Kelenjar liur

Kelenjar liur

Kelenjar liur: #1 adalah Kelenjar Parotis, #2 adalah Kelenjar Submandibula, #3 adalah

Kelenjar Sublingua

Latin glandulae salivariae

Kelenjar liur atau kelenjar ludah pada mamalia adalah kelenjar eksokrin, yaitu kelenjar yang mempunyai saluran sendiri, yang memproduksi air liur. Kelenjar ini juga menyekresi amilase, enzim yang memecah karbohidrat menjadi maltosa. Pada organisme lain seperti serangga, kelenjar ini sering digunakan untuk memproduksi protein yang penting secara biologis, seperti sutra atau lem. Kelenjar liur lalat mengandung kromosom politenol yang berguna dalam riset genetik.

Kelenjar ini pada manusia terdapat di bawah lidah. Produksi air ludah dapat terganggu apabila terjadi dehidrasi, panas dalam, atau disebabkan oleh suatu penyakit.

Daftar isi

 [sembunyikan]

1 Anatomio 1.1 Kelenjar Parotiso 1.2 Kelenjar Submandibulao 1.3 Kelenjar Sublinguao 1.4 Kelenjar Liur Minor

2 Inervasi3 Lihat pula4 Catatan

]Anatomi]Kelenjar ParotisKelenjar parotis adalah kelenjar-liur yang terbesar. Ia dikelilingi oleh ramus mandibula dan menyekresikan air liur melalui Duktus Stensen menuju kavum oral untuk membantu mengunyah dan menelan.

[sunting]Kelenjar SubmandibulaKelenjar Submandibula adalah sepasang kelenjar yang terletak di rahang bawah, di atas otot digatrik. Produksi sekresinya adalah campuran serous dan mukous dan masuk ke mulut melalui duktus Wharton. Walaupun lebih kecil daripada kelenjar parotis, sekitar 70% saliva di kavum oral diproduksi oleh kelenjar ini.

[sunting]Kelenjar SublinguaKelenjar Sublingua adalah sepasang kelenjar yang terletak di bawah lidah di dekat kelenjar submandibula. Sekitar 5% air liur yang masuk ke kavum oral keluar dari kelenjar ini.

[sunting]Kelenjar Liur MinorTerdapat lebih dari 600 kelenjar liur minor yang terletak di kacum oral di dalam lamina propria mukosa oral. Diameternya 1-2mm. Kelenjar ini biasanya merupakan sejumlah asinus yang terhubung dalam lobulus kecil. Kelenjar liur minor mungkin mempunyai saluran ekskresi bersama dengan kelenjar minor yang lain, atau mungkin juga mempunyai saluran sendiri. Secara alami, sekresi utamanya adalah mukous (kecuali Kelenjar Von Ebner) dan mempunyai banyak fungsi, seperti membasahi kavum oral dengan saliva. Masalah gigi biasanya berhubungan dengan kelenjar liur minor.[1]

Kelenjar Von Ebner terletak di papilla sirkumvalata lidah. Kelenjar ini mensekresikan cairan serous yang memulai hidrolisis lipid. Kelenjar ini adalah komponen esensial indra perasa.

[sunting]InervasiKelenjar liur diinervasi, baik secara langsung maupun tidak, oleh sistem saraf otonom simpatis dan parasimpatis. Keduanya menghasilkan kenaikan output amilase.

Inervasi parasimpatis kelenjar liur dibawa oleh saraf kranial. Kelenjar parotis menerima input parasimpatisnya dari nervus

glossopharingeus (N IX) melalui ganglion otikum, sedangkan kelenjar submandula dan sublingua menerima input parasimpatisnya dari nervus facialis (N VII) melalui ganglion submandibula. Saraf ini melepaskan asetilkolin dan substansi P, yang masing-masing mengaktifkan jalur IP3 dan DAG.

Inervasi langsung simpatis kelenjar liur terjadi melalui nervus preganglion di segmen thorak TI-III yang bersinap di ganglion servikalis superior dengan neuron postganglion yang melepaskan norepinefrin, yang kemudian diterima oleh reseptor β-adrenergic di sel duktus dan asiner kelenjar lir. Efeknya adalah peningkatan sekresi air liur.

