Maintaining the right blood sugar level is super important for our health. Our glucose levels change throughout the day, especially after meals, and this can lead to health issues. But don't worry, our body has ways to keep our blood sugar in check. It uses various methods to stop glucose from going too high or too low, and keep it at a stable level. That's why it's crucial to control our blood glucose concentration for our overall well-being.

What is the regulation of Blood Glucose Concentration?

Glucose is a type of sugar that our body needs to function properly. It dissolves in our blood and travels to cells throughout our body. These cells is necessary for their survival Without enough glucose, cells, especially brain cells, can't produce energy and may even die. That's why it's important to keep our blood glucose levels around 5 mmol dm-3 or 90 mg cm-3. However, if glucose levels get too high, it can cause damage to blood vessels and lead to health problems like heart disease, stroke, kidney disease, vision impairment, and nerve problems. That's why it's crucial to control our blood sugar levels to avoid these issues. To learn more about how solutes affect water movement in our body, check out our article on osmosis.

Sources of glucose in the body

There are main ways

     1 -ucose absorbed from the food we eat, especially carbohydrates like pasta, rice, and fruit.

2. Glycogenolysis - Glucose is released when we break down glycogen, which is stored in our liver and muscle cells.
3. Gluconeogenesis - Glucose is produced from non-carbohydrate sources like lipids and amino acids.

To keep our blood glucose levels stable, our body uses hormones that detect changes in glucose concentration and help restore normal levels. Without this regulation, our glucose levels would be too high after meals and too low just a few hours later, which would be bad for our cells.

The liver plays an important role in regulating blood glucose levels. It's responsible for three key processes: glycogenolysis, gluconeogenesis, and glycogenesis. Glycogenolysis and gluconeogenesis happen when glucose levels get too low, and the liver produces glucose from glycogen or non-carbohydrate sources. Glycogenesis, on the other hand, happens when glucose levels get too high, and the liver stores excess glucose as glycogen.

Gluconeogenesis is especially important during prolonged hunger when glycogen stores are depleted, and the liver needs to produce glucose to maintain blood glucose levels and prevent them from getting dangerously low.

The role of Hormones in Blood Glucose Control

Our diet and activity levels can vary, leading to fluctuations in the supply and demand of glucose in our body. To maintain a constant blood glucose level, three hormones - insulin, glucagon, and adrenaline - work together in a coordinated effort. Insulin and glucagon are produced by the pancreas adrenaline is produced the glands. These hormones act on the liver to help achieve blood glucose homeostasis.

Insulin is responsible for lowering blood glucose levels by promoting the uptake of glucose into cells and tissues. It also promotes the conversion of glucose into glycogen, which is stored in the liver and muscle cells. Glucagon, on the other hand, increases blood glucose levels by promoting the breakdown of glycogen into glucose, which is then released into the bloodstream. Adrenaline also increases blood glucose levels by promoting the breakdown of glycogen in the liver and muscle cells. These hormones work together to ensure that glucose is available when needed and stored when it's not needed. This helps maintain a constant blood glucose level, which is essential for proper cell function and overall health.

How do Hormones work?

Hormones are highly potent chemicals that are effective at low concentrations. They travel through the bloodstream to their target cells, where they bind to specific receptors on the cell surface or inside the cell. Hormones are produced by endocrine glands and are directly secreted into the bloodstream. They are sometimes referred to as the first messengers. In some cases, hormones bind to their complementary receptor on the target cell and stimulate the production of another molecule, which acts as the second messenger inside the cell. This mechanism of action is used by hormones like adrenaline and glucagon. The second messenger then triggers cascade of intracellular events that ultimately produce the desired response in the target cell. Hormones play a crucial role in regulating various physiological processes, including growth and development, metabolism, and homeostasis. They work in concert with other signaling molecules, such as neurotransmitters, of in

Adrenaline

Adrenaline is an amine hormone produced by the adrenal gland, and it increases blood glucose levels by stimulating the breakdown of stored glycogen in the liver to glucose, a process known as glycogenolysis. Unlike glucagon, adrenaline-mediated glycogenolysis is usually triggered by the fight-or-flight response, which is an automatic physiological response to a perceived life-threatening situation.

The mechanism of action of adrenaline involves the binding of the hormone to its complementary receptor on the membrane of liver cells, which triggers a change in the receptor. The activated receptor then activates an intr called Adenyly cycl converts (cAMP). cAMP acts as the second messenger and binds to protein kinases, triggering a conformational change in the enzymes that activates them. The activated protein kinase enzyme then accelerates the conversion of glycogen to glucose, facilitating the release of glucose into the bloodstream. This process helps to provide the body with the energy needed to respond to a perceived threat, enabling it to fight or flee. Overall, adrenaline plays a critical role in the body's response to stress and is essential for maintaining glucose homeostasis.

