Unit 3.5 - Non Specific Body Defences

Question 1

What are examples of physical defences against infection?

Answer 1

Epithelial cells which form a physical barrier

Question 2

How and where are epithelial cells found?

Answer 2

Closely packed epithelial cells are found in the Skin and inner lining of the digestive and respiratory systems

Question 3

What are examples of chemical defences against infection?

Answer 3

Secretions such as tears, saliva, mucus and stomach acid

Question 4

Why are chemical secretions produced?

Answer 4

To protect against invading pathogens

Question 5

What is a pathogen?

Answer 5

A bacterial, virus or other organisms that can cause disease

Question 6

Describe the inflammatory response

Answer 6

Something carrying bacterial breaks skin
Mast cells release histamine
Histamine causes blood capillaries to dilate which is called vasodilation and become more permeable
Clotting elements and phagocytes accumulate at sight of infection due to the increase in blood flow

Question 7

Describe phagocytosis?

Answer 7

Phagocytes recognise pathogens
Phagocyte engulfs pathogen
Thee are destroyed by digestive enzymes in lysosomes

Question 8

What happens when phagocytes release cytokines?

Answer 8

It attracts more phagocytes to the site of infection

Question 9

What are cytokines?

Answer 9

Protein molecules that act as a signal to specific white blood cells causing them to accumulate at the site of infection