Salivary gland (Endocrine system)
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The salivary glands in are that produce . They also secrete , an that breaks down into . In other organisms such as , salivary glands are often used to produce biologically important proteins like or glues, and salivary glands contain that have been useful in research.
The glands are enclosed in a capsule of and internally divided into . Blood vessels and nerves enter the glands at the and gradually branch out into the lobules.
In the duct system, the lumens formed by , which in turn join to form . These drain into ducts situated between the lobes of the gland (called or excretory ducts).
All of the human salivary glands terminate in the mouth, where the saliva proceeds to aid in digestion. The saliva that salivary glands release is quickly inactivated in the stomach by the acid that is present there.
The salivary glands are situated at the entrance to the to help begin the process of digestion.
The are a pair of glands located in the of the face overlying the and anterior and inferior to the . The secretion produced by the parotid glands is in nature, and enters the through the after passing through the which are prominent in the gland. Despite being the largest pair of glands, only approximately 25% of saliva is produced by the glands.
The are a pair of glands located beneath the floor of the mouth, superior to the . The secretion produced is a mixture of both and and enters the via . Approximately 70% of saliva in the oral cavity is produced by the submandibular glands, even though they are much smaller than the .
The are a pair of glands located beneath the floor of the mouth anterior to the . The secretion produced is mainly in nature, however it is categorized as a mixed gland. Unlike the other two major glands, the ductal system of the sublingual glands do not have striated ducts, and exit from 8-20 excretory ducts. Approximately 5% of saliva entering the oral cavity come from these glands.
Minor Salivary Glands
There are over 600 minor salivary glands located throughout the within the of the . They are 1-2mm in diameter and unlike the other glands, they are not encapsulated by only surrounded by it. The gland is usually a number of connected in a tiny lobule. A minor salivary gland may have a common excretory duct with another gland, or may have its own excretory duct. Their secretion is mainly mucous in nature (except for ) and have many functions such as coating the oral cavity with . Problems with dentures are usually associated with minor salivary glands.
Von Ebner's Glands
are glands found in of the tongue. They secrete a serous fluid that begin lipid hydrolysis. They are an essential component of .
Salivary glands are innervated, either directly or indirectly, by the and arms of the .
Parasympathetic innervation to the salivary glands is carried via . The receives its parasympathetic input from the (CN IX) via the , while the submandibular and sublingual glands receive their parasympathetic input from the (CN VII) via the .
Direct sympathetic innervation of the salivary glands takes place via preganglionic nerves in the thoracic segments T1-T3 which synapse in the superior cervical ganglion with postganglionic neurons that release norepinephrine, which is then received by в-adrenergic receptors on the acinar and ductal cells of the salivary glands, leading to an increase in cyclic adenosine monophosphate (cAMP) levels and the corresponding increase of saliva secretion. Note that in this regard both parasympathetic and sympathetic stimuli result in an increase in salivary gland secretions. The sympathetic nervous system also affects salivary gland secretions indirectly by innervating the that supply the glands.
Role in disease
may cause blockage of the ducts, causing pain and swelling of the gland.
Tumors of the salivary glands may occur.