Hepatobillary System Flashcards
If you can feel someones liver or Gall Bladder what does this mean?
They are too BIG as these are both in the thoracic region so you not be able to fell them past here?
Describe the Anterior, Posterior and Inferior structure of the Liver?
(Look at the anterior picture- thel left lobe starts fromtwhere the diaphragm bit begins)
Inferior vena cava splits the liver in hald, AFTER this landmark come the left lobe
Whar supplies the liver with blood?
Hepatic Artery(red) -25%
Portal Vein(blue) - 75%
What vessels take things away from the liver?
- Left hepatic duct joins the right hepatic duct and joins at the HYLIN. Between this point and the CYSTIC duct where the Gall Bladder joins we call this the COMMON HEPATIC DUCT and after this call it the COMMON BILE DUCT
- 3x Hepatic Portal Veins
Describe the functional anatomy of the Liver?
Coming of the inferior vena cava is the right, left, middle and right inferior hepatic vein
The RIGHT HEPATIC VEIN divides the right side into the anterior and posterior sector
The left picture is actually how you see the liver in the body, the right picture is a liver that has been taken out of the body and the segments put in an order
What are the sections that the liver is divided into?
Right Posterior Section
Right anterior Section
Left Medial Section
Left Lateral Section
There are 8 segements, 2 in each section
What is the clinical relevance of knowing functional anatomy?
If you want to do a right anterior or posterior sectorectomy it is important that you know what vessels go to which part as then you can tie of these vessels and safely do the surgery without a huge amount of blood loss
What is the Hepatic Lobule and what is its structure?
- HEXAGONAL Building block of liver tissue
- PORTAL TRIANGLE in each corner of the hexagon
-CENTRAL VEIN in the middle of the lobule collecting blood from the Hepatic Sinusoids (low pressure vascular channels that receive blood from terminal branches of the hepatic artery and portal vein)->hepatic vein->systematic veins
-HEPATOCYTES along each of the c=vessels and the bile canaliculi
BILE CANALICULI- secrete bile
What does the portal triad consist of?
Portal vein-mixed venous blood from the GIT and spleen
Hepatic artery-brings o2 to the liver to support the hepatocytes
Bile Duct-
What are the functions opf Hepatocytes?
(3 things)
- synthesis and utilise lipids, porteins and fats
- synthesis and secrete proteins, bile and waste
- breakdown of indigested pathogens(detoxification) and porcessing of drugs
What is the acinus?
- Consist of 2x 1/6ths of adjacent hepatic lobules
- share 2 paortal triads
-
What is structure and features of the Hepatic Acinus ?
3 zone structure:
Zone 1(A)-blood is coming in(portal triad)
-most blood, oxygen and toxins
Zone 3(B)- blood is going out(central vein)
-least blood, oxygen and toxins
Zone 2-medum O2 and Toxins
What are the 5 different cell types in the liver and briefly their functions?
SINUSOIDAL ENDOTHELIAL- No basement membrane, have fenestrations(gaps between them)=leaky=things coming from the GIT(lipids and large molecules) can get through and get to the Hepatocytes
KUPPFER CELLS- In the sinosoids, macrophages(phagocytose), eliminate toxins
HEPATIC STELLATE CELLS- exist in dormant state beteen hepatocyes and sinusoids(low pressure vascular channels that recieve blood form hepatic artery and portal vein and deliver to central vein in lobules), stores VIT A, act as fibroblasts when activated by liver damage(causes fibrosis=decreases function of the liver)
HEPATOCYTES- 80% of liver mass, produce Albumin, clotting factors and bile salts,metabolise drugs etc
CHOLANGIOCYTES- secrete HCO3- AND H20 into bile
What is the Cori Cycle?
- Lactate produced from anaerobic respiration is shuttled to the liver
- It is converted ionto Pyruvate
- Pyruvate converted to glucose via Gluconeogenesis
- This glucose can then be reused by the muscle
- cycle starts again
How are proteins synthesised by the liver?
- Amino Acids come either from the fed state or the fasted stated(where proteins are broken down into amino acids by the muscles)
- amino acid transferred to the liver and used as building blocks to produce proteins
What non essential amino acids are produed from:
- Alpha-ketoglutarate
- Pyruvate
- OAA
Alpha-Ketoglutarate-glutamate, proline
Pyruvate- alanine
OAA- asparate
How can you check how well the Liver is working?
