GI- liver and pancrease Flashcards
lobes of the liver
right, left, caudate, quadrate
ligamentum teres
remnant of umbilical vein nestled within the falciform ligament
what is the function of hepatic ducts?
to bring bile and bile salts from the diff. parts of the liver
where do bile/bile salts go in-between meals?
they go up through the cystic duct to be stored in the gallbladder
gallstones
aggregations of cholesterol salts that can block the cystic duct opening and create pressure within the gallbladder (may req. surgical removal)
where is the pancreas located?
it is nestled within the curvature of the duodenum
pancreatic duct
conducts pancreatic juice from the pancreas to the small intestine; another duct combines w/ common bile duct to receive secretions from pancreas + liver and gallbladder
porta hepatis
central area of the liver where the portal vein, common duct, and hepatic artery enter
common hepatic duct
large bile duct leading from liver; brings bile salt being secreted by the liver out
Sphincter of Oddi
the valve controlling release of bile and pancreatic juice into the small intestine; it is closed in-between meals
dual blood supply of liver
- liver receives oxygen-rich blood from the abdominal aorta via the celiac trunk
- mixes w/ deoxygenated nutrient rich blood from GI via hepatic portal vein
- blood is then drained by the haptic vein to travel to the IVC
hepatocytes
most predominant cell type in liver
Kupffer cells Responsibility
- phagocytosis of microbes
- cytokine production
- recycle heme
liver lobule
basic functional unit of the liver
- six-sided structure
portal triad of liver
- bile duct receiving bile from canaliculi
- portal venule from hepatic portal vein
- hepatic/portal arteriole
central vein
drains blood from sinusoids and out of liver (becomes hepatic vein)
what are the roles of the liver?
- process and/or store intestinal nutrients (carbohydrates, amino acids, lipids & vitamins)
- synthesis of serum proteins
- process drugs and hormones
- storage of iron & excretion of bilirubin
- deals with microbes (Kupffer cells)
- aids in digestion (bile)
processing of carbohydrates
- the liver stores glucose as glycogen to provide 1-2 days/ supply of gluco
- glucose can be converted into FAs or triglycerides,
- galactose and fructose can be converted to glucose, gluconeogenesis and glycogenolysis
gluconeogenesis
formation of glucose from noncarbohydrate sources e.g. lactic acid, pyruvate, amino acids, glycerol
processing of amino acids
essential a.a.’s are used for protein synthesis (serum proteins)
processing of lipids
the liver packages fats into forms that can be transported to/from tissues
VLDL
transports fats made by hepatocytes to adipocytes
LDL
transports dietary/synthesized cholesterol to tissues
HDL
returns excess cholesterol from tissues to liver (catabolized & secreted in bile salts)
synthesis of serum proteins
the liver synthesizes most plasma proteins such as albumin (60%), coagulation factors, complement proteins, and alpha and beta globulins (angiotensinogen and transferrin)
albumin
- protein in blood
process drugs and hormones
- most drugs pass through the liver
- excreted in bile, inactivated or converted into a form the kidneys can also excrete
- can also alter/excrete thyroid & steroid hormones
ferritin
- iron storage protein
- storing 10% of iron in the liver
transferrin
iron transport protein
what happens to heme from damaged RBCs?
it is returned to the liver where iron is scavenged and the heme is discarded as bilirubin
bilirubin
pigment released by the liver in bile
jaundice
accumulation of bilirubin in tissues
how does the liver aid in digestion of fats?
by producing bile
what is bile essential for?
- lipid digestion + absorption
- cholesterol metabolism
- excretion of lipid-soluble drugs
what is bile composed of?
bile acids (salts) - emulsification, cholesterol, bilirubin and electrolytes
gallbladder
thin green sack w/ muscular wall that concentrates and stores bile until needed
in which way is gallbladder function controlled?
neurally and hormonally
PNS control of gallbladder
weak contractions
CCK control of gallbladder
intense contractions (release of stored bile)
secretin control of gallbladder
increased prod. of bicarbonate-rich bile by liver hepatocytes
pancreas composition
primary exocrine gland but has clusters of endocrine cells
exocrine products of pancreas
pancreatic enzymes that enter the duodenum via the hepatopancreatic ampulla (90%)
endocrine products of pancreas
insulin and glucagon which enter the bloodstream
how is exocrine function of the pancreas regulated?
