Biology Human physical and chemical barriers

Question 1

Name all the Physical barriers and name how it prevents entry of pathogens

Answer 1

Skin:
Stop entry of pathogens unless its
damaged but blood clotting stops entry

Tears:
Trap bacteria and fall from the body

Mucus:
Trap bacteria and we either swallow it or
blow it out

Hair:
Trap bacteria in nose, ears

Question 2

Name all the Chemical barriers and name where each is located

Answer 2

Acid in stomach PH 2 so kills pathogens

Lysozyme in tears, mucus and saliva
Enzyme that breaks down the cell wall
of bacteria so kills them

Glands in skin
Produces chemicals

Question 3

Name some examples of diseases that are transmitted though Sexual activity / exchange of bodily fluids. (4)

Answer 3

Examples:
* HIV (virus)
* Clamydia (a bacterium)
* Gonnarhea
* Syphilis

Question 4

How do you prevent their spread?

Answer 4

1. Using a condom = artificial barrier during sexual
   intercourse
2. Use clean needled and disposed after use (for HIV)
3. Doctors should wear gloves

Question 5

Where can these pathogens be spread by?

Answer 5

• Pathogens are spread through semen or vaginal fluid
• Or from mother to her unborn baby
• HIV can also be passed through blood, such as when needles are shared when
  injecting drugs