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Liver and Pancreas Flashcards

1
Q

What organ produces bile?

A

Liver

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2
Q

How do bile and hormones from the pancreas enter the duodenum?

A

Common bile duct at the ampulla of Vater

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3
Q

What does the Sphincter of Oddi control?

A

The opening of the common bile duct into the duodenum

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4
Q

What protein causes the Sphincter of Oddi to relax and open?

A

Cholecystokinin

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5
Q

Does the gall bladder expand easily to store bile?

A

yes

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6
Q

Why is there sometimes an accessory pancreatic duct (duct of Santorini)?

A

Because the pancreas starts as two components during development

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7
Q

What is the parasympathetic innervation of the liver and pancreas?

A

Vagus

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8
Q

What are neuroendocrine cells?

A

Neural cells that have migrated to end up in epithelium

E.g. APUD cells (amine precursor uptake and decarboxylation)

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9
Q

What is the role of Vasoactive intestinal peptide (VIP)?

A

modifies the function of smooth muscle in the bowels

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10
Q

What is the pathway of VIP?

A

neurocrine

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11
Q

What is the pathway of CCK?

A

endocrine + paracrine

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12
Q

What is endocrine?

A

Secretes products directly into blood

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13
Q

What is exocrine?

A

Secretes products into ducts that lead to the target tissue

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14
Q

What is paracrine?

A

Acts only on nearby cells

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15
Q

What is neurocrine?

A

Similar to paracrine (acts on nearby cells) but involves neurones

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16
Q

What is the main role of gastrin?

A

To cause acid secretion in the stomach

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17
Q

What stimulates the release of CCK?

A

fatty acids and amino acids in the duodenum

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18
Q

Where is CCK released?

A

From I cells in duodenum and jejunum

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19
Q

Where is secretin released?

A

S cells in the duodenum

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20
Q

What stimulates the release of secretin?

A

acid in duodenum and small intestine

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21
Q

What is the pathway of secretin?

A

endocrine + paracrine

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22
Q

What is the pathway of gastrin secretion?

A

endocrine

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23
Q

What is the role of cholecystokinin-pancreozymin (CCK)?

A

Peptide hormone secreted by I cells (APUD cells - neuroendocrine) that stimulates pancreatic secretion and gallbladder emptying into the duodenum

24
Q

How does CCK stimulate gall bladder emptying into the duodenum?

A

By causing the sphincter of Oddi to relax

25
Q

What stimulates the release of CCK?

A

Lipids and peptides in the small intestine

26
Q

What hormone is very similar to CCK?

A

gastrin, they share receptors (CCK-A and CCK-B)

27
Q

How is CCK released?

A

fatty acids are sensed by the epithelium and a releasing peptide for CCK is released, which triggers I cells to release CCK

28
Q

How does CCK work and what does it cause the pancreas to secrete?

A

Travels to pancreas, causing it to secrete proteolytic enzymes. Pancreas secretes a monitor peptide which activates the I cells to make more CCK –> positive feedback

29
Q

How is CCK release stopped?

A

Pancreas releases trypsin, and when all protein is digested it digests the CCK monitor peptide released by the pancreas and CCK releasing peptide –> negative feedback loop

30
Q

Where is secretin released from?

A

S cells in duodenum

31
Q

Whats the longer peptide, secretin or CCK?

A

CCK

32
Q

What stimulates secretin release from S cells in duodenum?

A

acid in small intestine

33
Q

What are the 3 roles of secretin?

A

stimulates bicarb and fluid secretion by ductal cells in pancreas and liver

has a trophic effect on the pancreas - maintains growth

modest inhibition of gastric acid production from the stomach –> negative feedback loop

34
Q

What do bile salts form at high concentrations?

A

Micelles

35
Q

What are bile pigments formed from?

A

breakdown of haemoglobin from old RBCs

36
Q

What are the components of bile?

A 
Bile salts/acids
phospholipids
cholesterol
haemoglobin
inorganic ions (mainly cations because bile acids are negative)
37
Q

Where is bile pigment formed and why?

A

Spleen
Red cells go tot he spleen to die, so heamoglobin is broken down to bilirubin which travels round in the plasma attached to albumin
In the liver this is bound to glucuronic acid forming bilirubin glucuronide which is water soluble and excreted in bile

38
Q

How is bilirubin glucuronicde (formed in the liver) removed?

A

Faeces

Broken down by bacteria back to bilirubin

39
Q

What is urobilinogen and how is it removed from the blood?

A

Forms when bilirubin comes into contact with acid

Absorbed and carried to liver, re-excreted/filtered by kidneys into urine

40
Q

Why is urine dark in liver disease?

A

more bile ends up in the urine, and bilirubin makes urine dark

41
Q

What are sinusoids?

A

specialised vessels int he liver which are a mix of artery and vein

42
Q

How do fluids (+ glucose, calcium, amino acids) get into bile?

A

Pass passively through tight junctions between hepatocytes

43
Q

What do bile ducts in the liver secrete into bile? What hormone stimulates this?

A

bicarb (swapped for chloride from cells)
salt (flows passively to balance charge)
water (dilutes bile fluid)

secretin (with minor effects from glucagon and VIP)

44
Q

Why does the gall bladder reabsorb salt and water from bile?

A

To increase conc of bile salts and lipids so that they start to form micelles (precipitation), so lots of bile salts can be stored without the fluid volume rising too high (small volume but still isotonic)

45
Q

How is water easily exchanged in the gallbladder?

A

leaky tight junctions

46
Q

Why are protons secreted into the gallbladder?

A

Acidifies the bile to reduce the risk that molecules like Ca2+ will precipitate and cause gallstones

47
Q

Why do fatty foods aggregate gallstones?

A

I cells secrete CCK enzymes and this causes the gallbladder to contract. Gallstones can then get trapped somewhere and cause pain.

48
Q

Where are most bile salts recycled?

A

Move down to terminal ileum where Na+ linked co-transporters transport them into the blood stream and they are then transported back to the liver

49
Q

What happens to bile salts that end up in the colon?

A

deconjugated by bacteria, become uncharged and are absorbed back across the intestinal wall

50
Q

Why are proteases secreted from the pancreas as inactive precursors (zymogens)?

A

so they don’t damage the pancreas

51
Q

Whats the role of trypsin inhibitors in the pancreas?

A

stop any zymogens that do become active from damaging the pancreas

52
Q

What is a zymogen?

A

An inactive precursor to an enzyme

53
Q

What do acinar cells in the pancreas secrete?

A

enzymes, NaCl and water

isotonic fluid

54
Q

What controls secretion by acid cells?

A

parasympathetic - ACh

CCK indirectly controls in the absence of parasympathetic control

55
Q

What secretes bicarbonate?

A

Pancreatic ducts

56
Q

What stimulates the secretion of bicarbonate?

A

Secretin, potentiated by CCK via vagus

gi (10 decks)

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