 5

How does phagocytosis work? [Neutrophils}

Answer 5

Pathogens will produce chemicals that attract phagocytes.

Phagocytes recognise as non self and will engulf the pathogen and encloses it in a phagosome.

Phagosome combines with a lysosome to form a phagolysosome will contains enzymes that destroy the pathogen

Question 6

How do macrophages work?

Answer 6

Macrophages digest a pathogen, combine with its antigens from the pathogen surface membrane with specifically glycoproteins called the major histocompatibility complex. The MHC will move the pathogens antigen to its own surface membrane and will become an antigen presenting cell to stimulate over cells in the specific immune system.

Question 7

What do cytokines do?

Answer 7

Cytokines are cell signalling molecules that inform other phagocytes that the body is under attack and stimulate them to move to site of infection, They can also increase body them and stimulate specific immune system.

Question 8

What do opsonins do?

Answer 8

Chemicals that bind to pathogens and tag them to make them more easily recognised by phagocytes.

Phagocytes have receptors on cell membrane to bind to opsonins and then engulf the pathogen