Question

A lubricant mucin, in saliva is made up of (a) polyunsaturated fats (b) actin and myosin (c) glycoproteins (d) phospholipids.

Short answer

Mucins in saliva are made up of (c) glycoproteins.

Step-by-step solution

Identify the Composition of Mucins

Mucins are large glycoproteins that are the main component of mucus. They are formed from a protein backbone with many carbohydrate groups attached to it. They are not composed of fats or muscle proteins like actin and myosin.

Eliminate Incorrect Answers

Based on the composition of mucins, we can rule out (a) polyunsaturated fats and (b) actin and myosin, as these are not components of mucins. Phospholipids (d) are components of cell membranes and not typically associated with mucins.

Select the Correct Answer

Knowing that mucins are made from carbohydrate-rich proteins, we can conclude that (c) glycoproteins is the correct answer since it best matches the description of mucins.

Key concepts

Glycoproteins in Saliva

Understanding glycoproteins is crucial when studying the nature of saliva and its functions. Glycoproteins are macromolecules that play significant roles in the body, especially in the formation of saliva. These molecules are essentially proteins that have carbohydrate groups attached to them through a process called glycosylation.

Glycoproteins in saliva, particularly mucins, are responsible for the lubrication and protection of the oral cavity. Their structure allows them to form a slick, viscous layer that coats the mouth, aiding in speech, swallowing, and the initial stages of digestion. More than just facilitating movement, they help protect the lining of the mouth from mechanical damage, pathogens, and toxins. To make learning about glycoproteins more tangible, think of them as tiny biological brushes, sweeping and trapping unwanted particles, thereby keeping the mouth clean and moist.

Composition of Mucus

Mucus is a slimy substance that serves many purposes throughout the human body, with its composition being essential to its function. Primarily made up of water, mucins, and various other components, mucus acts as a protective barrier and a lubricant in many parts of the body, including the mouth, nose, lungs, and digestive tract.

At the core of mucus lies mucins, which, as we've discussed, are glycoproteins with a high carbohydrate content. These carbohydrates are negatively charged, which attracts water molecules, keeping mucus moist. This characteristic also enables mucus to trap dust, bacteria, and other foreign particles, preventing them from entering the body's systems. Additionally, certain ions and immune cells are scattered throughout the mucus, providing further defense against invading pathogens. Considering its importance, an exercise improvement advice for students would be to visualize mucus as a sticky security guard that not only blocks harmful agents but also ensures smooth operations within our body systems.

Biology of Salivary Glands

The salivary glands are key players in the production of saliva. They are exocrine glands, which means they secrete substances through ducts to the site of action—in this case, the oral cavity. Humans typically have three pairs of major salivary glands: the parotid, submandibular, and sublingual glands, each contributing differently to the saliva composition.

The salivary glands produce saliva through a network of cells designed to synthesize the various components like enzymes, electrolytes, and, most notably, glycoproteins such as mucins. Their activity is controlled by both the parasympathetic and sympathetic nervous systems, which can adjust the flow and composition of saliva in response to various stimuli, such as the sight or smell of food. An interesting feature about these glands worth emphasizing is the fact that their secretions can change—becoming thicker and more mucous-like or thinner and more watery—depending on the body's needs. For students aiming to truly grasp the biology behind these glands, consider them as customized fluid factories, adapting their production to optimize digestion and oral health.