Salivary Glands Overview

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Questions and Answers

What is the primary function of secretion from the parotid gland?

Production of saliva low in viscosity

Production of profuse watery saliva (correct)

Production of saliva with low electrolyte content

Production of saliva high in organic materials

Which nerve is associated with the parasympathetic supply to the parotid gland?

Trigeminal nerve

Glossopharyngeal nerve (correct)

Vagus nerve

Facial nerve

Which of the following acts as a cotransmitter with acetylcholine in some postganglionic parasympathetic neurons?

Serotonin

Substance P

Neuropeptide Y

VIP (correct)

What role do buffers in saliva play regarding oral health?

They maintain a stable oral pH around 7.0 Signup and view all the answers

Which of the following stimuli can trigger the secretion of saliva as an unconditioned reflex?

Taste sensations from food Signup and view all the answers

What is the consequence of atropine or other cholinergic blocking agents on salivary secretion?

Reduces salivary secretion Signup and view all the answers

Which component of saliva is important for neutralizing acidic conditions in the mouth?

Buffers Signup and view all the answers

Which kind of secretion is characterized by a secretion of a small amount of saliva rich in organic constituents?

Submandibular saliva Signup and view all the answers

Which type of secretion is primarily secreted by the parotid glands?

Watery secretion Signup and view all the answers

What percentage of saliva is secreted by submandibular glands?

70% Signup and view all the answers

What is the primary composition of saliva?

Proteins and electrolytes Signup and view all the answers

How is salivary secretion primarily controlled?

Nervous control Signup and view all the answers

What happens during the secondary stage of salivary secretion in the ducts?

Bicarbonate ions are actively secreted into duct lumen Signup and view all the answers

What ion is actively reabsorbed in the salivary ducts, resulting in lower concentrations in the saliva?

Sodium ions Signup and view all the answers

Which cells in the acini secrete the primary secretion containing the enzyme ptyalin?

Serous cells Signup and view all the answers

What type of innervation do salivary glands receive primarily from the parasympathetic nervous system?

Sublingual and submaxillary glands supply Signup and view all the answers

Study Notes

Salivary Glands

Three pairs of glands produce saliva: parotid, submandibular, and sublingual glands.
There are also buccal glands.
The glands contain acini that secrete a primary secretion
- Serous cells in the acini secrete a watery solution that contains ptyalin (α amylase enzyme)
- Mucous cells in acini secrete a viscous solution containing mucin
Salivary ducts open into the oral cavity.

Types of Salivary Glands

Parotid glands acini are serous and make up 25% of saliva.
Sublingual glands acini are mucous and make up 5% of saliva.
Submandibular glands acini are mixed and make up 70% of saliva.
Buccal glands secrete only mucous.

Salivary Secretion

Saliva volume is ~ 1500 ml per day
Resting saliva pH is approximately 7.0.
Saliva contains:
- Proteins: ptyalin (enzyme) and mucin (protein)
- Electrolytes: K+, HCO3-, Na+, Cl-
Saliva is hypotonic.
Aldosterone plays a role in electrolyte balance.
Salivary secretion is regulated by the autonomic nervous system (ANS).

Mechanism of Secretion

Primary secretion occurs in the acini and contains ptyalin/mucin in solution.
Secondary secretion takes place in the salivary ducts.
Na+ is actively reabsorbed in the ducts, while K+ is simultaneously actively secreted.
Na+ reabsorption is greater than K+ secretion.
Cl- is passively reabsorbed.
Na+ and Cl- concentrations are reduced, while K+ concentration increases within salivary ducts.
HCO3- is actively secreted into duct lumen
Ducts are mostly impermeable to water which makes saliva hypotonic.

Innervation

Salivary glands are innervated by both parasympathetic and sympathetic fibers.
Parasympathetic fibers originate from:
- Superior salivary nucleus (medulla) for sublingual and submaxillary glands.
- Inferior salivary nucleus (medulla) for the parotid gland.
Sympathetic fibers originate from the lateral horn of the first and second thoracic segments.

Parasympathetic Innervation

Sublingual and submaxillary glands:
- Chorda Tympani (facial nerve)
- Submandibular ganglion.
Parotid gland:
- Glossopharyngeal nerve
- Otic ganglion.

Sympathetic Innervation

Origin: lateral horn cells of the first and second thoracic segments.
Relay: superior cervical ganglion.
Postganglionic fibers supply all salivary glands.

Functional Differences

Parasympathetic stimulation:
- Profuse watery saliva secretion.
- High electrolyte content with relatively low organic material.
- Marked vasodilation caused by vasoactive intestinal peptide (VIP).
Sympathetic stimulation:
- Vasoconstriction.
- Secretion of small amount of saliva rich in organic material.
- VIP is a cotransmitter with acetylcholine in some postganglionic parasympathetic neurons.

Control of Salivary Secretion

Salivary secretion is influenced by:
- Conditioned reflexes: sights, smells, sounds, and thoughts of food.
- Unconditioned reflex: presence of food in the mouth (taste, touch, temperature).
The appetite area in the hypothalamus receives signals from the taste and smell areas of the cerebral cortex.

Functions of Saliva

Protection of oral mucosa:
- Cooling hot foods
- Neutralizing acids: saliva buffers maintain a pH of approximately 7.0.
- Maintaining oral hygiene:
  - Washing away bacteria and food remnants.
  - Lysozyme attacks bacterial walls.
  - Antibodies (IgA) destroy pathogens
  - Lactoferrin has bacteriostatic effects
Teeth Protection:
- Buffers in saliva maintain oral pH at ~7.0. This pH prevents teeth from losing calcium which leads to dental caries.
- Fluoride protects tooth enamel.

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Description

Explore the structure and function of the salivary glands in this quiz. Discover details about the parotid, submandibular, and sublingual glands, as well as their secretion processes and compositions. Test your knowledge on saliva's role in digestion and its physiological properties.