Liver Physiology Flashcards
What are the main liver functions?
Exocrine Endocrine Clotting Plasma proteins Excretory/degradative Organic metabolism Storage
How much oxygen does the liver use?
20% of what is breathed in
What are the fuels of the liver?
Sugars, ethanol, amino acids
Fat when fasting
What does the liver need for detox and synth?
A lot of ATP and NADPH
What does the liver need a lot of sugar for?
To my glycoproteins, proteoglycans, glucouronides
What are the main functions of the liver as an exocrine organ?
Synthesize/secrete bile salts
Secrete bicarbonate to neutralize stomach acid
what are the main functions of the liver as an endocrine organ?
Secretes insulin-like growth factor in response to growth hormone
Synthesizes T3 and T4
Activates some Vit D
Secretes angiotensinogen (renin acts on this)
Secretes cytokines and metabolizes hormones
What is growth hormone most important for?
Post-natal growth
Describe the path of growth hormone.
Synthesized i the anterior pituitary gland to stimulate cell division is many tissues
Liver responds to GH by releasing IGF-1 to stimulate growth
Excretion or metabolism of hormones to clear form serum
What are the main function of the liver as a clot helper thing?
Synthesizes clotting factors like prothrombin, fibrinogen, factors V, VII, IX, X, alpha2-macroglobulin
What if a pt has liver disease/damage?
Clotting will heavily be effective
What is the main function of the liver in terms of plasma protein?
Synth albumin, acute phase proteins, hormone and trace element binding proteins, lipoprotein, lymph
Describe albumin.
55-60% of serum protein
Critical role in buffering osmotic pressure of blood
Carrier of many molecules
Describe acute phase proteins.
Can inc (positive) or dec (negative) in response to systemic inflammation, infection
What are the main functions of the liver in excretion/degradation?
Secretes bilirubin, cholesterol and bile pigment
Many xenobiotics, metal etc into bile
Biotransformitive of endogenous molecules
Recycles old erythrocytes
What happens to heme degraded to bilirubin?
Carried in the blood by albumin, conjugated to form diglucuronide in the liver and excreted in the bile. Iron is returned to the body’s iron stores
Describe CYP450.
57 genes for them
Located primarily in liver and intestines
Intracellular - located in mitochondrial membrane or ER
Heme cofactor
Electrons come from NADPH by CytP450 reductase
What are the organic metabolism functions of the liver?
Sugar metabolism
Amino acid metabolism
Fat metabolism
Sterol metabolism
What pathways are sugar metabolism?
Glycolysis
Gluconeogenesis
Pentose phosphate pathway
Glycogen
How is glycogen metabolism controlled?
Glycogen phosphorylase allosterically activated by AMP and inhibited by ATP, glucose 6 and phosphate
Glycogen synthase stimulated by glucose-6-P
What are the storage functions of the liver?
Stores blood
Vitamins and minerals
Glucose (glycogen)
