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Energy is a very important factor which aids the survival of all living organisms. Energy is produced when food is broken down by a process called metabolism. Metabolism is a set of chemical reactions which occur within the body's cells. The process begins when food is eaten, enzymes break down the food and once it has all been broken down, the compounds are then absorbed into the blood stream and are transported to different cells in the body. The body then burns this converted energy to maintain the survival of the living organism. The enzymes break proteins down into amino acids, fats into fatty acids and carbohydrates into simple sugars.
The chemical reactions that occur in metabolism are caused by the secretion of hormones by the endocrine glands. The endocrine glands are ductless glands which secrete hormones directly into the blood stream, which are then carried to the different cells via the bloods plasma. Chemical reactions occur in two main places: in the gut and in the cells. The reactions which occur in the gut are concerned with digesting food and the reactions that occur inside the cells is the process of metabolism.
Growth hormone, which is secreted by the pituitary gland, plays a very important part in the metabolism of proteins, carbohydrates and fats. It regulates certain aspects of metabolism in many organs like the liver, intestines and pancreas and also promotes the breaking down of fats and increases the blood glucose levels (Waugh & Grant, 2006).
There are two process involved in metabolism: anabolism and catabolism. Anabolism uses energy to construct components of cells such as proteins and nucleic acids and catabolism is the breaking down of large molecules into smaller ones releasing chemical energy. Both anabolism and catabolism involves a series of chemical reactions known as the metabolic pathways, which are controlled by hormones.
Thyroxin, which is produced by the thyroid gland, is another hormone which influences metabolism. This hormone regulates a cells metabolic rate and works closely in conjunction with insulin. The thyroid gland is controlled by the pituitary gland situated in the brain. When there is an abnormal thyroid function, this can cause excessive levels of the hormone, thyroxin. This is known as hyperthyroidism and speeds up the basal metabolic rate. When the thyroid gland produces insufficient thyroxin this is called hypothyroidism and slows down the basal metabolic rate. These two abnormalities are commonly known as an under active thyroid and over active thyroid.
The pancreas is another organ which aids metabolism by secreting insulin and glucagon. Insulin is a hormone that regulates the glucose level within the blood and glucagon helps regulate the body's energy.
After meals, the glucose level in the blood tends to rise which stimulates the pancreas to secrete insulin. Once the insulin has been secreted, it travels through the blood to the liver, where excess glucose is converted into another carbohydrate calle glycogen, which is insoluble and is stored in the liver.
Between meals, the glucose in the blood is constantly being used up, thus the level of glucose in the blood falls. When a low level of glucose is detected, the pancreas is stimulated to release the hormone glucagon. Glucagon converts some of the stored glycogen back into glucose, which is then released into the blood to raise the blood glucose level back to normal.
Insulin and glucagon have a very important function by regulating the blood glucose level, and it is vital that it remains as steady as possible. If the blood glucose level rises or fall too much, it can cause the individual to become very ill.
When insulin is not present, then glucose will not be able to enter the cells. This causes diabetes.
Diabetes affects roughly 2-3 million people in the UK (NHS Choices, 2009). There are two types of diabetes; type 1 and type 2. Type 1 diabetes occurs when the body produces no insulin and is often referred to as insulin-dependent diabetes. Type 1 diabetes is a lifelong condition which requires insulin injections and also requires regular monitoring of blood glucose levels to ensure they remain balanced. These levels can also be regulated by maintaining a healthy diet. (NHS Choices, 2009).
Type 2 diabetes is a less serious condition than Type 1diabetes, but it can progress to Type 1 if not cared for properly. It is also known as insulin resistance and occurs when there is not enough insulin being produced within the body. Type 2 diabetes is far more common than Type 1 diabetes, and roughly 95% of people with diabetes have type 2 diabetes (NHS Choices, 2009) Type 2 diabetes is often linked to obesity and can be managed by eating a healthy diet and monitoring blood glucose levels.
When the body does not produce enough glucose, the individual can suffer from a condition called Hypoglycemia.
Hypoglycaemia occurs mainly in people with diabetes (usually type 1 diabetes) who have overdosed on their medication, missed a meal, or consumed alcohol on an empty stomach. People withType 2 diabetes who manage their blood glucose levels without medication will generally not have a hypoglycaemic attack (NHS Choices, 2009). To prevent having a Hypoglycaemia attack blood sugar levels should be monitored regularly and knowing the symptoms will reduce attacks.
In conclusion, we have found that metabolism is a very important process that not only produces energy from the food that we eat, but it also keeps living organisms healthy. We have also concluded that the body's metabolism can be affected by hormones, which are secreted by the endocrine system and that problems with certain hormones such as the growth hormone and thyroxine which can lead to conditions such as an underactive or overactive thyroid and the hormones insulin and glucagon which lead to problems such as diabetes and hypoglycaemia.