What is the main function of insulin in the body?

Question

BlackTom AI · Accepted Answer

Insulin's primary role is to lower blood glucose by facilitating glucose uptake into cells and promoting glucose storage.

1. Relevant knowledge points and concepts
- Insulin is a peptide hormone produced by beta cells in the pancreatic islets. 
- It is released in response to elevated blood glucose (for example after a meal). 
- Insulin binds to insulin receptors on liver, muscle, and adipose tissue, activating signaling pathways that increase glucose uptake and storage. 
- Key physiological effects include increased GLUT4 translocation to the cell membrane (muscle and adipose), stimulation of glycogen synthesis in liver and muscle, inhibition of gluconeogenesis in the liver, and promotion of lipogenesis. These combined actions lower circulating blood glucose.

2. Step-by-step reasoning process
- After carbohydrate ingestion, blood glucose rises.
- Pancreatic beta cells sense the increase and secrete insulin.
- Insulin binds to receptors on target cells, triggering intracellular signaling (e.g., PI3K/Akt pathway).
- In muscle and adipose tissue, this signaling causes GLUT4 transporters to move to the plasma membrane, allowing glucose to enter the cells by facilitated diffusion.
- In the liver, insulin stimulates glycogen synthase to convert glucose to glycogen and suppresses enzymes for gluconeogenesis.
- As glucose moves into cells or is stored, blood glucose concentration falls toward normal.

3. Calculations
- Not applicable; this is a physiological mechanism rather than a numeric calculation.

4. Why the correct answer is correct
- The described mechanisms directly result in regulation (specifically lowering and stabilizing) of blood glucose levels, which is the main and well-established physiological function of insulin.

5. Why other options are incorrect
- Aiding digestion: digestive enzymes and GI hormones (e.g., gastrin, secretin) perform this role, not insulin. 
- Building muscle tissue: growth hormone, testosterone, and resistance exercise are primary factors; insulin is anabolic regarding nutrient storage but not the main agent for muscle building. 
- Regulating blood pressure: blood pressure is regulated by the renin-angiotensin-aldosterone system, sympathetic nervous system, and vascular factors, not insulin.

6. Conclusion
- The correct answer is Regulating blood sugar levels, which matches the provided answer.

What is the main function of insulin in the body?单项选择题

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Several hours after a meal

Multiple Choice: Which of the following is NOT True concerning blood sugar regulation?

When blood glucose levels are high, the pancreas releases [ Select ] pancreatic juices glucagon insulin to induce the liver and body to take up circulating glucose. When blood glucose is low, the pancreas releases [ Select ] insulin glucagon to induce the liver to increase blood glucose levels.

When blood glucose levels are low, the pancreas releases [ Select ] pancreatic juices insulin glucagon to induce the liver to increase blood glucose levels. When blood glucose is high, the pancreas releases [ Select ] glucagon insulin to induce the body to take up circulating glucose.

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