GIT Secretion: Salivary Flashcards
Salivary gland that contributes the most to salivary secretion
Submandibular
contributes to 70% of the salivary secretion
types of Secretory cells in Parotid gland Acini
Serous
types of Secretory cells in Sublingual gland
Mixed (mucoserous)
types of Secretory cells in Submandibular Gland
Mixed (mucoserous)
types of Secretory cells in Small buccal Glands
Mucous
Describe ionic composition of first stage (primary Secretion) of salivary secretion
Ionic composition is same as that of plasma (ECF) with ptyalin & mucin enzymes , therefore It’s Isotonic saliva
Second stage of salivary secretion
It’s the modification of primary secretion at the ducts
1. By sodium potassium pump stimulated by aldosterone, 3 sodium (Na+) reabsorbed in exchange for 2 Potassium (K+)
2. This causes Passive reabsorption of Cl-
3. Bicarbonates is both, Actively secreted into the saliva, and exchanged with Cl- into saliva
4. Due to Decrease in Ionic concentration, Osmosis should occur out of saliva, but doesnt due to impermeability of ducts to water
5. So Saliva (secretion) becomes Hypotonic
Describe what changes in saliva Secondary secretion during parasympathetic stimulation
There is Rapid flow of saliva, therefore:
* Decrease in Ductal modification
* Composition becomes similar to that of Plasma
* Potassium doesnt increase as much
* Bicarbonate may Increase
Enumerate protective function of Saliva to Oral mucosa
- Cooling of hot food
- Neutralization of Acid by buffer (bicarbonate): maintain pH 7 & relieves heartburn in GERD
- Protect against Pathogenic bacteria
Describe how saliva protects against pathogenic Bacteria
- Causes Washing away of bacteria
- contains Lysozymes
- Contains IgA
- Contains Lactoferrin which is Bacteriostatic
Describe how saliva protects the teeth
- Buffers keep pH at 7, where Calcium doesnt dissolve
- Fluoride (added in drinking water) is exerted in saliva protects teeth enamel
- Proline-rich proteins protect teeth enamel & binds to toxic tannins
Explain effect of Xerostomia
it causes dried oral mucosa, resulting in ulceration and dental Caries
When does Salivary amylase is deactivated and reactivated
- Deactivation: in stomach by low pH
- Reactivation: In small intestine by high pH
Lubrication & wetting function of saliva
- Swallowing: lubricates food
- Speech: keep mouth moist
- Taste: acts as solvent for molecules
Parasympathetic Centers of the salivary secretions
- Superior Salivary Nuclei
- Inferior Salivary Nuclei
Efferent of Superior Salivary Nuclei
Chorda tympani of the Facial N, Relay in submandibular Ganglion
Efferent of Inferior Salivary Nuclei
Glossopharyngeal N, relay in the Otic Ganglion
Glands supplied by Chorda tympani (Superior salivary Nucleus)
Sublingual & submandibular gland
Glands Supplied by Glossopharyngeal N (Inferior Salivary Nucleus)
Parotid gland
effect of Parasympathetic NS on Salivary secretion
- Local Release of VIP
- Causes Vasodilatation
- Profuse Secretion of Saliva with High electrolytes & relatively low content of organic material
Parasympathetic innervation of Saliva is inhibited by
Atropine
Center of Sympathetic innervation of Salivary secretion
1 & 2 thoracic segments
effect of Sympathetic innervation on Salivary secretion
Vasoconstriction, Secretion of small amounts of Saliva with high organic content
Stimulus of Unconditional reflex of Salivary secretion
Food in mouth (in Newborns)
Center of Unconditional reflex of Salivary secretion
Superior and Inferior Salivary Nuclei
Stimulus of conditional reflex of Salivary secretion
Thinking of food
Center of conditional reflex of Salivary secretion
- Cerebral Cortex
- Appetite Area in hypothalamus
