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GI > Pancreas and Liver > Flashcards

Pancreas and Liver Flashcards

1
Q

What is chyme?

A

the contents from the stomach that goes through to the duodenum through the pyloric sphincter

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2
Q

What are the characteristics of the chyme?

A
  • low pH
  • hypertonic
  • partially digested (still many proteins, fats and CHO’s to digest)
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3
Q

Why is the chyme hypertonic?

A

due to it being partially digested, there are many solutes in it
-water from the ECF and circulation would move in too the solution

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4
Q

Why can water move in to the duodenum but not the stomach?

A
  • the walls of the stomach are impermeable to water coming in
  • in the duodenum, it can move through the walls from the intestine allowing the chyme to become diluted til the contents are isotonic
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5
Q

NOTE

A

the chyme leaves the stomach hypertonic and leaves the duodenum isotonic

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6
Q

Why must the chyme release into the duodenum be controlled?

A

don’t want to lose too much water

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7
Q

How is the low pH and need for digestion to continue managed?

A

secretions from the liver and pancreas

-pancreases releases the enzymes and bicarbonate and liver released bicarbonate and bile

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8
Q

What does the duodenum secrete?

A

CCK and secretin in response to chyme entering the duodenum

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9
Q

What does secretin do?

A

acts on the pancreas to stimulate release of aqueous and HCO3- component of pancreatic secretion which neutralises the pH

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10
Q

What does CCK do?

A

acts on pancreas to stimulate release of enzyme component of pancreatic secretion
-also causes gallbladder to contract and relaxes the sphincter of oddi

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11
Q

What is the major function of the pancreas?

A

exocrine function (about 90%) the rest is endocrine function (10%)

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12
Q

What are pancreatic exocrine function stimulated by (secretions)?

A
  • CCK
  • secretin
  • also autonomics (sympathetic inhibits and parasympathetics stimulate (vagus))
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13
Q

What does the common bile duct do?

A

drains the gallbladder and connects it to the pancreatic duct

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14
Q

What are the components of the acina (pancreatic ducts)?

A
  • ducts are lined by duct cells
  • terminal duct
  • acinar cell
  • centroacinnar cell
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15
Q

What are islets of langerhans?

A

cells that produce hormones like insulin

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16
Q

Where are enzymes released from?

A

CCK stimulates acini cells to produce enzymes

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17
Q

What are the enzymes that are released in the pancreas?

A

amylases
lipases
proteases

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18
Q

What form are the enzymes released in?

A

amylases and lipase released in their active forms but protease is released in its inactive form as it would digest the pancreas if active - the enzymes are stored in zymogen granules

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19
Q

What can occur if the zymogens are secreted in its active form?

A

can cause pancreatitis as can digest the pancreas

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20
Q

What are the inactive forms of proteases?

A
  • carboxypeptidase
  • chymotrypsin
  • trypsin
  • elastase
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21
Q

When are the enzymes activated?

A

once they have been released into the duodenum

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22
Q

Where is the aqueous and HCO3- component released from?

A

the duct cells

23
Q

How does the pancreatic secretions reach the duodenum?

A

through the pancreatic duct and ampulla of vater and enders the duodenum through the sphincter of oddi

24
Q

What does the liver secrete in response to chyme?

A

-bile (secreted by the liver and stored in the gall bladder)

25
Q

What does bile consist of?

A

bile acids and bile pigments and alkaline solution

26
Q

What is the role of bile?

A

key role in emulsifying fats in the duodenum so they can be readily digested by lipase secreted by the pancreas

27
Q

What does “emulsify fats” mean?

A

increases the SA of the large fat globules so that they can be more easily digested by lipase secreted from the pancreas

28
Q

What are the “chief functional cell” of the liver?

A

hepatocytes (80% of the mass of the liver)

29
Q

Due to the high metabolic activity of the liver, what does it have lots of?

A
  • rough and smooth ER
  • lots of golgi membranes
  • glycogen
30
Q

Where does the blood from the gut drain?

A

into the liver via the portal vein

31
Q

What are the 4 parts of the liver lobe?

A

left, right, caudate and quadrate (next to gallbladder)

32
Q

What are liver lobules?

A

the histological structural unit
6 sided lobule
hexagonal arrangement of cells, bile ducts and blood vessels
the hepatocytes are arranges in sheets towards a central hepatic vein

33
Q

What is there in each corner of a liver lobule?

A

triad of structures

  • branch of portal vein
  • branch of hepatic artery
  • branch of bile duct
34
Q

What is the direction of blood flow in the lobule?

A

blood enters a lobule via branches of the hepatic artery and portal veins and flows in towards the central vein via sinusoids

35
Q

How does til flow out?

A

bile is produced by the hepatocytes and moves along canaliculli through the bile duct into the duodenum

36
Q

What is the functional area of the lobule called?

A

the acinus - the functional part of the kidney lobule - splint into zones

37
Q

What do the zones correspond to?

A

distance from the blood supply

38
Q

Which area is more likely to be affected by hypoxia?

A

zone 3 as the oxygen can’t reach that far if there is a lack of oxygen

39
Q

Which zone is more likely to be affected first by toxins and give an example of a time this would happen?

A

zone 1 as that is where the blood reaches first (entry point of the toxins)
an example is paracetamol overdose

40
Q

Where is bile created?

A

by hepatocytes and duct cells in the liver

-it is continuously produced but only needed intermittentY

41
Q

Where is bile stored and what happens there?

A

in the gallbladder
-bile is concentrate by removal of water
(needs to be regulated as can lead to gallstones)

42
Q

How is bile released from the gallbladder?

A

CCK released from duodenum stimulates the contraction of the gallbladder

43
Q

How does bile get into the duodenum?

A

through the common bile cute, ampulla of vater into the duodenum

44
Q

What are bile salts?

A

arise from bile acids (which are secreted into canaliculi by the hepatocytes and are conjugated together to produce a bile salt to increase the efficiency of emulsification)

45
Q

What is the structure of bile salts?

A

-amphipathic structure with a hydrophobic and hydrophilic end

46
Q

Where are alkaline juices secreted from?

A

bile duct cells and are stimulated by secretin

47
Q

What do bile salts do?

A

emulsify large globules of lipids aiding their digestion by lipases - increases the SA

48
Q

What do bile salts do after they have emulsified fat?

A

creates micelles with products of lipid breakdown like cholesterol, free FA and monoglycerides

49
Q

What are micelles job and why are they needed?

A

transport hydrophobic molecules (products of lipid digestion) towards an enterocyte (cell of the intestinal lining)
-the lipids diffuse into the intestinal epithelial cell but bile salts can’t hence the need for micelles

50
Q

What happens to the bile salts after they have transported the lipids to the enterocyte?

A

bile salts remain in the gut and are reabsorbed in the terminal ilium and returned to liver in portal blood where the liver recycles them

51
Q

What happens to the lipids after they are diffused into the enterocyte?

A

the lipid molecules are built back up (re-estified) to triglycerides, phospholipid and cholesterol and packed with apoproteins within the enterocyte to form chylomicrons

52
Q

What do chylomicrons do?

A

they are exocytosed from the basolateral membrane of the enterocyte into the lymphatic capillaries via lacteals (they are too large to enter capillaries)

53
Q

What is steatorrhoea?

A

due to certain pathologies, bile acids and bile salts or pancreatic lipase may not be secreted in adequate amounts so the undigested fat appears in the faeces

54
Q

What are the characteristics of steatorrhoea?

A
  • pale
  • foul smelling
  • floating

GI (10 decks)

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