Physiology of salivary glands

• what type of glands are salivary glands?

  exocrine glands
• what is an exocrine gland?


  A gland that makes substances and releases them through a duct or opening to a body surface.
• Where do the major & minor salivary glands secrete onto?

  The surface of the mouth
• Where are the minor salivary glands located?

  In the submucosal surface of the oral mucosa (unlike the major salivary glands)
• How big are minor salivary glands?

  1-2mm in diameter
• What are tubarial glands?

  Newly discovered pair of salivary glands located in the nasopharynx
• What are the 3 pairs of major salivary glands?

  - Parotid

  - Submandibular

  - Sublingual

  
• where are the parotid glands?

  near the ears
• where are the submandibular glands?

  beneath the lower jawbone.
• where are the sublingual glands?

  beneath the tongue.
• what is the ductal system of a salivary gland?


  the network of ducts that carry saliva from the glandular tissue to the oral cavity, where it is released
• describe the ductal system of the submandibular gland

  - has ducts called Wharton's ducts

  - Wharton's ducts open into the mouth on either side of the frenulum under the tongue.
• describe the ductal system of the parotid gland

  - has ducts known as Stensen's ducts

  - Stensen's ducts open into the mouth near the upper second molar teeth.
• describe the ductal system of the sublingual gland

  They have numerous small ducts called the ducts of Rivinus

  
  

  - the Bartholin's duct is the largest sublingual duct and it opens into the mouth along the floor of the mouth.
• what do ductal systems look like?

  ductal trees with acini secretory units that produce saliva at the end of fine ducts

  
• what do Sialograms allow us to see?

  Sialograms are imaging studies used to visualize the salivary ductal system and the salivary glands.

  
  

  They involve the injection of a contrast dye into the ducts of the salivary glands followed by X-ray or other imaging techniques such as computed tomography (CT) or magnetic resonance imaging (MRI).

  
• Which cells produce saliva?

  Acinar cells
• What are acinar cells filled with?

  Secretory granules which contain the salivary proteins
• Where do acinar cells secrete saliva to?

  the intercalated ducts

  -> the saliva makes its way through the ductal system, passing through the striated ducts, & into the excretory ducts

  
• Why are striated ducts named as such?

  Because they have invaginations of the basal plasma membrane & they're quite rich in mitochondria
• What is the function of myoepithelial cells?

  To stabilise the acinus when it secretes; it prevents the acinar cells from becoming expanded as a result of the pressure that builds up in the acinus
• What are acinar cells surrounded by?

  Myoepithelial cells
• salivary reflex

  
  

  Is salivary secretion a reflex?

  yes

  ( it is an involuntary response to a stimulus)
• salivary reflex

  
  

  what are the stages of the salivary reflex?

  1. Stimulus

  2. Sensory Input

  3. Central Processing

  4. Motor Response

  5. Saliva Secretion

  6. Response Termination
• salivary reflex - 1. Stimulus

  
  

  what stimuli stimulate the salivary reflex?

  - gustatory (taste)

  - masticatory (chewing)

  - olfactory (smell)

  - thermoreceptive (temperature)

  - nociceptive (harm)

  
• salivary reflex- 1. Stimulus

  
  

  what are the stimuli detected by?

  sensory receptors located in the mouth, nose, and sometimes even in the brain.
• salivary reflex- 2. Sensory Input

  
  

  what happens once the receptors detect the stimulus?

  - The receptors send nerve impulses to the brain.

  - The impulses travel along sensory nerves to specific regions in the brain responsible for processing sensory information, including the brainstem and cerebral cortex.
• salivary reflex- 2. Sensory Input

  
  

  Where do afferent signals go to in the salivary reflex?

  Nucleus of the solitary tract (brainstem)
• salivary reflex- 3. Central Processing

  
  

  what happens in the brainstem when it receives signals from receptors to trigger salivation?

  In the brainstem, particularly in the medulla oblongata:

  
  

  - Sensory information is processed

  - The brainstem then sends signals to the salivary glands to initiate saliva production and secretion
• salivary reflex- 4. Motor Response

  
  

  what nerves carry the signals from the brain stem to the salivary glands after central processing?

  Motor nerves
• salivary reflex- 4. Motor Response

  
  

  where exactly do the motor nerves in the CNS deliver signals?

  - the inferior & superior salivary nuclei

  OR

  - down the thoracic spinal cord
• salivary reflex- 4. Motor Response

  
  

  What happens when the signal reaches the salivary nuclei?

  From there, there are efferent parasympathetic nerves which deliver signals to the different major glands
• salivary reflex- 4. Motor Response

  
  

  What happens when the signal goes down the thoracic spinal cord?

  From there, there are efferent sympathetic nerves which deliver signals to the submandibular & parotid glands
• salivary reflex- 4. Motor Response

  
  

  What happens once all the signals reach the major salivary glands?

  Saliva is secreted

  
• salivary reflex- 4. Motor Response

  
  

  What is special about the parasympathetic and sympathetic nerves in the salivary reflex?

  They work collaboratively, rather than against each other
• salivary reflex- 4. Motor Response

  
  

  What type of innervation do the different major glands receive in the salivary reflex for secretion?

  Submandibular- parasympathetic & sympathetic

  Parotid- parasympathetic & sympathetic

  Sublingual- parasympathetic
• salivary reflex- 4. Motor Response

  
  

  What innervates the acini, myoepithelial & ductal cells?

  Autonomic nerves
• salivary reflex- 4. Motor Response

  
  

  Summarise the effects of the ANS during the salivary reflex


  -> stimuli from sympathetic nerves are responsible for most of the protein secretion

  -> stimuli from parasympathetic nerves are responsible for most of the fluid secretion

  
• salivary reflex- 4. Motor Response

  
  

  how d o the autonomic nerves also control blood flow through blood vessels?


  - provides fluid (water) for saliva

  - provides energy for secretory process
• salivary reflex- 4. Motor Response

  
  

  What is the primary neurotransmitter for parasympathetic nerves?

  Acetylcholine