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104 Theme 1 > Lecture 5: Salivary and Gastric Secretion > Flashcards

Lecture 5: Salivary and Gastric Secretion Flashcards

1
Q

what are the glands involved in salivary secretions

A
  • parotid
  • submandibular
  • sublingual
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2
Q

what are the enzymes present in saliva

A
  • alpha amylase
  • lysozyme
  • lingual lipase
  • lactoferrin
  • kallikrein
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3
Q

what does alpha amylase do

A

hydrolyses α-1,4 glycosidic bonds in starch to disaccharides and trisaccharides

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4
Q

what do lysozymes do

A

hydrolyse peptidoglycans in gram negative bacteria walls

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5
Q

what does lingual lipase do

A
  • hydrolyse triglycerides to fatty acid and diglycerides

- optimal in low pH

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6
Q

what does lactoferrin do

A

chelates iron to prevent microbial multiplication

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7
Q

what does kallikrein do

A

converts plasma protein α-2-globulin to bradykinin

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8
Q

what are the constituents of saliva

A
  • water
  • electrolytes
  • enzymes
  • secretory IgA
  • mucin
  • organic urea and uric acid
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9
Q

what does the parasympathetic ANS signal to for saliva production

A

superior and inferior salivatory nuclei

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10
Q

which nerves carry parasympathetic impulses to salivary glands

A
  • cranial nerve VII for sublingual and submandibular gland

- cranial nerve IX for parotid gland

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11
Q

what effect does parasympathetic stimulation have on salivary glands

A
  • increase salivary secretion
  • vasodilation
  • myoepithelial cell contraction
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12
Q

what are inhibitors of the parasympathetic ANS for saliva secretion

A
  • fatigue
  • sleep
  • fear
  • dehydration
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13
Q

effect of sympathetic neural stimulation on salivary glands

A
  • overall slight increase in secretion
  • produces mucin and enzyme rich saliva
  • initial vasoconstriction as noradrenaline released
  • later vasodilation as bradykinin released
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14
Q

how is sympathetic activity of salivary glands regulated

A

via superior cervical ganglion

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15
Q

what happens in Sjogren’s syndrome

A
  • autoimmune disease that destroys exocrine salivary glands
  • commonly affects tear and saliva production
  • dry eyes and dry mouth, known as sicca symptoms
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16
Q

what happens in xerostomia

A
  • patients lack adequate saliva
  • dental caries and halitosis common due to bacterial overgrowth
  • difficulty speaking or swallowing solid food due to inadequate lubrication
17
Q

what are the exocrine cells of the gastric glands and what do they secrete

A
  • mucous neck cells: thin mucus
  • parietal cells: HCl and intrinsic factor
  • chief cells: pepsinogen, gastric lipase and rennin in neonates
18
Q

what are the endocrine cells of the gastric glands and what do they secrete

A
  • G cells: gastrin
  • D cells: somatostatin
  • ECL cells: histamine
19
Q

what are the gastric glands in the body and fundus

A

gastric / oxyntic glands

20
Q

what are the gastric glands in the antrum

A

pyloric glands

21
Q

what is the purpose of mucus in gastric juice

A

protects surface epithelium from acid / pepsin

22
Q

what is the purpose of pepsinogen in gastric juice

A
  • is a proenzyme

- active form is pepsin

23
Q

what is the purpose of rennin in gastric juice

A
  • in neonates only

- coagulates milk through casein proteolysis

24
Q

what is the purpose of gastric lipase in gastric juice

A

converts triglycerides to fatty acids and diglycerides

25
Q

what is the purpose of HCl in gastric juices

A
  • converts pepsinogen to pepsin
  • denatures proteins
  • kills microorganisms
26
Q

what is the purpose of intrinsic factor

A
  • vitamin B12 absorption in the ileum
  • erythropoeisis in bone marrow
  • deficiency can cause pernicious anaemia
27
Q

what are the components of gastric juice and what are they secreted by

A
  • water and electrolytes
  • mucus by mucus neck cells
  • pepsinogen pro enzyme, rennin in neonates and gastric lipase by chief cells
  • HCl and intrinsic factor by parietal cells
28
Q

what stimulates gastric acid secretion

A
  • acetylcholine release from vagus nerves
  • gastrin from G cells
  • histamine from ECL cells
29
Q

which hormones inhibit gastric acid secretion

A
  • somatostatin from D cells

- mucosal prostaglandin

30
Q

which drugs inhibit gastric acid secretion

A
  • omeprazole: proton pump inhbitor
  • cimetidine: H2 receptor antagonist
  • atropine: muscarinic receptor inhibitor and inhibits vagal stimulation of acid secretion
31
Q

what promotes gastrin secretion

A
  • vagus nerve
  • distension
  • peptides
32
Q

what effects does gastrin have

A
  • promotes parietal cell secretion of pepsinogen
  • chief cell secretion of pepsinogen
  • lower oesophageal sphincter contraction
  • increased motility of stomach
  • relaxation of pyloric sphincter
33
Q

what happens in gastritis and what are its causes

A
  • inflammation of the gastric mucosa
  • most commonly caused by Helicobacter pylori bacteria
  • gram negative bacteria produce urease. forms ammonia which neutralises bactericidal acid and is toxic to mucosal barrier
  • also caused by smoking, alcohol, NSAIDs and chronic stress
34
Q

what happens in autoimmune atrophic gastritis

A
  • antibody mediated destruction of gastric parietal cells
  • causes hypochlorhydria
  • and intrinsic factor insufficiency
  • loss if IF results in vitamin B12 malabsorption and pernicious anaemia

104 Theme 1 (13 decks)

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