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First year semester 2 > Pancreas and Liver > Flashcards

Pancreas and Liver Flashcards

1
Q

Describe the functional anatomy of the exocrine pancreas

A

Exocrine responsible for digestive processes
1. V shaped organ
2. Microscopically = acini (groups of secretory cells) simple cuboidal epithelium surrounding an excretory duct
3. Major part of pancreas
4.

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2
Q

What is the role of the pancreas?

A
  1. to secrete substances (pancreatic juice) into the duodenum
  2. 2 major functions = digestion (exocrine) and Regulation of metabolism (endocrine)
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3
Q

Functional anatomy of endocrine pancreas?

A 
Principle function = regulation metabolism
1. consists of lots of isolated clumps of cells surrounding a capillary = islets of langerhans
2. minor part of pancreas (1-2%)
3. 3 diff cells: beta, alpha, delta
4. Hormone secretion into blood stream:
Insulin - beta cells 65%
Glucagon - alpha cells 25%
Somatostatin = delta cells 10%
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4
Q

What is saliva production in ruminants equivalent to horse/ pig?

A
  1. pancreatic juice
  2. R = fermentation in stomach = lot of secretion from salivary gland
  3. others = fermentation in large intestine so secretion from pancreas.
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5
Q

What is the enzyme composition in pancreatic juice?

A
  1. Enzymes for carb (not non hydrolysable or fibre), fat and protein breakdown
  2. proteases - inactive fform to prevent digestion of stoamch
  3. Amylase breaks down starch to maltose
  4. Lipases/ phospholipases break down fat to glycerol/ fatty acids
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6
Q

List 3 pancreatic enzymes and what break down

A
  1. Trypsin(ogen) –> protein, peptides
  2. Lipase –> triglycerides
  3. Amylase –> polysaccharides
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7
Q

How is trypsinogen activated?

A
  1. inactive protease
  2. duodenal epithelial contains enteropeptidase on brush border = trypsinogen into trypsin = activated
  3. Trypsin auto catalyses trypsinogen into T as well as activating other proteases (remember pepsin down this too)
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8
Q

What if trypsin activated within pancreas not duodenum?

A
  1. as precaution pancreatic cells also secrete trypsin inhibitor to prevent auto digestion
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9
Q

What are the 3 phases to digestion? What are their 3 roles?

A
  1. cephalic
  2. Gastric
  3. Intestinal
    Roles are to increase pancreatic juice secretion
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10
Q

How are the cephalic and gastric regulations of secretion mediated? What does this result in for carnivores and horse/ pig

A
  1. by the vagus nerve and hormone gastrin
  2. C = only enzymatic component
  3. Horse/ Pig = ionic component as well (for large intestinal fermentation
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11
Q

How are the cephalic and gastric regulations of secretion mediated? What does this result in for carnivores and horse/ pig

A
  1. by the vagus nerve and hormone gastrin
  2. C = only enzymatic component
  3. Horse/ Pig = stimulate ionic component of pancreatic juice as well (for large intestinal fermentation) = need larger vol of secretion
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12
Q

How is the intestinal phase mediated in the regulation of secretion?

A

Hormonal phase

  1. by 2 hormones secretin/ CCK
  2. most pancreatic juice secreted
  3. Vasoactive inhibitory peptide (VIP) hormone inhibits effect of secretin
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13
Q

What is the purpose of secretin?

A
  1. To increse bicarbonate (HCO3-) secretion
  2. it is releases from duodenum in response to acid (H+)
  3. acid detected by endocrine cells = production of secretion into blood stream, back to pancreas which secretes more bicarbonate
  4. neutralises acid
  5. Negative feedback
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14
Q

Purpose of CCK and real name?

A
  1. Cholecystokinin
  2. Released into blood stream from duodenum in response to metabolites to have effect on pancreas = inc enzyme secretion
  3. pos feedback - inc enzyme secretion from pancreas, produces more metabolites, stimulates further CCK release
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15
Q

Pancreas comparative physiology depends on…

A

eating.

