Intro To Doabetes Flashcards
GLUT 4
Found in myocytes and adipocytes
Respond to insulin
Recruited and enhanced by insulin
How does insulin affect proteolysis and protein synthesis respectively in myocytes in the fed state?
Inhibits proteolysis as protein is not needed as a fuel source
Stimulates protein synthesis to use the proteins for storage
What effect does GH and IGF-1 have on protein synthesis in myocytes
Stimulates it as it converts amino acids into protein for storage
- What effect does cortisol have on proteolysis in myoctes?
Stimulates it
What hormone leads to an increase in uptake of gluconeogenic amino acids in the liver?
Glucagon
What is the effect of glucagon on the liver in the fasting state?
- Gluconeogenic amino acids released from myocytes enter liver which glucagon helps
- Glucagon stimulates proteolysis to produce more gluconeogenic amino acids
- Glucagon increases gluconeogenesis (to form glucose) to increase hepatic glucose output (HGO) → cortisol also does this
What is the effect of insulin on the liver in the fed state?
- Insulin inhibits gluconeogenesis in liver to reduce hepatic glucose output
- Stimulates protein synthesis
How long do carb, protein and fat stores in the body last?
- Carb- 16 hours → are depletable within a 1 day fast
- Protein- 15 days
- Fat- 30 to 40 days
What does Lipoprotein Lipase break Triglycerides (in the blood stream) down into and what hormone is this process stimulated by?
Glycerol and non esteriged fatty acids
Stimulated by insulin
How does insulin interact with adipocytes in a fed state? (2 things)
Increases uptake of glucose via GLUT-4
Converts Glycerol and NEFA into triglycerides again for later use when needed - lipogenesis
- Insulin also inhibits breakdown of triglycerides in adipocytes as you don’t need alternative energy source
What happens to adipocytes in fasting state (recall the two hormones involved)?
- Blood glucose and insulin is low so GH and cortisol secretedThese stimulate breakdown of triglycerides into Glycerol and NEFA to be used as an alternative energy source once transported into the liver - stimulates lipolysis
In the fasting state what happens to the glycerol taken up by the liver?
It is converted into glucose in process, gluconeogenesis
Increasing hepatic glucose output
-
In the fed state what happens to the glycerol taken up by the liver
Converted into triglycerides
What fuel can the brain use?
- Glucose- preferred energy source
-
Ketone bodies
Can’t use NEFA as a fuel
- How are ketone bodies produced?
-
- NEFA released from adipocytes are taken up by liver
- In fasting state, glucagon is released which promotes conversion of NEFA into ketone bodies to be used as alternative energy source
In the fed state, what does insulin do once NEFA is uptaken by the liver?
NEFA converted into fatty Acyl-CoA
Insulin inhibits the conversion of Fatty Acyl-CoA into ketone bodies
This prevents it from being used as an alternative metabolic substrate to glucose
The opposite happens in the fasting state where ketone bodies are produced
In the fed state what happens to glucose in the liver?
It is converted into Glucose-6-P
This is then converted into Glycogen (stimulated by insulin)
In the fasting state what happens to glycogen in the liver?
is broken down into glucose-6-p which gets turned into glucose and outputted from liver (process stimulated by glucagon) - Glycogenolysis
What does it mean if there is a high level of ketones and glucose?
There is an issue with insulin secretion
In the fed state what happens to Glucose in myocytes?
It is converted into glycogen to be stored and used only when the myocyte needs energy
It is also used in aerobic respiration
What effect does Glucagon and GH have on the GLUT-4 transporters in myocytes?
Inhibits uptake of glucose via GLUT-4 to allow more glucose to remain in circulation and increase the blood glucose levels
In the fasting state why is amino acid concentration increased initially and then decreased when prolonged?
Increased due to increased proteolysis and then decreased due to more gluconeogenesis to increase hepatic glucose output
What is the spike in insulin when you eat referred to as?
First Phase Insulin Release
What overall happens in body in fasted state?
- Low insulin-to-glucagon ratio
- (normal glucose is maintained at 3-5.5 mmol/L)
- Increased NEFA from increased lipolysis
- Increased proteolysis so increased amino acids but they decrease when prolonged fast
- Increase in HGO from glycogen and gluconeogenesis
- Muscles use lipids and brain uses glucose and later ketones
- Increased ketogenesis when prolonged
