Energy is a very important factor which aids the survival of all living organisms, not just humans, and the required energy our bodies need is received from food through a process called metabolism. Metabolism can be described as the chemical reactions which occur within the body's cells that convert the fuel from food into the energy needed to do everything from moving, to thinking and even growing.
The process begins when food is eaten. Molecules, known as enzymes, break down the food into smaller compounds which are then absorbed into the blood stream and are transported to the 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. After they enter the cells, other enzymes act to speed up or regulate the chemical reactions involved with metabolizing these compounds.
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.
There are two process involved in metabolism which occur at the same time: anabolism and catabolism. Anabolism, also known as constructive metabolism, Is a process which is concerned with building and storing. Energy is used to construct components of cells such as proteins and nucleic acids. It supports the growth of new cells, the maintenance of body tissues and the storage of energy for future use. During Anabolism, small molecules are changed into larger, more complex molecules of carbohydrate, protein and fat. Catabolism, also known as destructive metabolism, is the process that produces the energy required for all activity in the cells. This process is the breaking down of large molecules into smaller ones releasing chemical energy. This chemical energy provides fuel for anabolism, heats the body, enables muscles to contract and helps the body to move. 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, influences metabolism by playing a key role in determining how fast or slow the chemical reactions in the body should progress. Thyroxin is released directly into the blood stream, it controls the body's growth and metabolism, affects the heart rate, body temperature and turns food into energy. High levels of this hormone can cause a condition known as hyperthyroidism, or overactive thyroid, which speeds up the basal metabolic rate and can be fatal if left untreated. Low levels of this hormone can cause a condition known as hypothyroidism, or underactive thyroid, which slows down the basal metabolic rate and is not as serious as hyperthyroidism. Both of these conditions are more common in women than in men and both can be treated effectively using medication. (NHS Choices, 2010)
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 called 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 and suffer from diabetes.
Diabetes affects roughly 2.3 million people in the UK (NHS Choices, 2009). There are two types of diabetes, known as type 1 and type 2. Type 1 diabetes occurs when the body produces no insulin and is often referred to as insulin-dependent diabetes. It is a lifelong, chronic condition which requires insulin injections and regular monitoring of blood glucose levels. Blood glucose levels can also be successfully 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 with obesity and can be successfully managed by eating a healthy diet and regularly monitoring blood glucose levels.
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.
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