Question

Which of the following is a barrier against pathogens provided by the skin? a. low pH b. mucus c. tears d. cilia

Short answer

The correct barrier against pathogens provided by the skin is 'a. low pH'. The skin's slightly acidic environment helps protect the body from harmful bacteria and fungi.

Step-by-step solution

Understanding Skin Barriers

Skin barriers protect the body from external pathogens and harmful substances. There are various types of barriers, including physical, chemical, and biological barriers.

Analyzing Option A - Low pH

The skin has a slightly acidic pH (ranging from 4.5 to 6), which creates an environment that is unfavorable for the growth of many harmful bacteria and fungi. This acidic environment is an essential barrier against pathogens that the skin provides.

Analyzing Option B - Mucus

Mucus is a slimy substance produced by the mucous membranes found in respiratory and gastrointestinal tracts. It helps trap and remove pathogens from entering the body through these pathways. Mucus is not directly related to the skin's barrier properties.

Analyzing Option C - Tears

Tears are produced by the lacrimal glands, and they help keep the eyes clean and lubricated. They contain a protein called lysozyme, which can break down the cell walls of certain bacteria, thus protecting the eye from infection. Tears are a barrier function primarily for the eyes, not the skin.

Analyzing Option D - Cilia

Cilia are tiny, hair-like structures found in the respiratory tract, including the nose and lungs. They move in coordinated waves, helping to move mucus and trapped pathogens out of the airways. Cilia are not part of the skin's barrier system.

Identifying the Correct Barrier

Among the given options, the low pH (option A) is the barrier against pathogens provided by the skin. This acidic environment helps protect the body from various harmful microorganisms. So the correct answer is 'a. low pH'.