neural and hormonal:
- vagal nerve stim. causes release of pancreatic juice during cephalic + gastric phase
- chyme entering duodenum causes enteroendocrine cells to release secretin & CCK which enters bloodstream
- upon reaching the pancreas CCK induces enzyme secretion, secretin induces secretion of bicarb-rich juice
pancreatic endocrine function
blood glucose homeostasis
how does the pancreas fix high blood sugar?
promotes insulin release therefore stimulating formation of glycogen from glucose in the liver to lower blood sugar
how does the pancreas fix low blood sugar?
promotes glucagon release therefore stimulating glycogen breakdown to glucose in the liver to raise blood sugar
Caudate Lobe
towards the tail
Quadrate lobe
square shaped
How are the exposed lobes of the liver separated
falciform ligament
What structure is inferior to the liver
gallbladder
function of gallbladder
tiny muscular sac that stores bile
What structure makes bile
liver hepatocytes make bile to emulsify fats; stored in gallbladder until needed
Where is the pancreas located
tucked into the curvature of the duodenum
Pancreas responsibility
secreting pancreatic enzymes and bicarb rich mucous to neutralize acid chyme from stomach
Where do the products from the liver, gallbladder and pancreas end up?
hepatopancreatic ampulla
Porta Hepatis
door to the liver
Hepatic portal vein
delivering nutrient rich but oxygen poor blood to liver
Hepatic artery
delivering oxygen rich blood to liver
Is there mixed blood in the liver and why?
Yes; hepatic portal vein and artery
What occurs during meal time?
sphincter opens up to the duodenum and bile flows from the liver and gallbladder
Primary blood supply coming into the liver is from?
hepatic portal vein; can be oxygen poor because intestines have taken some already
Where does the mix with arterial blood come from?
celiac trunk
Hepatocytes responsibility
responsible for synthesis, storage, detoxification and metabolism
How are endocrine hormones cleared out of circulation?
by the liver
Kupffer cells
aid in inflammation and help break down red blood cells to recycle
Sinusoidal Endothelial cells
- have huge gaps between them
- formed by sinusoidal capillaries
- albumin and all the clotting factors and compliment proteins made by liver need to go into circulation by sinusoids
At each of the 6 corners there is duct work that contains
artery, vein and bile duct
Where do portal vein blood and hepatic arterial blood come into the liver from…
liver lobule from periphery and drain into the centre
What do hepatocytes do?
pull up digested nutrients
What do macrophages do?
look for pathogens
Bile Canalicular
exists between hepatocytes of the liver creating the bile and sending it to the edges of the lobules collected by the bile ducts
Glucose can be converted to
- into FAs or triglycerides,
What can be converted into glucose?
galactose and fructose can be converted to glucose, gluconeogenesis and glycogenolysis
Glycogenolysis
breaks up glyocogen (1-2 days worth) into glucose
How does skeletal muscle store glucose?
for itself; phosphorylated and cannot pass plasma membrane to share
How is ammonia produced?
during the breakdown of amino acids in the liver for energy purposes
Ammonia is converted to
The liver can convert ammonia to urea
Is urea water soluble?
yes so the kidneys can get it out
Cholesterol generation
mostly from liver itself and some from dietary
Fibre is needed to
trap cholesterol
Vitamin A (fat soluble vitamins)
A - converted to retinyl esters for vision (rods
Vitamin D (fat soluble vitamins)
D - utilized in bone metabolism (calcium absorption)
Vitamin E (fat soluble vitamins)
E - antioxidant (free radical scavenger)
Vitamin K (fat soluble vitamins)
K - utilized by hepatocytes to form coag. factors)
albumin functions
- maintains the proper amount of water in the blood via colloid osmotic pressure
- binds hormones, cations, bilirubin, drugs, etc.
- any lipid soluble hormone will use albumin to transport
Does albumin ever cross the capillary bed?
No it will draw it back with oncotic pressure
Coagulation factors
- made in the liver
- every singe component of coagulation cascade comes from hepatocytes
Compliment proteins
involved in the inflammatory response
- come from hepatocytes
Globulins
- come from hepatocytes
- alpha globulins (antitrypsin)
- beta globulins (angiotensinogen and thyroxine binding globulin)
Where is most of the bodies iron located?
on hemoglobin in RBC
Jaundice occurs
hepatocytes are scarred or damaged (hepatisis or drugs)
Where do most macrophages reside
in the liver
Natrual killer cells
innate immune cells responsible for killing virus infected host cells
Why is bile released?
in response to parasympathetic stimulation and CCK
how do exocrine products pancreatic enzymes and bile enter the duodenum through?
the hepatopancreatic ampulla
Exocrine function
make digestive enzymes
