Describe how the human body can prevent the entry of organisms that cause disease. Include physical barriers and chemical defences in your answer.

Physical barriers:

• skin to prevent entry of organisms into the bloodstream

• cilia lining the nasal passages / bronchi to prevent entry to lungs / remove mucus 

• scabs to prevent entry of microorganisms into the bloodstream

• eyelashes prevent entry into the eye

• nasal hairs trap organisms entering breathing system

• ear wax traps organisms

Chemical defences:

-  (hydrochloric) acid in the stomach kills organisms

-  lysozymes / enzymes in tears kill organisms