Secretin

Secretin is the first hormone discovered by William Bayliss. Intestinal glands contain the secretin hormone, which regulates water homeostasis in the body that influences the environment of the stomach, pancreas, and liver. The hormone has an essential part to play; it helps the body function properly. An organ produces the hormone in the body like the small intestine produces the secretin hormone in the body and stimulates the secretion of pancreatic juice.

Benefits of Referring to Vedantu

Vedantu has explained the Secretin hormone in detail in the notes. These notes help students gain a clear consciousness about the topic, and also, experts have provided a brief history about the introduction of the hormone. Biology experts at Vedantu have provided students with information about the role and function of the secretin. Vedantu notes a piece of long and accurate information that has explained the role and the process of secretion of secretin hormone in the body. A lot of additional points from the textbook are added in the notes by Vedantu to deliver more than exam-oriented content.  It is fascinating to read about the history of hormones. 

Learn about Function of Secretin Hormone

Secretin hormone has a lot of functions to perform in the body; in the notes, Vedantu experts have explained each function in detail that can help students solve questions like multiple-choice questions (MCQ) in the exams readily. You can learn more about the function or purpose of the secretin hormone in the body at Vedantu, experts of biology conduct online tuition, where you learn each concept using three-dimensional examples that help you understand the topics in an easy way, and you can retain the things for a long duration.

Secretin Hormone Balance with Vedantu

In the notes, you can find a thorough explanation about keeping your secretin hormone at a balanced level. Experts have shared the diet to optimize your hormones as a protein-rich diet can help with it. Also, they have explained the importance of exercising regularly, and most important sugary and carbonated drinks can affect the body and functions of hormones. Even stress could harm the release of hormones; subject matter experts of biology have cited several reasons to help students with the balance of hormones.

Imbalance hormones affect the health, which may cause irritation, mood swings, hair loss at an early stage, difficulty concentrating on studies or any work, infertility, etc. These are a few symptoms of hormone imbalance. 

Learn more about it in the Vedantu online biology class, where experts of this field teach you concerning your exam and day-to-day life problems, where you not just learn but become knowledgeable.

Role of Secretin Hormone in the Body

Secretin was discovered by William Bayliss and Ernest Starling in the year 1902 when they were researching the role of the nervous system in the digestion process and they determined that a substance secreted by the intestinal lining stimulates the pancreas and not the nervous system, after being transported via the bloodstream. They named this intestinal secretion “secretin” and it was the first hormone to be discovered however the term “hormone” was coined much later in the year 1905 by Starling. The secretin hormone was first identified and recognized as a ‘chemical messenger.’ Before diving into the secretin function and its effects on the body of the secretin hormone, let us understand the pathway of the digestive tract to understand the secretin hormone better.

Digestive System Pathway

The gastrointestinal tract has 12 parts that work together to process the food and in their order of function it starts from the mouth- where food is broken down into smaller digestible matter via chewing, this enters the esophagus which is a long tube that transports food from the mouth to the stomach, the stomach releases several hormones and acids for further digestion post which it enters the small intestine which consists of three parts, the duodenum, jejunum, and ileum and then enters the large intestine where waste products which do not aid in the betterment of the body reach the rectum followed by the anus.  Helping them along the way in the motility, digestion of food, absorption of food, and secretion of hormones are the various other organs like the pancreas, gallbladder, and liver.

Secretin is produced by the small intestine of the digestive tract whose main function is maximum absorption of nutrients from the food consumed. When the food reaches the stomach hormone gastrin is released which creates an acidic environment for further digestion. After which the food reaches the small intestine and secretin hormone is secreted by the duodenum the S cells of the duodenum, which are located in the intestinal gland produce it. People often mistake these main hormones released by the gastrointestinal tract when in reality secretin and gastrin counteract each other’s function and maintain the equilibrium. Gastrin is a hormone that is secreted by the stomach-pyloric mucosa which stimulates the production of gastric acid in the stomach while secretin is a peptide hormone produced by the duodenum to regulate and balance the acidity created by the gastrin.

Release of the Secretin Hormone

The precursor of the secretin hormone is the prosecretin which is already during digestion. Secretin which is stored in the duodenum S cells in an inactive and unstable form is activated when prosecretin in the digested food enters the duodenum of the small intestine along with the gastric acid. The secretin release is thus triggered by the gastric acid for the purpose of protecting the duodenum from any sort of acid damage. When the duodenum increases above the pH of 4.5, the secretin release is blocked by the H2 antagonists and the basic pH is maintained once the secretion of the secretin hormone stops. 