Insulin

Insulin is a globular protein hormone secreted from the β cells in the islets of Langerhans, which is a cluster of cells in the pancreas. During hyperglycaemia, usually after having a meal, the β cells in the islets of Langerhans detect the rise in BGC and in return release insulin into the bloodstream. The insulin specific receptor is expressed in almost all cells (except red blood cells). After binding to insulin, the receptor undergoes conformational changes that lead to the activation of various intracellular cascades of events. The signalling events triggered by insulin action include:Activation and increase in the number of glucose transport carrier proteins (GLUT 4 proteins). This results in the increased uptake of glucose via facilitated diffusion. In the absence of insulin, these glucose transporters are stored in the vesicles part of the plasma membrane. Activation of the enzyme that catalyses the conversion of the excess glucose in the cell to glycogen (glycogenesis) and fat.

To sum up, insulin lowers blood glucose concentration mainly by:

Increasing the glycogenesis rate.Increasing the cellular respiration rate. (glucose consumption)Increasing the glucose uptake rate in cells. (especially in muscle and liver cells) Insulin is constantly secreted when the BCG is high because this hormone is automatically broken down in the liver. When the blood glucose levels return to the optimum point, insulin release ceases from β cells in the pancreas. This is an example of a negative feedback system! Negative Feedback systems are homeostatic self-regulation processes whereby changes to a biological system are reversed and returned back to the previous optimal level. Read our article Negative Feedback to learn more about how these systems contribute to Homeostasis!

Glucagon

It's important to note that insulin and glucagon work in a delicate balance to maintain blood glucose levels within a narrow range. When blood glucose levels are high, insulin is released to lower them. When blood glucose levels are low, glucagon is released to raise them. This balance is crucial for overall health and any disruption can lead to serious metabolic disorders, such as diabetes. Understanding the role of these hormones in regulating blood glucose levels is key to maintaining optimal health. 

Blood Glucose Concentration Diagram

The two hormones, insulin and glucagon, work in opposite ways (antagonistically) to maintain blood glucose levels stable. They are both released from the pancreas which plays a very role in monitoring and controlling the BGC, and both act on the liver.  Other hormones like adrenaline are also involved in the regulation of blood glucose levels. These hormones are susceptible and are controlled by negative feedback. These features allow them to control the BGC at an optimum point. It is also important to mention that since there is often a lag between the release of hormones and their response, the BGCs typically fluctuate within a narrow range at around 5mmol.dm-3 (in healthy individuals).

Diabetes and the Control of Blood Glucose Concentration

It's important to note that maintaining a healthy lifestyle can greatly reduce the risk of developing type 2 diabetes. Eating a balanced diet, engaging in regular physical activity, and maintaining a healthy weight can all help to prevent or control diabetes. Additionally, regular check-ups with a healthcare professional can help to monitor blood glucose levels and detect any potential issues early on. With proper management and care, it's possible to live a long and healthy life with diabetes.

Control of Blood Glucose Concentration - Key takeaways There are three sources of glucose in the body: The diet.The breakdown of glycogen (glycogenolysis).The conversion of sources other than carbohydrates (gluconeogenesis).The three main hormones insulin, glucagon, and adrenaline work together to achieve homeostasis and maintain a constant BGC. The liver is one of these three hormones' main sites of action. It is responsible for glycogenesis, glycogenolysis, and gluconeogenesis. Insulin and glucagon are released from the islets of Langerhans in the pancreas. Glucagon acts on the liver and stimulates glycogenolysis and gluconeogenesis to raise the BCG. Insulin acts on the liver and other tissue cells to stimulate glucose uptake and lower the BCG.

Control of Blood Glucose Concentration

Why is it important to maintain blood glucose concentration?

Some cells can only respire glucose as their source of energy. Therefore, too low blood glucose levels would be detrimental and damaging to these cells.On the other hand, too high blood glucose (hyperglycemia) concentration leads to high water potential in the blood. As a result, less water would move from the blood to the tissues which could lead to tissue dehydration and damage. 

Why does blood glucose concentration increase?

As part of food intake, we ingest carbohydrates that get broken down into glucose.

What does the concentration of blood glucose affect?

The Respiration of cells and blood osmolality. 

What happens when blood glucose concentration is too low?

Hypoglycaemia leads to weakness, confusion, sleepiness and eventually passing out.

What is blood glucose concentration?

Also called glycaemia, it’s the amount of glucose (sugar) in the blood.

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