Describe how the physical defences of human body prevent the invasion of microooragnisms which cause infections.

Our skin surrounds almost all parts of our body and can act as a mechanical barrier between microorganisms and our body. If the skin is damaged or cut, a scab will be formed to prevent microorganisms from entering into our body to cause an infection.Apart from the skin, other parts of our body also have physical defences to prevent infection. For example, our eyes can produce tears which contain enzymes to break down bacterial cell wall. Our trachea are lined with mucus-secreting cells which secrete mucus to trap pathogens and are then sweeped up by the beating action of cilia to be coughed or sneezed out.