GI Physiology 2 Flashcards
Types of saliva
Serous
Mucus
Types of saliva - Serous
Watery product that contains salivary enzymes such as alpha amylase
Types of saliva - Mucus
Product that contains water, electrolytes, phospholipids, and mucin
Types of saliva - Mucus contains mucin which
Is a highly glycosylated protein with multiple functions
It can coat and protect the oral mucosa and esophagus
Secretion of water and enzymes - Salivary secretion is primarily regulated by
Neuronal input
Secretion of water and enzymes - Key stimulus for salivary secretion of acinar cells is what
Ach
Secretion of water and enzymes - Ach promotes
the secretion of both enzymes and fluid/electrolytes by regulating secretory vesicles and chloride ion channels
Secretion of water and enzymes - The fluid secreted into the lumen of the acinar cell is
isotonic - so the concentration is the same in the lumen as it is in the plasma
The tonicity will change as the fluid moves through the duct though
Change in tonicity and fluid retention - As salivary fluid moves through the duct..
the tonicity of the fluid will change
In general, the salivary glands will secrete a hypotonic solution
Change in tonicity and fluid retention - the change in tonicity is accomplished by
the reabsorption of NaCl and secretion of KHCO3
So a solution low in NaCl and rich in KHCO3 is secreted
Change in tonicity and fluid retention - Water
is retained and not absorbed in the lumen of the duct because the ductal cells express tight junction proteins that decrease the permeability of water
Secretory products of the salivary glands - Key salivary secretions
Alpha amylase Immunoglobulin A Lysozyme Lactoferrin Mucin H20, Na, K, Cl HCO3
Secretory products of the salivary glands - Key salivary secretions - Alpha amylase function
Starch digestion
Secretory products of the salivary glands - Key salivary secretions - IgA, Lysozyme, Lactoferrin function
Maintain oral hygiene via antimicrobial properties
Secretory products of the salivary glands - Key salivary secretions - Mucin
Lubrication and protection of oral mucosa
Secretory products of the salivary glands - Key salivary secretions - H20, Na, Cl, K
Lubrication for mastication and swallowing
Taste/smell
Speech
Secretory products of the salivary glands - Key salivary secretions - HCO3
Neutralize gastric acid reflux
Swallowing - beginning and end of GI you have ___ ____
voluntary control
Swallowing - mm in upper 1/3 vs. lower 2/3
Upper 1/3 is striated muscle
Lower 2/3 is smooth muscle
Both somatic and autonomic regulation of mm in the esophagus
Swallowing - primary and secondary peristalsis - Primary
Initiated with swallowing and will move the contents from the oral cavity all the way to the stomach
Vagus mediates it
Stimulus sensed by mechanoreceptors
Ach induces contraction and NO allows for distal relaxation
Swallowing - primary and secondary peristalsis - Secondary
When primary is not enough you will stimulate this at the site of distention (within the esophagus) and will keep happening until the boluis is moved from that region and to the stomach
ENS mediates this!
Stimulus sensed by mecho or chemo and ENS coordinates release of Ach and NO to get contraction upstream of the bolus (Ach) and relaxation downstream of the bolus (NO)
Pathophysiology of GERD - characterized by…..
Characterized by the reflux of the gastric contents into the esophagus
Can lead to inflammation of the mucosal surface of the esophagus
Pathophys of GERD - what can cause GERD
Delayed gastric emptying
Inc frequency of transient LES relaxations
Inc acidity
Loss of secondary peristalsis following transient LES relaxations
Dec LES tone
Pathophys of GERD - what can cause GERD - Delayed gastric emptying
The longer contents sit in the stomach, the more liklihood that they are able to move the other way - so when the sphincter relaxes, they can move up into the esophagus
Pathophys of GERD - what can cause GERD - inc freq of transient LES relaxations
we all have some level of this but people differ in the how freq it relaxes and the more it relaxes, the more susceptible you are to reflux disease
Pathophys of GERD - what can happen if GERD is not treated
Scarring and then further damage to LES - recurrent injury
Can lead to stricture, dysphagia, obstruction, perforation, internal bleeding, and eventually pre cancerous
Spontaneous relaxation of the LES as a cause for GERD
pH of LES drops suggesting that acid is coming up into the esophagus and causing damage
Barrett’s esophagus is what
Characterized by the replacement of squamous epithelial cells with columnar epithelial cells giving the surface a dark red appearance
So you have a group of cells where they are not supposed to be and they are not under their appropriate regulation
Associated with an ins risk in the development of esophageal CA
Possible tx for GERD (pharm)
Proton pump inhibitor - will block acid secretions
Ex - prilosec
