32. The Liver Flashcards
What are the main functions of the liver?
Detoxification and secretion, and metabolism of proteins and lipids
What are the anatomical regions of the liver?
Diaphragmatic surface and visceral surface
Where does the subphrenic recess lie?
Between the diaphragm and liver
How is the liver attached to the diaphragm?
Falciform ligament (runs through middle of liver), coronary ligament (directly below diaphragm), and left and right triangular ligaments (posterior surface)
What parts of the liver are peritonised?
All but porta hepatic and gallbladder bed
Which lobes form the right lobe of the liver?
Caudate (superior posterior), quadrate inferior posterior), and right lobe
How is the liver parenchyma supplied with oxygen?
Via the hepatic artery (branches from celiac artery)
How is nutrient rich blood received by the liver?
Via the portal vein (from the intestine and GI system)
What is the structure of a hepatic lobule?
Contains plates of hepatocytes with many sinusoids between. One central vein and a portal triad at each corner
What is contained within a portal triad?
Portal venue (from portal vein), portal arteriole, and a bile duct (receives bile from bile canaliculi)
What does the liver have instead of capillaries?
Sinusoids, where hepatic arterial blood mixes with portal venous blood
What are the characteristics of sinusoids in the liver?
Low resistance
Fenestrated with no basement membrane
Contain Kuppfer cells (hepatic macrophages)
What is the function of stellate cells in the liver?
Store retinoids, store GFs, may produce collagen
What is contained in the space of Disse?
Where is it located?
Loose CT, the site of stellate cells
Between hepatocytes and sinusoidal lumen
What are the phases of detoxification by the liver?
Modification
Conjugation
Further modification + excretion
Where does modification occur in the liver?
What does the process entail?
Why does this occur?
Primarily in ER of hepatocytes
Enzymatic incorporation of polar groups
Prevent free diffusion across membrane/reduces reuptake by SI
What does the process of conjugation entail?
On what substances does this occur?
Why does this occur?
Conjugation to charged species
Carboxyl, hydroxyl, amino, sulfhydryl
Allows active transport of molecules
How are smaller metabolites excreted?
How are larger metabolites excreted?
By the kidney
In bile
How is bilirubin formed?
By the breakdown of Hb (80%) and from heme-containing proteins
How does bilirubin travel in the blood?
Bound to albumin
Where is albumin and bilirubin separated?
In the Space of Disse
How is bilirubin excreted?
In bile
Why is the maintenance of blood glucose essential?
The brain is sensitive to glucose levels. Too high causes complications (diabetes) and too low impairs NS function
How does the liver maintain blood glucose levels?
Through the use of insulin and glucagon
What will occur due to an increase in blood glucose?
Uptake of glucose by GLUT2 transporters
Insulin release
Glucose retention by hepatocytes
Glycogenesis in liver
How does decreased blood glucose affect the liver?
Glucagon release from pancreas
Glycogen -> G1-P -> glucose in liver
Gluconeogenesis (from AA and triglycerides)
How does the liver metabolise lipids?
Turns excess glucose and acetyl CoA into triglycerides to be stored or transported to adipose tissue and muscle
Also synthesises cholesterol
Which proteins are synthesised in the liver?
All non-essential AA, nearly all plasma proteins
