Mouth and esophagus

Question 1

To know the characteristics of the two types of secretions from the salivary glands.

Answer 1

Serous = watery and contains alpha amylase.
Although insignificant in adults, it’s involved in carb digestion.

Mucinous secretion = found throughout the GIT. Contains mucin (highly glycosylated protein that coats and protects things).

Parotid is mostly serous, submandibular is a mix and sublingual is mostly mucinous (still technically a mix). Minor glands form mucous product.

Question 2

To understand the mechanism by which water and salt is secreted into the lumen of the salivary gland.

Answer 2

Ach stimulates acinar cells at muscarinic receptors to push Chloride out into the lumen via Ca2+ signaling.
Water and Na follow passively.
As fluid progresses up the duct, Na and Cl are removed and “replaced “ by bicarb and K.
Na reabsorption is greater than K secretion.
The net result of this differential of secretion is an increase in hypotonicity of the liquid as it rises.
Ductal cells do not express aquaporins (preventing movement through the cell) and tight junctions prevent paracellular movement of water. Ach also stimulates enzyme production via the same mechanism – from acinar cells.

Question 3

To know the composition of saliva, the function of those components, and what would happen if the ability to secrete these components was impaired.

• pg. 15 of handout chart

Answer 3

alpha amylase - starch digestion

IgA, lysozyme, lactoferrin - antimicrobial

lingual lipase - fat digestion

mucin - lubrication and protection

water- taste, swallowing, speech

Na+, K+, Cl- HCO-, H2O - alkalinization and HCO3 neutralize gastric acid *8

Question 4

To know the primary stimulus that increases salivary secretion.

Answer 4

Ach via a muscarinic receptor and Ca2+ signaling to a chloride channel

Question 5

To know how swallowing is regulated by both skeletal and smooth muscle.

Answer 5

initiated voluntarily, followed by reflex control and respiration is inhibited.

oral: voluntary phase. food pressed against hard palate, move to pharynx where stimulates touch receptors and swallowing reflex initiated.
pharyngeal: soft palate pulled to prevent nasopharyngeal reflux. larynx and vocal cords upward. epiglottis downward. UES relax, pharynx contract. peristaltic wave initiates.
esophageal: UES constricts. 1 peristalis wave below UES. 2 peristalsis at site of distension (upstream contraction, downstream relaxation)

Question 6

1. To know the following pathophysiological conditions and how the physiology of the mouth and esophagus is altered during these conditions: gastroesophageal reflux disease (GERD), dysphagia, hiatal hernia, Barrett’s esophagus, Sjögren syndrome, and cystic fibrosis.

Answer 6

GERD and barret’s esophagus: reflux of gastric contents into the esophagus. causes include weakened LES, weak peristalsis, hiatal hernia gastric ulcer, delayed gastric emptying, or transient relaxation of LES, or impaired salivary secretion. continual damage –> barrets esophagus and cancer possibility.

dysphagia: difficulty swallowing either mechanical or functional. (achalasia is denervation of esophageal sm and impaired LES function)

hiatal hernia: protrusion of stomach through the diaphragm and into the thorax. sliding or paraesophageal.

Sjogren syndrome and cystic fibrosis: both involve impaired salivary secretions. CFTR genetic problem Cl- ion channel doesnt work and ducts clog. Sjogren is autoimmune disease of salivary glands leading to dry mouth.