Check if ALBUMIN levels are normal as this is the main protein secreted by the liver
- also can check clotting factor levels and lipoproteins
- can measure the TRANSAMINASES (ALT-Analine transaminases, ASP-Asparate transaminases)
How does the liver synthesis non-essential amino acids?
- amino group from ANALINE (amino acid you can get from the diet) is transferred to alpha-ketoglutarate and this transfers ketone group to analine in the liver via a TRANSAMINATION REACTION
- This produces PYRUVATE and GLUTAMATE(amino acid)
you can produce lots of different amino acids in a similar way
What are the problems with muscles using amino acids to produce glucose?
What is the glucose-alanine cyce?
Problems:
- converting pyruvate into glucose requires energy
- to remove nitrogen as urea requires energy
glucose-alanine cycle-making glucose from amino acids in the LIVER instead=solution
Describe the glucose-alanine Deamination cycle?
- You have Glutamate from amino acide breakdown, pyruvare from glycolysis, analine transaminase all in the muscle
- Pyruvate converted to ALANINE via alanine transferase and converation of glutamate->alpha-ketoglutamate
- Alanine and Alpha-ketoglutamate shuttled to the liver
- alanine->pyruvate(via 6 alpha-ketoglutarate->glutamate transmination reaction)
- GLUTAMATE undergoes DEAMINATION (amino group removed), the amino group is converted into ammonia which can then be neutralised into UREA (via 4 ATP)
- Urea removed as waste and glucose leaves liver and used by the muscles
- PYRUVATE->GLUCOSE via 6ATP
What happens when glycogen stores are full?
Liver converts excess GLUCOSE and AMINO ACIDS into fat and stores in Liver and Adipose tissue
Describe briefly triglyceride metabolism in the liver?
- Triglyceride-> fatty acids (in adipose tissue) and shuttled to the liver
- Fatty acids-> Acetyl CoA (beta-oxidation)
- Acetyl CoA enters TCA cycle to produce ATP
0R
for 3rd step 2x Acetyl CoA can join resulting in AcetoAcetate which can be used by body tissue as an energy source
Describe Lipoprotein synthesis in the Liver?
- Glucose enters the liver and is converted directly into GLYCEROL or Glucose-> Pyruvate-> Acetyl CoA -> Fatty Acids/Cholesterol
- Glycerol+ 3 Fatty acids-> Triglyceride
- Triglyceride+Apoproteins+Phospholipids+cholesterol-> Lipoproteins
What are the 2 important lipoproteins produced by the liver?
VLDL- transports fatty acids to tissues once it gets rid of fatty acids they are now LDLs and transport cholesterol to tissues
HDL-empty so picks up excess cholesterol
What are the 2 main uses of Cholesterol?
- Maintain cell membrane Integrity
- Make lipoproteins
What do hepatocytes store?
- fat soluble vitamins(A, D, E, K)
- stores are sufficient for 6-12 months (except for vit K as this store is small and a deffiecieny can cause clotting problems)
- Iron stored as Ferritin
- Copper
Describe the Morphological anatomy of the Bilary System?
- COMMON BILE DUCT enter the pacnrease and joins with MAIN PANCREATIC DUCTS(controlled by Sphincter of Oddi) and then
- This joint duct comes out in the DUODENUM in the AMPULLA and is know as the AMPULLA OF VATER
What does the Bilary System do?
Produce Bile
What is the composition of Bile ?
What are the 3 main uses of Bile?
cholesterol Homeostasis
Abosorption of Lipids and lipid soluble vitamins(A, D, E, K)
Excretion of:
-xenobiotic drugs(foreign tings)
-cholesterol metabolites
-Adrenocortical and other steroid hormones
Alkaline Phosphate
How much bile is porduced each day and by what?
500ml per day
- 60% by Hepatocytes(Primary secretion)
- 40% by Cholangiocytes(secondary modifications of bile-add water, alter pH, glucose and acids reabsorbed into the bile, cl- and hco3- secreted into bile)
What is the colour of bile?