Perlu diperhatikan bahwa stimulus simpatis maupun parasimpatis berakibat pada peningkatan sekresi kelenjar liur. Sistem saraf simpatis juga memengaruhi sekresi kelenjar liur secara tidak langsung dengan menginervasi pembuluh darah kelenjar.

[sunting]Lihat pula

Air ludah Lidah Mulut

Salivary Glands and Saliva

Salivary Glands

Saliva is produced in and secreted from salivary glands. The basic secretory units of salivary glands are clusters of cells called an acini. These cells secrete a fluid that contains water, electrolytes,mucus and enzymes, all of which flow out of the acinus into collecting ducts.

Within the ducts, the composition of the secretion is altered. Much of the sodium is actively reabsorbed, potassium is secreted, and large quantities of bicarbonate ion are secreted. Bicarbonate secretion is of tremendous importance to

ruminants because it, along with phosphate, provides a critical buffer that neutralizes the massive quantities of acid produced in the forestomachs. Small collecting ducts within salivary glands lead into larger ducts, eventually forming a single large duct that empties into the oral cavity.

Most animals have three major pairs of salivary glands that differ in the type of secretion they produce:

parotid glands produce a serous, watery secretion

submaxillary (mandibular) glands produce a mixed serous and mucous secretion

sublingual glands secrete a saliva that is predominantly mucous in character

The basis for different glands

secreting saliva of differing composition can be seen by examining salivary glands histologically. Two basic types of acinar epithelial cells exist:

serous cells, which secrete a watery fluid, essentially devoid of mucus

mucous cells, which produce a very mucus-rich secretion

Acini in the parotid glands are almost exclusively of the serous type, while those in the sublingual glands are predominantly mucous cells. In the submaxillary glands, it is common to observe acini composed of both serous and mucous epithelial cells.

In the histologic sections of canine salivary gland shown above, the cells stained pink are serous cells, while the white, foamy cells are mucus-secreting cells.

Secretion of saliva is under control of the autonomic nervous system, which controls both the volume and type of saliva secreted. This is actually fairly interesting: a dog fed dry dog food produces saliva that is predominantly serous, while dogs on a meat diet secrete saliva with much more mucus. Parasympathetic stimulation from the brain, as was well demonstrated by Ivan Pavlov, results in greatly enhanced

secretion, as well as increased blood flow to the salivary glands.

Potent stimuli for increased salivation include the presence of food or irritating substances in the mouth, and thoughts of or the smell of food. Knowing that salivation is controlled by the brain will also help explain why many psychic stimuli also induce excessive salivation - for example, why some dogs salivate all over the house when it's thundering

Functions of Saliva

What then are the important functions of saliva? Actually, saliva serves many roles, some of which are important to all species, and others to only a few:

Lubrication and binding: the mucus in saliva is

extremely effective in binding masticated food into a slippery bolus that (usually) slides easily through the esophagus without inflicting damage to the mucosa. Saliva also coats the oral cavity and esophagus, and food basically never directly touches the epithelial cells of those tissues.

Solubilizes dry food: in order to be tasted, the molecules in food must be solubilized.

Oral hygiene: The oral cavity is almost constantly flushed with saliva, which floats away food debris and keeps the mouth relatively clean. Flow of saliva diminishes considerably during sleep, allow populations of bacteria to build up in the mouth -- the result is dragon breath in the morning. Saliva also contains lysozyme, an enzyme that lyses many bacteria and prevents

overgrowth of oral microbial populations.

Initiates starch digestion: in most species, the serous acinar cells secrete an alpha-amylase which can begin to digest dietary starch into maltose. Amylase does not occur in the saliva of carnivores or cattle.

Provides alkaline buffering and fluid: this is of great importance in ruminants, which have non-secretory forestomachs.

Evaporative cooling: clearly of importance in dogs, which have very poorly developed sweat glands - look at a dog panting after a long run and this function will be clear.

Diseases of the salivary glands and ducts are not uncommon in animals and man, and excessive salivation is a symptom of

almost any lesion in the oral cavity. The dripping of saliva seen in rabid animals is not actually a result of excessive salivation, but due to pharyngeal paralysis, which prevents saliva from being swallowed.