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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
What does bile consist of?
bile acids and bile pigments and alkaline solution
26
What is the role of bile?
key role in emulsifying fats in the duodenum so they can be readily digested by lipase secreted by the pancreas
27
What does "emulsify fats" mean?
increases the SA of the large fat globules so that they can be more easily digested by lipase secreted from the pancreas
28
What are the "chief functional cell" of the liver?
hepatocytes (80% of the mass of the liver)
29
Due to the high metabolic activity of the liver, what does it have lots of?
- rough and smooth ER - lots of golgi membranes - glycogen
30
Where does the blood from the gut drain?
into the liver via the portal vein
31
What are the 4 parts of the liver lobe?
left, right, caudate and quadrate (next to gallbladder)
32
What are liver lobules?
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
What is there in each corner of a liver lobule?
triad of structures - branch of portal vein - branch of hepatic artery - branch of bile duct
34
What is the direction of blood flow in the lobule?
blood enters a lobule via branches of the hepatic artery and portal veins and flows in towards the central vein via sinusoids
35
How does til flow out?
bile is produced by the hepatocytes and moves along canaliculli through the bile duct into the duodenum
36
What is the functional area of the lobule called?
the acinus - the functional part of the kidney lobule - splint into zones
37
What do the zones correspond to?
distance from the blood supply
38
Which area is more likely to be affected by hypoxia?
zone 3 as the oxygen can't reach that far if there is a lack of oxygen
39
Which zone is more likely to be affected first by toxins and give an example of a time this would happen?
zone 1 as that is where the blood reaches first (entry point of the toxins) an example is paracetamol overdose
40
Where is bile created?
by hepatocytes and duct cells in the liver | -it is continuously produced but only needed intermittentY
41
Where is bile stored and what happens there?
in the gallbladder -bile is concentrate by removal of water (needs to be regulated as can lead to gallstones)
42
How is bile released from the gallbladder?
CCK released from duodenum stimulates the contraction of the gallbladder
43
How does bile get into the duodenum?
through the common bile cute, ampulla of vater into the duodenum
44
What are bile salts?
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
What is the structure of bile salts?
-amphipathic structure with a hydrophobic and hydrophilic end
46
Where are alkaline juices secreted from?
bile duct cells and are stimulated by secretin
47
What do bile salts do?
emulsify large globules of lipids aiding their digestion by lipases - increases the SA
48
What do bile salts do after they have emulsified fat?
creates micelles with products of lipid breakdown like cholesterol, free FA and monoglycerides
49
What are micelles job and why are they needed?
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
What happens to the bile salts after they have transported the lipids to the enterocyte?
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
What happens to the lipids after they are diffused into the enterocyte?
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
What do chylomicrons do?
they are exocytosed from the basolateral membrane of the enterocyte into the lymphatic capillaries via lacteals (they are too large to enter capillaries)
53
What is steatorrhoea?
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
What are the characteristics of steatorrhoea?
- pale - foul smelling - floating

GI (10 decks)

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