  1. continuously eating? ruminant (herbivore)
  2. intermittent eating? (carnivore/ omnivore)
  3. Horse continuous flow BUT also increases after feeding as stomach is AFTER small itnestine, unlike ruminant. Also pancreatic jucie is relatively low in bicarbonate - ileum can secrete some bicarbonate
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16
Q

Insulin

A
  1. produced and secreted by beta cells
  2. peptide hormone released in response to increased plasma levels of glucose and amino acids (eating)
  3. Overall ANABOLIC (build up) effect
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17
Q

How is the nervous system involved in insulin secretion?

A
  1. Autonomic nervous system
  2. Parasympathetic activity via vagus nerve increases inculin secretion = when eating
  3. Sympathetic activity and adrenaline release DECREASES insulin secretion
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18
Q

What insulin actually does.

A
  1. binds to receptor cells on target cell
  2. incorporation of GLUT4 transporter protein to cell membranes
  3. stimulates inc in glucose absorption
  4. most important anabolic mediator
  5. ALSO amino acid uptake enhanced especially in skeletal musce and adipose tissue
  6. ALSO increases triglyceride synthesis
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19
Q

Diabetes mellitus “sweetened urine”

A
  1. Hyperglycaemia due to decreased uptake by cells
  2. capacity for kidney to re absorb glucose is exceeded (glucosuria) = sugar in urine
  3. Type 1 = insulin dependent = insulin production impaired
  4. Type 2 = Non insulin dependent - cells not responding (receptors impaired)
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20
Q

Hyperglycaemia

A
  1. results in PUPD (polyiria/ polydypsia)
  2. excessive production of urine/ excessive drinking
  3. specific gravity expect to be low but artificially normal/ high due to glucosuria
  4. degredation of lipids into fatty acids. Incomplete metabolism = ketone bodies = inc = metabolic acidosis as ketones cause blood pH to decrease = leads to coma and death
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21
Q

Hypoglycaemia

A
  1. glucose levels too low
  2. most often caused by insulin overdose (animal not eat meal but owner injects) or tumour of pancreatic beta cells
  3. Treatment = oral/ intravenous glucose
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22
Q

Glucagon

A
  1. peptide hormone released in response to decreased levels of insulin and amino acid
  2. CATABOLIC effect = break things down to release glucose
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23
Q

Describe the gross anatomy of the liver

A
  1. Located in dome of diaphragm within abdominal cavity
  2. 4 lobes: left, quadrate, right and caudate
  3. Dog, cat, pig: left and right lobe split into medial and lateral part- allow to movement due to diaphragm
  4. Caudate lobe in msot species by horse has 2 parts: caudate and papillary processes
  5. carnivores, ruminants, pigs, mice have gall bladder. Horse and rat don’t
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24
Q

Describe the gross anatomy of the liver

A
  1. Located in dome of diaphragm within abdominal cavity
  2. 4 lobes: left, quadrate, right and caudate
  3. Dog, cat, pig: left and right lobe split into medial and lateral part- allow to movement due to diaphragm
  4. Caudate lobe in msot species but horse has 2 parts: caudate and papillary processes
  5. carnivores, ruminants, pigs, mice have gall bladder. Horse and rat don’t
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25
Q

Location of liver in horse and why. Also splitting pattern of lobes adn why

A
  1. Development of large intestine mean liver is pushed over to RHS
  2. RH lobe not split as not impinged by diaphragm, however LH lobe is so IS split
26
Q

Location of liver in ruminants and why and splitting pattern of lobes

A
  1. Liver pushed to RHS by development of large stomach

2. NO splitting of liver as not impinged on at all.

27
Q

Liver histology

A
  1. connective tissue capsule that surrounds liver

2. this CT also extends into liver as SEPTAE, dividing it into anatomical units which are called hepatic lobules

28
Q

Liver histology

A
  1. connective tissue capsule that surrounds liver
  2. this CT also extends into liver as SEPTAE, dividing it into anatomical units which are called hepatic lobules = roughly hexagonal
29
Q

What is the main cell of the liver?

A
  1. Hepatocyte
30
Q

Where is bile produced from how does it leave?

A
  1. the biliary system
  2. conveys bile from liver to duodenal lumen
  3. controlled by sphincter of oddi which controls bile going into duo from liver
  4. secreted across hepatocyte membrane
  5. If animal has a gall bladder (carnivore, omnivore, ruminant, mice) = moves via cystic duct into gall to be stored ready for next meal.
31
Q

Where is bile produced from how does it leave?