More Bilirubin=more yelow
More Biliverdin=more green
How are things entering/leaving the Bile Caniculi ?
BILARY TRANSPORTERS (on the surface of Hepatocytes and Cholangeocytes)
What are the 4 main types of Bilary Transporters?
BILE SALT EXCRETARY PUMP(BSEP)- active transport of bile acids/salts into bile
MDR RELATED PROTEINS- (MRP1 + MRP3)
PRODUCTS OF FAMILIAL INTRAHEPATIC CHOLESTASIS GENE (FIC1)
PRODUCT OF MULTIDRUG RESISTANCE GENES -MDR1(excretion of xenobiotics and toxins), MDR3
What are bile acids/ salts made from?
Cholesterol
What are the 2 Primary Bile acids/slats made in the Liver and what secondary bile acids do they form?
Cholic acid-> Deoxycholic Acid
Chenodeoxycholic->Lithocolic Acid
Converted by gut bacteria in the Bilary Tree
How do bile salts work?
- Reduce surface tension of fats so they can be emulsified prior to digestion and absorption
- They are able to do this because they are AMPHIPATHIC ( has 2 faces)
- 1st face is HYDROPHILIC (faces outwards) = dissolvable in water
- 2nd face is HYDROPHOBIC(faces inwards)=dissolves in fat
1-bile salts and phospholipids coat fat globules and emulsify them into drplets
2-LIPASE + COLIPASE further break these down into FATTY ACIDS+ MONOGLYCERIDES which form MICELLES that cna be absorbed
How is bile flow and secretion regulated?
When not eating-SPHINCTER OF ODDI is closed = bile stored in the GALL BLADDER
Eating-Shincter relaxes= Gastric contents (amino acids and fatty acids) enter DUODENUM = causes release of CHOLECYSTOKININ (CKK) =causes the bladder to contract = increase Bile secretion
Decribe the Enterohepatic circulation?
- 95% of Bile Salts absorbed from the terminal ileum by Na+/ bile salt co-transport and Na+/ATPase system
- these are absorbed back to Liver and re-excreted in bile
- 5% converted to sencondary Bile salts in COLON ( Deoxycholic acid is absorbed and Lithocolic acid is excreted in the stool)
What are the functions of the Gall Bladder?
Not very important
- stores Bile
- Gall Bladder contractions triggered by CCK
What are the features of Bilirubin?
TOXIC -so has to be precessed properly
H20 insoluble
FREE BILIRUBIN-is unconjugated/indirect(bound to a protein in the blood)
What is the source of Bilirubin?
75% from Hb from the breakdown of erythrocytes
22% fromt the catabolism of other haemoproteins
3% form ineffective bone marrow erythropoiesis
How is Bilirubin processed?
- Free BR bound to ALBUMIN in the blood(becase its insoluble)
- Gets to the liver and is unbound from albumin and enters Hepatocytes
- It conjugates with 2 molecules of UDP-GLUCURONATE= BILIRUBIN DIGLUCURONATE (direct bilirubin) Making it SOLUBLE
- secreted into Bilary Canulculi->GIT across concentration gradient
- 85% is excreted into faeces( BR->urobilinogen->stercobiliogen->stercobilin(brown)
- 15% enters the enterohepatic Circulation
- 1% peed out
How much Biirubin is excreted into the Bile daily?
200-250mg
Why do you get Pre-Hepatic Jaundice?
-Producing more Indirect Bilirubin than you usually do do to breaking down of abnormal erythrocytes and their Hb
Why do you get intrahepatic Jaundice?
Liver is not working properly due to:
- decreased secretion, uptake, or conjugation of bilirubin
- outflow of bilirubin blocked
What are the causes of Post Hepatic Jaundice?
Interruption to the drainage of bile containing conjugated bilirubin
What problems do Gallstones cause?
CHOLELITHIASIS-stones can tleave the gall bladder =pain
CHOLECYSTITIS-gall stones get stuck in the cystic duct=infection of the gall bladder as things cant leave, it could also block the bile duct
CHOLANGITIS-stone can escape and get stuckin common bile duct=infection
PANCREATITIS-stone gets stuck in main pancreas duct and then pancreatic juice cant gwt out = back pressure
