The Structure Of The Liver (OCR Biology A2)

A basic revision sheet on the structure of the liver.

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  • Created on: 21-01-12 16:15
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The Liver
Liver Structure
Liver cells ­ hepatocytes ­ carry out hundreds of metabolic processes ­
homeostasis.
Internal structure ­ gives good blood supply to most liver cells.
Blood Flow To and From the Liver
Liver is supplied with oxygenated and deoxygenated blood.
Oxygenated blood:
From heart aorta via hepatic artery liver.
Supplies O2 (essential for aerobic respiration).
Liver cells ­ very active from metabolic processes which require energy (ATP) so O2 supply is v. important.
Deoxygenated blood:
From digestive system hepatic portal vein.
Rich in digestion products ­ uncontrolled concentrations of various compounds (maybe toxic) that's been
absorbed in intestine.
Blood leaves liver by hepatic vein re-joins vena cava blood returned to norm. circulation.
Bile duct is 4th vessel connected to liver and is excretory and digestive ­ carries bile secreted from liver to gall
bladder. Gall bladder stores until needed to aid fat digestion in small intestines.
Cell Arrangement
Cells, blood vessels and chambers inside liver are arranged for best contact between blood and liver cells.
Liver is divided into lobes which are divided into cylindrical lobules.
Hepatic artery + hepatic portal vein enter liver + split into
smaller + smaller vessels which run parallel + between
lobules ­ inter-lobular vessels.
Branches from hepatic artery + portal vein enter lobules at
intervals.
Blood is mixed + passes through sinusoid (special chamber)
lined by liver cells which empty into intra-lobular vessel
(branch of hepatic vein).
Branch of hepatic veins join to form hepatic vein ­ drains
blood from liver.
Blood flows through sinusoid ­ close to liver cells + can
remove/pass molecules from/into blood.
Liver cells manufacture bile ­ released through bile canaliculi (small canals) which join to form bile duct ­
transports bile to gall bladder.
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Liver Cells
Unspecialised ­ simple cuboidal shape with many microvilli on
surface.
Have many metabolic functions ­ protein synthesis,
transformation + storage of carbs, cholesterol + bile salt synthesis,
detoxification...
Dense cytoplasm specialised in amounts of certain organelles.
Kupffer Cells
Specialised macrophages
Move about within sinusoids
Involved in breakdown + recycling old red blood cells.
Products of haemoglobin breakdown ­ bilirubin, excreted
as part of bile + brown pigment in faeces.
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