Liver Microanatomy Alice and Drew

Hepatocytes Main functional cell of the liver Joined together in cords towards a central vein Cords separated by sinusoids Granular appearance - lots of mitochondria Other organelles - RER, SER, large golgi body, lysosomes and peroxisomes. Glycogen deposits and lipid droplets can be visible Hepatocytes are the main functional cell of the liver. They are joined together in cords, which converge on a central vein. The individual cords are seperated by sinosoids, which carry blood. The granular appearance of the hepatocytes is due to lots of mitochondria, which is related to their high energy requirement. They have many different organelles, so the RER (which is to do with protein synthesis), the SER (which is to do with the enzymes involved in the inactivation of drugs and toxins) and the golgi body. The golgi is continuous with RER and SER vesicles and tubules. There are also visible glycogen deposits and lipid droplets. Different functional domains - sinusoidal, canalicular, intercellular

Hepatocyte Ultrastructure N - Nucleus GI - Glycogen deposits M - Mitochondria BC - Biliary canaliculi This is an electronmicrograph of the hepatocyte. Could ask them to label it?

Sinusoids Fenestrated, made up of endothelial cells, Kupffer cells and Ito cells Kupffer - tissue macrophages. Partially responsible for bilirubin production Ito - Store fat Combination of arterial (30%) and venous (70%) blood Sit on reticulin (Collagen III) Separated from hepatocytes by space of Disse Sinusoids are fenestrated, made up of endothelial cells, kupffer cells and ito cells. Kupffer cells are the resident tissue macrophages of the liver. They display phagocytic activity against blood borne materials entering the liver. The ito cells store fat and are also known as Stellate cells. The sinusoids are a combination of arterial and venous blood. They are supported by a reteculin mesh (which is collagen III). The sinusoids are separated from hepatocytes by the space of Disse - where transfer of materials takes place

Biliary Canaliculi Where bile is secreted to from hepatocytes Drain in opposite direction to blood flow The bile canaliculi are the channels where bile is secreted from the hepatocytes. The bile canaliculi drain towards the bile ductile, in the opossitee direction to the blood flow (which flows towards the central vein). In the picture above the bile ductiles are labelled green.

Portal Triad Portal vein. Carries deoxygenated nutrient-rich blood Hepatic arteriole. Small and muscular Bile ductule The portal triad form at the ‘corners’ of the lobule and it the ‘entrance’ into the lobule. The potal bein carries deoxygenated nutrient rich blood which comes from the GI tract. The hepatic arteriole is small and muscular and carries oxygenated blood from the hepatic arteries. Both the arterial and venous blood then runs toward the central vein through the sinusoids. The bile ductule is also present.

Lobule Structure This is the functional unit of the liver. It is roughly hexagonal in shape. Each lobule has a central portal vein, and the portal triads are at each corner of the hexagon

Zones This is an alternate picture of the organisation of the liver. The Acinus - double triangle, cluster of cells Zone 1 - Closest to the portal triad = Highest O2 concentration = contains the enzymes for oxidative reactions = make and store glycogen and produce and secrete proteins Zone 2 - mixture of functions of Zone 1 and 2 Zone 3 - Lower oxygen - contain many esterases - conjugating and detox reactions (There is another session on detox)

General Histology Advice Anki!!! http://ankisrs.net/ Only use the pics that are on minerva Learning them = easy exam marks Free, available for pc, mac, tablets and netbooks