Lecture 17 - Liver and Pancreas Flashcards
What is the path of the blood flow through the lobules of the liver?
L17 S6
Portal vein/hepatic artery
- > sinusoids
- > central vein
- > hepatic veins
What cells form the sinusoids?
L17 S6
- endothelial cells
- Kupffer cells
How much blood flow does the liver receive per minute and where from?
What is the total volume of blood normally stored in the liver?
What major factors affect blood flow?
L17 S10-11
-1050 mL/min from portal vein
-300 mL/min from hepatic artery
—total of 450 mL in the liver at a time
Portal pressure is 9 mmHg and vena cava pressure is 0 mmHg.
Cirrhosis increase blood resistance and decrease flow.
What are the functions of the liver? (8)
L17 S13-15
Carbohydrate metabolism:
- stores glucose
- converts sugars
- generates glucose
Fat metabolism:
- oxidation of fats for energy
- synthesis of cholesterol, phospholipids, and lipoproteins
- synthesis of fats from protein and carbohydrates
Protein metabolism:
- formation of plasma proteins
- interconversion of AAs
Vitamin storage:
- vitamin A
- vitamin D
- vitamin B12
Immune function
Formation of coagulation factors
Removal of toxic substances
Bile formation
What factors stimulate release of bile from the gall bladder?
L17 S16
Presence of fatty food in duodenum
What is the path of bile production to bile action? What occurs in each location?
L17 S16-18
Liver:
-bile salts produced continuously by hepatocytes
Gallbladder:
-bile is stored and concentrated
Intestine:
-secreted and emulsifiers fat to form micelles
How is bilirubin produced and what substances can it be conjugated with?
L17 S21-23
Unconjugated bilirubin is formed by the reticuloendothelial system via phagocytized hemoglobin.
Bilirubin is conjugated in the liver with glucuronic acid (80%), sulfate (10%), or others.
Transported to the intestine (converted into urobilinogen) or the urine to be excreted
What are the main types of cells in pancreatic islets and what is the function of each?
L17 S25
Alpha:
- secrete glucagon
- 25%
Beta:
- secrete insulin and amylin
- insulin inhibits glucagon and amylin inhibits insulin
- 60% of cells
Delta:
- secretes somatostatin
- inhibits insulin, glucagon, and gastrin
What are the exocrine functions of the pancreas?
L17 S28
Digestive enzymes for proteins:
- trypsin, chymotrypsin, and carboxypolypeptidase
- trypsin inhibitor (glandular cells
Digestive enzymes for carbohydrates:
-amylase
Digestive enzymes for fat:
-lipase, cholesterol esterase, phospholipase
What are the characteristics of pancreatic secretions and how do these change at different flow rates?
L17 S29
Normal:
- isotonic
- normal [Na] and [K]
- high [HCO3]
- low [Cl]
Low flow rate:
-mostly Na and Cl
High flow rate:
-mostly Na and HCO3
What cells are responsible creating pancreatic secretions?
L17 S30
Acinar cells:
-secretes Na and Cl ions
Ductal cells:
-secretes HCO3- and reabsorbs Cl- via exchange
What enzymes regulate pancreatic secretion?
L17 S31-32
Acetylcholine:
- from parasympathetic and enteric nervous system in response to H+, peptides, AAs, and fatty acids
- stimulates secretion of acinar cells
Cholecystokinin:
- stimualted by peptides, AAs, and fatty acids
- stimulates secretion of pancreatic enzymes and HCO3-
Secretin:
- stimulated by H+
- stimulates HCO3- secretion
What conditions affect insulin’s regulation of its own receptor and how?
L17 S36
Starvation increase the down-regulation of receptor.
Obesity decreased down-regulation of receptor.
What is one of the most important functions of insulin?
L17 S39
Control whether fat (low insulin) or carbohydrate (high insulin) is used for energy
What are the effects of increase blood glucose?
L17 S55
- increased osmotic pressure
- loss of glucose through urine
- osmotic diuresis (increase urine output leading to loss of electrolytes)
- damage to tissue and blood vessels
