Liver and Pancreas Flashcards
What is the blood flow from the portal vein through the lobule?
Portal vein –> sinusoids –> central vein –> hepatic veins
What is the blood flow from the hepatic artery through the lobule?
hepatic artery –> sinusoids –> central vein –> hepatic vein –> IVC
How many layers are the liver cell plates composed of?
two layers of hepatocytes
Where are the bile canaliculi located?
Between two layers of hepatocytes in each cell plate
What are sinusoids lined with?
Endothelial cells Kupffer cells (marophage derived)
Where is the Space of Disse located?
between endothelial cells and hepatocytes
What do the bile canaliculi secrete?
bile down into the bile duct
What is the blood flow and resistance like in the liver?
High blood flow and low vascular restistance
What percent of cardiac output is the liver vascular supply?
27%
What is the portal pressure into the liver?
9 mmHg
What is the pressure from the liver to the vena cava?
0 mmHg
What is the effect of cirrhosis on blood flow?
Cirrhosis increases liver resistance to blood flow
What is the effect of clot blocking potak vein or a major branch?
Blockage of return blood from spleen and intestine
Increase in capillary pressure in intestinal wall –> loss of fluid –> death
What is the normal volume of the liver?
450 ml (10% of body’s blood volume)
How will the liver vascular supply change during cardiac failure with peripheral congestion?
high pressure in right atrium –> backpressure of liver –> increased blood volume in liver up to 1.5 L
T/F Liver can store blood in times of excess and supply blood in times of diminished volume
True
What are hepatic sinusoids highly permeable to?
proteins – efferent lymph has a protein concentration of 6g/dl
What happens when there is higher than normal pressure in hepatic veins?
- back pressure causes fluid to transude into lymph
- fluid leaks through liver capsule into abdominal cavity
- fluid is almost pure plasma
- large amount of fluid in abdominal cavity = ascites
What are the functions of the liver concerning carbohydrate metabolism?
- stores glycogen
- converts galactose and fructose to glucose
- gluconeogenesis
- forms intermediate products of carb metabolism
What are the functions of the liver concerning fat metabolism?
- oxidation of fatty acids for energy
- synthesis of cholesterol, phospholipids, lipoproteins
- synthesis of fats from proteins and carbs
What are the functions of the liver concerning protein metabolism?
- deamination of amino acids
- formation of urea
- formation of plasma proteins
- interconversion of various amino acids and synthesis of other compounds from amino acids
What are the functions of the liver concerning vitamin storage?
- vitamin A
- vitamin D
- vitamin B12
What are the functions of the liver concerning formation of coagulation factors?
- fibrinogen
- prothrombin
- accelerator globulin
- Factors VII, IX, X
What are the functions of the liver concerning removal or excretion of drugs, hormones, and other substances?
- detoxify or excrete into bile (sulfonamides, penicillin, ampicillin, erythromycin)
- excretes excess calcium into bile
- detoxification and removal of ammonia and ethanol
Where is hepatic bile produced and secrete?
the liver
Where is hepatic bile stored?
gallbladder
What are the 4 components of bile?
- Bile acids
- Water and electrolytes
- Cholesterol and phospholipids
- Pigments and organic molecules
What is the major pigment in bile?
bilirubin
What are the 2 major bile acids synthesized by hepatocytes?
Cholic acid and chenodeoxycholic acid
What are the 2 major bile acids converted by bacteria?
Deoxycholic acid and lithocholic acid
What are the fates of Urobilinogen?
- oxidized into excreted products
- reabsorbed into blood and carried back to the liver to be re-excreted by liver or excreted in urine
What are the characteristics of jaundice?
- yellowish tint to the body tissues
- caused by quantities of bilirubin in extracellular fluids
What are the common causes of jaundice?
- Increased hemolysis
- obstruction of bile ducts or damage to liver
What are the three main types of inlet cells?
Alpha, Beta, Delta
What are the characteristics of alpha cells?
- secrete glucagon
- 25% of total cells
What are the characteristics of beta cells?
- secrete insulin and amyling
- 60% of total cells
What is the function of insulin?
inhibits glucagon secretion
What is the function of amylin?
inhibits insulin secretion
What are the characteristics of delta cells?
-secrete somatostatin
What is the function of somatostatin?
inhibit insulin and glucagon secretion
How is insulin found in the blood?
unbound form
What is the half-life of insulin?
6 minutes
Where is insulin destroyed if not bound to receptor?
liver
What are the four potential outcomes of insulin binding to a receptor?
- Increased uptake of glucose
- Increased permeability to amino acids, potassium and phosphate ions
- Increased activity for many enzymes
- Changes in rates of translation and transcription
What is the structure of proinsulin?
a, b. and c chains are linked together
a and b chains are linked by sulfide bonds
What are the insulin receptor substrates due to phosphorylation of enzymes
- glucose transport
- protein synthesis
- fat synthesis
- glycogen synthesis
- growth and gene expression
Where is most glucose absorbed after a meal?
stored as glycogen in the liver
What is the glucose uptake mechanism for the liver?
insulin inactivates liver phosphorylase –> insulin activates glucokinase and enhance uptake of glucose from blood –> insulin increases activities of enzymes needed for glycogensis
What is the process that causes glucose to be released into the blood?
- decreased blood glucose from decrease insulin
- lack of insulin reverses glycogen synthesis pathway
- lack of insulin activates phosphorylase which splits glycogen into glucose phosphate
- glucose phosphatase remoces phosphate from glucose and allows it to diffuse into blood
- insulin inhibits gluconeogenesis
