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

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Flashcards in Physiology and Pharmacology of Salivary and Gastric Secretion and Gastric Motility Deck (91):
1

What are the three pairs of salivary glands?

Parotid
Submandibular
Sublingual

2

Where is the parotid gland located?

Below ear and over the masseter

3

Where is the submandibular gland located?

Under lower edge of mandible

4

Where is the sublingual gland located?

In floor of mouth under tongue

5

What makes the saliva anti-bacterial?

Lysozymes, lactoferrin and immunoglobulisn

6

What - in the saliva - digests complex carbohydrates?

Amylase

7

How does the saliva neutralise acid?

Bicarbonate

8

In the formation of saliva, what does primary secretion?

Acinus

9

In the formation of saliva, what does secondary secretion?

Duct cells

10

What does the formation of saliva require?

ATP

11

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

Acinus

12

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

Duct cells

13

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

5ml

14

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

1. Simple unconditioned reflex (citrus fruits)
2. Conditioned (acquired) reflex

15

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

Food

16

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

Impulses are send via afferent nerves

17

Where is the salivary centre?

In the medulla

18

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

Cerebral cortex

19

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

Salivary glands increase production

20

What stimulation is the dominant role in normal saliva production?

Parasympathetic

21

What nerves does the parasympathetic stimulation control?

Glossopharyngeal and facial nerves

22

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

M3 muscarinic acetylcholine receptors

23

At what times is sympathetic stimulation dominant at?

Stressful times - dry mouth when nervous!

24

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

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

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