Digestion: the liver Flashcards
name the key functions of the liver
filtering for circulation by removing foreign particles synthesis or secretion of bile metabolise carbohydrates fat metabolism detoxification
anatomy of the lobes of the liver
right lobe
left lobe
caudate lobe
quarate lobe
descrbe the anatomy of the liver
ligament separates the left anf right lobes and connects it to the diaphram
what are iver lobules
boarded by connective tissue
central vein in each lobule
made up of hepatocytes
what is the portal traid
hepatic artery
bile duct
hepatic poral vein
how does hepatic cirulation work
2 supplies: artery going in
vein out
function of the gal bladder
storage of bile
concentrate the bile
absorbs na, chloride, bicarbonate and water
what happens in the gall bladder during interdigestive periods
sphincter of oddi closed
bile stored and concetrated during wait
what happens to the gal bladder after eating
lipids and proteins present CCK secreted relaxes the sphincter of oddi gall blader contracts bile released into duodumun
function of the bile
eliminates waste products from the body such as bilirubin and cholestrol
digestion and absorption of lipids
how is bile produced?
- hepatocytes secrete bile into the bile ducts
- ductual epithelial tissues modify the primary secretions by releasing watery, bicarbonate-rich fluid
- means, half the bile delivered to the gallbladder to be stored
what is the livers primary role
synthesis and excretion of cholestrol
what happens to chylomicrons
acted on my lipoprotein lipase to unpackage it
remnants of cholesterol sent to liver to make LDL
its bound to lipoproteins
what is a LDL
Low-density lipoprotein
more fat than lipoprotein
what do LDLs do
deposit fat in the extra hepatic tissues
what are HDLs
more lipoprotein than fat
takes fat and cholestrol fro hepatic tissues to the liver
how can cholesterol be made in the liver
synthesised from acetyl CoA in the mevalonate pathway
what are procursors of bile acids made from
synehsised from cholestrol
describe the process of bile salt circulations
secreted bie sats mainly recycled
most of the salts are reabosrbed by the intesine
and are recycled by the enterohepatic circulation
what happens to most primary bile salts
conjugated to amino acids, glycine
what is enterohepatic circulation
the circulation of biliary acids, bilirubin, drugs, or other substances from the liver to the bile, followed by entry into the small intestine, absorption by the enterocyte and transport back to the liver.
what happens to excess cholesterol
it cannot be dispered into a micelle so forms a crystal
what is the role of micellation
allows cholesterol to remain in solution
what is bilurubin
breakdown of haem products produces this
in the spleen
insoluble
in the liver what is bilirubin conjugated with
the glcuronic acid which is water soluble and secreted as a component of bile
what happens to bilurbin in the large intestine
hydrlysed by bacteria into :
urobilogen
serocobin
urobilin
what is jaundice
high concentrations of bulirubin the the blood
yellow discolouration of the skin, sclera of eyes and tissues
causes of jaundice
excessive disurption of RBC
impaire uptake of bilirubin
obstructive bile flow, it cant go anywehre
types of jaundice
hemolytic jaundice
hepatic jaundice
what stimulattes the production of bile
parasympatetic along the vaugs nevres stimulates bile by the liver
what stimulate CCK
fatty acids, amino acids, chyme entering duodenum
4 stages of bile regulation
- parapsympttic stimulate bile production
- fatty acids, amino acids/ chye stimulate CCK into blood
acidic chyme stimulates secretin - CCk causes contraction of gall bladder
- secretin enhances flow of bicarbonate rich bile from liver
by product of liver metabolism
ammonia
urea cycle is then used to get rid of this as its toxic
how does the liver use the TCA cycle
gluocse goes through it
oxidative phosphorylation to mkae ATP and energy
what is ketogensisi
ketone bodies made in extreme conditions to make energy
what happens if glucose levels are too high
can induce break down of muscles
needs to be converetd to glycogen
what happens when glucose levels are loow low
glucagon released
glycogenlysis
glycogen stores used to make glucose
gluconeogensis
syntehsis of glucose from non-carbohydrate procurors
used in fasting
what does lactate do?
causes pyruvate to enter the citric acid cycle to alow the body to build glucose levels
glucogenesis
formation of glycogen from gluose
glucogenolysis
breakdown of stored glycogen in the liver or muscle cells
what enters the pathway if energy is requried immediately
glucose-6-phosphate
how are proteins taken into the liver
portal vein
what is amino acids catabolism
The breakdown of amino acids occur by transamination and
deamination. The by-product of this reaction, ammonia will be detoxified in the urea cycle
what role does the liver have in lipid metabolism
Oxidation of fatty acid to acetyl-CoA
Synthesis of cholesterol, phospholipids and lipoproteins
Formation of triglycerides from proteins and
carbohydrates
what happens to any ammonia in the system
released during deamination and is rapidly removed by the liver and convereted to urea
what is a xenobiotic
substances that are not normlly found in the body
what does the liver do to xenobiotics
neutralise them
biotransformation
what does the liver do to drug
the drug is first in the plasma
then through oxidation adn reduction modifies it
conjugation then allows the drug to be excreted
makes the substance more soluble
pathways for dealing with alcohol
Alcohol dehydrogenase
(ADH) system
Catalase pathway (minor
pathway)
whats wrong with the metabolism of alcohol
ethanol converetd to acehehyde this is toxic causes a build up f NADH pyruvate converted to lactate an this builds up tp steals all the NAD for other stuff NAD thinks you have enough enery and causes syntehsis of fats from liver not enough acetyl CoA become hypoglycaemic acehehdye toxic
describe the ADH system of alchol metabolism
irst, ADH metabolizes alcohol to acetaldehyde, a highly toxic substance and known carcinogen Then, in a second step, acetaldehyde is further metabolized down to another, less active byproduct called acetate which then is broken down into water and carbon dioxide for easy elimination
what are the bad effects of alcohol
excess NADH reduction in NAD high acetehedyde increased free radicals hinderes electron transport chain fatty acid synthesis instead
how does alhocol hinder mitochondria eleectron transport chain?
excess NADH conversion of pyruvate to lactate increase in lactic acid so impairs gluconeogensis depletion of glygogen stores fatty acid oxidation stops
what is wrong with exxcess NADh
causes signal for fatty acids to be syntheises instead
glutathione low
liver accumlates fat
causes alcohol hepatitis and cirrhosis
what is asian flush syndrome
polymorphisms in dehydrogenase
changes in ucleotides make enzymes which causes a reaction and the alchol is converted to acethyde which causes dilation of blood vessels and hence the flush
how can you indicate liver injur
elevaed serum enzye test results
test for liver finction
ALT: alanine aminotransferene ASL: aspartate aminotranference excretory function serum function and protein levels CT scans for size etc
