What is the Pancreas?
The pancreas is a (15~20)-cm-long tubular digestive gland, also called pancreatic gland, which is located across the back of the abdomen, just behind and below the stomach.
The pancreas has two main functions:
- Digestive function of pancreas: To produce pancreatic juice, which contains enzymes for the intestine to digest food – This pancreas function is called exocrine function of pancreas. Exocrine shows that it occurs outside the pancreatic gland.
- Endocrine and metabolic function of pancreas: To produce specific hormones: Insulin and glucagon, which play a central role in the regulation of blood sugar in the body. – This pancreas function is called the endocrine function of pancreas. Endocrine means that it has to do with hormones.
The product of pancreas exocrine cells is the pancreatic juice, that is a clear, alkaline (pH 7.8-8.4) liquid of 1-2 L/d containing digestive enzymes, which can help the intestine to break down the food for nutrient absorption.
Protective functions of the pancreas: The pancreatic juice contains bicarbonate (alkaline) that can neutralize acidic liquid coming from stomach, so that it protects the intestinal mucosa to avoid erosion.
Digest foods for nutrient absorption: The pancreatic juice has digestive enzymes to break down the food and nutrients, such as protein, fat, starch, which are the three major nutrient material.
The above-mentioned functions of pancreas are both the exocrine function associated with intestinal digestion. In addition, the pancreas has another function – endocrine function, that regulates the blood sugar connected with glucose metabolism, as follow:
Pancreas releases insulin to lower the level of glucose in blood, and on the other hand, for the balance, it also secretes glucagon to elevate the level of glucose.
Pancreatic tissue damage or dysfunction
If the pancreatic function and/or tissues and cells are damaged, that will cause:
- an inflammatory change/ inflammation in the pancreas – pancreatitis
- sugar in urine – a sign of diabetes.
What is insulin?
Insulin is a hormone which is released by Islet B cells of pancreas, and enter the blood. That promotes anabolic metabolism and has profound effects on body growth and energy storage, i.e. store sugar and fat to perform some useful operation at a later time.
Glucose metabolism: Insulin ensures that glucose can be absorbed in the body’s cells to facilitate cells uptake of glucose. Glucose is the fuel for the cells, and you get the energy in this way to work. In addition, reduce the amount of circulating glucose in the blood, so blood sugar will be lower. The higher the blood we have, the more insulin is produced, so that the concentration of glucose should not rise too much. Having high blood sugar over a long time is harmful for the body and this is an illness called diabetes. If lack of insulin, it will elevate the level of blood sugar, so as to cause diabetes mellitus. Taking hypoglycemic agents and/or supplying insulin can control the disease. However, the excessive use of drugs will cause low blood sugar.
Fat metabolism: Insulin can promote the formation and storage of fat, and inhibit breakdown of fat into the blood. If lack of insulin, it will cause hyperlipidemia (high blood fat), arteriosclerosis (hardening of the arteries), cardiovascular disease (e.g. coronary heart disease, myocardial infarction), cerebrovascular disease (cerebral infarction, cerebral hemorrhage). A large number of ketones will be produced due to the breakdown of fat, to lead to ketoacidosis (acidosis accompanied by the accumulation of ketone bodies in the body) and coma (unconsciousness).
Protein metabolism: Insulin plays an important role on protein formation, and also encourages cells uptake of amino acids. In other words, the insulin is one of essential hormones for the growth of body.
Exocrine function of pancreas
Enzymes break down food by cleaving specific chemical compounds in food so that the molecules are smaller and can easily be absorbed through the intestinal wall and into the blood. The various enzymes are different from each other by cleaving different chemical compounds.
The enzyme-producing part of the pancreas is called the exocrine section. This part of the gland works closely with the liver and gall bladder, both of which secrete substances that are important for digestion of food.
It can occur in both acute and chronic pancreatitis (acute and chronic pancreatitis). Often these diseases are associated with prolonged and excessive alcohol intake. Acute pancreatitis can be life threatening. Chronic pancreatitis results in decreased production of enzymes. Thus, the food is not break down in the intestine sufficiently; Many of nutrients are without being absorbed in the blood, when the food passes through the digestive system.
Pancreatic exocrine insufficiency?
If the pancreas exocrine function is insufficient, for example, lack of pancreatic juice, it will affect the digestion and absorption of fat and protein, so as to cause chronic diarrhea, vitamin deficiency and malnutrition.
Endocrine function of pancreas
The endocrine part of pancreas – pancreas islet – produces chemical substances (hormones) that go into the bloodstream to reach other organs whose functioning they affect.
Hormones are chemical substances secreted directly into the bloodstream. Together with the nervous system, coordinates and controls the hormonal function of the body’s various tissues and organs so that they work together in an appropriate, effective and accurate way.
The hormone-producing part of the pancreas is called the endocrine section. These areas can be seen as “islands” of hormone-producing cells located in the enzyme-producing section which can be regarded as “sea”. Each island is called a Langerhans island. This island produces several types of hormones, and the two most important hormones are insulin and glucagon:
Insulin: Insulin facilitates the body’s absorption of sugar in the form of glucose (one of the most important form of energy of body); and simultaneously, converts glucose into glycogen and fat as reserve energy; And it also promotes the formation and storage of fat and protein.
