Mucins MUC5AC and MUC5B in the Airways: MUCing around Together

Upper respiratory tract disorders, including viral infections and allergic rhinitis, cause significant discomfort and disrupt daily life. Managing these conditions involves a variety of drugs, such as antihistamines, intranasal steroids, decongestants, antitussives, expectorants, and mucolytics. Specific examples of drugs in each category are provided.
Antihistamines (e.g., Benadryl) block histamines from binding. Histamines are chemicals released during an allergic reaction in the body. As a...

The gastric glands contain parietal cells that secrete hydrochloric acid (HCl) for digestion. The cells secrete HCl because it is highly corrosive and essential for breaking down food. To achieve this, they secrete hydrogen and chloride ions into the lumen of the gastric glands, which combine to form HCl.
Within parietal cells, carbonic acid is first formed through the reaction of water and carbon dioxide. The dissociation of carbonic acid releases bicarbonate and hydrogen ions. The bicarbonate...

The skin and mucous membranes serve as the primary line of defense against pathogens by providing both physical and chemical protection. These barriers are essential in preventing the entry and establishment of microbes, thereby maintaining the integrity of the host.
The outer layer of the skin, the epidermis, is a robust barrier comprising layers of closely packed keratinized cells. This dense arrangement prevents microbes from penetrating the body. The periodic shedding of epidermal cells...

The human bronchi and bronchial tree play a crucial role in the respiratory system, facilitating the exchange of oxygen and carbon dioxide. Let's delve into the intricate structure and functions of these respiratory components.
The trachea, commonly known as the windpipe, is a tube that connects the larynx (voice box) to the bronchi. At a point called the carina, it bifurcates into two primary bronchi. The right primary bronchus is wider, shorter, and more vertical than the left primary...

Respiratory symptoms, such as congestion and cough, commonly accompany respiratory tract conditions. Various medications, such as antitussives, expectorants, and mucolytics, play crucial roles in providing relief.
Antitussives include codeine, dextromethorphan (Robitussin), and benzonatate (Tessalon). Codeine and dextromethorphan exert their effects centrally by suppressing the cough reflex center in the medulla.  Benzonatate operates peripherally within the respiratory tract by...

The pharmacological actions of acetylcholine are elicited via its binding to two families of cholinergic receptors or cholinoceptors, namely, muscarinic and nicotinic receptors. Muscarinic receptors are G protein-coupled receptors and have five subtypes, M1–M5. All mAChR subtypes are activated by acetylcholine and blocked by the antagonist, atropine. 
The subtypes M1, M3, and M5 couple with the Gq subunit and activate the phospholipase C (PLC) activity, mobilizing intracellular Ca2+....