Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Block 1 > Gastric Motility and Secretions and Drugs > Flashcards

Gastric Motility and Secretions and Drugs Flashcards

1
Q

What are the 5 functions of the stomach?

A

To store food

To minimise ingestion of bacteria

To dissolve and partially digest the macromolecules in food

To regulate the rate at which the contents of the stomach empty into the small intestine

To secrete intrinsic factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the one indispensable function of the stomach?

A

To secrete intrinsic factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Gastric motility allows the stomach to:

A

Serve as a reservoir for large volumes of food

Fragment food and mix it with gastric secretions

Empty gastric contents into the duodenum at a controlled rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Name the 3 divisions of the stomach

A

Fundus

Body

Antrum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the four layers of the stomach, from the lumen outwards?

A

Mucosa

Submucosa

Muscularis

Serosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

In which layer of the stomach do the enteric neurons lie?

A

Submucosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name the three layers of the mucosa, from the lumen outwards

A

Epithelium
Lamina propria
Muscularis mucosae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When the stomach is empty, which 2 layers are folded and what are they called?

A

The mucosa and submucosa are folded into rugae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Name the 2 plexus found in the enteric nervous system.

A

Myenteric plexus

Submucosal plexus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Where does the enteric nervous system get input from?

A

Autonomic nervous system:

Parasympathetic

  • vagus nerves
  • pelvic nerves (sacral spinal cord)

Sympathetic postganglionic fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

In which layer of the stomach/GI tract is the submucosal plexus found in?

A

Submucosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

In which layer of the stomach/GI tract is the myenteric plexus found?

A

Muscularis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Outline the 3 stages of receptive relaxation of the stomach

A

It is mediated by the vagus nerve (CN X)

CN X coordinates with the enteric nerve plexuses

Enteric neurons release (NO) and serotonin, which relax the smooth muscle of the stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What 2 chemicals do the enteric neurons release to mediate receptive relaxation?

A

Nitric oxide (NO)

Serotonin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the peristaltic wave movements in the stomach

A

Begin in the body and move towards the antrum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is retropulsion?

A

When strong peristaltic movements force food towards the antrum of the stomach, closing the pyloric sphincter. This then forces food backwards towards the body of the stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Define peristalsis

A

Waves of alternating contractions and relaxations of smooth muscle layers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Define segmentation

A

Cycles of contraction that mix contents but do not push them in any one direction.

Aims to mix gastric contents with secretions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What 2 types of electrical activity start contractions in the GI tract?

A

Slow waves

Action potentials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the basic electrical rhythm of the GI tract?

A

When smooth muscle cells undergo spontaneous cycles of depolarisation and repolarisation (spontaneous movement of Na+)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the rate of gastric slow waves?

A

3 per minute

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Where is the rhythm of gastric slow waves generated?

A

In the pacemaker zone in the body of the stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are slow waves?

A

Fluctuations in membrane potential spreading to adjacent sections of muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Describe the relationship between slow waves and action potentials

A

They do not elicit contractions, but coordinate them by controlling the appearance of action potentials.

