Hormones Heart Kidney GI

Introduction

Hormones are the chemical messengers that are secreted in trace amounts by the endocrine cells. They transmit the information from one tissue to another tissue by diffusing it into the bloodstream. The messages transmitted to the target tissue help to control the metabolic and physiological activities in the target cells. A single hormone involves multiple effects on one target tissue or many different tissues. They are predominantly synthesized and released by the endocrine glands including the pituitary gland, adrenal gland, thyroid gland, pancreas, pineal gland, testes, and ovaries, however, they can also be produced and released in the non-endocrine tissues.

Hormones by Non-Endocrine Tissues

The hormones secreted in the non-endocrine tissues or organs including the heart, kidney, liver, and gastrointestinal tract of humans regulate the metabolism of the body. The non-endocrine organs have a particular site of release for hormones and these hormones are carried into the target spot to facilitate various functions.

Hormones of Heart

Atrial natriuretic factor (ANF) also known as Atrial natriuretic peptide (ANP)

• It is a peptide hormone that is secreted by the cardiac tissues of the body.

• It is released by the cardiac cells of the atrial wall to control atrial blood pressure and blood volume.

• It is a vasodilator that expands the blood vessels to reduce pressure.

• It also increases the discharge of sodium and water causing diuresis and natriuresis, therefore, it helps to ease the pumping of the heart and is useful in congestive heart failure.

Hormones of Kidney

Erythropoietin

• It is a hormone released by the kidney during low oxygen levels in the blood, therefore, it maintains the normal oxygen levels in the body.

• It stimulates the production of red blood cells (RBC) in the bone marrow.

• The abnormal function of the kidney causes inadequate secretion of this hormone, therefore, it reduces the production of RBCs and results in anemia.

Vitamin D or calciferol

• It is essential for several functions in the body. The activated form of vitamin D helps the absorption of calcium from food, which is necessary for the strong structure of bones and muscles.

• It also regulates the response of the immune system to infections.

Renin

It is an enzyme that is a part of the renin-angiotensin-aldosterone system, which is primarily responsible for the regulation of blood pressure by sodium reabsorption, secretion of potassium, water reabsorption, and alternating volume of blood.

Hormones of the GI Tract

Gastrin

• It is produced by the mucous membrane in the pyloric region during the presence of food in the stomach.

• It induces the secretion of gastric juices such as hydrochloric acid and pepsinogen for digestion.

Secretin

• It is secreted and released by the duodenum into the blood circulation.

• It stimulates the bile ducts and pancreas for secreting a bicarbonate base and fluid to neutralize the acid.

• It reduces the secretion of gastric juices.

• It involves the contraction of a pyloric sphincter.

Motilin

• It can be produced in the upper small intestine during fasting such as between meals or in sleep.

• It helps the movement of food from the small intestine into the large intestine.

• It also stimulates the secretion of the enzyme pepsin to digest the protein.

Cholecystokinin

• It is secreted by mucosa in the duodenum and is responsible for the digestion of protein and fat.

• It involves the rhythmic contraction of the gallbladder when the food substances enter the small intestine and induces the bile to flow into the duodenum.

It also stimulates the secretion of pancreatic enzymes in the pancreas.

Gastric inhibitory polypeptide (GIP)

• It is secreted by the intestinal mucosal cells.

• It inhibits the action of gastric glands, therefore, it inhibits the secretion of gastric juices in the stomach.

• It stimulates insulin secretion.

Hormones of Liver

Insulin-like growth factor-1 (IGF-1)

• It is also called somatomedin and has a similar molecular structure to insulin.

• It acts as a mediator of growth hormone because it induces the somatic growth of an individual.

• It regulates the growth and function of the kidney.

Thrombopoietin

• It is predominantly produced in the parenchymal cells of the liver and few amounts are made in the bone marrow and kidney.

• It acts as a regulator for the production of platelets, which is important for blood clotting.

Angiotensinogen

• It is a protein hormone released into the blood and facilitates the narrowing of blood vessels.

• It supports the maintenance of blood pressure and fluid balance in the body.

Hepcidin

• It is a peptide iron-regulating hormone produced in the liver and is a primary regulator for systemic iron homeostasis.

• It triggers the distribution of iron to various organs of the body.

Hormones of Other Organs (Skeleton, Adipose Tissues, Skin, Thymus)

Skeleton

It consists of calcium-regulating hormones such as calcitriol, parathyroid hormone, and calcitonin.

Adipose Tissues

These tissues have important hormones that are adiponectin, leptin, and resistin.

Skin

Retinoids, Vitamin D, glucocorticoids, neuropeptides, eicosanoids, and growth hormones are the primary hormones that are active on the skin.

Thymus

• It secretes and releases various hormones that include thymopoietin, thymic humoral factor, thymosin, and thymulin.

• It also has some other hormones which are similar to the hormones produced in other glands such as growth hormone, insulin, prolactin, and melatonin.

Conclusion

Hormones are produced by endocrine in minute quantities and they carry chemical information from one tissue to another tissue to perform various biological and metabolic functions in the body. There are several endocrine glands in the human body and the hormones can also synthesize in the non-endocrine organs such as the kidney, liver, heart, and gastrointestinal tract. They are primarily responsible for the normal function of the organ that facilitates an individual to become a healthy human. They are also produced and released in various organs including skin, skeleton, adipose tissues, and thymus.

FAQs

Q1. How are hormones different from enzymes?

Ans. Hormones are steroid or peptide molecules produced by an organism. It transmits chemical information from one tissue to another tissue that helps the metabolic functions of the body.

Q2. What is diuresis?

Ans. Diuresis is a condition of excretion of too much water and salts through urine. The hormone atrial natriuretic peptide increases the elimination of water and sodium causing diuresis.

Q3. What is the role of secretin?

Ans. Secretin is a significant hormone that is released into the bloodstream. It induces the pancreas and bile ducts for the secretion of sodium bicarbonate and water to neutralize the acid. It helps the contraction of the pyloric sphincter.

Q4. How does renin regulate blood pressure?

Ans. Renin is an enzyme that regulates blood pressure by water and sodium reabsorption, secretion of potassium, and modifications of the volume of the blood.

Q5. How is anemia related to erythropoietin?

Ans. Anemia resulting from the abnormal function of the kidney causes inadequate secretion of this hormone, therefore, it reduces the production of red blood cells.