Histology - Liver, Pancreas and Gall Bladder Flashcards
liver and pancreas development
outgrowth of the gut
parenchyma of the liver and pancreas
composed of glandular epithelial cells
parenchyma
the functional tissue of an organ as distinguished from the connective and supporting tissue
functions of the liver
most diverse tissue in the body
liver capsule
covered by collagenous connective tissue capsule
that is covered by a layer of mesothelial cells (simple squamous epithelium) derived from the peritoneum
liver structure
made up of segments called lobules
hexagonal
branch of the hepatic vein called the centrolobular vein (central vein) at its centre and portal triads at each corner
portal triads
branches of the vessels which enter at the aorta hepatic (hepatic vein and the hepatic artery)
include a third ‘tube’ - a branch of the conduit which leaves the liver at the aorta hepatic, the bile duct
portal tracts include branches of….
hepatic portal vein
hepatic artery
bile ductule - lined by simple cuboidal ells called cholangiocytes
include lymphatic vessels
hepatocytes
main cells of the liver
polyhedral epithelial cells form plates or sheets of cells with spaces in between form blood to flow through
blood channels = sinusoids
sinusoids
lined by endothelial cells
narrow space between these lining cells and the hepatocytes - space of Disse (perisinusoidal space)
microvilli of the hepatocytes project into the space
endothelial = fenestrated
liquid component of the blood generally has free access to the hepatocytes
connective tissue of the liver
portal tracts are accompanied by collagenous connective tissue
parenchyma of the liver is also supported by reticular fibres along with some Type 1 collagen that is found in the space of Disse
connective tissue of the liver
hepatic stellate cells are found scattered in the space of Disse
modified fibroblasts and make connective tissue
store vitamin A within fat droplets in their cytoplasm
PATHOLOGICAL CONDITIONS
transform into myofibroblasts and produce scar tissue in the liver
macrophages of sinusoids - KUPFFER CELLS
scattered within the sinusoids
remove particulate matter from the blood and help remove worn out red blood cells
bile
alkaline solution containing water, ions, phospholipids, bilirubin and bile salts
bilirubin
pigment which results from the breakdown of haemoglobin in the spleen
excreted in the bile - brown colour feces
bile salts
necessary for the emulsification of its in the digestive tract
primary bile that is produced by the hepatocytes
modified in several ways by cholangiocytes, the cells that line the biliary tree
bile production
all hepatocytes produce bile
bile flows via bile canaliculi towards the bile ducts in the portal tracts and thence to the hepatic ducts
bile canaliculi
small channels
formed by tight junctions in the cell membranes of adjacent hepatocytes
gall bladder
muscular sac
gall bladder - structure
lined by simple columnar epithelium backed by a lamina propriety of loose connective tissue rich in blood vesslels and lymphatic vessels, a coat of smooth muscle and an outer collagenous layer of adventitia
gall bladder - function
stores bile
has a folded mucosa when empty - this flattened when distended
modifies the bile stored within it
removal of bile by the gall bladder
actively pumping Na and Cl ions from the bile into the spaces between adjacent epithelial cells
water then follows de to the increase in osmotic pressure in these spaces, which become distended with fluid when the gall bladder is actively concentrating bile
water is carried away, largely by the lymphatic vessels of the lamina propria
stimulation of the gall bladder
to contract and deliver bile to the duodenum
under nervous control and hormonal
