Flashcards in Exam #5: Mouth & Esophagus Deck (18):
Where is the majority of saliva produced? What are the two types of secretions from the salivary glands?
90% of saliva is produced from the parotid, submandibular, and sublingual salivary glands. Two secretions are:
Describe the composition of the serous portion of saliva.
Serous or watery secretion contains:
Describe the composition of the mucous portion of saliva.
Mucous secretion contains:
*****Mucin has a number of functions, but the primary one is protection of the GI tract by coating the mucosa
Describe the mechanism by which water and salt are secreted into the lumen of the salivary gland. What happens in the duct of the salivary gland?
- ACh stimulation of apical membrane chloride channel
causes secretion of Cl- into the lumen of the salivary duct
- Na+/ H20 follow
- ACh also stimulates the release of a-amylase
- Na+ & Cl- are reabsorbed as fluid moves through the duct
- Water does NOT follow b/c of tight junctions between ductal cells
- Bicarbonate & K+ are secreted
Final product= HYPOTONIC
Identify the composition of saliva and the function of those components.
Saliva functions to:
1) Water-->prevent dehydration of oral mucosa
2) Water & mucin-->Lubrication for swallowing
3) IgA, lysozyme, & lactoferrin-->Oral hygeine
6) HCO3--->neurralize gastric acid
What would happen if the ability to secrete saliva was impaired?
1) Dehydration of oral mucosa
2) Impaired swallowing
3) Higher risk of infection
4) Impaired starch digestion
5) Impaired smell & taste
6) Inability to neutralize reflexed gastric acid
What is the primary stimulus that increases salivary secretion? What are the secondary stimuli?
ACh--ACh is the KEY EZYME for both fluid and enzyme secretion into the salivary fluid, which is why anti-cholinergic drugs-->dry-mouth
1) Substance P
2) NE (paradoxical increases secretion but decreases blood flow)
What are the three phases of swallowing? What happens in each phase?
- tongue pushes against hard palate
- food bolus stimulates touch receptors
- swallowing reflex
- food into pharynx
- soft palate pulled down to prevent nasal reflux
- epiglottis swings down to cover trachea
- UES relaxes
- Peristalsis is initiated
- UES contracts
- primary peristaltic wave moves food into stomach
- IF primary isn't enough, a secondary peristaltic wave is initiated FROM THE SITE OF DISTENSION
What is the role of skeletal muscle in swallowing?
Upper 1/3 of the esophagus is striated muscle that is under "voluntary" control
What is the role of smooth muscle in swallowing
Lower 2/3 of the esophagus is smooth muscle that is under involuntary control of the enteric nervous system
What is the difference between primary & secondary peristalsis in swallowing?
Primary= moves food into the stomach from mouth
Secondary= Occurs from the site of bolus distension
- protective & clears H+ into the stomach
What neurotransmitters coordinate peristalsis?
Motor input is regulated by vagal input onto smooth & striated muscle
- Upstream of bolus= ACh leads to contraction
- Downstream of bolus= NO/VIP cause relaxation that allows clearance
How is the physiology of the mouth & esophagus altered in GERD?
- GERD= reflux of the gastric contents into the esophagus caused by:
1) Delayed gastric emptying
2) Decreased LES tone
3) Transient LES relaxtation
4) Loss of secondary peristalsis following transient LES relaxation
5) Increased acidity that damages the LES
****GERD leads to inflammation of mucosal surface & continued reflux-->ulcer, edema, precancerous lesion, bleeding
How is the physiology of the mouth & esophagus altered in Barrett's Esophagus?
- Barrett's esophagus is characterized by replacement of the esophageal epithelium with gastric epithelium i.e. squamous with columnar due to damage of the squamous from GERD
- This is a cell type in the wrong anatomical location-->lack of proliferative control & neoplasia
How is the physiology of the mouth & esophagus altered in dsyphagia?
Dsyphagia i.e. difficulty swallowing can be separated into two classes of impairment, mechanical or functional:
1) Mechanical= structural e.g. tumor, stricture, herniation caused by:
- Viral infeciton
2) Functional= neuronal
- Achalasia (denervation of esophageal smooth muscle)
How is the physiology of the mouth & esophagus altered in hiatal hernia?
Normally, the stomach sits below the diaphragm; hiatal hernia occurs when weakness in the diaphragm leads to protrusion of the stomach into the thoracic cavity
- Sliding= goes back & forth
- Paraesophageal= stays
Symptoms= reflux esophagitis & vascular disruption
How is the physiology of the mouth & esophagus altered in Sjogren Syndrome?
This is an autoimmune disorder characterized by auto-antibodies directed at the salivary glands; primary symptom is dry mouth