A
  1. the biliary system
  2. conveys bile from liver to duodenal lumen
  3. controlled by sphincter of oddi which controls bile going into duo from liver
  4. secreted across hepatocyte membrane
  5. If animal has a gall bladder (carnivore, omnivore, ruminant, mice) = bilemoves via cystic duct into gall to be stored ready for next meal.
32
Q

Name the structures bile moves through

A
  1. Hepatocyte
  2. canaliculi
  3. Ductules (intrahepatic)
  4. Ductus (intrahepatic)
  5. HEpatic bile ducts (extrahepatic)
  6. If gall = cyctic duct to gall
  7. when eats = gall through cyctic duct
  8. to common bile duct
33
Q

What vessels are important for supplying/ taking blood away in the liver?

A

3 main: HPV, HA, HV

  1. Hepatic portal vein:
  2. Hepatic artery = 25% blood = from aorta
  3. Hepatic vein
    (4. Sinusoids = receive blood from terminal branches of hepatic artery and hepatic portal vein and deliver into central veins)
34
Q

Describe hepatic portal vein

A
  1. supplies 75% blood to liver
  2. Blood from GI and spleen
  3. bringing blood with absorbed things from GI
  4. like an “Extra”
35
Q

Describe Hepatic artery

A
  1. supplies liver with 25% blood which is from from aorta

2. think of this as normal artery

36
Q

Describe Hepatic vein

A
  1. Brings blood from liver back to heart via caudal vena cava
  2. think of this as normal vein
37
Q

What vessels “come into liver” and what leaves?

A

comes in: 1. Hepatic portal vein and Hepatic artery

2. Leaves = Hepatin vein

38
Q

Between the lobules of the liver are what structures? and what are the 3 main components of these?

A 
1. portal tracts
Consists of:
1. Bile duct
2. Hepatic artery
3. Hepatic portal vein
39
Q

Sinusoids

A
  1. considered as vascular channels
  2. lines with fenestrated endothelial cells
  3. surrounded by layers of hepatocytes
  4. MAcrophage within to destroy any bacteria.
40
Q

Functions of liver

A
  1. detoxification of body wastes, drugs etc
  2. Storage of glycogen, iron, copper, vitamins, synthesis of cholesterol, bile acids, plasma proteins
  3. breakdown RBC: degrades haem which is hard to degrade
  4. carbo, lipid, amino acid metabolism
  5. removal of bacteria
  6. production of clotting factors
41
Q

How does the liver affect the dosage of a drug we give?

A
  1. If liver metabolises therefore detoxifies it quickly = higher dosage
42
Q

Liver metabolism of the 2 types of food stuff brief

A
  1. Carbo metabolism: gltcogenesis, glyconeolysis, gluconeogenesis
  2. Lipid met: synthesis cholesterol, phospholipids and bile acids. Oxidation of FA and ketone body formation
  3. Protein met: Deamination and transamination of amino acids. Synthesis of non-essential AA (AA we can make ourselves = not reliant on food)
43
Q

Detoxification and clearance

A
  1. everything passses through liver from GI via hepatic portal vein
  2. Toxic substances (drugs, toxins) converted into something less toxic
  3. Removes harmful substances from blood
  4. degraded, made water soluble and excreted in urine or bile
44
Q

NAme toxins

A
  1. DRUGS
  2. toxins (plant)
  3. Endrogenous metabolites e.g. break down protein, end product = toxin ammonia. Liver converts into urea, liver excretes as urine. Also hormones and haem
45
Q

Degradation of RBC

A
  1. REmoved from blood by macrophages in spleen and liver
  2. degraded to yield haem from haemoglobin
  3. Haem converted to bile pigments
46
Q

Describe the function of bile

A
  1. Promotes hydrolysis by lipases: acts as emulsifying agents
  2. Facilitates intestinal absorption of lipids: micelles improves solubilisation therefore uptake of lipids
  3. Exit route for waste products and drugs: excretion in faeces + only way we can eliminate cholesterol
47
Q

Describe the composition of bile

A
  1. Water
  2. Electrolytes: HCO3- making it alkaline
  3. Biliary proteins
  4. Bile pigments (bilirubin)
  5. Cholesterol
  6. Phospholipids
  7. Bile acids: cholic acid adn chenodeoxycholic acid
48
Q

Describe the storage of bile

A
  1. stored in gall bladder (carnivores, omnivores and mice)

2. benefits those with intermitted digestion

49
Q

How do horses cope if no gall bladder?