They set the rate of contractions by controlling action potentials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Action potentials elicit ___
Muscle contraction
26
What determines the strength of a muscle contraction?
The number of action potentials appearing at the peak of a slow wave
27
Why is it important to regulate gastric emptying?
It allows for optimal digestion and absorption of ingested material
28
What is the pyloric sphincter?
A ring of smooth muscle and connective tissue between the gastric antrum and the duodenum
29
What are the 2 functions of the pyloric sphincter?
Allows regulated gastric emptying at a rate consistent with the ability for the duodenum to process it To prevent regurgitation of duodenal contents into the stomach
30
What do sympathetic nerves do to the pyloric sphincter?
Increase constriction of it | fight or flight, ANS
31
What do vagal (parasympathetic) nerves do to the pyloric sphincter?
Can be excitatory or inhibitory
32
What hormones act on the pyloric sphincter?
Gastrin Cholecystokinin (CCK) Gastric inhibitory peptide (GIP) Secretin
33
What do hormones do to the pyloric sphincter?
Constrict it
34
What 3 things decrease the rate of gastric emptying?
High fat Low pH Hypertonic solution
35
What can the duodenum and jejunum detect in chime? Where are these receptors found? Why is this useful?
Acidity Osmotic pressure Fats Amino acids Peptides Mucosae of the duodenum and jejunum The receptors cause the release of intestinal hormones, which inhibt antral contractions and/or elicit constricting the pyloric sphincter, decreasing the rate of gastric emptying
36
What are the four main components of gastric secretion?
Hydrochloric acid (HCl) Mucus Enzymes Intrinsic factor
37
Where is gastric juice secreted from?
Gastric glands of the gastric mucosa
38
What 2 types of enzyme does the stomach secrete?
Pepsinogens Gastric lipase
39
Name the 5 major cell types found in the mucosa of the stomach in gastric glands
Surface mucus cell Mucous neck cell Parietal cell Chief cell G cell
40
What does the parietal cell secrete
HCl Intrinsic factor
41
Which type of cell secretes HCl and intrinsic factor?
Parietal cell
42
What do chief cells secrete?
Pepsinogen
43
What type of cell secretes pepsinogen?
Chief cells
44
What do G cells secrete?
Gastrin
45
What type of cell secretes gastrin?
G cell
46
Where are parietal cells (HCl, IF) found?
Proximal 80% of the stomach
47
What does the body of the stomach secrete?
Mucus Pepsinogen HCl
48
What does the antrum of the stomach secrete?
Mucus Pepsinogen Gastrin
49
Where are G cells found?
In the antrum of the stomach
50
Where are gastric hormones secreted from?
Gastric glands
51
What is the purpose of gastric hormones?
To control the secretion of gastric juice
52
What are the 3 gastric hormones?
Gastrin Histamine Somatostatin
53
Which of the 3 gastric hormones has a paracrine effect?
Histamine
54
Name the 3 gastric effects of gastrin
Stimulates secretion of acid, pepsinogen, mucus, HCO3- Stimulation of gastric motility Inhibition of gastric emptying
55
Name the 3 GI wide effects of gastrin
Stimulation of pancreatic enzyme and HCO3- secretion Stimulation of insulin release Stimulation of intestinal motility
56
Which cells secrete histamine?
Enterochromaffin-like (ECL) cells
57
Name the 2 gastric effects of histamine
Stimulation of acid secretion Increased local blood flow to support the increase in metabolism
58
Which cells secrete somatostatin?
D cells
59
Where are D cells found?
Antrum and body of the stomach
60
What are the 2 gastric effects of somatostatin?
Inhibition of gastrin release Inhibition of acid secretion
61
What is the average gastric luminal pH?
pH 1-2
62
How much HCl does the stomach secrete per day?
2-3 litres
63
Describe the shape and structure of a parietal cell
Truncated pyramidal shape, apex towards lumen Invaginations of the luminal membrane (canaliculi), membranes lined with ion pumps High mitochondrial content
64
Why is a parietal cell's structure related to it's function
High mitochondrial content = lots of ATP for ion pumps to push acid into stomach Large surface area to secrete HCl
65
What are the 4 stages of acid secretion by the parietal cell?
1. H+ and HCO3- are produced from CO2 and H2O 2. H+ is pumped into lumen by H+/K+ ATPase pump 3. HCO3- moves out of basolateral membrane in antiport with Cl- 4. Cl- passively diffuses into the lumen via Cl- channel
66
Which enzyme converts CO2 and H2O into H2CO3 (carbonic acid)?
Carbonic anhydrase
67
What 3 things stimulate acid secretion?
Gastrin Acetylcholine Histamine
68
What 3 things inhibit acid secretion?
Somatostatin Prostaglandins E2 and I2 Intestinal hormones
69
DIAGRAM: Draw out the relationship between an ECL cell, parietal cell, with muscarinic, gastrin, and H2 receptors
Slide 44 of gastric motility lecture
70
What 5 receptors does a parietal cell have on its surface and what hormones act on those receptors?
