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1Principles of Biomedicine - MD1 > 135 - Liver and Pancreatic Secretions > Flashcards

135 - Liver and Pancreatic Secretions Flashcards

1
Q

Where is CCK produced?

A

In the duodenum

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2
Q

Why is CCK released?

A

In response to chyme (partially digested food) released into the duodenum from the stomach

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3
Q 
CCK action
1
2
3
4
A

1) Gall bladder contraction.
2) Digestive enzyme release by pancreas.
3) Acts on CNS, promotes feeling of fullness
4) Assists in insulin release

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4
Q

Ionic composition of serum

A

Mostly Na+ and Cl-.

Some HCO3

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5
Q

Ionic composition of gastric juice

A

Mostly H+ and Cl-.

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6
Q

Ionic composition of bile

A

Mostly Na+ and Cl-.

More HCO3- than serum

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7
Q

Ionic composition of pancreatic juice

A

A lot of Na+, Cl- and HCO3-.

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8
Q

Enteropeptidase substrate

A

Trypsinogen

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9
Q

Major components of bile

A 
Water (80-90% of bile in the liver and gallbladder)
Bile pigments 
Bile salts
Fatty acids
Cholesterol
Lecithin
Inorganic salts
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10
Q

Bile salts

A

Detergent derivatives of cholesterol

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11
Q

Lecithin

A

Generic name for phospholipids.

Acts as a detergent.

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12
Q

Bile pigments

A

Products of breakdown of Hb. Mostly bilirubin diglucuronide in bile.

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13
Q

Gall stones

A

Bile salts are normally right at the limit of ability to keep cholesterol in micelles.
If too much cholesterol or too little bile salts, then cholesterol precipitates as gall stones.
Often stained with bilirubin derivatives

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14
Q

Stercobilin precursor

A

Urobilinogen

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15
Q

Constituents of bile that aren’t bile salts

A

Fatty molecules taken up by hepatocytes (not subject to renal excretion) that are modified in liver and excreted into the bile.

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16
Q

Bile acid chemistry

A

Various derivatives of cholesterol, cholic acid.

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17
Q

What generates cholic acid from cholesterol?

A

CYP450 system

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18
Q

Desoxycholic acid

A

Bile acids are recycled in the body.
Bacteria can modify cholic acid to desoxycholic acid.
Humans can not produce desoxycholic acid.

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19
Q

Amphipathic

A

Hydrophilic end and a hydrophobic end.

Detergents.

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20
Q

Cholic acid amphipathicity

A

Is a kind of crinkled shape.
One face of the molecule has a - charge (with a COOH and 3xOH groups).
The other face is uncharged.

21
Q

Are triacyl glycerols hydrophobic or hydrophilic?

A

Neither. They are amphipathic (detergents)

22
Q 
TAG digestion 
1
2
3
4
5
A

1) Emulsion droplet in gut
2) Lipase and colipase secreted from pancreas.
3) Bile acid released from gallbladder/liver
4) TAG digested into fatty acids and 2-monoacylglycerol micelles
5) Enter enterocytes, form triacylglycerols, packaged into chylomicrons

23
Q

Colipase

A

Mr12,000 protein. Procolipase from pancreas is converted to colipase in the intestine. It binds to lipase activating the lipase and preventing bile salt inhibition of lipase

24
Q

Where in gut are fats absorbed?

A

Upper gut.

25
Q

Where are cholesterol and bile salts absorbed in the hut?

A

Lower gut

26
Q

Orlistat

A

Inhibits lipase.

Makes fats indigestible

27
Q

Steatorrhoea

A

In the absence of bile, fats become indigestible and are instead excreted in faeces (steatorrhea). Faeces lack their characteristic brown colour and instead are white or grey, and greasy. Steatorrhea can lead to deficiencies in essential fatty acids and fat-soluble vitamins because they remain associated with other lipids.

28
Q

Effect of orlistat

A

Artificial steatorrhoea

29
Q

Amount of cholesterol made by an average liver per day

A

0.8g per day

30
Q

Amount of cholesterol secreted by the liver each day as bile salts

A

20-30g

31
Q

Essential enzyme in cholesterol synthesis

A

HMG-CoA

32
Q

Amount of cholesterol excreted in faeces each day

A

0.8g

33
Q

Old way that some foods lowered cholesterol

A

Bile salts + complex fibre (or cholestryramine, a synthetic anion binding polymer) lead to insoluble complex excreted with faeces.

34
Q

Problems with cholestyramine treatment for cholesterol

A

Discomfort in the gut.
Normal ability of negative-feedback regulated cholesterol synthesis to make up for the excreted cholesterol. T

The side effects of cholestyramine are stomach upset, heartburn, constipation, belching, gas, nausea, loss of appetite, aggravated hemorrhoids, change of taste, headache and itching

35
Q

Newer way to regulate cholesterol in food

A

Natural plant sterols can be added to margarine to compete with bile salt absorption receptors. 2 to 3 grams a day of a supplemented margarine can reduce total and LDL cholesterol levels 9 to 20 percent. A potentially negative side effect is that sterols reduce the ability to absorb β-carotene and vitamin E.

36
Q

Regulation of cholesterol synthesis in the liver

A

Cholesterol from reabsorbed bile salts negatively feedbacks, inhibits cholesterol synthesis.

37
Q

How are bile salts reuptaken?

A

Actively in ileum

38
Q

Pancreatic acinar cell stimulus for release of digestive enzymes
1
2
3

A

1) Enteric nerves (ACh) stimulate receptors.
2) CCK from duodenum
3) Secretin from duodenum

39
Q

Where in the pancreas is most bicarbonate released?

A

Pancreatic duct cells (not acini)

40
Q 
Examples of pancreatic zymogens 
1
2
3
4
A

Chymotrypsinogen
Trypsinogen
Procarboxypeptidase
Proelastase

41
Q

Trypsinogen activation

A

Intestine enteropeptidase removes tail, trypsin is activated.

42
Q

Regulation of trypsin activation

A

The pancreas makes a trypsin inhibitor (shown in red), that binds to any traces of active trypsin present before it is secreted into the intestine.

43
Q

Function of trypsin

A

Activates chymotrypsin, elastase, carboxypeptidase, colipase

44
Q

Example of a protein that isn’t completely digested in the glu

A

Gluten

45
Q

Pancreatitis

A

Inappropriate activation of pancreatic zymogens.

46
Q

Most common causes of pancreatitis

A

Gallstones and alcohol abuse

47
Q

When do most alcoholics with pancreatitis present?

A

Pancreatitis from alcohol usually occurs in long-term alcohol drinkers and is often chronic by the time the person seeks medical attention (usually for severe pain). A decrease in pain may signal advanced destruction of the pancreas

48
Q

Demographic most at risk of gallstones

A

Women over 50 years of age

49
Q

Enzymes elevated in pancreatitis

A

Serum amylase and lipase

1Principles of Biomedicine - MD1 (157 decks)

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