Mouth, Salivary Glands and Esophagus

Question 1

describe the serous cell vs mucus cell secretions of saliva

Answer 1

serous cell: low glycoprotein, high amylase

mucous cell: high mucin glycoprotein

Question 2

describe the % of saliva secretions of the salivary glands

Answer 2

• parotid (serous) = 25%
• sublingual = 5%
• submandibular = 70%

Question 3

describe Sjogren’s syndrome

Answer 3

• autoimmune destruction of glands
• xerostomia (dry mouth), difficulty swallowing
• inability to transport ions and water via Cl-, bicarb, exchangers and aquaporins
• given cholinergic stimulation

Question 4

describe the acinar cells (the acinus)

Answer 4

• acinar cells are leaky
• secretion: digestive enzymes, mucin, electrolytes and water (isotonic NaCl)
• Cl is cotransported with Na into the cell at the basolateral membrane
• electrochemical potential of Cl changes
• Cl diffuses down the gradient
• channel allows bicarb to enter the lumen
• Na and H2O follow paracellularly

Question 5

describe the duct of the salivon

Answer 5

• ductal cells are tight; low water permeability
• secretion is modified
• the Na/K/ATPase pump on BL membrane determines:
  
  • active absorption of Na
  • extra K brought into cell is actively secreted
  • anionic exchanger reabsorbs Cl and secretes HCO3 secreted

Question 6

give a summary of the secretion and modification of the salivon

Answer 6

Question 7

describe how the composition of saliva changes with the flow rate

Answer 7

Question 8

describe the modfication of saliva with flow rate

Answer 8

• low flow rate: hypotonic, rich in K+ (NaCl absorption, K secretion)
• high flow rate: saliva begins to resemble plasma (less time for ductal modification)
• HCO3 secretion is selectively stimulated when saliva secretion is stimulated (e.g. by PS stimulation)

Question 9

describe the control of secretion of saliva

Answer 9

• increased secretion: smell, taste (especially acidic)
  
  • ​increases the salivary nucleus of the medulla oblongota
  • increased ACh increases salivary gland secretion, vasodilation and myoepithelial contraction

Question 10

describe influence of autnomics on salivary secretion

Answer 10

• agonist releasing Ca (Ach, VIP, substance P)
  
  • greater effect on the volume of secretion
• Agonist elevating cAMP (NE)
  
  • increase enzyme and mucous content

Question 11

describe primary and secondary peristlasis

Answer 11

• primary peristalsis is:
  
  • initiated by voluntary act of swallowing, irrespective of presence of food
• secondary peristalsis is initiated by:
  
  • distension of the esophagus
  • low pH

Question 12

describe dysphagia flowchart

Answer 12

Question 13

describe achalasia

Answer 13

• failure of LES to relax (remains constricted)
• impaired peristalsis in lower 2/3 of esophagus