Final answer:
Cilia are short, hair-like structures found on eukaryotic cells, used for locomotion and movement of extracellular particles. They have a 9+2 microtubule arrangement, are numerous on the cell surface, and differ from flagella which are fewer and longer. They are essential in the respiratory tract, brain ventricles, Fallopian tubes, and in protists like ciliates.
Step-by-step explanation:
Important Characteristics of Cilia
Cilia (singular: cilium) are short filamentous structures found on the surface of some eukaryotic cells. Each cilium is composed of microtubules arranged in a characteristic 9+2 array and is anchored to the cell by a basal body. Ciliated epithelial cells line various parts of the body where they play a role in locomotion, feeding, and the movement of extracellular particles across the cell surface.
For example, in the respiratory tract, ciliated epithelial cells beat rhythmically to push mucus secretions and trapped debris away from the lungs. This process is referred to as a mucociliary escalator. Additionally, cilia are found on the surface of ciliates, a group of protists that use these structures for locomotion and feeding. Moreover, cilia are also present in the ventricles of the brain, where they help circulate cerebrospinal fluid, and in the Fallopian tubes, aiding in the movement of the ovum towards the uterus.
It is important to differentiate cilia from flagella; cilia are short and numerous whereas flagella are longer and typically fewer in number. Both structures share a common framework involving microtubules and motor proteins such as dynein and kinesin which facilitate their motion.