Hormones Of Heart, Kidney And Gastrointestinal Tract: Overview, Topics

Edited By Irshad Anwar | Updated on Jul 02, 2025 06:50 PM IST

What Is Homeostasis?

Homeostasis in the body is maintained by the interplay between the nervous and endocrine systems that act to control and coordinate physiological functions. While the endocrine system includes traditional endocrine glands involved in hormone production, nonendocrine tissues will also be endocrine in nature. This means that the heart, kidneys, and gastrointestinal tract also produce certain hormones required for a variety of bodily functions.

Hormones By Non-Endocrine Tissues

Hormones are the chemical messengers that help in regulating metabolism and physiological processes. These can be secreted by nonendocrine tissues to exert local or systemic functions. These hormones have their specific sites of release and action that then act on target sites like the heart, muscles, or other organs.

Hormones Of The Heart

The Hormones Of The Heart are:

Atrial Natriuretic Factor (ANF):

Production: It is secreted by cardiac cells lining the walls of atria.

Function: Regulates blood volume and arterial blood pressure as a vasodilator by decreasing the blood pressure because of blood vessel dilation.

Brain Natriuretic Peptide (BNP):

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Production: Ventricles of the heart.

Function: Similar to ANF, BNP lowers blood pressure and fluid overload by increasing sodium and water excretion.

Adrenomedullin:

Produced: Produced in several tissues, including the heart.

Function: It is a vasodilator that helps in blood pressure and blood flow regulation.

Kidney Hormones

Renin:

Production: Released by the juxtaglomerular cells of the kidney.

Function: This hormone initiates the renin-angiotensin aldosterone system, which regulates blood pressure and fluid balance through the conversion of angiotensinogen to angiotensin I.

Calcitriol:

Production: The active form of vitamin D is produced in the kidneys.

Function: Increases calcium absorption in the intestines and balances calcium with phosphate in the blood.

Prostaglandins:

Production: Produced locally in the kidneys.

Function: Involved in the regulation of blood flow, glomerular filtration rate, and sodium reabsorption.

Hormones Of The Gastrointestinal Tract

The Hormones Of The Gastrointestinal Tract are:

Gastrin:

Production: Released from cells known as G cells in the stomach

Function: Stimulates gastric acid release from parietal cells and the release of enzymes from chief cells to digest food

Secretin:

Production: Produced by S cells of the duodenum.

Action: Stimulates pancreatic bicarbonate secretion and bile production.

Cholecystokinin:

Secretion: Released by I cells in the duodenum.

Action: Stimulates bile release and pancreatic enzyme secretion for digestion.

Gastric Inhibitory Peptide:

Secretion: Released by K cells in the duodenum.

Action: Inhibits gastric acid secretion and motility.

Motilin:

Secretion: Released by M cells in the small intestine.

Action: Regulates gastric motility and promotes the migrating motor complex during fasting.

Somatostatin:

Secretion: Produced by the D cells of the gastrointestinal tract.

Action: Inhibits the release of stomach acid and digestive enzymes.

Coordination With The Endocrine System:

This modulation often occurs in association with classical endocrine hormones to maintain homeostasis. For example, the RAAS system integrates signals from kidney hormones along with signals from adrenal glands to control blood pressure and fluid balance.

Conclusion

Hormones produced by nonendocrine tissues, such as the heart, kidneys, and gastrointestinal tract, participate in the regulation of various physiological processes. The fact that they interact with typical endocrine hormones and are present in the feedback loops involved underscores their importance in general health and maintenance of homeostasis.

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Frequently Asked Questions (FAQs)

1. What is the function of Brain Natriuretic Peptide in heart functioning?

Like ANF, BNP would appear to play a role in blood pressure and fluid balance regulation through its effects on sodium and water excretion.

2. What is the role of renin in blood pressure control?

Renin initiates the RAAS system by converting angiotensinogen to angiotensin I to regulate blood pressure.

3. What are the activities of calcitriol produced in the kidneys?

Calcitriol promotes increased calcium absorption from the gut and maintains calcium and phosphate homeostasis in the blood.

4. What is the effect of motilin on the gastrointestinal tract?

Motilin regulates gastric motility and promotes the migrating motor complex during fasting.

5. Why are hormones from nonendocrine tissues important in clinical diagnostics?

This makes hormones like BNP and erythropoietin diagnostic markers for conditions such as heart failure and anaemia, which would aid ineffectual treatment planning.

6. What are hormones and how do they differ from enzymes?

Hormones are chemical messengers produced by endocrine glands that travel through the bloodstream to target specific cells or organs. Unlike enzymes, which catalyze chemical reactions, hormones regulate physiological processes by binding to receptors on target cells, triggering a cascade of cellular responses.

