Homeostasis and blood glucose

In a nutshell

Homeostasis maintains the constant internal environment of the body. This environment is important to ensure the conditions of the body are correct for cells and enzymes to function. Homeostasis controls blood glucose levels to prevent them from getting too high or low. Type $1$ and type $2$ diabetes are conditions that a disruption in homeostasis can cause.

Homeostasis

Definition

Homeostasis means maintaining a constant internal environment so the conditions in your body and cells are at the right level. This happens in response to changes inside and outside of your body. It ensures that your cells and enzymes have the right conditions to work properly.

Examples

Blood glucose regulation	This ensures the amount of glucose in the blood doesn't get too high or too low.
Osmoregulation	This is the regulation of water content. This is important to keep the balance between the water you gain from food, drinking and respiration and the water you lose via urination, sweating and breathing out.
Thermoregulation	This is the regulation of body temperature. You need to reduce your body temperature when you're too hot and increase it when the environment is too cold.

Negative feedback

As with control of the hormone thyroxine, homeostasis requires negative feedback to maintain the constant internal environment.

Controlling blood glucose

There are specific ways that blood glucose can be controlled by the body.

1.	Eating foods that contain carbohydrates puts glucose in the blood as it is absorbed in the small intestine.
2.	Normal cell metabolism removes glucose from the blood.
3.	Vigorous exercise removes a lot more glucose from the blood.
4.	Excess glucose can be stored as glycogen in the liver and in muscles.
5.	When glycogen stores are full, excess glucose is stored as lipid in tissues.
6.	Changes in blood glucose are monitored and controlled by the pancreas. It produces the hormones insulin and glucagon.

Insulin and glucagon- higher tier only

If blood glucose concentration gets too high, the pancreas releases insulin. Insulin causes glucose to move into cells which removes glucose from the blood. If blood glucose concentration is too low, the pancreas produces the hormone glucagon which makes the liver turn glycogen into glucose so blood glucose concentration increases. Glucagon and insulin interact in a negative feedback cycle to control the level of glucose in the blood.

Diabetes

Diabetes is an example of when homeostasis doesn't work. There are two types: type $1$ diabetes and type $2$ diabetes.

Type $1$ diabetes

Type 1 diabetes is a condition where a person's pancreas produces little or no insulin. This can cause their blood glucose level to reach dangerous levels that could kill them.

A person with type $1$ diabetes is treated with insulin therapy. This involves injecting insulin into the fatty tissue under the skin so it can enter the bloodstream. This is normally done at mealtimes to ensure glucose is removed from the bloodstream quickly after the food has been digested. This stops the person's glucose level from getting too high and is, therefore, a very effective treatment.

The amount of insulin injected depends on a person's diet and activity level. This is why a person with type 1 diabetes needs to consider limiting their intake of food rich in simple carbohydrates and regular exercise to remove excess glucose from the blood.

Type $2$ diabetes

Type $2$ diabetes is a condition where the pancreas does not produce enough insulin or when the body cells do not respond properly to insulin. Both of these cases cause the blood glucose level to rise.

There is a link between obesity and type $2$ diabetes: obese people have an increased risk of developing type $2$ diabetes. Storing excess fat around the tummy area is associated with an increased risk of developing type $2$ diabetes. Both risks can be calculated using the body mass index calculation and the waist-to-hip ratio.

Type $2$ diabetes can be controlled by eating a healthy diet, getting regular exercise and losing weight. Some people also take medication or insulin injections.