BCHM-3050 Lecture Notes - Lecture 12: Blood Sugar, Diabetes Mellitus Type 1, Insulin Resistance
3 Jul 2018
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Interdependence of major organs in fuel metabolism
Major organs: brain, muscle, liver, adipose tissue, heart
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Major fuel reserves: triacylglycerols (adipose tissue), proteins (skeletal
muscle), glycogen (liver and muscle)
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Fuel characteristics of major organs
Brain
Require 100 g/day of glucose
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No fuel reserves
Can adapt to fasting
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Ketone bodies: acetone, acetoacetic acid, beta-hydroxy
butarate
Breakdown fatty acid
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Muscle
Use: glucose, FA and ketone bodies
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At rest: FA are prime fuel
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Under exertion = glycogen prime fuel
Release lactate because glycolysis produces pyruvate faster
then TCA
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Glucose: released via glycogenolysis
Doesn’t have glucose-6-phosphate
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Use lactate
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Heart
Highly aerobic
No energy reserves
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Require continuous supply of fuel and oxygen
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Adipose
Major fuel depot
Store triaglycerol (TAG)
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Need glycolysis to make glycerol-3-phosphate for TAG
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When glucose falls = release it frm here
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Liver
Synthesis of FA and glucose
From glycogen mobilization and gluconeogenesis
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Malonyl-CoA levels regulate FA metabolism
Inhibit carnitine acyltransferase I
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Buffer blood glucose
High Km of hexokinase + control of intracellular location of
glucose transport
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Blood: vehicle of gas and metabolite transport
Energy needs met primarily from glycolysis
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Has no mitochondria
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Hormonal regulation
Major hormones:
Insulin
Released when blood glucose levels are high
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Stimulate glycogen formation
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Glucagon
Released when blood glucose levels are low
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Stimulate glycogen breakdown
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Actions of Glucagon
Lead to increase in blood glucose levels
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G6P (glucose-6-phosphatase) in cell cant be exported
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Insulin: shut down glucose production and activation of energy production
pathways
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Diabetes
Type I: insulin deficiency
Treat w insulin
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Type II: insulin resistance
Patients don’t respond well to insulin
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Chapter 17
Thursday, June 21, 2018
3:07 PM
