Atrial Natriuretic Peptide (ANP): Definition, Role & Function

Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

In this lesson, you'll learn the definition of atrial natriuretic peptide and a bit about where it's made. You'll also learn its most important roles and functions in the body.

Heart Function

What does the heart do? It beats to pump blood around the body, right? Most people know that much. But the heart actually has a lot of other important functions many people simply never think about. And one of these functions has to do with things like heart failure, water, sodium, urination, and hormones.

In this lesson, you're going to learn exactly what this is about as we define atrial natriuretic peptide and its major roles and functions in the body.

Atrial Natriuretic Peptide

Atrial natriuretic peptide, or ANP, is a cardiac (heart-based) hormone composed of 28 amino acids that are synthesized and released by the heart. For completeness sake, you should know that it sometimes goes by other names in literature, including:

  • A-type natriuretic peptide
  • Atrial natriuretic factor
  • Atriopeptin
  • Auriculin
  • Cardiodilatin
  • Natriodilatin

The term atrial, in ANP, refers to the atria, which are the top two (and smaller) chambers of the heart. This is where ANP is principally made, stored, and released from in people, especially the right atrium.

A representation of the structure of ANP.
A representation of the structure of ANP

The term natriuretic, in ANP, refers to something that promotes natriuresis. That is to say:

  • The urinary excretion (-uresis)
  • Of sodium (natri-), where natri- comes to us from natrium, which means sodium in Latin. You can remember this by recalling that 'Na' in the periodic table, stands for 'na'trium, or sodium.

Finally, the peptide part of ANP refers to a compound that is composed of two or more amino acids. In this case, it's 28 amino acids (in people).

This hormone was first isolated from a rat, and later human atria, in the early 1980s.

Role & Function

So at this point, you already know a bit about what ANP does. It's a hormone that promotes the excretion of salt out of the body via the urine.

The better question to ask is: why? You need to know one very simple but important fact about physiology. Water follows sodium in the body. If sodium is excreted in urine, water follows suit. That means the water content of the body decreases in response to an elevation of ANP.

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