Metabolism 11 (Exam 4) Flashcards
What is the liver often called?
The body’s major biochemical factory
Why are sharks buyoant?
The liver makes lots of LDLs for them!
How do hepatocytes access venous blood?
Portal vein
How do hepatocytes access arterial blood?
Hepatic artery
What is the capillary network in the liver called? What does it permit?
Sinusoids
Permits exchange between the hepatocytes and blood
Once blood drains from the liver, where does it go?
It drains into the hepatic vein which connects to the inferior vena cava
What is the primary cell of the liver? What is its function?
Hepatocyte
It has quite high metabolic and secretory functions that are complemented by phagocytic activity in resident macrophages
What % of total body weight does the liver make up?
2%
What is the liver’s functional unit
lobule
What is a lobule?
cylindrical structure several mm in length and diameter
How many lobules are in the liver?
50,000-100,000
The individual bile ducts converge to form what? What does that do?
Hepatic duct
The hepatic duct delivers bile to the duodenum
Explain liver blood flow starting with the portal vein
Portal vein –> small portal venules –> flat branching hepatic sinusoids (between the plates) –> central vein
Where are hepatic arterioles present?
In the interlobular septa
They frequently terminate into hepatic sinusoids
What are the three cell types of the liver?
Hepatocytes, Liver sinusoidal endothelial cells, and large kupffer cells
What are the large pores in the liver endothelial lining called? what do they do?
Fenestra
Allow plasma proteins to fit through
What are the spaces of Disse
they are perisinusoidal spaces between the endothelial lining and the hepatic cells
What do the spaces of Disse connect to?
They connect with lymphatic vessels in the interlobular septa. Excess fluid in these spaces is removed via lymphatics
What are kupffer cells also known as?
Reticuloendothelial cells
Resident macrophages
What do kupferr cells do?
Capable of phagocytizing bacteria and foreign matter
How fast is liver blood flow from the portal vein into the liver sinusoids?
Pretty fast
~1,000 ml/min
Additional 300 ml/min from the hepatic artery
Total is ~27% of CO
Explain how the liver has very low vascular resistance even despite the high volume
Pressure in the portal vein averages 9 mmHg
Pressure in the hepatic vein from the liver into the vena cava averages 0 mmHg
How can the liver function as a blood reservoir?
It’s a large, expandable organ
Its normal blood volume is ~450 mL (10% of total blood volume)
High atrium pressure can expand the liver to another 0.5-1 mL of blood
How does liver lymph compare to normal lymph?
It has 3 times the amount of protein
How do the hepatic sinusoids compare to other capillaries in terms of permeability?
the hepatic sinusoids have pores that are very permeable so lymph draining has about 6g of protein/dL (only slightly less than the protein in the plasma)
What does the high permeability and flow of the hepatic sinusoids allow?
It allows for about half of all lymph in the body to be generated in the liver
What is portal hypertension in small animals?
Elevated pressure within the portal venous system
Describe what prehepatic portal hypertension in small animals looks like.
Portal vein obstruction and hepatic arteriovenous fistula
Symptom: Ascites (the accumulation of fluid in the peritoneal cavity)
Describe what Intrahepatic portal hypertension in small animals looks like.
Likely fibrosis caused by toxins or infections, AKA cirrhosis
Describe what posthepatic portal hypertension in small animals looks like.
Posthepatic causes involve the heart, cranial vena cava, and hepatic veins
Partial hepatectomy (excision of the liver) (up to 70%) will result in?
It causes the remaining lobes to enlarge and restore the liver to original size (regeneration)
It’s pretty rapid, believed to involve the hepatocytes replicating once or twice before re-entering quiescent state
