Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

ESA 3 - Gastrointestinal System > Stomach > Flashcards

Stomach Flashcards

1
Q

If a hormone is secreted from the stomach, where does it end up?

A

Peptides released from endocrine cells into portal circulation (venous system). They then pass through the liver to enter the systemic circulation. This means that, in the end they end up pretty close to where they were released from.

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

What are paracrine hormones?

A

Hormones that act locally and diffuse short distances

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

What are the main gastrointestinal hormones?

A

Gastric family:
-Gastrin and Cholecystokinin (CCK)

Secretin family:
-Secretin and Gastric inhibitory polypeptide (GIP)

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

What does CCK do?

A

Released by I cells in the duodenum to increase pancreatic and gall bladder secretions.

Stimulated by fat and protein

This works because the Gall bladder contracts which stimulates the pancreas.

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

What does secretin do?

A

Released by S cells in duodenum

Stimulated by H+ and fatty acids

Increases HCO3 from pancreas / gall bladder and decreases gastric acid secretion

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

What does GIP do?

A

GIP = gastric inhibitory polypeptide

Released by cells in the duodenum and jejunum

Stimulated by sugars, amino acids and fatty acids

It increases insulin and decreases gastric acid secretion

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

What are the basic functions of the stomach?

A

Receives food - short term storage
Disrupt food - vigorous contractions of the smooth muscle
Continue / commence digestion
Disinfect

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

Where is the stomach?

A

Upper left quadrant

Lying somewhat under left lobe of liver

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

How is the stomach designed to prevent reflux?

A

Right crust of diaphragm and angle at which the stomach sits means that substances will go into the fundus rather than into the oesophagus.

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

What are rugae?

A

Temporary folds in the stomach (only there when it is empty)

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

What types of cells are in the stomach epithelia?

A 
Mucous cells (secrete mucus) 
Parietal cells (secrete HCl and intrinsic factor)
Chief cells (secrete pepsinogen and chymosin)
G cells (secrete gastrin)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the role of the stomach smooth muscle?

A

There is an extra oblique layer of muscle to allow for mechanical digestion.

Contractions - mix / grind contents and move contents along.

Upper stomach - sustained contractions to create basal tone.

Lower stomach - strong peristalsis mixes stomach contents, contractions every 20 seconds or so (coordinated) proximal to distal.

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

Why is shape of muscles important?

A

Larger part is proximal and smaller part is distal.

This means that the contents accelerates so that lumps are left behind (separates contents) and only liquid chyme is ejected into the duodenum. This ejection occurs roughly 3 times per minute.

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

What are the three main branches of the coeliac trunk?

A

Splenic artery
Left gastric
Common hepatic artery

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

What is the venous drainage of the stomach?

A

Portal vein to liver

Then hepatic vein into IVC

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

What is receptive relaxation?

A

tells stomach stuff is coming so it can relax and create pressure.

Fatally mediated relaxation of the stomach. This allows food to enter the stomach without raising intra-gastric pressure too much. It prevents reflux of the stomach contents during swallow. Also, the gastric mucosal folds (rugae) allow distention.

17
Q

Why is the stomach acidic?

A

Unravel proteins

Activates proteases (Pepsinogen to pepsin) - stops us digesting ourselves

Disinfects stomach contents.

18
Q

What does the stomach secrete?

A

HCL (parietal cells)
Intrinsic factor (parietal cells)
Mucus / HCO3- (mucus cells)
Pepsinogen (chief cells)

19
Q

What are some important cells in the stomach and what do they produce?

A

Parietal cells - HCl and intrinsic factor
G cells - Gastrin
Enterochromaffin like cells (ECLs) - Histamine
Chief cells - pepsinogen
D cells - somatostatin
Mucous cells - Mucus and bicarbonate

20
Q

How do we control HCL production?

A

Parietal cells that secrete HCl are stimulated by gastrin, histamine and ACh.

21
Q

How do we control gastrin secretion?

A

G cells located in Antrum

G cells stimulated by:

  • peptides / aminos cids
  • Vagus nerve (stimulated by ACh and GRP) can activate parietal and G cells
22
Q

How do we inhibit HCL production?

A

Inhibit G cells.

When food leaves the stomach, pH drops as old acts as a buffer.

This low pH activates D cells which release somatostatin.

This somatostatin inhibits G cell (and ECL cells) which therefore reduces the distension of the stomach and therefore the vagal activity.

23
Q

How exactly is HCL produced

A

Split water to make H+

Anion antiport protein bring Cl- into Stomach lumen and out using CL- channel protein.

H+ leaves via H+/K+ ATPase (protein pump)

This means H+ and Cl- an make HCl.

24
Q

What are the three phases of digestion?

A

Cephalic
Gastric
Intestinal

25
Q

What happens in the cephalon phase of digestion?

A

30% of HCl is secreted.
Parasympathetic stimuli:
-Smelling, tasting, chewing, swallowing
-Direct stimulation of parietal cells by vagus nerve
-Stimulation of G cells by vagus (GRP released)

This ‘anticipation food’ also slightly increases gastric motility.

26
Q

What happens in the gastric phase of digestion?

A

This is where 60% of total HCl is secreted.

Distention of stomach stimulates vagus which then stimulates parietal cells and G cells.

The presence of amino acids and small peptides stimulates G cells.

Food acts as a buffer in stomach so it removes the inhibition on Gastrin production.

The enteric NS and Gastrin then cause strong smooth muscle contraction.

27
Q

What happens in the intestinal phase of digestion?

A

The remaining 10% of HCl is produced here.

Chyme initially stimulates gastrin secretion. Partially digested proteins are detected in the duodenum. This is only sort.

Soon overtaken by the inhibition of G cells. Presence of lipids activate enterogastric reflex which reduces vagal stimulation. Chyme stimulates CCK and secretin (help suppress secretion).

28
Q

What are the stomach defences (to stop it digesting itself)?

A

Mucus / HCO3- - released by surface mucus cells in the neck cells of gastric glands. It forms a thick alkaline viscous layer that adheres to epithelium. The epithelial surface is therefore keeps at a higher pH.

High turnover of epithelial cells - keeps epithelia intact

Prostaglandins - maintain mucosal blood flow and supply the epithelium with nutrients.

29
Q

What things breath stomach defences?

A

Alcohol - breath mucus layer

H. pylori - chronic active gastritis

NSAIDS (ibuprofen) - inhibit prostaglandins

ESA 3 - Gastrointestinal System (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions