Hormones are generally secreted by the endocrine glands. They function as chemical messengers which signal and regulate the body’s metabolism. However, there are other tissues in the human body which are not a part of the endocrine system by secreting important hormones that play a major role in various bodily activities. Some of these tissues are tissues of the heart, kidney and the gastrointestinal tract. They have active sites of release for hormones and then these hormones travel to the target sites and are used in various functions. The following is a summary of the different types of hormones produced by non-endocrine tissues. These are:

Kidney hormones
Heart hormones
Git hormones

The kidneys produce two major types of hormones and some hormones like substance:

Hormones Secreted by Kidney

Hormones Produced by Kidney	Function
Erythropoietin	The hormone is released by kidney when oxygen levels in the blood are low. It acts in the bone marrow and stimulates the production of mature red blood cells (RBCs). The hormone also maintains healthy oxygen levels in our tissues.
Calcitriol or Vitamin D	Most of the Calcitriol in the blood is inactive and it is modified by the kidney and other tissues to activate it. Active calcitriol stimulates the uptake of calcium from food. The hormone is important for the maintenance of healthy bones. It also helps to regulate the response of the immune system to infection.
Prostaglandins	These are hormone-like substances, made from lipid. Prostaglandins are one way in which the production of renin is stimulated. Renin is an enzyme, also produced by the kidneys that has a major role in the renin-angiotensin-aldosterone hormonal system, which helps to control blood pressure.

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Hormones Secreted by Heart

Hormones Produced by Heart	Function
Atrial Natriuretic Factor (ANF)	It is also called the Atrial Natriuretic Peptide (ANP), it is a peptide hormone that secreted from the cardiac cells of the body. This hormone regulates blood volume and arterial blood pressure. It is also a potential vasodilator and dilates blood vessels to reduce pressure.

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Hormones of Gastrointestinal Tract (GIT)

The gastrointestinal tract is one of the non-endocrine tissues that secretes several hormones which help in the digestion process by acting as stimulants for different enzymes and gastric juices.

Hormones of GIT	Function
Gastrin	The presence of food in the stomach induces the mucous membrane in the pyloric region to produce this hormone. Gastrin stimulates the secretion of gastric juices such as HCI and enzymes from the oxyntic and peptic cells of the stomach mucosa.
Secretin	The presence of food particles in duodenum causes the secretion of secretin from duodenal mucosa into blood. The target site of this hormone is the pancreas. Secretin promotes secretion of pancreatic juice from pancreas.
Pancreozymin	It is secreted from the duodenal mucosa and its target site is the pancreas like that of secretin. This hormone controls the number of pancreatic enzymes to be secreted while secretic controls the volume of pancreatic juice.
Cholecystokinin	The duodenal mucosa secretes this hormone, in response to the presence of food in the duodenum. The hormone reaches its target site, which is the gallbladder and contracts it rhythmically so that flow of bile occurs into the duodenum.
Enterocrinin	This hormone is secreted from the mucous membrane of both small and large intestines. It stimulates the small intestine to produce intestinal juice or succus entericus (a mixture of many enzymes).
Enterogastrone	The presence of fat particles in the small intestine stimulates the intestinal mucosa to produce Enterogastrone. It stops the secretion of gastric juice in the stomach. This is a protective adaptation by which excess HCI secretion in the stomach is regulated.
Gastric inhibitory peptide	This hormone inhibits the action of gastric glands and inhibits gastric secretion.

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Hormones Secreted by the Liver

Hormones of Liver	Function
Angiotensin	In the presence of renin produced from the kidney, this hormone controls the rise in blood pressure.

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FAQs on Hormones - Heart, Kidney, GIT

Q1: What are the Different Types of Natriuretic Peptides Secreted by the Heart?

A: The cardiac or heart cells secrets two types of Natriuretic peptides. These are:

A-Type natriuretic peptide
B-Type natriuretic peptide

Both hormones have the same functions. These are:

Inhibiting the secretion of aldosterone and renin.
Inhibition of the reabsorption of sodium ions by kidneys.
Relaxing arterioles.

Q2: How Does ANP Decrease Blood Pressure?

A: The ANP hormones secreted by cardiac cells are potential vasodilators. They can dilate blood vessels to reduce the pressure. In response to high blood pressure, cardiac cells secrete Atrial natriuretic factors which result in increased volume of urine and excess sodium is excreted out of the body via the urine. The net effect of these actions is to reduce blood pressure by reducing the volume of blood in the circulatory system.

Q3: What are the Heart Hormones and Their Functions?

A: Please refer to the ‘Hormones secreted by heart’ section.

Q4: What are Kidney Hormones and Their Functions?

A: Please refer to the ‘Hormones secreted by kidney’ section.