Hepatic 3 Flashcards
Does the liver have a lot of mitochondria?
YES, very metabolically active
What % of systemic blood flow goes to the liver?
28%
What % of oxygen used in the body goes to the liver?
~20%
3 Roles of the Liver in Metabolism
- Synthesis and degradation of carbohydrates, lipids, and proteins
- Sorting molecules for metabolism, energy, or distribution
- Export glucose and ketone bodies to provide energy to other tissues
Two Locations of Glucose Synthesis
- Liver (80%)
- Kidneys (20%)
2 Major Pathways for Liver to produce Glucose between meals (low insulin)
- Gluconeogenesis
- Glycogenolysis
Glycogen accounts for ____% of liver weight
7-10%
Where else besides the liver can the body store glycogen?
skeletal muscle
Histological appearance of Heaptcytes with Glycogen Storage Disease
lacy, pale cytoplasm, swollen and obscuring any sinusoids
What type of drug administration in dogs can promote glycogen storage in hepatocytes?
steroid (steroid hepatopathy)
During the urea cycle in the liver, what % of ammonia is detoxified?
95%
Where besides the liver detoxifies ammonia?
kidneys
hepatic encephalopathy
caused by buildup of ammonia
seen in horses after eating toxic grasses and then the liver can’t fiilter and ammonia goes to the brain
Major plasmaprotein made by the liver that’s important for transport?
albumin
C-reactive protein
released during acute inflammation of the liver
Most specific marker for heaptic injury?
Alanine Transaminase (ALT)
What is the only clotting factor not synthesized in hepatocytes?
clotting factor VIII (8)
Inhibitors of Coagulation
antitrypsin, antithrombin, a2 macroglobulin, protein S, protein C
Fribrogen synthesis occurs where?
in the liver
plasminogen
involved in fibrinolysis to breakdown the fibrin in the blood clot
transamination
converts amino acids (alanine) to pyruvate, and eventually glucose via gluconeogenesis
Why is ALT the best marker for hepatic injury?
alanine can be used as a substrate to produce lucose ONLY IN THE LIVER
Metabolism of protein in the liver occurs via what main process?
transamination
Aspartate transaminase (AST)
enzyme found in liver, heart, muscle, kidney, and brain
Alkaline phosphatase (ALP)
many isoforms (ex: bALP for bone), can increase due to stress
Liver specific enzymes in horses, ruminants, and swine?
sorbitol dehydrogenase (SDH) and ornithine carbamoyltransferase (OCT)
Fat is stored in the liver as either ______ or ________
triglycerides or cholesterol
3 Sources of Cholesterol for the Liver
- Diet
- De novo synthesis (not solely in the liver)
- LDL via endogenous pathways
What happens to most lipids in mammals?
secreted as bile
4 Fates of Cholesterol in the Body
- Secretion as bile
- Sloughing of skin and intestinal epithelium
- Hormone synthesis
- Exported into blood as VLDLs from liver
Trglyceride
a fatty acid and glycerol
Fatty acids oxidized in the liver eventually become _______
acetyl CoA
What happens to excess acetyl-CoA in the liver?
condensed to acetoacetate, eventually yields ketone bodies, which can be exported and used as fuel by the heart, brain, and skeletal muscle
Can the liver use ketone bodies?
no, only export them
Hepatic Lipidosis
condition caused by anorexic events in cats; fat accumulates in hepatocytes and liver becomes pale and firm; visible histologically
Does liver normaly float or sink in formalin?
sink
Oil Red O
stains lipids
What is stored in stellate (Ito) cells?
fat soluble vitamins (A, D, E)
What is stored in hepatocytes and Kupffer cells?
iron and copper
Where is the majority of body iron stored?
hemoglobin of the RBCs (50-70%)
What other body organs store iron?
liver, spleen, bone marrow
Ferroportin
iron transporter within enterocytes (basolateral aspect), for exporting iron
Transferrin
transports Fe3+ in the blood
2 Forms of Fe2+ Storage
- Ferritin (water soluble, mobile; in RBCs, enterocytes, hepatocytes)
- Hemosiderin (brownish, main storage in macrophages of liver, spleen, and marrow)
Hepcidin
peptide hormone produced by the liver that regulates iron [negatively]; prevents iron absorption or release from storage
How does hepcidin work?
binds to ferroportin (the transporter of iron) and internalizes said transporter, so iron cannot be released
Hypoxia effect on hepcidin?
decreases hepcidin, therefore inc. iron absorption/mobilization
Inflammation effect on hepcidin?
increases hepcidin via IL-6 stimulation, therefore dec. iron absorption/mobilization (aka anemia)
How does inflammation lead to anemia?
Inflammation increases hepcidin, ferroportin transporter internalized, iron not being released into blood so heme synthesis diminished, can’t make RBCs = anemia
