Liver Flashcards
Where is the liver located?
Located in the upper right quadrant of the abdomen, beneath the diaphragm and above the stomach.
Where does the blood supply to the liver come from?
The GI tract via the hepatic portal vein
Also lesser amount of (oxygenated) blood from hepatic artery
Name the two places in the body that have a portal blood system
Liver
Hypothalamo-hypophyseal system (supplies anterior pituitary)
What is a portal system?
Two capillary systems in series (in liver has the hepatic portal vein in between)
What is contained in the hepatic portal blood?
Water Water soluble vitamins Electrolytes Toxins (e.g. Ammonia) Carbohydrates Proteins Hormones
What is urea (krebs) cycle and where does it take place?
The liver only.
CO2 + 2NH3 -> H2O + CO(NH2)2
Produces urea - soluble - excreted in urine
What are there none of in the hepatic portal vein?
Lipid and lipid soluble vitamins (A, D, E, K)
Why are there no lipids in the hepatic portal vein?
They are digested by lipases (requires bile acids) to form micelles which are taken up by cells, processed into chylomicrons. Released into lymphatics (called lacteals) and eventually drain into thoracic duct to join the venous system.
What are the six key functions of the liver?
Storage - of iron, vitamin A, B12, D, K and glycogen
Production - of albumin, glycogen, coagulation factors, complement components
Breakdown - of drugs, haemoglobin, hormones, poisons
Filtering - kupffer cells (macrophages)
Exocrine function - secretes bile
Endocrine function
Discuss the endocrine function of the liver
Produces angiotensin, Thrombopoietin, and insulin like growth factor 1 (IGF1)
Modifies and activates vitamin D and thyroxine
Breaks down insulin, glucagon, oestrogen and progesterone
What enzymes in the liver function in drug metabolism?
Cytochrome p450 - haem containing isoenzymes
What are the main cells of the liver ?
Hepatocytes
What are some key features of hepatocytes?
Lots of mitochondria
Lots of peroxisomes
Lots of RER, SER, ribosomes, Golgi
Glycogen deposits
What three things make up the portal triad?
Hepatic arteriole
Portal venule
Bile canaliculus
What are sinusoids?
Like a wide capillary vessel - for passage of blood into central canal. (Takes place of capillaries and venules in liver, spleen and bone marrow).
Surrounded by simple squamous epithelium with large gaps
What is the periportal space of Mall?
The space between the stroma of the portal canal and the outermost hepatocytes in the hepatic lobule.
Where lymphatic vessels arise from in the liver
What is a liver lobule?
Polygonal shaped, repeating structures of the liver
What is a liver acinus?
The functional unit of the liver
What is the space of disse?
Located between hepatocytes and a sinusoid (contains blood plasma). Microvilli of hepatocytes extend into space - allows proteins/plasma components from sinusoids to be absorbed into hepatocytes
What is a kupffer cells?
Specialist macrophages that line sinusoids. Make up ~80% macrophages of the body. Constantly exposed to gut derived bacteria and toxins
What are stellate (Ito) cells?
Cells in the liver - full of vacuoles containing vitamin A
What happens to stellate cells in liver cirrhosis?
Stellate cells lose vitamin A storage capability and differentiate into myofibroblasts which deposit collagen in perisinusoidal space (fibrosis)
