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JL Gastrointestinal > Physiology and Pharmacology of Salivary and Gastric Secretion and Gastric Motility > Flashcards

Physiology and Pharmacology of Salivary and Gastric Secretion and Gastric Motility Flashcards

1
Q

What are the three pairs of salivary glands?

A

Parotid
Submandibular
Sublingual

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2
Q

Where is the parotid gland located?

A

Below ear and over the masseter

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3
Q

Where is the submandibular gland located?

A

Under lower edge of mandible

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4
Q

Where is the sublingual gland located?

A

In floor of mouth under tongue

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5
Q

What makes the saliva anti-bacterial?

A

Lysozymes, lactoferrin and immunoglobulisn

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6
Q

What - in the saliva - digests complex carbohydrates?

A

Amylase

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7
Q

How does the saliva neutralise acid?

A

Bicarbonate

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8
Q

In the formation of saliva, what does primary secretion?

A

Acinus

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9
Q

In the formation of saliva, what does secondary secretion?

A

Duct cells

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10
Q

What does the formation of saliva require?

A

ATP

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11
Q

What cells produce a primary secretion with Na+, K+, Cl- and HCO3- content similar to plasma, plus mucus and amylase?

A

Acinus

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12
Q

What cells modify secretion by removing Na+ and Cl- and to a lesser extent adding K+ and HCO3- no movement of H2O - hence diluting?

A

Duct cells

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13
Q

How much saliva a minute do we actively produce when salivating?

A

5ml

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14
Q

What two things reflex regulate (neuronal control) the rate of formation of saliva?

A
  1. Simple unconditioned reflex (citrus fruits)

2. Conditioned (acquired) reflex

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15
Q

In the simple (unconditioned) control of salivary secretion, what can activate pressure receptors in the mouth?

A

Food

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16
Q

In the simple (unconditioned) control of salivary secretion, what happens after pressure receptors are activated by food?

A

Impulses are send via afferent nerves

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17
Q

Where is the salivary centre?

A

In the medulla

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18
Q

In the aquired (conditioned) control of salivary secretion, where does the signal go before reaching the salivary centre in the medulla?

A

Cerebral cortex

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19
Q

What occurs as a result of the salivary centre in the medulla, sending impulses via extrnisic autonomic nerves - both paraysmpathetic and sympathetic stimulation?

A

Salivary glands increase production

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20
Q

What stimulation is the dominant role in normal saliva production?

A

Parasympathetic

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21
Q

What nerves does the parasympathetic stimulation control?

A

Glossopharyngeal and facial nerves

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22
Q

In parasympathetic stimulation of saliva secretion, what receptors are mediated to produce large volumes of watery saliva?

A

M3 muscarinic acetylcholine receptors

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23
Q

At what times is sympathetic stimulation dominant at?

A

Stressful times - dry mouth when nervous!

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24
Q

In the sympathetic stimulation of saliva secretion, what do postganglionic fibres from superior cervical ganglia cause?