7. How do incretins like GLP-1 and GIP affect glucose metabolism?

Incretins, such as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), are hormones produced by the intestines in response to food intake. They enhance insulin secretion from pancreatic beta cells, suppress glucagon release, slow gastric emptying, and promote satiety. These actions help regulate blood glucose levels and improve insulin sensitivity.

8. Why are the heart, kidneys, and gastrointestinal tract considered endocrine organs?

These organs are considered endocrine organs because they produce and secrete hormones in addition to their primary functions. They release hormones directly into the bloodstream to regulate various physiological processes, contributing to the body's overall endocrine system.

9. How does leptin, produced by adipose tissue, interact with the gastrointestinal system?

Leptin, although primarily produced by adipose tissue, interacts with the gastrointestinal system by suppressing appetite and food intake. It acts on the hypothalamus to promote satiety and increase energy expenditure. Leptin also influences gut motility, nutrient absorption, and the secretion of other gastrointestinal hormones, contributing to overall energy homeostasis.

10. What is the enteric nervous system, and how does it relate to gastrointestinal hormones?

The enteric nervous system is a network of neurons in the gastrointestinal tract often called the "second brain." It works in conjunction with gastrointestinal hormones to regulate digestion, absorption, and motility. The enteric nervous system can both influence and be influenced by hormone secretion, creating a complex interplay between neural and endocrine control of digestive functions.

11. How does the hormone hepcidin, produced by the liver, affect iron absorption in the gastrointestinal tract?

Hepcidin, produced by the liver, is a key regulator of iron homeostasis. It acts on the gastrointestinal tract by binding to ferroportin, a protein that exports iron from enterocytes into the bloodstream. When hepcidin levels are high, it causes ferroportin degradation, reducing iron absorption from the gut. This mechanism helps prevent iron overload and maintains appropriate iron levels in the body.

12. How does the gastrointestinal hormone nesfatin-1 affect food intake and glucose homeostasis?

Nesfatin-1 is a hormone produced by various tissues, including the gastrointestinal tract. It acts as a potent anorexigenic peptide, reducing food intake and body weight. Nesfatin-1 also improves glucose homeostasis by enhancing insulin sensitivity and glucose uptake in peripheral tissues. These actions make nesfatin-1 an important regulator of energy balance and metabolism.

13. How does the kidney hormone Klotho affect calcium homeostasis and aging?

Klotho is a hormone primarily produced by the kidneys that plays a crucial role in calcium homeostasis and has anti-aging effects. It regulates calcium reabsorption in the kidneys and works with fibroblast growth factor 23 (FGF23) to control vitamin D activation. Klotho also has antioxidant properties, promotes cell survival, and helps maintain vascular health, contributing to its anti-aging effects.

14. What is the role of adrenomedullin in cardiovascular and renal function?

Adrenomedullin is a hormone produced by various tissues, including the heart and kidneys. It has potent vasodilatory effects, reducing blood pressure and increasing blood flow. Adrenomedullin also promotes natriuresis and diuresis in the kidneys, contributing to fluid balance regulation. Additionally, it has cardioprotective effects, reducing oxidative stress and inflammation in the cardiovascular system.

15. How does the kidney hormone erythroferrone regulate iron metabolism?

Erythroferrone is a hormone produced by erythroblasts in response to erythropoietin stimulation. It acts on the liver to suppress hepcidin production, the main regulator of iron homeostasis. By reducing hepcidin levels, erythroferrone increases iron availability for erythropoiesis. This mechanism creates a link between erythropoiesis and iron metabolism, ensuring adequate iron supply for red blood cell production.

16. How does gastrin contribute to digestion in the gastrointestinal tract?

Gastrin is a hormone produced by G cells in the stomach and duodenum. It stimulates the secretion of gastric acid by parietal cells in the stomach, promotes the growth of gastric mucosa, and increases gastric motility. These actions help in the breakdown of food and the absorption of nutrients during digestion.

17. What is the function of cholecystokinin (CCK) in the digestive process?

Cholecystokinin (CCK) is a hormone produced by I cells in the small intestine. It stimulates the release of pancreatic enzymes and bile from the gallbladder, slows gastric emptying, and promotes satiety. CCK plays a crucial role in the digestion of fats and proteins and helps regulate food intake.

18. How does secretin regulate pancreatic secretions?

Secretin is a hormone produced by S cells in the duodenum in response to acidic chyme. It stimulates the pancreas to secrete bicarbonate-rich fluid, which neutralizes stomach acid in the small intestine. Secretin also inhibits gastric acid secretion and gastrin release, helping to maintain optimal pH for digestive enzymes.

