Liver And Hepatobilary System Flashcards
What is the anatomy of the liver?
• Functions
○ Most important for this module is the bile production (liver is constantly adding bile into gall bladder)
§ bile is stored under the liver
§ Bile enters through ampulla of vater
§ CCK goes to gall bladder to stimulate contraction of it and release of bile into duodenum
○ Helps to digest and absorb lipids
§ Fat soluble vitamins eg vit D,K,A,E ….need lipid digestion to be absorbed
§ Vit D to maintain tooth health
§ Vit K for blood clotting
○ Liver can store iron and glucose as glycogen
○ Help body fight infection
○ Creation of proteins to help clot blood
○ remove dead red blood cells and process the waste left over
○ Stores nutrients to prevent shortage
• Blood supply
○ From gut to liver via hepatic portal vein
§ Contains many absorbed nutrients
§ Not oxygenated
§ 80% of the blood to the liver is from the gut
§ Liver will clean out the blood (eg from pathogens
○ From heart via Hepatic artery
§ 20% of blood in liver from heart/branched off aorta
§ Provides oxygen to the liver
○ To the heart Hepatic vein
§ Low O2 concentration
§ High in minerals
§ Toxins removed
○ Blood from hepatic portal vein and hepatic artery mix together
• Liver lobules
○ 3D Hexagonal shaped
○ Central vein runs thorugh the middle
○ Hepatic portal vein, hepatic artery and bile duct runs down all 6 edges of the lobule
What is the composition and functions of bile?
• Liver cells make bile 250-1000ml daily
• Contains
○ Bile salts - aid in digestion and absorption of lipids
○ bilirubin and excess cholesterol (insoluble waste)
§ Limit to how much cholesterol (not lipid soluble) can be removed
○ HCO3- to neutralise acid in duodenum
Only 2 ways to remove waste from body - urine via kidneys or poop via small intestine.
If soluble by liquid will absorb into blood so urinated out
If too big to be filtered by kidneys liver can put it into bile so it will be pooed out
• Bile salts - aid in digestion and absorption of lipids
○ Amphipathic
○ Have a hydrophilic head and hydrophobic tail therefore form clusters where heads out outside and tails are inside ( micelles)
○ Wedge shaped so multiple form a sphere
○ Can transport non polar substances inside
What is enterohepatic circulation?
• the movement of bile acid molecules from the liver to the small intestine and back to the liver.
○ If the liver contains any non polar waste products the molecule will be surrounded by a bile salt (micelle). This allows the micelle and the molecule to move around in the bile as the bile’s is a lot of water. Waste product is then excreted.
○ Bile salts can be recycled so use less energy - bile slats are absorbed at end of small intestine and will be sent back to liver via hepatic portal vein this is called enterohepatic circulation of bile salts
Talk about bilirubin in the liver
• Red blood cells die and are eaten by splenic macrophages
○ Iron is in the red blood cells and is important in our body (no way to get rid of it)
• splenic macrophages choose what to recycle : iron, globin
• Haem of haemoglobin is toxic
○ Haem of haemoglobin is covered to unconjugated bilirubin by splenic macrophages in the spleen Bilirubin is insoluble so can’t be removed by kidneys
• Bilirubin and albumin are bound in the blood (unconjugated bilirubin) and is sent to liver
• Un-conjugated Bilirubin is converted into conjugated bilirubin by glucuronic acid (now soluble)
○ Conjugated bilirubin is water soluble can be secreted into the bile so micelles not needed
• Conjugated Bilirubin moves into small intestine via gall blader and duct
Not absorbed so pooped out
What is the functions of the gallbladder?
• Liver creates Bile and it is stored in the gall blader
• Gall bladder removes water from the bile to increase he bile concentration by 10-20x
• Bile is ready when needed
• Bile is toxic/ irritating so must be stored
• If gall blader wasn’t present the bile would go straight to the duodenum and it would be damaged. Also wouldn’t be as concentrated so less effective
• If gall bladder wasn’t present lipid gestion wouldn’t be as effective
How is bile secretion controlled?
• Fatty chyme in duodenum stimulated the release of CCK
• CCK travels to gall bladder to cause contraction and relace of bile into the duodenum
• Also is relaced during a meal
Released into cystic duct
What is jaundice?
• Accumulation of Bilirubin in blood stream
• Caused by
○ Red blood cells die faster than they are processed
○ Impaired liver cells
Before live problem (in blood)= prehepatic jaundice
In liver problem= hepatic jaundice
After liver problem (in intestines) = postherpetic jaundice
○ Obstruction of flow to gall bladder or from gall bladder
• Bilirubin accumulates in skin, teeth, eyes etc…
