W3-L2: Glucose Metabolism Flashcards
What are the 3 fates of Glucose Metabolism?
What are the Hormones involved in Blood Glucose Metabolism? (5)
Released by the Adrenal Gland:
- Epinephrine
- Norepinephrine
- Cortisol
Released by the Pancreas
- Glucagon
- Insulin
What is the effect of Epinephrine on Blood Glucose Levels?
- Activates Gluconeogenesis & Glycogenolysis
- Increases Blood Glucose
What is the effect of Norepinephrine on Blood Glucose Levels?
- Activates glycogenolysis
- Increases Blood Glucose
What is the effect of Cortisol on Blood Glucose Levels?
- Activates Gluconeogenesis
- Sustains Blood Glucose Levels
What is the effect of Glucagon on Blood Glucose Levels?
- Activates gluconeogenesis & glycogenolysis
- Increases Blood Glucose
What is the effect of Insulin on Blood Glucose Levels?
- Activates glycolysis & glycogen synthesis
- Decreases Blood Glucose
What is Glycogenesis?
Glucose molecules are branched together to form glycogen
What is Glycogenolysis?
Breakdown of glycogen into glucose
What are Gluconeogenesis?
Creating glucose from non carbohydrate precursors
e.g. glycerol and amino acids
What is Glycolysis?
Breakdown of glucose into 2 x pyruvate
What is Lipolysis?
breakdown of triglycerides into glycerol and fatty acids in the mitochondria
What is Beta oxidation?
breakdown of fatty acids into acetyl-CoA for entry into the Krebs cycle
What is Lipogenesis?
Excess acetyl Co-A is converted to fatty acid chains
What is normal Blood Glucose level?
What happens to it after eating carbs?
- Blood glucose is normally maintained within the range of 3.9 – 5.5mmol/L (70 to100 mg/dl) under fasting conditions
- Will rise after a meal containing carbohydrates – approx. 7mmol/L
- Blood glucose levels usually return to resting level between 30 and 120 min after eating has finished
Glucose impairment is associated with diabetes mellitus, suspected when fasting blood glucose levels exceed 7mmol/L (126 mg/dl)
What is the purpsoe of GLUT 4 Receptors?
What is average Blood Glycogen Levels:
In the Blood?
In Skeletal Muscle?
In the Liver?
- Blood (4-5g glucose)
- Skeletal muscle (approx. 300 - 400g)
- Liver (75 – 100g)
What triggers Glycogenesis?
Glycogenesis: assembles glucose molecules into branched chains for storage as glycogen
- Triggered by rest (post activity) and consumption of carbohydrates (increasing insulin)
What is the Rate limiting enzyme in Glycogenesis?
Rate limiting enzyme = glycogen synthase
How is the storage of glycogen related to the term “water weight”?
Every 1g of glycogen is stored w/ approx. 3g water
What is the difference b/w Liver & Muscle Glycogen?
Liver glycogen – glucose reserve for blood
* Depleted after an overnight fast
Muscle glycogen – glucose reserve for muscle (cannot be released into the blood)
What level of excersize do Glycogen stores support?
Glycogen stores will support:
moderate intensity exercise for 90 mins or
high intensity exercise for approximately 30 - 45 mins
What hormones trigger Glycogenolysis?
Glucagon, norepinephrine and epinephrine
What happens to Lipogenesis during times of excess calorie consumption?
- Lipogenesis: Excess Acetyl Co-A is converted to fatty acid chains in the cytosol
- Biosynthetic pathway accelerated during times of excess calorie consumption
What is the key hormone in stimulating lipogenesis?
- Insulin is a key hormone in stimulating lipogenesis – Insulin
promotes the activity of enzymes involved in fatty acid synthesis and inhibits the breakdown of fat by inhibiting lipases
What is the function of lipoprotein lipase?
- During lipogenesis surplus fatty acids are combined with glycerol to form triglycerides
- Adipose tissue releases lipoprotein lipase which breaks down triglycerides in circulating lipoproteins, releasing fatty acids which are then taken up for storage in the adipocyte