19. What is the role of ghrelin in appetite regulation?

Ghrelin is a hormone primarily produced by the stomach. It stimulates appetite and food intake, earning it the nickname "hunger hormone." Ghrelin levels increase before meals and decrease after eating, playing a crucial role in meal initiation and energy balance. It also has effects on growth hormone release and glucose metabolism.

20. What is the role of somatostatin in the gastrointestinal tract?

Somatostatin is a hormone produced by D cells in the pancreas and gastrointestinal tract. It acts as a general inhibitory hormone, suppressing the release of various gastrointestinal hormones, including gastrin, cholecystokinin, and secretin. Somatostatin also inhibits gastric acid secretion, pancreatic enzyme release, and intestinal motility, helping to fine-tune digestive processes.

21. What is the role of atrial natriuretic peptide (ANP) in the heart?

Atrial natriuretic peptide (ANP) is a hormone produced by the heart's atrial cells in response to increased blood volume. It promotes sodium and water excretion by the kidneys, reduces blood pressure, and inhibits the renin-angiotensin-aldosterone system, helping to maintain fluid balance and blood pressure homeostasis.

22. How does brain natriuretic peptide (BNP) differ from ANP?

Brain natriuretic peptide (BNP) is primarily produced by ventricular cells in the heart, while ANP is mainly produced by atrial cells. BNP is released in response to ventricular stretch and has similar effects to ANP, including promoting sodium and water excretion and reducing blood pressure. BNP levels are often used as a diagnostic marker for heart failure.

23. How does the heart hormone cardiotrophin-1 affect metabolism and inflammation?

Cardiotrophin-1 is a hormone produced by the heart that has both metabolic and inflammatory effects. It improves glucose tolerance and insulin sensitivity, promotes fat oxidation, and reduces lipid accumulation in the liver. Cardiotrophin-1 also has anti-inflammatory properties, protecting against tissue damage in various organs. These actions highlight the heart's role in systemic metabolic regulation and inflammation control.

24. What is the function of urotensin II in cardiovascular and renal regulation?

Urotensin II is a peptide hormone produced by various tissues, including the heart and kidneys. It is a potent vasoconstrictor, affecting both systemic and renal blood vessels. Urotensin II also influences cardiac contractility, promotes cell proliferation, and affects sodium and water homeostasis in the kidneys. These actions contribute to the regulation of blood pressure and fluid balance.

25. What is the function of urodilatin in the kidneys?

Urodilatin is a hormone produced by cells in the distal tubules and collecting ducts of the kidneys. It is similar to atrial natriuretic peptide (ANP) but acts locally within the kidneys. Urodilatin promotes sodium and water excretion, increases glomerular filtration rate, and helps regulate blood pressure and fluid balance through its natriuretic and diuretic effects.

26. What is the function of erythropoietin (EPO) produced by the kidneys?

Erythropoietin (EPO) is a hormone produced primarily by the kidneys in response to low oxygen levels. Its main function is to stimulate the production of red blood cells (erythropoiesis) in the bone marrow, increasing oxygen-carrying capacity in the blood and improving tissue oxygenation.

27. How do the kidneys regulate blood pressure through hormone production?

The kidneys regulate blood pressure through the renin-angiotensin-aldosterone system (RAAS). When blood pressure drops, the kidneys release renin, which triggers a cascade of events leading to the production of angiotensin II and aldosterone. These hormones increase blood pressure by promoting sodium and water retention and vasoconstriction.

28. What is the role of calcitriol produced by the kidneys?

Calcitriol, also known as active vitamin D, is produced by the kidneys from its precursor. It plays a crucial role in calcium homeostasis by increasing calcium absorption in the intestines, promoting calcium reabsorption in the kidneys, and regulating bone mineralization. Calcitriol also has important functions in immune regulation and cell differentiation.

29. How does the kidney hormone renin contribute to blood pressure regulation?

Renin is an enzyme produced by juxtaglomerular cells in the kidneys in response to low blood pressure or decreased sodium levels. It initiates the renin-angiotensin-aldosterone system (RAAS) by cleaving angiotensinogen to form angiotensin I. This cascade ultimately leads to the production of angiotensin II and aldosterone, which increase blood pressure through vasoconstriction and sodium retention.

30. What is the function of uroguanylin in the intestines and kidneys?

Uroguanylin is a hormone produced by the intestines that acts on both the intestines and kidneys. In the intestines, it stimulates chloride and bicarbonate secretion, regulating fluid balance. In the kidneys, uroguanylin promotes sodium excretion and helps maintain electrolyte balance. This dual action creates a link between the gastrointestinal tract and renal function in fluid homeostasis.

