Nasal cavity structure

The sensor response depends not only on the polarity of the analyte, but also on the flow environment. In the mammalian olfactory system, the nasal cavity structure plays an extremely important role in odor discrimination13. 

Fig. 2.8 Turtle schematic TS, accessory structures lower nasal cavity and dorsal bulb region (after Parsons, 1958).

McMartin C, Hutchinson LE, Hyde R, Peters GE (1987) Analysis of structural requirements for the absorption of drugs and macromolecules from the nasal cavity. J Pharm Sci 76 535-540. 

In humans and other mammals, the sense of smell begins when we inhale some odorant through our nose. The inhaled air enters the nasal cavity where it encounters a large number of olfactory neurons located in the nasal epithelium associated with bony structures located at the rear of this cavity. These bony structures are known as turbinates. In a human, these turbinates create a surface area of a few square inches. In a medium-size dog, in contrast, the turbinates have a surface area several times larger. It is small wonder that dogs have a more acute sense of smell than we do. 

The upper respiratory tract, like the nasal cavity, consists of epithelium with columnar structure (30-40 pm thick) that is relatively impermeable to large molecules (Figure 13.4). On the other hand, the deep lung consists of alveolar (air sac) epithelium that is only 0.1 to 0.2 pm thick and substantially more permeable to peptides and proteins. When insuhn (51 aa) and growth hormone (192 aa) are instilled into the deep lung, about 10% to 15% of these therapeutic agents are bioavailable. Because the alveoli surface is large, an estimated... 

Between February 1999 and July 2001, a total number of 96 patients (52 females, 44 males mean age 31 years), suffering from nasal hyperreactivity symptoms, were enrolled from those attending our ENT Department. Inclusion and exclusion criteria were evaluated examining the description of clinical signs and symptoms, the morphological structure of nasal cavities, and causal factors. 

The signs and symptoms considered were rhinorrhea, nasal obstruction and sneezing. The morphological structure of the nasal cavities was examined with anterior rhinoscopy. Skin prick tests, nasal provocation tests, nasal microbiological tests and mucociliary clearance time (MCT) were used to identify the causal factors. The skin prick tests were used to... 

A primary function of the nasal cavity is olfaction. The location of the olfactory mucosa, recessed on the roof of the respiratory passage, means that it is accessed only by diffusion of volatile or airborne substances in inhaled air. The specialized epithelium features sensitive olfactory neurons that provide a direct link to the CNS. The structural features of the epithelium and potential for drug delivery are considered in detail in Section 19.6.1. 

Nasal anatomy and physiology. The nose is the first organ of the respiratory tract. The structure of the nasal cavity is shown in Fig. 2.8. 

Give a general overview of the structure of the nasal cavity... 

Deposition mechanisms in the nose include inertial impaction, sedimentation, diffusion, interception and electrostatic attraction. The structure and physiology of the nasal cavity, with the small cross-section for airflow and sharp curves, suggests that inertial impaction is the most significant mechanism for drag deposition in the nasal cavity. 

The sophisticated structure and specialized function of airways and membranes in the nasal cavity, and also the small surface area of this region, may limit its capacity for drug delivery. The effect of chronic drug exposure on the integrity of nasal membranes must also... 

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