Brainscape's Knowledge GenomeTM

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


See full index

Gastrointestinal > Physiology of Digestion and Absorption > Flashcards

Physiology of Digestion and Absorption Flashcards

1
Q

What are the respective sizes of the duodenum, jejunum and ileum?

A

Duodenum - 30cm. Jejunum - 3.5m.

Ileum - 2.5m.

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

What substances does the small intestine receive and where do they come from?

A

Chyme from stomach, pancreatic juice from pancreas and bile from gall bladder.

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

What does the small intestine secrete?

A

Intestinal juice (succus entericus).

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

What hormone causes the ileocaecal valve to open?

A

Gastrin.

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

What are the 3 structures of the small intestine that make it well adapted for absorption?

A

Circular folds (of Kerckring), villi and microvilli (brush border).

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

What cells secrete gastrin, cholescystokinin (CKK), secretin and motilin and where are they located?

A

Gastrin - G cells of antrum and duodenum.
CCK - I cells of duodenum and jejunum.
Secretin - S cells of duodenum.
Motilin - M cells of duodenum and jejunum.

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

What are the 2 incretins?

A

Glucagon-like insulinotropic peptide (GIP) and glucagon-like peptide-1 (GLP-1).

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

What is another name for GIP?

A

Gastric inhibitory peptide.

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

Where are GIP and GLP-1 secreted from?

A

GIP - K cells of duodenum and jejunum.

GLP-1 - L cells of gut.

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

What are the functions of incretins?

A

Act upon B-cells of pancreas in feed-forward manner to stimulate the release of insulin.

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

What type of receptor do hormones secreted by the gut act on?

A

GPCRs.

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

How much succus entericus is secreted per day by the small intestine?

A

2 litres.

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

How does the composition of the succus entericus vary?

A

At different parts of the small intestine.

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

What are the control mechanisms of the small intestine secretions?

A

Distension/irritation, gastrin, CCK, secretin, parasympathetic stimulation (increases), sympathetic stimulation (decreases).

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

What are the 2 components of the succus entericus and their functions?

A

Mucus (protection/lubrication from goblet cells), aqueous salt (enzymatic digestions from crypts of Lieberkuhn).

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

Does the succus entericus have digestive enzymes?

A

No.

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

What transporter brings chloride into the enterocyte from the circulation?

A

Na+/K+/2Cl- co-transporter.

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

What channel does chloride enter the gut lumen through?

A

CFTR?

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

How does sodium and water enter the lumen after chloride?

A

Because of the osmotic gradient (goes around the cell rather than through it).

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

When does segmentation occur very vigorously?

A

After a meal.

21
Q

Why is segmentation in the duodenum activated after a meal?

A

Due to distension by entering chyme.

22
Q

What causes segmentation in the empty ileum?

A

Gastrin from the stomach (gastroileal reflex, feedforward mechanism).

23
Q

What is the net movement in segmentation and why?

A

Aboral. Duodenal has 12 contractions per min, ileum has 9 per min.

24
Q

When does the migrating motor complex (MMC) occur?

A

Between meals every 90-120 mins.

25
Q

What is the MMC?

A

A strong peristaltic contraction passing the length of the small intestine (stomach to ileocaecal valve).

26
Q

What is the purpose of the MMC?

A

Clears small intestine of debris, mucus and sloughed epithelial cells between meals.

27
Q

What inhibits and triggers the MMC?

A

Inhibits: feeding and vagal activity, gastrin and CKK.
Triggers: motilin.

28
Q

Why may macrolide antibiotics cause GI disturbances?

A

They may mimic the effect of motilin.

29
Q

What does the exocrine part of the pancreas produce?

A

Digestive enzymes and aqueous sodium bicarbonate.

30
Q

What cells produce digestive enzymes and bicarbonate in the pancreas?

A

Digestive enzymes - acinar cells. Bicarbonate - duct cells.

31
Q

Describe the path of the pancreas from acni cells into the duodenum.

A

Acni cells to ducts which then combine into bigger ducts which flow into the main pancreatic duct. This then flows into the duodenum.

32
Q

How much alkaline fluid does the pancreas secrete per day?

A

1-2 litres.

33
Q

Why is the alkaline fluid important?

A

It neutralises acidic chyme which provides optimum pH for pancreatic enzyme function and protects the mucosa from erosion by acid.

34
Q

When are enzymes stored in zymogen granules released in acinar cells?

A

When intracellular calcium concentration is elevated.

35
Q

What causes an increase in calcium concentration in acinar cells?

A

Parasympathetic or hormonal stimulation.

36
Q

Why are the proteases produced by the pancreas inactive?

A

They would autodigest the pancreas if they were active.

37
Q

What enzyme in the mucosal cells of the duodenum activates trypsinogen (produced trypsin)?

A

Enterokinase.

38
Q

What are the enzymes that the pancreas secretes?

A

Trypsinogen, chymotrypsinogen, procarboxypeptidase A and B, pancreatic amylase and pancreatic lipase.

39
Q

What enzymes can trypsin activate?

A

Trypsinogen (autocatalysis), chymotripsinogen (produced chymotrypsin) and procarboxypeptidase A and B (produces carboxypeptidase A and B).

40
Q

What are the 3 phases of the control of pancreatic secretion?

A

Cephalic (mediated by vagal stimulation of mainly the acinar cells [20% secretion]), gastric (distension evokes vagovagal reflex causing parasympathetic stimulation of acinar and duct cells [5-10% total secretion]), and intestinal.

41
Q

In the intestinal phase, what does acid in the duodenal lumen cause?

A

Increase of secretin release from S cells, carried by blood to pancreatic duct cells, increased secretion of bicarbonate into duodenal lumen.

42
Q

In the intestinal phase, what does fat and protein in the duodenal lumen cause?

A

Increased CCK release from I cells, carried by blood to pancreatic acinar cells, increases secretion of digestive enzymes into the duodenal lumen.

43
Q

What are the main constituents of carbohydrates?

A

Starch, cellulose, glycogen, disaccharides.

44
Q

What are the 2 types of digestion that occurs in the small intestine?

A

Luminal digestion - mediated by pancreatic enzymes.

Membrane digestion - mediated by enzymes on brush border of epithelial cells.

45
Q

What membranes do things have to travel across to be absorbed?

A

The apical and basolateral.

46
Q

What is assimilation?

A

The overall process of digestion and absorption.

47
Q

Can di, tri or tetrapeptides be absorbed by the gut epithelium and where are they broken down?

A

Yes, in the enterocyte.

48
Q

What types of sugars can be absorbed?

A

Only monosaccharides.

Gastrointestinal (26 decks)

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