31. How does the gastrointestinal hormone pancreatic polypeptide affect digestion and energy metabolism?

Pancreatic polypeptide is a hormone produced by PP cells in the pancreas and released in response to food intake. It reduces appetite and food intake, slows gastric emptying, and decreases pancreatic exocrine secretion. Pancreatic polypeptide also influences energy metabolism by increasing energy expenditure and fat oxidation, contributing to the regulation of body weight and glucose homeostasis.

32. How does motilin regulate gastrointestinal motility?

Motilin is a hormone produced by M cells in the small intestine. It stimulates gastrointestinal motility, particularly during the interdigestive period (between meals). Motilin initiates the migrating motor complex, a series of contractions that sweep through the gastrointestinal tract, clearing residual content and preventing bacterial overgrowth.

33. What is the role of vasoactive intestinal peptide (VIP) in the digestive system?

Vasoactive intestinal peptide (VIP) is a hormone produced by neurons in the gastrointestinal tract. It stimulates the secretion of water and electrolytes from the intestinal mucosa, relaxes smooth muscle in the gastrointestinal tract, and dilates blood vessels. VIP also inhibits gastric acid secretion and promotes the release of other hormones, contributing to the regulation of digestive processes.

34. How does the gastrointestinal hormone peptide YY (PYY) affect appetite and digestion?

Peptide YY (PYY) is a hormone released by L cells in the ileum and colon in response to food intake. It acts as an appetite suppressant, promoting satiety and reducing food intake. PYY also slows gastric emptying, inhibits gastric and pancreatic secretions, and decreases intestinal motility. These actions help regulate energy balance and optimize nutrient absorption.

35. What is the role of oxyntomodulin in glucose regulation and energy balance?

Oxyntomodulin is a hormone produced by L cells in the intestine. It has dual effects on glucose regulation and energy balance. Oxyntomodulin stimulates insulin secretion and improves glucose tolerance, similar to GLP-1. It also reduces food intake, increases energy expenditure, and promotes weight loss. These combined actions make oxyntomodulin an important regulator of metabolism and body weight.

36. What is the function of guanylin in the intestines?

Guanylin is a hormone produced by intestinal epithelial cells. It regulates fluid and electrolyte balance in the intestines by activating guanylate cyclase C receptors. This activation leads to increased chloride and bicarbonate secretion and reduced sodium absorption, resulting in increased fluid secretion into the intestinal lumen. Guanylin helps maintain proper intestinal hydration and contributes to the regulation of stool consistency.

37. What is the role of chromogranin A in the regulation of gastrointestinal function?

Chromogranin A is a protein produced by various endocrine cells, including those in the gastrointestinal tract. It serves as a precursor for several bioactive peptides that regulate gastrointestinal function. These peptides can influence gastric acid secretion, intestinal motility, and pancreatic enzyme release. Chromogranin A also acts as a marker for neuroendocrine tumors and can be used in their diagnosis and monitoring.

38. How does the gastrointestinal hormone obestatin affect appetite and digestion?

Obestatin is a hormone derived from the same precursor as ghrelin but has opposing effects. While ghrelin stimulates appetite, obestatin is thought to suppress appetite and reduce food intake. Obestatin also slows gastric emptying and intestinal motility, potentially contributing to feelings of fullness. However, its exact physiological role and mechanisms of action are still subjects of ongoing research.

39. What is the function of urocortin in stress response and gastrointestinal regulation?

Urocortin is a peptide hormone related to corticotropin-releasing factor (CRF) and is expressed in various tissues, including the gastrointestinal tract. It plays a role in the stress response by modulating anxiety-like behaviors and activating the hypothalamic-pituitary-adrenal axis. In the gastrointestinal system, urocortin affects motility, secretion, and inflammation, potentially contributing to stress-related gastrointestinal disorders.

40. What is the role of apelin in cardiovascular and renal function?

Apelin is a peptide hormone produced by various tissues, including the heart and kidneys. It has positive inotropic effects on the heart, improving cardiac contractility. Apelin also causes vasodilation, reducing blood pressure. In the kidneys, it increases glomerular filtration rate and promotes diuresis. These actions contribute to the regulation of cardiovascular function and fluid balance.

41. How does the gastrointestinal hormone glucose-dependent insulinotropic polypeptide (GIP) affect bone metabolism?

While primarily known for its incretin effects, glucose-dependent insulinotropic polypeptide (GIP) also plays a role in bone metabolism. GIP receptors are present on bone cells, and GIP stimulates bone formation by increasing osteoblast activity and inhibiting osteoclast function. This action helps maintain bone mass and provides a link between nutrient absorption and bone health.

42. What is the function of relaxin in cardiovascular and renal systems?

Relaxin, although primarily known for its role in pregnancy, also has important functions in the cardiovascular and renal systems. It causes vasodilation, increases cardiac output, and promotes angiogenesis. In the kidneys, relaxin increases renal blood flow and glomerular filtration rate.