Upper Respiratory — 7-topic bundle

Your upper respiratory tract includes your nose, nasal cavity, pharynx (throat), and larynx (voice box). Its primary job isn't just to let air in, but to filter, warm, and humidify that air before it reaches your lungs, and to protect you from inhaled threats.

Let's break down the key defenses and how they relate to symptoms:

Histamine is a chemical messenger (neurotransmitter) found naturally in your body, primarily stored in mast cells and basophils. When released, it binds to specific receptors (H1, H2, H3, H4) to cause various effects. For allergies, the H1 receptor is the most important.