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Physiology III > Lecture 20: Secretions from Salivary Glands and Stomach > Flashcards

Lecture 20: Secretions from Salivary Glands and Stomach Flashcards

1
Q

What triggers the cephalic phase

A

Anticipation of food

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2
Q

Cephalic phase is activated due to activation of ___efferents

A

PNS

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3
Q

What does PNS activity during cephalic phase result in

A

Increased secretion of saliva, gastric acid, gastrin and pancreatic enzymes

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4
Q

The cephalic reflex serves to ___ the GI tract

A

Prepare

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5
Q

What are the 3 phases of salivary and gastric secretion

A
  1. Cephalic
  2. Gastric
  3. Intestinal phase
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6
Q

What stimulates the gastric phase of salivary and gastric secretions

A

Mechanical stimulation of oral cavity and stomach

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7
Q

What stimulates the intestinal phase of gastric secretion

A

Regulation of stomach emptying and digestion/absorption in small intestine

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8
Q

What stimulates release of HCl in the cephalic phase

A

Vagus—> parietal
Vagus—> gastrin—> parietal

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9
Q

What % of HCl secretion occurs in cephalic phase

A

20%

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10
Q

What triggers HCl secretion in gastric phase

A
  1. Vagus—> parietal
  2. Vagus—> gastrin—> parietal
  3. Local reflex—> gastrin—> parietal
  4. Gastrin—> parietal
  5. Gastrin—> ECL—> histamine—> parietal
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11
Q

What inhibits the release of HCl in the gastric phase

A

PH <2 in stomach will trigger release of somatostatin which will inhibit parietal cells and decrease gastric acid

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12
Q

What % of HCl is secreted in gastric phase

A

70%

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13
Q

What triggers HCl release in intestinal phase

A
  1. Intestinal G cells activated
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14
Q

What inhibits HCl release in intestinal phase

A
  1. Low pH in duodenum activates somatostatin to inhibit parietal cells and decrease gastric acid
  2. Block G cells—> decrease gastrin
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15
Q

What % of HCl is secreted in intestinal phase

A

10%

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16
Q

What 4 glands produce saliva

A

Parotid, mandibular, lingual, and baccalaureate

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17
Q

In cattle saliva is a major source of what

A

Water and bicarbonate to the rumen

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18
Q

What is saliva composed of

A

Water, proteins, electrolytes and urea (ruminants)

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19
Q

What are some functions of saliva

A
  1. Stimulate taste buds
  2. Food lubrication
  3. Keeps mouth clean
  4. Contains lysozymes, buffer and antitoxic proteins
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20
Q

Salivary glands are ___glands

A

Acinar

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21
Q

What is the secretory unit of salivary glands

A

Acini

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22
Q

Fluid is secreted into the lumen of the acini and is modified through what

A

Intercalated and striated ducts

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23
Q

All salivary glands are composed of multiple ___that drain into ___ before being secreted into ___cavity

A

Acini, collecting ducts, buccal cavity

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24
Q

What is the salivary enzyme responsible for breaking down starch

A

Ptyalin (alpha-amylase)

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25
Q

What is the ideal pH in dogs, cats and pigs for ptyalin/alpha-amylase

A

6-7

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26
Q

What is mucin

A

Lubricant that facilitates swallowing and protects buccal surfaces

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27
Q

What ions are reabsorbed and secreted in salivary glands

A

Reabsorbed: Na+ and Cl-
Secreted: K+ and HCO3-

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28
Q

What is a salivary mucocele

A

Painless swelling in the neck or oral cavity that is a collection of saliva as a result of a damaged salivary gland or duct

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29
Q

__osmotic secretion by acini cells and selected reabsorption by duct cells creates a ___saliva

A

Iso-osmotic, hypotonic

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30
Q

What is the tonicity of normal saliva

A

Hypotonic

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31
Q

Acinar cells release ___ and ___ via exocytosis and secrete ___, ___ and ___

A

Proteins and mucous

Chloride, bicarbonate, and potassium

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32
Q

Salivary duct cells reabsorb __ and ___

A

Na+ and Cl-

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33
Q

What can not pass through tight junctions in salivary glands and what is the result

A

Tight junctions are impermeable to water, therefore creating the hypotonic saliva

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34
Q

What determines salivary osmolarity

A

Flow rate

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35
Q

Saliva is hypotonic at __salivary flow rates

A

Low

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36
Q

Saliva is isotonic at __salivary flow rates. And why?

A

High because there is not enough time to reabsorb Na+, Cl- and HCO3-

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37
Q

The pH ___ when salivary secretion rate increases

A

Increases

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38
Q

What salivary gland consists of just serous cells that provide proteins to saliva

A

Parotid gland

39
Q

What salivary glands consist of a mixture of serous and mucous cells

A

Sublingual and submandibular

40
Q

Ptyalin (alpha-amylase) hydrolyzes starch to what

A

Maltose

41
Q

What enzyme is frequently present in young animals on a milk diet but less in mature animals

A

Lingual lipase

42
Q

What does lingual lipase do

A

Hydrolysis of triglycerides into diacylglyceride and free fatty acids

43
Q

In ruminants and other herbivores saliva contains ___ and ___

A

Lysozymes and antitoxic proteins

44
Q

What is the purpose of lysozymes in ruminants and other herbivore saliva

A

Antibacterial effect- breaks beta 1-4 glycosidic bond between N-acetylmuramic acid and N-acetylglucosamine in peptidogylcan which is the major bacterial cell wall polymer

45
Q

The loss of peptidoglycan via salivary lysozymes results in ___ in a ___environment

