Liver Flashcards
Anatomy Which ligament attaches it to the diaphragm? How many lobes? Names? Blood flow to organ+ out of organ? How many segments?
Falciform
4 lobes- Left (biggest), Right, Caudate, Quadrate
Blood comes from hepatic portal vein and hepatic artery and leaves by hepatic vein
8 segments functionally seperate (own blood supply+ venous drainage)
Blood supply to liver What % of CO goes to liver What % arterial blood from hepatic artery/ vein Purpose of blood from both vessels? Where does blood ultimately drain to? Difference between both vessel contents?
25% CO
20% from hepatic artery
80% from hepatic portal vein (blood= poorly oxygenated)
Hepatic artery= delivers oxygenated nutrient rich blood
Hepatic vein= takes blood containing absorbed products to liver (no blood that has been in contact with gut goes to systemic circulation until goes through liver)
Drains to inferior vena cava by hepatic vein
Artery= more o2 conc
Vein= more nutrient rich
Morphological unit of liver: Lobule structure (not the same as liver lobe) 3 zones? What's on each corner? (+detail) Vein+ artery connect to form what?
Hexagonal
Centrilobular, Midzonal, Periportal
Portal Tract:
1. Bile duct (bile containing breakdown products produced by hepatocytes flows along canaliculus (interface between sinusoids+ hepatocytes) into bile duct which travels from centre of lobule to portal tract eventually excreted into gut+ ends up as faeces)
2. Branch of hepatic portal vein (de-oxygenated but nutrient-rich blood travels to central vein)
3. Arteriole (oxygenated blood travels to central vein)
Vein+ artery branches combine to form sinusoid that passes through lobule to central vein, sinusoids found all through lobule (depth as well)+ anything can diffuse into surrounding tissue
Functional unit of liver:
Acinis structure
3 zones? Dependent on what?
Which is nearest to what? What does this mean?
Unit of hepatocytes divided into zones dependent on proximity to arterial blood supply.
Diamond shaped appearance of the morphological appreance divided into 3 zones:
1. Periportal- Nearest to entering vascular supply+ receives most oxygenated blood= least susceptible to ischaemic injury but most susceptible to viral hepatitis/ anything being delivered to liver because first point of contact
Involved in gluconeogenesis, fatty acid oxidation, cholesterol synthesis
2. Transition zone
3. Pericentral
Liver 4 functions
Biosynthesis
Energy Metabolism
Degradation+ Detoxification
Digestion
Cell types in liver (5 types)
Appearance
Function
Problems?
Hepatocytes (80% liver mass) (large cells with pale+ rounded nuclei) Endothelial cells (line blood vessels+ sinusoids), Function: fenestrated (leaky) to allow lipid+ other large molecule movement to and from hepatocytes
Cholangiocytes (bile duct epithelial cells)
Kupffer cell (Liver macrophages) (flattened dense cell nuclei) Function: 1. Phagocytosis inc. RBC breakdown (prevents infectious insult from becoming systemic) 2. Cytokine secretion in pro-inflammatory environments promoting stellate activation= proliferation, contraction+ fibrogenesis.
Hepatic stellate cells (Vitamin A storage cells) (flattened dense cell nuclei)
Function: Activation= ECM production (fibrogenesis) Problem= respond to pro-inflammatory environments by laying down excess ECM+ promote fibrosis= cirrhosis= loss of functional tissue
Glucose production in liver End result? Glycogen store lasts how long? Carbohydrate metabolism process Not enough oxygen?
End result= stored as glycogen in liver+ muscle
Glycogen storage= 24 hours
Glucose taken up into muscle cell= glycolysis= pyruvate production= ATP production for muscle contraction (TCA+ ETC)
Not enough oxygen= TCA cycle inhibition= pyruvic acid accumulation= anaerobic respiration required= reconvert glucose (pyruvate –> lactate) but energy dependent so liver is used for this
1. Fermentation- Lactate produced by muscle= sent to liver
2. Liver converts lactate to pyruvate by lactate dehydrogenase
3. Gluconeogenesis from pyruvate which requires 6ATP
4. Glucose transported to muscle for glycolysis
Protein metabolism of liver
Where do amino acids come from in fast state+ fed state?
Examples of proteins produced by liver
Fast state= liver breaks down muscle, fed state= amino acids come from diet
1. Amino acids enter liver
2. Liver produces secreted proteins
E.g. Plasma proteins, clotting factors, lipoproteins (HDL/LDL/VLDL)
Transamination in liver- e.g. alanin
Purpose?
Can’t get some amino acids from diet
1Alanine from diet enters liver+ amino group taken+ transferred to α-ketoglutarate= pyruvate+ glutamate using transaminase enzyme
Used to produced non-essential amino acids
Process= reversible
Amino acids (Non-essential+ Essential) that can be formed from
α-keto glutarate
pyruvate
oxaloacetate
Non-essential: Glutamate, Proline, Essential: Arginine
Non-essential: Alanine, Essential: Valine, Leucine
Non-essential: Aspartate, Essential: Methionine, Lysine
Deamination/ Glucose-Alanine cycle in liver
Purpose
Purpose: To use amino acids to produce glucose for energy
- Pyruvate from glycolysis+ Glutamate from amino acid breakdown both in muscle cell used to produce alanine (transamination)
- Alanine travels to liver
- Alanine converted to glutamate in liver using α-keto glutarate in liver= pyruvate also produced
- Glutamate metabolism produces NH3= too toxic= converted to water-soluble urea using 4ATP, urea leaves liver to the blood
- Pyruvate used to produce glucose (6ATP required)
- Glucose transferred to muscle cell for glycolysis
Glutamate uses
Can be reversibly converted to α-keto glutarate which is used in Kreb’s cycle
Can be reversibly converted to glutamine= nitrogen carrier+ found in blood plasma
Alanine uses
Substrate for hepatic gluconeogenesis
Transamination required for fasting blood glucose concentration
Fat storage
When does it occur?
How is it stored?
Where is it stored?
When fat is required how+ where is it broken down?
Where do the products go+ what happens to them?
When glycogen stores full
Stored as triglycerides
Stored in adipose tissue
Triglycerides broken down into fatty acids in adipose tissue+ sent to liver
Beta-oxidation occurs in liver to convert fatty acids into acetyl CoA which is used in the Kreb’s Cycle
Liver ketone production
What is is used for?
Acetyl CoA production from fat (adipose tissue) is required first
Enzymatic condensation of 2x acetyl CoA, catalysed by thiolase to make acetoacetate instead of being used in the TCA cycle
Acetoacetate released into blood
Used as a tissue energy source for other parts of the body
