Digestive System I: Oral Cavity and Salivary glands. Overview A. The digestive system comprises the oral region and alimentary canal (esophagus, stomach, small and large intestines), and several extrinsic glands.
PowerPoint Slideshow about ' Digestive System I: Oral Cavity and Salivary glands' - kaye-lester
An Image/Link below is provided (as is) to download presentation
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
It is covered in most places by a stratified squamous epithelium whose epithelial ridges interdigitate with tall connective tissue papillae (connective tissue ridges) of the subjacent connective tissue.
The lips are divided into an external region, a vermilion zone, and an internal region.
The first two regions are covered by stratified squamous keratinized epithelium, whereas the internal region is lined by stratified squamousnonkeratinized epithelium.
A dense irregular connective tissue core envelops skeletal muscle.
Sebaceous glands, sweat glands, and hair follicles are present in the external region; minor salivary glands in the internal region; and occasional, nonfunctional sebaceous glands in the internal region and vermilion zone.
They are located on the dorsal surface of the anterior two thirds of the tongue.
a. Filiform papillae are short, narrow, highly keratinized structures lacking taste buds.
b. Fungiform papillae are mushroom-shaped structures interspersed among the filiform papillae; they contain occasional taste buds.
c. Foliate papillae are shallow, longitudinal furrows located on the lateral aspect of the posterior region of the anterior two thirds of the tongue. Their taste buds degenerate shortly after the second year of life.
d. Circumvallate papillae are 10 to 15 large, circular papillae, each of which is surrounded by a moat-like furrow. They are located just anterior to the sulcusterminalis and possess taste buds.
The major salivary glands consist of three paired exocrine glands: the parotid, submandibular, and sublingual.
Function. They synthesize and secrete salivary amylase, lysozyme, lactoferrin, and a secretory component, which complexes with immunoglobulin A (lgA) (produced by plasma cells in the connective tissue), forming a complex that is resistant to enzymatic digestion in the saliva.
They also release kallikrein into the connective tissue.
This enzyme enters the bloodstream, where it converts kininogens into the vasodilator, bradykinin.
a. Salivary gland acini consist of pyramid-shaped serous or mucous cells arranged around a central lumen that connects with an intercalated duct. Mucous acini may be overlain with a crescent-shaped collection of serous cells called serous demilunes.
b. They possess myoepithelial cells that share the basal lamina of the acinar cells.
c. They release a primary secretion that resembles extracellular fluid. This secretion is modified in the ducts to produce the final secretion.
d. Salivary glands are classified according to their types of salivary gland acini.
a. Intercalated ducts originate in the acini and join to form striated ducts. They may deliver bicarbonate ions into the primary secretion.
b. Striated (intralobular) ducts
(1) Striated ducts are lined by ion-transporting cells that remove sodium and chloride ions from the luminal fluid (via a sodium pump) and actively pump potassium ions into it.
(2) In each lobule, they converge and become the interlobular (excretory) ducts, which run in the connective tissue septa. These ducts drain into the main duct of each gland, which empties into the oral cavity.