A

Rapid cell lysis in a hypo-osmotic environment

46
Q

What are tannins

A

Plants defense mechanism as they provide a bitter taste

47
Q

What are some negative effects of tannins

A
  1. Decrease food intake
  2. Reduce ruminal protein digestion
  3. Inhibit digestive enzymes
  4. Overall negative effect on nutrient absorption in SI
48
Q

How do ruminants and other herbivores combat tannins that are present in their natural diet

A

Parotid gland produces proline-rich proteins which bind and neutralize tannins

49
Q

Do deers or cattle have larger parotid glands and why

A

Deer as their diet consists of more tannins

50
Q

How does saliva buffer rumen fluid

A

Bicarbonate

51
Q

Why does the saliva need to buffer ruminal fluid

A

Microbial activity in the rumen is producing VFA therefore bicarbonate production will control pH

52
Q

What are the 4 major components of gastric juce

A
  1. HCl
  2. Pepsinogen
  3. Mucus
  4. Intrinsic factor
53
Q

What is the purpose of HCl

A

Decrease pH of stomach, activate pepsinogen, aids in protein digestion, kills bacteria

54
Q

What is the purpose of pepsinogen and what is the active form

A

Pepsin is active form that digests proteins

55
Q

What is the purpose of mucus secretion

A

Protect the gastric mucosa from acidic actions of HCl

56
Q

What is the purpose of intrinsic factor

A

Necessary for absorption of Vitamin B12 in lieum

57
Q

What activates pepsinogen

A

HCl

58
Q

What species have a glandular stomach

A

Dogs and cats

59
Q

What species have a non-glandular and glandular stomach

A

Horses

60
Q

Which portion of the stomach contains chief cells, parietal cells, and enteroendocrine cells

A

Glandular

61
Q

What do chief cells do

A

Pepsinogen—> pepsin

62
Q

What do parietal cells do

A

Secrete HCl

63
Q

What do surface mucous cells do

A

Protect against acid and mechanical damage

64
Q

What do mucous neck cells do

A

Serve as stem/progenitor cells

65
Q

What do D cells, G cells and ECL cells do

A

Produce hormones that regulate gastric secretion and motility

66
Q

How do parietal cells form HCl

A

ATP dependent protein pump excretes H+ and Cl- enters lumen down electrical gradient

67
Q

Cl- is exchanged for ___ on basolateral membrane producing an alkaline tide

A

Bicarbonate

68
Q

What catalyzes bicarbonate from OH- and CO2

A

Carbonahydrase

69
Q

When does an alkaline tide occur

A

After meal

70
Q

During alkaline tide the ___ blood is more alkaline than ___ blood

A

Venous, arterial

71
Q

What 3 receptors stimulate HCl production

A

M3, CCK, and H2

72
Q

How does nervous system control HCl secretion

A

PNS and CNS activates parietal cells via M3 receptors

73
Q

How does the endocrine system control HCl secretion

A
  1. Gastrin is secreted from G cells and binds to CCK-B receptors
  2. Gastrin stimulates histamine release which binds to H2 receptors
74
Q

What receptor does gastrin bind to do secrete HCl

A

CCK-B

75
Q

What cell secretes histamine that then binds to __receptors

A

ECL cells, H2 receptors

76
Q

Gastrin is released in response to what 3 things

A
  1. Small peptides and AA in stomach
  2. Distention of stomach
  3. Vagal stimulation
77
Q

What two intracellular mechanisms mediate activation of H/K ATPase

A
  1. PNS (ACh) and gastrin released onto M3 and CCK-B receptors stimulate IP3/DAG which increase CA2+
  2. Histamine binds H2 receptors and increase cAMP
78
Q

___ and ___ stimulate the proton pump

A

Ca2+ and cAMP

79
Q

What are the 3 pathways and 2 intracellular mechanisms to secrete/increase HCl

A

3 pathways:
1. Gastrin binds CCK-B
2. ACh binds M3
3. Histamine binds H2

2 intracellular mechanisms:
1. Gastrin and ACh increase Ca2+
2. histamine increases cAMP

Ca2+ and cAMP stimulate proton pump, provides H+ for HCl

80
Q

___ and ___ down regulate HCl production

A

Somatostatin and prostaglandins

81
Q

How does somatostatin down regulate HCl

A

Inhibits cAMP

82
Q

How do prostaglandins down regulate HCl

A

Inhibit G cells which secretes gastrin and ECL cell which secretes histamine

83
Q

What 3 components make up the gastric mucosal barrier

A
  1. Compact epithelial cell lining
  2. Gastric mucus covering
  3. Bicarbonate
84
Q

What are some causes of gastric ulcers

A
  1. Defect in mucosal barrier
  2. Hyper secretion of HCl
  3. Helicobacter pylori
85
Q

What are some therapeutic approaches to treating gastric ulcers (broad approaches)

A
  1. Reduce acid production (vagotomy or pharmacologically via proton pump inhibitors)
  2. Stimulate re-epithelialzation
  3. Antibiotics for Helicobacter
86
Q

What specific treatments can be done to control ACh secretion to decrease HCl secretion

A
  1. Vagotomy
  2. Atropine
87
Q

What specific treatment can be done to reduce histamine secretion to control HCl secretion

A

Cimetidine

88
Q

What specific treatment can be done to reduce activity of proton pump to reduce HCl secretion

A

Omeprazole

89
Q

Pepsinogen is produced and secreted by ___

A

Chief cells

90
Q

Pepsinogen is stored in what

A

Zymogen granules

91
Q

Why is pepsin released as proenezyme

A

To prevent auto digestion

92
Q

What is the function of pepsin

A

Cleave proteins to peptides

93
Q

How is pepsinogen stimulated

A
  1. PNS (vagus)
  2. Gastrin
  3. Secretin from duodenum

Physiology III (34 decks)

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