A
  1. Levels of fat in diet are usually low
50
Q

Who needs bile to be concentrated, who doesn’t and where does concentration occur?

A
  1. Conc occurs in gall bladder for intermittenet eaters (carni adn omni)
  2. Herbivores don’t need as continuous and low fat in diet
  3. Ruminants do have gall but ineffective concentrating mechanism due to presence of fermentation occuring before duodenum release of fats = more intermittent than continuous)
51
Q

How are bile acids synthesised?

A
  1. from cholesterol in the liver

2. synthesised into the 2 acids: cholic acid and chenodeoxycholic acid

52
Q

Only 2 bile acids are synthesised from cholesterol why is there 4 bile acids involved in fat digestion?

A
  1. from cholesterol = cholic acid and chenodeoxycholic acid
  2. these are hydrophobic so to make water soluble = conjugated with AA glycine or taurine
  3. = 4 primary bile acids as synthesised by liver itself
53
Q

What are secondary bile acids?

A

Acids that are made by bacteria NOT liver

  1. primary acids that have passed into Ileum after lip digestion and absorption
  2. They’re modified by intestinal bacteria.
54
Q

Summary of all bile acids:

A 
Primary bile acids (synthesised in liver)
• Glycocholic acid
• Taurocholic acid
• Glycochenodeoxycholic acid
• Taurochenodeoxycholic acid
Secondary bile acids (metabolisation of primary bile acids by bacteria)
• Lithocholic acid
• Deoxycholic acid
55
Q

Describe the secretion of bile acids

A
  1. BA transported into bile canaliculus
  2. Bile canaliculi is isolated from hepatocyte cell membrane by tight junctions to prevent leakage
  3. Bile canaliculi feed into large canals
  4. Bile emptied into duodenum at major duodenal papilla controlled by sphincter of oddi
  5. Bile salts not fat soluble so remain in small intestinal lumen until actively reabsorbed in ileum
56
Q

What is enterohepatic circualtion?

A
  1. the “recycling” of bile acids
  2. absorbed from terminal ileum by active transport
  3. Transported back to liver via hepatic portal vein
57
Q

How is bile secretion regulated?

A
  1. Parasympathetic nervous system (vagus nerve)
  2. Hormonal: CCK and secretin
  3. Enterohepatic circulation
58
Q

How do hormones regulate bile secretion?

A

CCK –> released in response to fat present in duodenum = contraction of gall, relation of sphincter of oddi
Secretin = released in response to presence of acid chyme in duodenum. Mainly stimulates release of pancreatic juice, also increases HCO3- production by liver

59
Q

How does the enterohepatic circulation regulate bile secretion?

A

During a meal: Enterohepatic circulation of bile salts increases
2. Between meals enterohepatic circulation of bile salts decreases

60
Q

Pathophysiology of liver disease (physiology going wrong!) can be caused by: and may affect what functions?

A 
Caused by:
1. Infection
2. Poisoning
3. Tumours
Functions affected:
1. Bile acid recycling
2. Detoxification
3. Metabolic functions
HOWEVVVER liver has the potential to regenerate
61
Q

What are some clinical signs of liver disease?

A

• Hepatic dysfunction
• Depression, decreased appetite & lethargy
• Stunting & weight loss
• Vomiting & diarrhoea (toxin build up)
• Polyuria & polydipsia (PU/PD)
• Ascites & altered liver size
a) Increase = hepatomegaly
b) Decrease = microhepatica
• Icterus (= jaundice)
a) Increased levels of bilirubin in blood
• Bleeding tendency

62
Q

How can we detect liver disease biochemically?

A
  1. Liver enzymes released into blood when liver damaged. Depends on species
  2. Detection of levels of liver metabolites e.g. pre and post bile acid (should decrease after meal)

First year semester 2 (50 decks)

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