Glucagon: Glucagon has the opposite effect of insulin. It breaks down fat and protein, raises blood glucose and blood ketone, and transforms amino acids into sugar. Glucagon is secreted when we have low blood sugar (hypoglycemia), and inhibited when we have high blood sugar (hyperglycemia).
What is pancreatic juice?
Pancreatic juice is the pancreatic exocrine fluid, which enters into the duodenum to implement its pancreatic exocrine function – digest the food and nutrients.
Components of pancreatic juice
The pancreatic juice consists of a clear, alkaline (pH 7.5-8.4) solution of 750-1500 ml/d containing digestive enzymes.
PH of pancreatic juice: 7.5~8.4.
Pancreatic juice contains: water and electrolytes – HCO3–, others like Na+, K+, Ca2+, Mg2+, HPO42+, and a variety of digestive enzymes.
Pancreatic juice enzymes: also called pancreatic digestive enzymes, including:
- Pancreatic lipase
- Pancreatic phospholipase
- Cholesterol esterase
- DNA enzyme
- RNA enzymes
In addition, pancreatic juice also contains trypsin inhibitors, that can prevent trypsinogen from being activated within the pancreas, thus avoiding the occurrence of pancreatitis.
Pancreatic juice function
The pancreatic juice contains a large amount of HCO3–, that can protect your intestinal wall from being destroyed by stomach acid. It is a so-called acid-base neutralization reaction, and therefore provides the best working environment (alkaline environment, Ph 7.5~8.5) for digestive enzymes to digest food. These pancreatic enzymes contained in pancreatic juice play an important role to break down fat, protein and starch for nutrient absorption.
In some children and young people, the production of insulin stops. They get high blood sugar and can be life-threatening illness. These have type 1 diabetes, and they must be treated with insulin given in the injection form, as injections.
A person who eats a lot of carbohydrate foods, will be able to “wear out” beta cells in the pancreas after a while (after a time). Amyloid protein produced along with the insulin namely amylin. Amylin can build up (accumulate) and form fibrils, so that beta cells may enter into apoptosis (programmed cell death). This may be a reason why beta cells of people with type 2 diabetes are unable to produce enough insulin, and glucose levels will thus not be lowered sufficiently. The insulin produced in people with type 2 diabetes, also has less effect on cells than normal. We say that they have insulin resistance.
beta-cell: a type of basophilic cell that makes up most of the bulk of the islets of Langerhans and secretes insulin.
Overweight people often produce insulin which works badly. We say that there is insulin resistance. Obese people may increase the production of insulin to compensate for the bad effects of insulin. This prevents the blood sugar becomes too high. Over time, however, this over-stimulation of the pancreas may lead to a gradual destruction of the cells that produce insulin. This increases the risk that the overweight will eventually develop type 2 diabetes.
Type-2-Diabetes occurs mostly due to a so-called insulin resistance, which means your body’s cells with a reduced sensitivity to insulin, so that the insulin can not play the role of lowering blood sugar. A disturbed insulin secretion and previous overproduction of insulin causing an existing exhaustion of the insulin-producing cells are both responsible for type-2-Diabetes. This diabetes is the most common form, that makes up approx. 93.5 percent ratio and mostly occurs in adults. Obviously, type 2 diabetes frequently involves obese population and families, which indicate the risk factors related to familial predisposition and dietary habits.
What causes diabetes?
Insulin is a hormone in the body that can lower blood sugar levels and is produced in pancreas. From the pathogenesis, any cause leading to a malfunction in insulin production or function, will trigger diabetes. In the etiology, genetic, autoimmune, environmental and dietary factors, are related to diabetes. There are four types of diabetes and many causes are responsible for them.
Type 1 diabetes
In type 1 diabetes, the body’s own defense destroys the insulin-producing cells (B cell) of the pancreas. The insulin production decreases and will be finally completely shutdown. Why the body forms these antibodies is unclear. Heredity and genetic factors appear to play a role to start autoimmune response. As a result of immune destruction, B-cell function and number are both reduced, then insulin is elevated and diabetes occurs.
In type 2 diabetes, the sensitivity of the body’s cells is reduced for insulin, that is called insulin resistance. The cells of person affected needs a lot more insulin to absorb glucose from the blood, than cells of healthy humans. The insulin-producing cells of the pancreas pour out more insulin. Over time, they are overloaded, thereby the reduction of insulin production is gradually increased.
Trigger of diabetes is also related to hereditary or genetic factor; Environmental factors are also important causes to trigger type 2 diabetes, including aging, nutritional factors, obesity, lack of exercise, urbanization, stress, and fetal undernutrition. In addition, there are drugs that interfere with the metabolism of sugar, and diabetes can be caused, such as diabetogenic drugs. It is very common that the type 2 diabetes occurs in connection with the metabolic syndrome (including diabetes, atherosclerosis-related cardiovascular disease, hypertension, dyslipidemia, visceral obesity).
In the course of development of diabetes, the patients experience a process from Phase I – high levels of insulin in the blood and/or insulin resistance, and abnormal insulin secretion, to Phase II – impaired glucose tolerance, to Phase III – diabetes.