Lecture 5: Salivary and Gastric Secretion Flashcards
what are the glands involved in salivary secretions
- parotid
- submandibular
- sublingual
what are the enzymes present in saliva
- alpha amylase
- lysozyme
- lingual lipase
- lactoferrin
- kallikrein
what does alpha amylase do
hydrolyses α-1,4 glycosidic bonds in starch to disaccharides and trisaccharides
what do lysozymes do
hydrolyse peptidoglycans in gram negative bacteria walls
what does lingual lipase do
- hydrolyse triglycerides to fatty acid and diglycerides
- optimal in low pH
what does lactoferrin do
chelates iron to prevent microbial multiplication
what does kallikrein do
converts plasma protein α-2-globulin to bradykinin
what are the constituents of saliva
- water
- electrolytes
- enzymes
- secretory IgA
- mucin
- organic urea and uric acid
what does the parasympathetic ANS signal to for saliva production
superior and inferior salivatory nuclei
which nerves carry parasympathetic impulses to salivary glands
- cranial nerve VII for sublingual and submandibular gland
- cranial nerve IX for parotid gland
what effect does parasympathetic stimulation have on salivary glands
- increase salivary secretion
- vasodilation
- myoepithelial cell contraction
what are inhibitors of the parasympathetic ANS for saliva secretion
- fatigue
- sleep
- fear
- dehydration
effect of sympathetic neural stimulation on salivary glands
- overall slight increase in secretion
- produces mucin and enzyme rich saliva
- initial vasoconstriction as noradrenaline released
- later vasodilation as bradykinin released
how is sympathetic activity of salivary glands regulated
via superior cervical ganglion
what happens in Sjogren’s syndrome
- autoimmune disease that destroys exocrine salivary glands
- commonly affects tear and saliva production
- dry eyes and dry mouth, known as sicca symptoms
what happens in xerostomia
- patients lack adequate saliva
- dental caries and halitosis common due to bacterial overgrowth
- difficulty speaking or swallowing solid food due to inadequate lubrication
what are the exocrine cells of the gastric glands and what do they secrete
- mucous neck cells: thin mucus
- parietal cells: HCl and intrinsic factor
- chief cells: pepsinogen, gastric lipase and rennin in neonates
what are the endocrine cells of the gastric glands and what do they secrete
- G cells: gastrin
- D cells: somatostatin
- ECL cells: histamine
what are the gastric glands in the body and fundus
gastric / oxyntic glands
what are the gastric glands in the antrum
pyloric glands
what is the purpose of mucus in gastric juice
protects surface epithelium from acid / pepsin
what is the purpose of pepsinogen in gastric juice
- is a proenzyme
- active form is pepsin
what is the purpose of rennin in gastric juice
- in neonates only
- coagulates milk through casein proteolysis
what is the purpose of gastric lipase in gastric juice
converts triglycerides to fatty acids and diglycerides
