Oral mucosa blood supply

Oral mucosae are composed of multiple layers of cells, which show various patterns of differentiation dependent on the functions of different regions in the oral cavity. The oral mucosa is covered by a stratified, squamous epithelium, and three different types of mucosa can be distinguished the masticatory, the lining, and the specialized mucosa. Blood supply to the oral cavity tissues is delivered via the external carotid artery, which branches to the maxiliary lingual and facial artery. There are no mucus-secreting goblet cells in the oral mucosa, but mucins are found in human saliva. These mucins are water-soluble and form a gel of 10-200 pm thickness. Saliva, mainly composed of water (99%), is continuously secreted in the oral cavity and exists as a film with a thickness of 0.07-0.1 mm. ... 

When dealing with oral dosage forms, it is important to study the various changes occurring within the oral cavity, particularly if a buccal or sublingual formulation is being considered. Table 7 lists the changes within the oral cavity that have thus far been elucidated [124,127,138-144], It is very important to note that there is a decrease in the capillary blood supply to the oral mucosa. This may make it difficult to predict accurately the absorption rates that will occur when... 

A rich blood supply and lymphatic network in the lamina propria serve the oral cavity, thus drag moieties which traverse the oral epithelium are readily absorbed into the systemic circulation. The blood flow in the buccal mucosa is 2.4 mL min 1 cm 2 whereas that to the sublingual mucosa is 0.97 mL min-1 cm 2. 

The vascular system and blood supply to the oral mucosa have been clearly described by Stablein and Meyer.Netter s excellent drawings of the blood supply to the mouth and pharynx, venous drainage of the mouth and pharynx, and lymphatic drainage of the mouth and pharynx have been published by Ciba. ... 

Stablein, M.J. Meyer, J. The vascular system and blood supply. In The Structure and Eunction of Oral Mucosa, Meyer, J., Squier, C.A., Gerson, S.J., Eds. Pergamon Press Oxford, 1984 237-256. 

The oral mucosa provides a near-ideal, non-invasive portal of entry into the systemic circulation, on the basis of four main reasons. First, the oral cavity is relatively permeable. Second, the oral mucosa has a very rich blood supply, with many superficial blood vessels, and this makes it... 

The rectal mucosa has a rich blood and lymph supply and, in general, dose requirements are either the same or slightly greater than those needed for oral use. Drugs chiefly enter the portal system, but those that are subject to hepatic first-pass elimination may escape this if they are absorbed from the lower rectum which drains directly to the systemic circulation. The degree of presystemic elimination thus depends on distribution within the rectum and this is somewhat unpredictable. 

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