Pancreatic Hormones and Glucose Metabolism

This set of flashcards covers pancreatic hormones, glucose metabolism, and their physiological significance, tailored for exam preparation.

What is the main function of insulin in glucose metabolism?

Insulin facilitates glucose uptake from the bloodstream into cells and promotes glucose storage as glycogen.

What are the two main tissues that respond significantly to insulin?

Liver and muscle tissue.

What is gluconeogenesis?

The process of synthesizing glucose from non-carbohydrate sources, primarily in the liver.

Which cells in the pancreas secrete glucagon?

Alpha cells of the Islets of Langerhans.

What role does glucagon play in blood glucose levels?

Glucagon increases blood glucose levels by promoting glycogen breakdown and gluconeogenesis.

How does insulin affect glycogen synthase?

Insulin activates glycogen synthase, promoting glycogen formation.

What happens to glucose levels in the absence of insulin?

Blood glucose levels rise, leading to hyperglycemia.

Which hormones regulate blood glucose levels?

Insulin and glucagon.

What triggers the release of insulin from the pancreas?

Elevated blood glucose levels stimulate insulin release.

What is the significance of fructose 2,6-bisphosphate in glucose metabolism?

It regulates the activity of phosphofructokinase, promoting glycolysis.

What happens to glucose transport in muscle cells when insulin is present?

Insulin increases GLUT4 transporter expression, facilitating glucose entry.

How does glucagon exert its effects on the liver?

By activating adenylate cyclase and increasing cAMP levels, thereby activating protein kinase A (PKA).

Which enzyme is inactivated by glucagon to decrease glycolysis?

Pyruvate kinase.

How does insulin affect fatty acid synthesis?

Insulin promotes fatty acid synthesis by increasing glucose uptake and its conversion to fatty acids.

What is the effect of somatostatin on insulin and glucagon secretion?

Somatostatin inhibits both insulin and glucagon secretion.

What is the action of hexokinase in glucose metabolism?

Hexokinase phosphorylates glucose to trap it in the cell as glucose-6-phosphate.

What is the significance of the potassium channel in insulin release?

Potassium channels help regulate depolarization and calcium influx, facilitating insulin exocytosis.

What metabolic pathway is activated when blood glucose levels fall?

Glycogenolysis and gluconeogenesis are activated to raise blood glucose.

How are amino acids involved in insulin release?

Amino acids can also depolarize beta cells, triggering insulin release.

What effect does chronic high blood glucose have on the pancreas?

It can lead to insulin resistance and dysfunction of pancreatic beta cells.

What is the role of glycerol in glucose metabolism?

Glycerol serves as a substrate for gluconeogenesis in the liver.

What happens during the energy investment phase of glycolysis?

ATP is used to phosphorylate glucose and its intermediates.

What are the effects of glucagon on lipolysis?

Glucagon stimulates lipolysis, leading to increased fatty acids and glycerol in circulation.

Which molecules act as insulin secretagogues when glucose levels are low?

Amino acids such as arginine and alanine.

What is the relationship between insulin and glucagon in maintaining blood glucose levels?

Insulin lowers blood glucose, while glucagon raises it, maintaining homeostasis.

How does exercise influence glucose uptake in muscle cells?

Exercise can stimulate GLUT4 translocation to the cell membrane independent of insulin.

What can result from absolute insulin deficiency?

High blood glucose levels and associated complications, including ketoacidosis.

What role does phosphofructokinase play in glucose metabolism?

It is a key regulatory enzyme that controls the rate of glycolysis.

What is the significance of the C-peptide in insulin production?

It is released when proinsulin is converted to insulin and helps in assessing endogenous insulin secretion.

What occurs during the starvation state in the body regarding glucose metabolism?

Gluconeogenesis is increased while glycolysis and glycogen synthesis are inhibited.

What is the main effect of insulin on adipose tissue?

Insulin promotes triglyceride synthesis and storage in adipocytes.

What is the function of the Islets of Langerhans?

They are responsible for the endocrine functions of the pancreas, including hormone secretion.

What happens in the liver when insulin levels are high?

Insulin promotes glucose uptake and storage while inhibiting gluconeogenesis.

What is the main pathway through which insulin mediates its effects?

The PI3K/Akt signaling pathway.

How does insulin affect protein synthesis?

Insulin stimulates protein synthesis by promoting amino acid uptake and translation processes.

What is the effect of glucagon on the activity of glycogen phosphorylase?

Glucagon activates glycogen phosphorylase, promoting glycogen breakdown.

What can high levels of free fatty acids (FFA) indicate in the body?

They can indicate insulin resistance and are associated with metabolic disorders.

What role does insulin play in muscle glucose uptake during rest?

Insulin facilitates glucose uptake through GLUT4 transporters.

How do high blood glucose levels affect kidney function?

They can overwhelm renal glucose reabsorption capacity, leading to glucosuria.

What can prolonged high blood sugar levels lead to in terms of blood vessel health?

They can cause stiffness in red blood cells and contribute to vascular complications.

What is the dual function of phosphofructokinase 2 (PFK-2)?

PFK-2 functions as both a kinase and a phosphatase, regulating fructose 2,6-bisphosphate levels.

What distinguishes type I from type II diabetes in terms of insulin?

Type I diabetes is characterized by absolute insulin deficiency, while type II diabetes involves insulin resistance.

How does excess glucagon affect the liver?

It promotes gluconeogenesis and inhibits glycolysis, increasing blood glucose levels.

What is the main purpose of energy production in the Krebs cycle?

To produce ATP, NADH, and FADH2 for subsequent energy production through oxidative phosphorylation.

How does the pancreas adapt to chronic high carbohydrate intake?

It may enhance insulin secretion temporarily but can lead to beta-cell exhaustion and diabetes over time.

What is the physiological response of the body to low blood glucose levels?

The body increases glucagon release, stimulates glycogenolysis, and reduces glycolysis.

What is the purpose of GLUT transport proteins?

They facilitate glucose transport across cell membranes.

What triggers the activation of protein kinase A (PKA) in glucagon signaling?

The increase of cAMP levels upon glucagon binding to its receptor.

How does the body respond to insulin resistance?

It attempts to produce more insulin, but eventually, glucose levels may remain elevated.