Question

A hormone that reduces blood glucose levels is ______, and a hormone that increases blood glucose levels is _________.

Short answer

A hormone that reduces blood glucose levels is insulin, and a hormone that increases blood glucose levels is glucagon.

Step-by-step solution

Hormone that reduces blood glucose levels

The hormone that reduces blood glucose levels is insulin. Insulin is released by the pancreas and helps in regulating the amount of glucose in the blood by promoting the uptake of glucose into the body's cells and storing it as glycogen. This results in a decrease in blood glucose levels.

Hormone that increases blood glucose levels

The hormone that increases blood glucose levels is glucagon. Glucagon is also released by the pancreas and has the opposite effect of insulin. It stimulates the breakdown of glycogen into glucose, which is then released back into the bloodstream, resulting in an increase in blood glucose levels. So, the complete sentence would be: A hormone that reduces blood glucose levels is insulin, and a hormone that increases blood glucose levels is glucagon.

Key concepts

Insulin

Insulin is a crucial peptide hormone synthesized and secreted by the beta cells of the pancreatic islets. It plays a vital role in the metabolism of carbohydrates and fats. Specifically, it regulates the metabolism by promoting the absorption of glucose from the blood into liver, fat and skeletal muscle cells.

In these cells, glucose is either used for energy or converted into glycogen for storage by the process of glycogenesis. When insulin binds to the insulin receptor on the cell wall, it initiates a cascade of reactions that lead to the uptake of glucose through facilitated diffusion by glucose transporter proteins. This hormone's effectiveness can be hindered in conditions such as diabetes mellitus, where either insulin production is inadequate, or the body's cells are resistant to its effects.

Glucagon

Glucagon, a peptide hormone produced by the alpha cells of the pancreatic islets, serves as a key player in the regulation of glucose metabolism, particularly when the body requires a boost in blood sugar levels. Its action is antagonistic to that of insulin.

When blood glucose levels fall below normal (hypoglycemia), glucagon is secreted into the bloodstream, initiating the breakdown of glycogen into glucose in the liver, a process known as glycogenolysis. In addition, glucagon promotes gluconeogenesis, the synthesis of glucose from non-carbohydrate precursors. Both of these pathways help to increase the glucose available in the blood, ensuring that energy demands can be met during fasting periods or between meals.

Pancreas

The pancreas is a glandular organ located in the abdomen, playing a central role in the digestive system and in the regulation of blood glucose levels. It has both exocrine and endocrine functions.

As an endocrine gland, it releases hormones like insulin and glucagon directly into the bloodstream, which are vital for blood sugar regulation. In its exocrine capacity, it produces digestive enzymes that are conveyed to the small intestine to aid in the breakdown of food. The coordination of these dual roles enables the pancreas to maintain energy homeostasis within the body, adapting to various metabolic demands imposed during different states such as feeding or fasting.

Blood Glucose Levels

Blood glucose levels indicate the concentration of glucose present in one's blood and are critical for the body's homeostasis. Maintaining glucose levels within a normal range is essential for bodily functions as glucose is the primary source of energy for the body's cells, especially brain cells which rely on a constant supply.

Several hormones influence blood glucose levels, with insulin and glucagon being the primary regulators. When blood glucose levels rise after eating, insulin facilitates the lowering of glucose. Conversely, when levels drop, such as between meals or during physical exertion, glucagon helps to increase the glucose levels. If glucose levels deviate significantly from the normal range, it can lead to immediate health issues, such as hypoglycemia (low blood sugar) or hyperglycemia (high blood sugar), and over time, contribute to chronic conditions like diabetes.