Hepatic lobule –Contains Central efferent hepatic venule with cords of hepatocytes and
sinusoids converging on to the venule.
|Arrangement of Liver cells|
- Highest O2 consumption
- Highest metabolic rate
- Protein synthesis
- Secrete glucose into sinusoids.
- Least oxygen supply
- High concentration cytochrome P-450
- Drug biotransformation
- Utilize glucose
- Liver sinusoids are low pressure microcirculatory system
- Sphincters at hepatic arteriole, hepatic venous sinusoid and arteriolar portal shunts.
- Reservoir for blood
|Cells of Liver|
Functions of Liver
- Maintain blood glucose – glucose buffer function
- Stores glycogen
- Into portal venous system from gut– energy dependent active process
- Into hepatocyte from portal venous system - passive
- Glycogen synthesis
- Reduced NADPH formation
- Hepatic nerve stimulation
- Gut wall activity
- Intrinsic control
- Extrinsic control
- Portal venous constriction
- Initial vasoconstriction followed by vasodilatation of hepatic artery
- Epidural & spinal – reduce total hepatic blood flow – reduced portal venous blood flow and MAP.
- Halothane – greatest reduction in total hepatic blood flow.Reduce hepatic arterial flow and portal blood flow. ‘Reduce buffer response’
- Enflurane- lesser reduction
- Isoflurane – reduced portal venous flow; normal or increased hepatic arterial flow;preserved buffer response
- TPS, etomidate, propofol