Atrial natriuretic peptide (ANP) is hormone secreted from the cells namely

KGMU 2024

Applied Physiology

Easy

Appeared in: KGMU 2024

Explanation

Atrial Natriuretic Peptide (ANP) is a hormone secreted by cardiac muscle cells (cardiomyocytes) located in the atria of the heart.
It is released in direct response to atrial stretch, which is a sign of increased blood volume (hypervolemia).
The right atrium is considered the primary site of ANP release because it is the chamber that first receives systemic venous return and therefore acts as the main sensor for the body's overall fluid volume.
ANP's function is to lower blood pressure and reduce blood volume by promoting sodium and water excretion by the kidneys.

Option B: Although the left atrium also contains cells that can secrete ANP, the right atrium is the principal source because it is more directly affected by changes in central venous pressure and systemic blood volume.
Option C: The right ventricle is not the primary source of ANP. The ventricles primarily secrete a different, but related, hormone called Brain Natriuretic Peptide (BNP).
Option D: Similar to the right ventricle, the left ventricle's main natriuretic hormone is BNP, not ANP. BNP is released in response to ventricular stretch and pressure overload, commonly seen in heart failure.

Visual 1: Diagram - An illustration of the human heart with the right atrium highlighted, indicating it as the primary site of ANP synthesis and release.
Visual 2: Flowchart - A flowchart demonstrating the ANP feedback loop: Increased Blood Volume → Right Atrial Stretch → ANP Release → Actions on Kidneys (increased Na+ and H₂O excretion) & Blood Vessels (vasodilation) → Decreased Blood Volume & Blood Pressure.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Secretion site of Atrial Natriuretic Peptide (ANP) as background academic context rather than a clinical decision trigger.
Understanding ANP is crucial for grasping the body's natural defense against hypertension and fluid overload. It is the physiological antagonist to the Renin-Angiotensin-Aldosterone System (RAAS).
Nurses monitor fluid balance through intake/output, daily weights, and assessing for edema. Elevated ANP is the body's compensatory response to the fluid retention nurses are trying to manage.
What if? If a patient develops atrial fibrillation, the rapid, chaotic atrial contractions can cause irregular stretching and lead to increased ANP release, resulting in polyuria (excessive urination) as the body tries to reduce volume.

How to Approach the Question

This is a factual recall question based on physiology.
First, identify the key term in the question: 'Atrial natriuretic peptide (ANP)'. The word 'Atrial' is a major clue, immediately pointing you towards the atria.
This allows you to eliminate the ventricular options (C and D).
Next, differentiate between the right and left atrium. Recall the path of blood flow. The right atrium receives deoxygenated blood from the entire body (systemic circulation). Therefore, it is the first chamber to detect an increase in overall blood volume.
Conclude that the right atrium is the most logical primary site for releasing a hormone that regulates blood volume.
Mentally distinguish ANP (from the atria, responding to volume) from BNP (from the ventricles, responding to pressure/stretch, a marker for heart failure).

Concept Tested & Keywords

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