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Lecture 24

BIOL 3070 Lecture Notes - Lecture 24: Anabolism, Glycogen, Glut4

3 pages40 viewsWinter 2017

Course Code
BIOL 3070

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Lecture 24
Hormonal influence on the metabolism; insulin and glucagon
o Endocrine function of the pancreas:
Islets of langerthans produce three different hormones which are placed in an
anatomical position that allows them to sense the change in the glucose of the
Beta islet: insulin
Alpha islet: glucagon
o Insulin:
Released by the beta islet cells into the blood when the glucose levels are high
to stimulate the uptake of glucose in muscle and adipose tissue
Increased uptake in the liver would be indirectly
Glycogenesis would increase in liver and muscle and decrease in glycogenolysis
Gluconeogenesis would decrease (production of glucose from molecules other
than carbohydrates such as carbon skeleton of a.a)
Uptake of fatty acids and triglycerides would increase by the fat cells
Increase in lipogenesis from glucose due to its abundance
Decrease in lipolysis
Decrease in ketone bodies
Increase uptake of a.a by muscle and liver
Increase protein synthesis and decrease in protein degradation
o Increasing the hexokinase in glycolysis would increase the uptake of glucose directly in
muscles and adipose tissue and indirectly in liver
o Indirect control and mechanisms for the rest
Facilitated diffusion through GLUT , there are 14 genes for GLUT
o Every cell has at least one of the transporters and many have more than one
o GLUT1 and 3 in brain
o GLUT 2 in liver, kidney, intestine and pancreatic beta cells (in mice, they have GLUT 2 in
pancreatic cells, in humans beta has GLUT 2 and 1)
o GLUT 4 in fat and muscle
Resting skeletal muscles and adipose tissue; increase in insulin would increase the glucose
uptake by RTK activation that activates the GLUT4 addition into the plasma membrane
glucose can be up taken through its concentration gradient using facilitated diffusion
In active skeletal muscles: GLUT 4 can be regulated through an insulin independent manner
(depending on the concentration of ATP/AMP that would activate AMPKinase) low ATP nd high
AMP would activate AMPK that would increase the GLUT4 in the plasma membrane that
increases the uptake of glucose.
Hepatocytes (liver cells): GLUT2 is non-regulated form of glucose transporter which is not
regulated by insulin.
o Absence of insulin due to low level of glucose: glucose would diffuse from high
concentrated hepatocytes to the low concentration gradient outside of the cell through
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