Muscarinic receptor - ACh H2 receptor - Histamine Gastrin receptor - Gastrine Somatostatin receptor - somatostain (inhibitory) PGE2 receptor - prostaglandin E2
71
What is the name given to the H+/K+ ATPase pump on the parietal cell?
Proton pump
72
Which 2 cells does ACh act on?
ECL cell (increase histamine --> parietal cell) Parietal cell (direct acid stimulation)
73
Give 3 functions of somatostatin
Inhibit gastrin (stops stimulation of ECL and parietal cell) Inhibit the action of the parietal cell (slow production of HCl) Inhibit the action of the ECL cell (inhibit histamine production --> less stimulation of parietal cell to produce HVl)
74
Give 3 symptoms and 3 complications of reflux oesophagitis
Heartburn Regurgitation Haematemesis Oesophageal ulceration Peptic stricture Barrett's oesophagus
75
What are prostaglandins?
A group of lipids derived from arachidonic acid
76
Mucus is a mixture of..
Glycoproteins and glycopolysaccharides
77
What is the gastric mucosal barrier?
Mucus and alkaline secretions entrapped within it
78
What converts pepsinogen to pepsin?
A low pH environment
79
Pepsin is used to accelerate...
Protein digestion
80
What is the oxyntic gland area?
The proximal 80% of the stomach that secretes HCl (parietal cells found here)
81
What is the pyloric gland area?
The antrum of the stomach that produces gastrin (G cells) near the pyloric sphincter
82
Which cell does PGE2 have its affect on?
Parietal cell - inhibits acid secretion
83
Local irritation of the mucosa stimulates.... What effect does this have?
The production of prostaglandins (PGs) Increase production of mucus and HCO3- Inhibit acid secretion The stimulation of acid secretion also promotes mucus and HCO3- secretion
84
Intrinsic factor is a..
Glycoprotein
85
Which cells in the stomach secrete HCO3-?
Gastric surface epithelial cells
86
What 3 types of drugs are used to treat disorders of acid secretion?
Antacids and alginates Histamine H2 receptor antagonists Proton pump inhibitors
87
Describe how NSAIDs impair the renewal of the gastric mucosal barrier
NSAIDs inhibit the enzyme COX - COX converts arachidonic acid into prostaglandins Prostaglandins inhibit acid production from parietal cells and stimulate gastric mucus production If prostaglandins are inhibited, they impair the renewal of the gastric mucosal barrier --> less mucus production, more acid production
88
Give the names of 2 antacids What is their MoA?
Aluminium hydroxide and magnesium hydroxide Calcium carbonate and magnesium carbonate They are a bases which buffer gastric acid, raising the gastric pH
89
Give the name of an alginate. What is its MoA?
Sodium alginate, sodium bicarbonate, calcium carbonate Anionic polysaccharides that form a viscous gel upon binding with water Increases viscosity of the stomach contents and protects the oesophageal mucosa from acid reflux. The gel floats on the surface of the stomach contents
90
Give the name of 2 histamine H2-receptor antagonists What is their MoA?
Ranitidine Cimetidine Competitively inhibit histamine actions at H2-receptors
91
What does cimetidine inhibit?
P450 enzymes
92
Give the name of 2 proton pump inhibitors What is their MoA?
Omeprazole Lansoprazole Irreversibly inhibit the H+/K+ ATPase pump. Inactive at neutral pH Accumulate in secretory canaliculi of parietal cells
93
Why does increasing the dose of a PPI disproportionally increase the plasma concentrations of the drug?
Given orally as enteric-coated capsules Increasing the dose leads to a less acidic environment, which means more of the enteric coating survives through the stomach More is then available
94
What is reflux oesophagitis?
Inflammation of the lower oesophagus produces by persistent episodes of reflux
95
What is the prescribed drug of choice for reflux oesophagitis?
PPIs
96
Where are the majority of peptic ulcers found?
Duodenum
97
Which artery is at risk of damage in a duodenal peptic ulcer?
Gastroduodenal artery
98
How can GI-adverse affects be reduced in NSAID prescriptions?
Alternative drug Lowest dose, shortest duration Avoid concomitant NSAIDs Frequent review Co-prescription of PPIs in increased risk patients
99
Helicobacter pylori is gram.....
Negative
100
Which bacteria is responsible for 80% of peptic ulcers?
H. pylori Gram-negative bacterial infection
101
How does H. pylori produce peptic ulcers?
Produces and secretes urease, which breaks urea into CO2 and NH3 (imonia) NH3 neutralises gastric acid H pylori then penetrates mucus barrier, facilitating acid penetration to the epithelial cells causing damage = ulcer
102
What is achlorhydria/hypochlorhydria? What is it caused by? What are the consequences?
Absence/deficiency of hydrochloric acid in gastric juice Iatrogenic (drugs) Atrophy of gastric mucosa (age) Impaired ability to digest and absorb iron + B vitamins Increased vulnerability of GI tract to infection

Block 1 (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions