Neurobiology And Immunobiology... Non-specific Body Defences

Question 1

What is a pathogen?

Answer 1

It is a bacterium, virus or other organism that can cause disease.

Question 2

Immunity is the ability of the body to…

Answer 2

• resist infection by pathogen

* destroy the pathogen if it invades the body.

Question 3

The body has an immune system for defence against…

Answer 3

• pathogens
• some toxins produced by living things
• cancer cells

Question 4

What are the two non-specific lines of defence in the body?

Answer 4

• Physical defence

* Chemical Defence

Question 5

Non-specific physical defence works because of…

Answer 5

• epithelial cells being closely packed and being found in the skin and inner linings of the digestive system and respiratory systems
• the skin forming a physical barrier against pathogens
• mucous membranes lining digestive and respiratory tracts

Question 6

Non-specific chemical defences work because of…

Answer 6

• chemical secretions are produced against invading pathogens.
  Examples)
  1) secretions of the skin eg sweat keeps the pH of skin low.
  2) tears and saliva contain the enzyme lysozyme which digests cell walls.
• mucus secreted by membranes traps microorganisms.
• ciliates cells in the trachea sweep mucus and trapped microbes up and away from the lungs.

Question 7

What is the inflammatory response?

Answer 7

It is a response to a physical injury.

For example, a cut or abrasion.

Question 8

What does the inflammatory response do?

Answer 8

• Prevents spread of infection.
• Disposes of pathogens and dead tissue cells.
• Promotes tissue repair.

Question 9

What chemical cleans the eyes?

Answer 9

Tears.

Question 10

What chemical cleans the mouth?

Answer 10

Saliva.

After mucous membranes trap microorganisms

Question 11

What chemical is found in the nasal cavity and traps microorganisms along with hairs?

Answer 11

Mucus.

Question 12

What chemical kills many microorganisms in the stomach?

Answer 12

Acidic juices.

Question 13

Mast cells…

Answer 13

• Are present in connective tissue.
• Are closely related to white blood cells.
• Have granules inside that contain histamine.

Question 14

What are the actions of the inflammatory response? (1-3ab)

Answer 14

1) Body suffers physical injury
2) Mast cells are damaged releasing histamine

3) Histamine causes…
A- vasodilation, increased blood flow to site, via capillaries, wound becomes inflamed & red
B- increases capillary permeability, wound swell as fluids leak into neighbouring tissue

Question 15

What are the actions of inflammatory response? (4-6)

Answer 15

4) increased blood flow leads to an accumulation of phagocytes -phagocytosis occurs- (white blood cells which destroy pathogens) and clotting agents (platelets clot the blood, sealing the wound)
5) breakdown products are absorbed by phagocyte (dead bacteria & phagocytes at injury site can form pus)
6) phagocytes release cytokines to attract more phagocytes to the site of infection

Question 16

What is a cytokines?

Answer 16

Protein molecules act as a signal to white blood Ella to accumulate at site of infection

Question 17

What do platelets do?

Answer 17

Clot the blood