Question

What is the function of the cilia of the respiratory tract in human beings?
a) Protect the epithelial cells from the inhaled air.
b) Increase surface area for the absorption of oxygen
c) Produce sweeping movements to remove excess mucus.
d) Provide structural support and stabilise the respiratory tract.

Answer 1

Hint: With hair-like projections the bronchus in the lungs are lined that moves microbes and debris up and out of the airways. Throughout the cilia, scattered are goblet cells that secrete mucus, which helps protect the lining of the bronchus and trap microorganisms. The length of the cilium is 1-10 micrometers and width is less than 1 micrometre

Complete answer;
Cilia are slender, microscopic hair like structures, or organelles that extend from the surface of nearly all mammalian cells. They are primordial. To the cell progression the ciliary apparatus is connected and proliferated and cilia play a vital role in human and animal development and in everyday life. This cilia are broadly divided into two types. Sometimes together and separately they function.
Motile: ‘Motile’ means moving cilia that are found in the lungs, respiratory tract and middle ear. These cilia include the rhythmic waving or beating motion. To keep the airways clear of mucus and dirt, they work instance, allowing us to breathe easily and without irritation. They also help with proper sperm.
Primary Cilia: On the apical surface of the cells, primary cilia appear typically as single appendages microtubules lack (eg: in kidney tubules). In Kidney for eg- with the urine flow the cilia, bend and to alert send a signal to the cells that there is a flow of urine.
Functions of Cilia: By Cilia the important functions performed involves- locomotive and sensory functions. In cell cycle, they play a major role and replication and also in the development of humans and animals. It also produces sweeping movements to remove excess mucus. As an antenna, few, on-motile cilia act that receive sensory information for the cells and processes these signals from the surrounding fluids.

Hence, the correct answer is option C i.e. produce sweeping movements to remove excess mucus.

Note:
In the cell body, ciliary proteins are synthesized and must be Transported to the tip of the axoneme. By Intraflagellar Transport (IFT), this is achieved by an ordered and highly regulated anterograde and retrograde translocation of polypeptide complex particles.