Structure of the Peptide Hormone Secretin

The Chemical Structure of the Secretin Hormone

The precursor prosecretin is a 120 amino acid protein that contains the secretin itself in the residues from 28-54, an N-terminal signal peptide, a 72- amino acid C-terminal peptide, and a spacer. When this matures into the activated and stable secretin peptide, it becomes a linear peptide hormone. In the mature peptide hormone, a helix is formed between positions 5 and 13 of the amino acids. It has a molecular weight of 3055 and is composed of 27 amino acids. The mature peptide Secretin hormone also has valine which is an amidated carboxyl-terminal.  The sequence of amino acids is similar to glucagon where 14 of them reside in the same position as that of the mature peptide hormone secretin, and 10 of them reside in the same position as GIP (gastric inhibitory peptide) and 7 of the amino acids have the same place of residence as VIP (Vasoactive Intestinal Peptide). 

Function of Secretin 

• Secretin helps regulate the pH to a more neutral to the basic state of the duodenum.

• Secretin inhibits the secretion of gastric acid when it is no longer required from the parietal cells of the stomach.

• Secretin functions by stimulating the production of various digestive chemicals and enzymes that help enhance the digestion and absorption process.

• The bicarbonate is stimulated by the secretin hormone from the ductal cells of the pancreas.

• Secretin also stimulates the liver for bile production that helps in emulsifying the dietary fats in the duodenum. 

• Alkalization of bile is also regulated by the secretin hormone.

• Secretion functions by regulating the water homeostasis in the entire body.

• Secretin plays an important role in osmoregulation which is the active regulation of the osmotic pressure of an organism's body fluids by acting on the hypothalamus, pituitary gland, and kidneys.

• In concert with secretin's actions, simultaneously cholecystokinin (CCK), another hormone is issued by the duodenum, that stimulates the gallbladder contraction which enables the delivery of stored bile.

• Secretin hormone modulates water and transportation of electrolytes in epididymis epithelial cells, liver cholangiocytes, and pancreatic duct cells.

• It plays a vital role in the vasopressin-independent regulation in the kidneys for renal water reabsorption.

Secretin is an important hormone for the regulation of water and other fluids in the body and often its functional activity extends beyond just the small intestine. It activates the pancreatic enzymes which lend themselves to the absorption of the nutrients from the digested food. When the pancreas fails to respond to the activated secretin it is to be assumed that one suffers from cystic fibrosis, chronic pancreatitis, and pancreatic cancer. One can experience symptoms due to disentanglement or disengagement with the secretin hormone by the pancreas through signs of abdominal pain, nausea, and vomiting, and initial stages of pancreatitis. 

Secretin Stimulation Test 

This condition of pancreatic insufficiency is tested through a secretin stimulation test wherein a tube is inserted through the nose that passes through the esophagus and stomach and extends till it reaches the duodenum. In the duodenum, the secretin hormone is injected intravenously and the response of the pancreas is then monitored and the damage or insufficiency is determined and the treatment is given accordingly. 

Ways to Balance Secretin Hormone Levels

• To optimise hormone health,  a protein-rich diet is a must and experts recommend a minimum of 20–30 grams of protein consumption per meal. A Protein-rich food or meal must include meat, especially lean meats, seafood, and poultry. 

• Regular activity and engaging in some form of exercise be it dancing, yoga, strength training, aerobics, etc. will keep the hormonal balance game strong and one will be devoid of health problems.

• Management of Stress: When one is stressed, the release of hormones is affected and in most cases declination is seen that can be very concerning and lead to severe health problems.

• Avoid refined foods and sugars that also damage the digestive system which messes up the secretin release as well.

• Have healthy habits like consuming green tea, avoid undereating like do not starve yourself in the name of diets and other fads and there is no need for overeating as well, both are damaging in the long run.

• Consume fatty fish and other healthy and good fats. Unlike the other diets that suggest avoiding fat, it is important to keep in mind that healthy fats are good for the body and aid hormone release. 

• Having eggs and eating fiber-rich food are very crucial for hormonal balance. Fruits like berries, oranges, melon and pear, broccoli, carrots, and sweetcorn are high fiber-containing vegetables and others are nuts and seeds.

• Stay away from sugary and carbonated drinks that can damage your entire body and its functions.

• The most important of all is to consistently get good sleep and not be sleep deprived to have a hormonally healthy and balanced body.

Conclusion

The digestive process is impossible without this important hormone secreted by the duodenum of the small intestine called secretin. The balance of it is important for physical and mental health as hormones like secretin also regulate water homeostasis. This chemical messenger also plays a major role in controlling the appetite as when there is no secretin, the acidity increases and slowly reaches other parts making it unlikely for the body to be able to consume more food. When secretin is produced in excess, it can also pose a problem. One must look at it that it is in an optimum release as per requirement and regular checkups and blood tests will help you keep a check on your health and when any issue is there, it can be diagnosed early and necessary changes can be made.

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