A

Small volume, thick, mucus rich saliva, mediated by B1-adrenoceptors

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25
How much capacity does the stomach have?
50 > 1000ml
26
What nerve causes relaxation of the stomach to accomodate food from the oesophagus?
Vagus
27
What two acids are secreted in the stomach, for the start of protein digestion?
Pepsin and hydrochloric acid
28
Where does the stomach secrete gastric juice from?
Gastric pits in the gastric mucosa
29
What wave strength determines the escape of chyme through the pyloric sphincter?
Antral ave
30
What do gastric factors and duodenal factors govern?
Antral wave
31
What does distention of the stomach increase?
Motility, due to stretch of smooth muscles
32
When smooth muscles of the stomach are stretched, what is stimulated, increased and released?
Intrinisc nerve plexuses, increased vagus nerve activity and gastrin release
33
What reflex can delay empyting of the stomach?
Enterogastric reflex
34
What does the enterogastric reflex do by signals from the intrinisc nerve plexus and autonomic nervous sytem?
Decrease antral peristalic activity
35
Name two enterogastrones?
Secretin and cholecystokinin (CKK)
36
What do release of enterogastrones from the duodenum inhibit?
Stomach contraction
37
What food substance has an imporant role in delaying gastric emptying required for digestion and absorption in small intestine?
Fat
38
What does acid in the duodenum do to stomach contractions?
Slows it to allow time for neutralisation by bicarbonate from pancreas
39
What are two main areas of the stomach, important in secretions?
``` Pyloric gland area (PGA) Oxyntic mucosa (OM) ```
40
What do D cells secrete?
Somatostatin
41
What do G cells secrete?
Gastrin
42
Where are D cells and G cells located?
In the pyloric gland area
43
What do chief cells secrete?
Pepsinogen
44
What do Enterochromaffin cells release?
Histamine
45
What do parietal cells secrete?
Hydrochloric acid and intrinsic factor
46
Where are parietal cells, enterochromaffin like cells and chief cells found?
In the oxyntic mucosa (OM)
47
What does gastrin stimulate?
HCl secretion
48
What does somatostatin inhibit?
HCl secretion
49
What are three functions of HCl released from parietal cells?
1. Activates pepsinogen to pepsin 2. Denatures protein 3. Kills micro-organisms ingested with food
50
What does pepsinogen released from chief cells do?
Inactive precursor of the peptidase, pepsin
51
What does intrinsic factor released from parietal cells do?
Binds vitamin B12, allowing absorption in the terminal ileum
52
What 4 receptors does the parietal cell have?
1. Muscarinic ACH receptor 3 2. Gastrin (CCK2) receptor 3. Histamine receptor 4. Prostaglandin receptor
53
Where does cholinergic nerve (postganglionic parasympathetic) meet, and what does this cause?
Meets M3 receptor on parietal cell, causing HCl release
54
What happens once gastrin has landed on an enterochromaffin like cell?
Cell releases histamine which acts on H2 receptors on parietal cell to release HCl
55
What two receptors are present on an enterochromaffin cell?
Gastrin CCK2 receptor | M1 ACh receptor
56
What does enterochromaffin cell release to cause HCl secretion?
Histamine
57
What inhibits gastrin between meals?
Somatostatin
58
What does activation of the PGE receptor on parietal cells do?
Inhibits all stimulating signals, and prevents HCl secretion
59
During the resting state of the parietal cell, what can be said about the H+/K+ATPase?
It is largely within the cytoplasmic tubulovesicles
60
What occurs to the H+/k+ATPase when the parietal cell is stimulated?
Traffics to the apical membrane taking residence in extended microvilli
61
What phase of gastric secretion occurs before food reaches stomach?
Cephalic
62
What phase of gastric secretion occurs when food is in the stomach?
Gastric
63
What phase of gastric secretion occurs when food has left the stomach?
Intestinal
64
What nerve is activated when smell and taste of food occurs?
Vagal activation
65
The vagal activation stimulates an enteric neurone to do what?
Increase ACh
66
What does ACh do to a D cell, and what does it do to ECL cell?
Inhibits D cell | Stimulates ECL cell
67
Other than ACh what else does enteric neurone increase?
Increases GRP (gastrin releasing peptide)
68
What does the GRP from enteric neurone, during eating stimulate?
G cells to secrete gastrin etc
69
What two factors in the gastric phase. cause increased secretion, and what do they act on to achieve this?
Distension - enteric neurone | Protein digestion products - G-cell
70
What does a low pH in the stomach, drive secretion of?
Somatostatin
71
What class of drugs block competitevly and an example of one is pirenzepine?
Muscarinic receptor antagonists
72
What class of drugs (ranitidine) block competitively the H2 receptor on parietal cells?
H2 receptor antagonistst
73
What drugs block cyclo-oxygenase (which stimulates prostaglandin receptor on parietal cells), and so increase acid secretion?
NSAIDs block irreversibly
74
What drugs (omeprazole) block by covalent modification at the H+K+ATPase?
PPIs
75
What three effects does locally produced prostaglandins (PGE and PGI) have in relation to protection of the mucosa from attack by HCl and pepsin?
1. Reduce acid secretion 2. Increase mucus and bicarbonate secretion 3. Increase mucosal blood flow
76
What term is given to ulcers in an area where the mucosa is exposed to hydrochloric acid and pepsin (stomach/duodenum)?
Peptic ulcers
77
What reduces prostaglandin formation (COX 1 inhibition)?
NSAIDS
78
What can gastric damage due to long-term NSAID treatment be prevented with?
PGE analogue (misoprostol)
79
Name a drug that inhibits basal and food stimulated gastric acid formation and maintains secretion and mucus and bicarbonate?
Misoprostol (stable PGE analogue)
80
What, protected in teh mucus gel, secretes agents causing a persistent inflammation that weakens the mucosal barrier?
H.pylori
81
Name a syndome that involves a rare, gastrin producing tumour?
Zollinger-Ellison syndrome
82
What condition causes heightened vagal tone, leading to acid hypersecretion?
Cushing's ulcer
83
What drugs inhibit the membrane inserted (micro villi) H+/K+dependent ATPase (proton pump)?
PPIs
84
What sort of proton pumps are not inhibited by PPIs?
Ones in the tubulovesicles
85
What kind of drugs are PPIs, because they are inactive at neutral pH (proton pump hidden in tubulovesicles)?
Prodrugs
86
Where are absorbed PPIs delivered to?
The secretory canaliculi of the stomach
87
When PPIs are in the secretory canalicula of the stomach, what are they activated to?
Sulfenamide (then block lumenal sulphydrl groups of membrane inserted proton pump)
88
What is a complex of aluminium hydroxide and sulphated sucrose?
Sucralfate
89
Name two mucosal strengtheners?
Sucralfate | Bismuth chealate
90
What does sucralfate release to acquire a strong negative charge?
Aluminium
91
What is used in combination with antibiotics, H2 receptor antagonists ro promote eradication of H.pylori?
Bismuth chealate

JL Gastrointestinal (33 decks)

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