A similar phenomenon occurs in cancer cells, where increased glucose utilization

Question

A similar phenomenon occurs in cancer cells, where increased glucose utilization is required as a source of energy and to support the increased rate of cell proliferation. Interestingly, across a tumor mass, interior cells may experience fluctuations in oxygen tension that in turn limit nutrient oxidation and become an important aspect for tumor survival. In addition, the increased glucose utilization generates high amounts of lactate, which creates an acidic environment and facilities tumor invasion. Another factor that dramatically affects the metabolism is the nutritional status of the individual - for instance, during fasting or fed states. After a carbohydrate - rich meal, blood glucose concentration rises sharply and a massive amount of glucose is taken up by hepatocytes by means of GLUT2. This type of transporter has very low affinity for glucose and is effective only when glucose concentration is high. Thus, during the fed state the liver responds directly to blood glucose levels by increasing its rate of glucose uptake. In addition to being the main source of energy, glucose is utilized in other pathways, such as glycogen and lipid synthesis by hepatocytes. The whole picture becomes far more complex when we consider how hormones influence our energy metabolism. Fluctuations in blood levels of glucose trigger secretion of the hormones insulin and glucagon. How do such hormones influence the use of fuel molecules by the various tissues? Hormones Regulate Cell Metabolism Human cells and tissues adapt to internal metabolic demands in many ways, mostly in response to hormones and/or nervous stimuli. Demands by one cell type can be met by the consumption of its own reserves and by the uptake of fuel molecules released in the bloodstream by other cells. Energy use is tightly regulated so that the energy demands of all cells are met simultaneously. Elevated levels of glucose stimulate pancreatic beta - cells to release insulin into the bloodstream. Virtually all cells respond to insulin; thus during the fed state cell metabolism is coordinated by insulin signaling.

Explanation / Answer

1. Uncontrolled proliferation is the characterisitc of cancer cells. Angiogenesis(generation of new blood vessels) is a key characteristic of cancer cells that draws nutrition into the cancer cells which is essential for their survival and propagation. Utilization of more nutrients creats an environment for the further expansion of tumours, the natural selection dominates!

2.

Insulin and glucagon are the two hormones produced by pancreas. They both are chemically protein. But, the physiological actions produced by both the hormones are quite opposite. Insulin reduces the blood glucose level, whereas, glucagon raises the blood glucose level.

Insulin influences glucose metabolism in various tissues, including liver. In liver, it inhibits the glycogen breakdown (glycogenolysis) and the synthesis of new glucose molecules (gluconeogenesis), but stimulates glycogen synthesis. Whereas, the effects produced by glucagon are opposite to insulin. So, these hormones act antagonistic to one another to maintain homeostasis.

3. Insulin converts glucose into glycogen, thus helps to regulate the circulating glucose levels.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.