Non-specific animals defences against pathogens

Question 1

What are the barriers on the body to the entry of pathogens?

Answer 1

• Skin
• Mucous membrane
• Lyzozymes
• Expulsive reflexes

Question 2

How does skin act as barrier?

Answer 2

• Prevents the entry of pathogens
• has a skin flora of healthy microorganism that outcompete pathogens
• produce sebum, an oily substance that inhibits the growth of pathogens

Question 3

How does mucous membranes act as barrier?

Answer 3

• secrete sticky mucus which traps microorganisms and contains lysozymes, which destroy bacterial and fungal cell walls.
• Also contains phagocytes, which remove remaining pathogens

Question 4

How does Lyzozymes act as barrier?

Answer 4

intears and urine, and the acid in the stomach
also help to prevent pathogens getting into our bodies

Question 5

How does expulsive reflexes act as barrier?

Answer 5

Coughs and sneezes remove pathogens in the respiratory system
Vomiting and diarrhoea remove pathogens in the gut

Question 6

What are the two substances secreted in blood clotting?

Answer 6

Thromboplastin
Serotonin

Question 7

What does thromboplastin do in blood clotting

Answer 7

triggers a cascade of reactions resulting in the formation of a blood clot

Question 8

What does serotonin do in blood clotting?

Answer 8

Makes the smooth muscle in the walls of the blood vessels contact, so they narrow and reduce the supply of blood to the area

Question 9

What are the three substance combined to make thrombin?

Answer 9

• Thromboplastin
• Prothrombin
• Ca2+

Question 10

What do thrombin and fibrinogen combined make?

Answer 10

fibrin, which form clot

Question 11

What is inflammatory response?

Answer 11

Localised response to pathogens resulting in inflammation at the site of a wound

Question 12

What are the characteristics of inflammation

Answer 12

pain, heat, redness and swelling of tissue

Question 13

Which two chemicals are released in inflammatory response?

Answer 13

• Histamines
• Cytokines

Question 14

How does histamines help inflammatory response?

Answer 14

• make the blood vessels dilate, causing localised heat and redness. the reised temperature helps prevent pathogens reproducing
• make blood vessel walls more leaky so blood plasma is forced out, forming tissue fluid. this causes swelling and pain

Question 15

How does cytokines help inflammatory rsponse?

Answer 15

• attract white blood cells to the site.
• they dispose phathogens by phagocytosis

Question 16

What are the non-specific defences