lecture 1 Flashcards
where is the pancreas located in the body?
the pancreas lies in the C-shape of the duodenum. Is essentially an accessory organ for the small intestine to provide enzymes. Lies just in front of major blood vessels.
what is the sphincter of oddi?
the major duct passing into the middle of the duodenum which combines excretions from the hepatic ducts of the liver, excretions from the gallbladder and the main pancreatic duct.
what are the primary functions of the exocrine pancreas?
neutralises stomach acid, deliver enzymes for macronutrient digestion in duodenum.
what is the purpose of the acinar cells in the pancreas?
these are the main secretory cells in the pancreas (secrete enzymes and ion secretions) Clusters are connected by intercalated ducts. lining cells of the ducts add ions and secretions (e.g. HCO3-)
how is the exocrine pancreas regulated in the cephalic phase?
by the vagus nerve which stimulates pancreatic secretions by releasing ACh and VIP. Accounts for near 25% of pancreatic secretions
how is the gastric phase of exocrine pancreas stimulated?
medicated by vasovagal reflexes. Accounts fro near 10% of pancreatic secretions.
how is the intestinal phase of exocrine pancreas secretion stimulated?
controlled hormonally by secretin (in response to H+) and CCK (in response to fatty acids, amino acids and monoacylglycerols) accounts for about 65% of pancreatic secretions
what are zymogen granules?
granules which are present in acinar cells which house active and inactive digestive enzymes. Mostly secreted the inactive form.
what stimulates the secretion of the zymogen granules?
hormones including CCK
how are zymogen granules released from acinar cells?
by exocytosis into the luminal space. this exocytosis is regulated hormonally and neurally. Mainly by CCK binding to receptors on the acinar cells.
which ions are affected by flow rate?
HCO3- concentration increases with increased flow rate and CL- concentration decreases with increased flow rate.
are the concentration of sodium and potassium ions affected by the flow rate?
no
where does the liver lie?
The liver lies in the upper abdomen, underneath the diaphragm, slightly to the right. surrounded by the peritoneum except for bare area related to the diaphragm. May be palpable below the costal margin.
what is glisson’s capsule?
a thin connective tissue layer that sends extensions into the organ, in between the lobules.
which blood vessel supplies the liver with nutrients?
the hepatic portal vein which brings absorbed nutrients from the stomach and gut.
what is the hepatic artery?
a blood vessel which supplies the hepatocytes (liver cells) with oxygen.
how is bile drained from the liver?
via canaliculi that lie between the hepatocytes into bile ductules which eventually become bile ducts which feed into the common hepatic duct.
describe the lobes of the liver
left lobe: lies medially.
Right lobe also contains the caudate lobe which has a groove for the inferior vena cava and the quadrate lobe which houses the gallbladder.
describe the synthesis and secretion of bile of the liver
the liver secretes bile which is composed of: bile pigments, cholesterol, phospholipids, fatty acids, water and electrolytes.
what ere bile pigments derived from?
the breakdown of haemoglobin; kupffer cells are involved in their formation. Bile salts are responsible for the detergent and emulsifying effect of bile on fats, and also increase the absorption of fats by the small intestine.
what direction is the flow of bile in relation to the flow of blood from the hepatic artery and portal vein?
the opposite direction
where does the bile go if the sphincter of Oddi is contracted?
mainly to the gallbladder
where does the bile go if the sphincter of Oddi is relaxed?
mainly to the duodenum
what is the relaxation of the sphincter of Oddi mainly controlled by?
CCK
how is bile concentrated?
by the movement of water out of it due to the reabsorption of sodium and chloride
what is the primary role of the gall bladder?
to store and distribute bile in a concentrated form
what stimulates the gallbladder to contract?
in response to CCK
what inhibits the secretion of bile acid?
somatostatin and noradrenaline
what is a metabolic function of the liver?
metabolism of carbohydrates, proteins and fats. Stores/releases carbohydrates (i.e. glycogenolysis, gluconeogenesis)
what is a detoxification function of the liver?
removal of ammonia and ethanol and drug biotransformation
what is an immune system function of the liver?
the removal of intestinal bacteria from portal blood so none is in the systemic circulation
what is the main purpose of bicarbonate ion secretion from the pancreas?
to neutralise stomach acid.
what other important materials does the liver store?
soluble vitamins and certain minerals
what is another function of the liver related to the immune system?
production of large amounts of lymph
