Exam #5: Mouth & Esophagus Flashcards

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1
Q

Where is the majority of saliva produced? What are the two types of secretions from the salivary glands?

A

90% of saliva is produced from the parotid, submandibular, and sublingual salivary glands. Two secretions are:

1) Serous
2) Mucous

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2
Q

Describe the composition of the serous portion of saliva.

A

Serous or watery secretion contains:

  • alpha-amylase
  • water
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3
Q

Describe the composition of the mucous portion of saliva.

A

Mucous secretion contains:

  • Water
  • Electrolytes
  • Phospholipids
  • Mucin

*****Mucin has a number of functions, but the primary one is protection of the GI tract by coating the mucosa

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4
Q

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?

A

Water
- 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

Duct

  • 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

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5
Q

Identify the composition of saliva and the function of those components.

A

Saliva functions to:

1) Water–>prevent dehydration of oral mucosa
2) Water & mucin–>Lubrication for swallowing
3) IgA, lysozyme, & lactoferrin–>Oral hygeine
4) Alpha-amylase–>digestion
5) Smell/taste
6) HCO3—>neurralize gastric acid

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6
Q

What would happen if the ability to secrete saliva was impaired?

A

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

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7
Q

What is the primary stimulus that increases salivary secretion? What are the secondary stimuli?

A

ACh–ACh is the KEY EZYME for both fluid and enzyme secretion into the salivary fluid, which is why anti-cholinergic drugs–>dry-mouth

Secondary=

1) Substance P
2) NE (paradoxical increases secretion but decreases blood flow)

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8
Q

What are the three phases of swallowing? What happens in each phase?

A

1) Oral=
- tongue pushes against hard palate
- food bolus stimulates touch receptors
- swallowing reflex

2) Pharyngeal=
- food into pharynx
- soft palate pulled down to prevent nasal reflux
- epiglottis swings down to cover trachea
- UES relaxes
- Peristalsis is initiated

3) Esophageal
- 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

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9
Q

What is the role of skeletal muscle in swallowing?

A

Upper 1/3 of the esophagus is striated muscle that is under “voluntary” control

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10
Q

What is the role of smooth muscle in swallowing

A

Lower 2/3 of the esophagus is smooth muscle that is under involuntary control of the enteric nervous system

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11
Q

What is the difference between primary & secondary peristalsis in swallowing?

A

Primary= moves food into the stomach from mouth

Secondary= Occurs from the site of bolus distension
- protective & clears H+ into the stomach

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12
Q

What neurotransmitters coordinate peristalsis?

A

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
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13
Q

How is the physiology of the mouth & esophagus altered in GERD?

A
  • 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

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14
Q

How is the physiology of the mouth & esophagus altered in Barrett’s Esophagus?

A
  • 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
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15
Q

How is the physiology of the mouth & esophagus altered in dsyphagia?

A

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:
- GERD
- Alcohol/tobacco
- Viral infeciton

2) Functional= neuronal
- CVA
- PD
- Achalasia (denervation of esophageal smooth muscle)

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16
Q

How is the physiology of the mouth & esophagus altered in hiatal hernia?

A

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

17
Q

How is the physiology of the mouth & esophagus altered in Sjogren Syndrome?

A

This is an autoimmune disorder characterized by auto-antibodies directed at the salivary glands; primary symptom is dry mouth

18
Q

How is the physiology of the mouth & esophagus altered in Cystic Fibrosis?

A

Mutations in the CFTR= inability to secrete Cl- into the salivary duct; water doesn’t follow & Bicarbonate secretion is impaired

  • Ducts consequently clog & damaged tissue is replaced with fibrotic & fatty tissue
  • Dry mouth occurs as well