liver Flashcards
liver function: identify the different cell types in the liver, their locations within the liver and their main functions
3 key functions of liver
metabolic and catabolic (synthesis and utilization of carbohydrates, lipids and proteins), secretory and excretory functions (synthesis and secretion of bile and waste products), detoxification and immunological functions (breakdown of ingested pathogens and processing of drugs)
where is bile stored and what is it secreted into
gallbladder into duodenum
3 key functions of bile
emulsification and absorption of fat to increase SA for lipase activity, cholesterol homeostasis for excreting excess as needed, toxic excretion (endogenous e.g. billirubin and exogenous e.g. drugs)
principle source of blood entry
hepatic portal vein
what is present in hepatic portal vein blood
nutrients, breakdown products of erythrocytes from spleen, toxic substances, lower oxygen content (hence hepatic artery)
liver perfusion percentages
portal vein: 80%, artery: 20%
what happens to branches of portal vein
split into sinusoids (large calibre vessels); hepatic arterial branches also join
why are the sinusoids wider
slower blood flow
where does plasma and plasma-born substances flow through
fenestrations in epithelial cells
where does plasma and plasma-born substances flow into
extravascular space between sinusoids and hepatocytes (space of disse)
what is adhered to the internal wall of the sinusoids
kupffer celss
what are kuppfer cells and relate to function
sinusoidal macrophages, so phagocytose some bacteria and toxins; release cytokines to activate hepatic stellate cells in space of disse
what shape are kuppfer cells
stellate shaped
where are hepatic stellate cells (ito cells) present
perisiusoidal (space of disse)
function of hepatic stellate cells when in quescent state
act as vitamin A storage reservoir, possible APC
what activates hepatic stellate cells
kuppfer cells or liver damage (e.g. alcoholic liver disease)
outcome of hepatic stellate cell activation
fibrogenesis and proliferation (e.g. collagen to ECM), causing fibrosis and cirrhosis
consequence on hepatocytes of fibrosis and cirrhosis
reduce functionality and number
name of activated hepatic stellate cells
fibroblasts
what shape are hepatocytes
cubical
function of hepatocytes
synthesis (including of albumin, clotting factors/products, bile salts), drug metabolism
where do hepatocytes receive nutrients from
sinusoid
function of cholanglocyte
secrete bicarbonate and water to form bile
7 organelles present in hepatocytes
nucleus, rough ER, smooth ER, mitochondria, Golgi apparatus, lysozomes, peroxisomes (detoxification)
2 other substances present in hepatocytes
glycogen, cytoplasmic enzymes
4 other liver functions
control of synthesis and metabolism of protein, maintenance of blood sugar, lipid metabolism, metabolism and excretion of bilirubin and bile acids
what circulating protiens are not synthesised in the liver
Y-globulins made by lymphocytes
4 examples of proteins made by liver relevant to other functions
albumin, transport and carrier proteins e.g. transferrin, factors involved in coagulation, components of complement system
function of albumin
maintains intravascular oncotic pressure and transports water-insoluble substances e.g. bilirubin, some drugs in plasma
what does the liver do to nitrogenous waste (proteins)
degrades amino acids, converts to urea, renal excretion
how does the liver maintain blood sugar
releases glucose into blood in fasted state
how does the liver release glucose into blood in fasted state
glycogenolysis, gluconeogenesis
what does the liver synthesise involved with lipid metabolism
cholesterol, lipoproteins, triglycerides
what is cholesterol used for
manufacture of bile salts and steriod hormones
