6.2.2 - Entry Routes Of Pathogens

Question 1

How Do Pathogens Cause Disease?

Answer 1

By entering the body.

Question 1

How Can Pathogens Enter The Body?
(4 Points)

Answer 1

~ Through cuts in the skin, providing direct access to tissues and the bloodstream.

~ Through the digestive system via contaminated food or drink.

~ Through the respiratory system, when inhaled.

~ Through mucosal surfaces. E.g. Nose, mouth and genitals.

Question 2

What Are All The Barriers That Prevent Infection?
(4 Points)

Answer 2

~ Stomach acid.

~ Skin.

~ Gut and skin flora.

~ Lysozyme.

Question 3

Describe ‘Stomach Acid’ As A Barrier Preventing Infection
(2 Points)

Answer 3

~ Contains hydrochloric acid, creating an acidic environment which is unfavourable to many pathogens.

~ Some pathogens may survive and pass into the intestines, where they can infect cells of the gut wall and cause disease.

Question 4

Describe ‘Skin’ As A Barrier Preventing Infection
(3 Points)

Answer 4

~ Provides a physical barrier against pathogens.

~ If damaged, leaves exposure to pathogens to tissues and the bloodstream.

~ Blood clots in the damaged area prevent entry to pathogens, but takes time to form allowing some pathogens to enter.

Question 5

Describe ‘Gut & Skin Flora’ As A Barrier Preventing Infection
(3 Points)

Answer 5

~ The intestines and skin are covered with microorganisms called ‘flora’.

~ They compete with pathogens for nutrients and space.

~ Limiting the number of pathogens in the gut and skin, making it harder to infect the body.

Question 6

Describe ‘Lysozyme’ As A Barrier Preventing Infection
(2 Points)

Answer 6

~ Mucosal surfaces produce secretions such as tears, saliva and mucus which all contain the enzyme lysozyme.

~ Lysozyme kills bacteria by damaging their cell walls, causing them to burst open (Lyse).