lõhnaepiteeli

Lõhnaepiteel, also known as olfactory epithelium, is a specialized tissue located in the nasal cavity responsible for the sense of smell. It covers a small area of the roof of the nasal cavity, the superior concha, and the nasal septum. This tissue is a pseudostratified columnar epithelium containing several types of cells.

The primary sensory cells within the olfactory epithelium are olfactory receptor neurons. These neurons have cilia that extend into the mucus layer lining the epithelium. Embedded within these cilia are odorant receptors, which are G protein-coupled receptors that bind to airborne odorant molecules. When an odorant molecule binds to a receptor, it triggers a signal transduction cascade, leading to the generation of an electrical signal in the neuron.

In addition to receptor neurons, the olfactory epithelium contains supporting cells (sustentacular cells) that provide structural and metabolic support, basal cells which act as stem cells for the regeneration of olfactory neurons, and brush cells which are believed to have a sensory function but are not directly involved in olfaction. Goblet cells are also present, contributing to the mucus layer that covers the epithelium.

The mucus layer is crucial as it dissolves odorant molecules, allowing them to reach the olfactory receptors. This mucus is constantly replenished by the secretion of serous glands located within the lamina propria beneath the epithelium. The olfactory receptor neurons are unique in that they are among the few neurons in the adult nervous system that are regularly replaced throughout life. Damage to or loss of these neurons can occur due to factors like head trauma or viral infections, but their regenerative capacity allows for the partial restoration of the sense of smell.