Question

10. What role does insulin play in the synthesis of glycogen? What effect does insulin have on GSK? What is the overall effect of this? 

11. What happens in type I and type Il diabetes? 

12. How does insulin affect glucose transport into the cell? 

13. What pathways are dysregulated in diabetes? Why? Provide details. What is the overall result.

Answer 1

ANSWER 10:

• Insulin is a major anabolic hormone and it favours storage. Therefore, Insulin stimulates the process of GLYCOGENESIS i.e., synthesis of glycogen  and inhibits GLYCOGENOLYSIS i.e, breakdown of glycogen to release glucose.
• EFFECT OF INSULIN ON GLYCOGEN SYNTHASE (GSK): Whenever blood glucose levels are high Insulin activates phosphoprotein phosphatase which results in removal of regulatory phosphate residues from GSK hence, converting it into DEPHOSPHORYLATED OR ACTIVE FORM thus stimulating glycogen synthesis.

ANSWER 11:

• TYPE-1 DM: It is seen in young adults. Antibodies are formed against BETA CELLS OF ISLET OF LANGERHANS IN Pancreas which results in BETA CELL destruction. Genetic predisposition and some environmental factors have also been held responsible for the pathogenesis of the disease. It is also known as INSULIN DEPENDENT DIABETES MELLITUS.
• TYPE-2 DM: There is decreased response of peripheral tissues like skeletal muscles, adipose tissue and liver to INSULIN which is termed as INSULIN RESISTANCE. Genetic factors and obesity play an important role in the pathogenesis of the disease.

​​​​​​​ANSWER 12: Insulin upregulates GLUT-4 receptors in three organs that is HEART, SKELETAL MUSCLES AND ADIPOSE TISSUE and allows blood glucose to enter these tissues, therefore it reduces blood glucose level.

ANSWER 13:

• Polyol pathway activation results in increased NADH/NAD+, increased sorbitol and increased osmotic pressure. This pathway results in oxidative stress build up in th cells which causes mitochondrial dysfunction and activation of caspases which results in apoptosis of cells and results in Retinopathy.
• Diabetes results in endothelial injury and other hemostatic disorders which can eventually result in coronary artery disease.
• Microangiopathy, myocardial fibrosis and abonormal metabolism can result in Diabetic Cardiomyopathy which can lead to heart failure in later stages.
• Increased NF-KB pathway and increased inflammatory mediators also result in oxidative injury to cells.
• High blood pressure damages small blood vessels of the kidney resulting in diabetic nephropathy.
• Hyperglycemia can also result in damage to nerves in peripheral nervous system resulting in pain and numbness.
• There is increased risk of stroke and cerebrovascular disease.
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