Sinoatrial Node
Also written as SAN.
• Pwave= sinoatrial nodes cells depolarise and initiate on action potential causing the atria to
What our notes say
- • Pwave= sinoatrial nodes cells depolarise and initiate on action potential causing the atria to (Medical Physiology Assorted SAQs — With Answers (Past Paper Study Guide))
- Sinoatrial node (SAN) — dominant pacemaker, located high in right atrium (CVS History, Physical Exam & ECG: Master Clinical Assessment)
Study material on Sinoatrial Node
- CVS History, Physical Exam & ECG: Master Clinical Assessment
- Basic Pharmacology - Study Guide
- Basic Pharmacology - Study Guide
- Weekly Pharmacology Exam - April 21, 2026 (Section A: MCQs)
- Weekly Pharmacology Exam - April 17, 2026 (Section A: MCQs)
Practice questions on Sinoatrial Node
Which of the following is the neurotransmitter agent normally released in the sinoatrial node (SAN) of the heart in response to an increase in blood pressure?
- Acetylcholine
- Dopamine
- Epinephrine
- Glutamine
- Norepinephrine
Answer: A. When blood pressure increases, baroreceptors activate parasympathetic (vagal) output to the heart. The vagus nerve releases acetylcholine at the SA node, which binds to M2 muscarinic receptors, causing bradycardia and reduced cardiac output to lower blood pressure. --- ---
Which of the following is the neurotransmitter agent normally released in the sinoatrial node (SAN) of the heart in response to an increase in blood pressure?
- Acetylcholine
- Dopamine
- Epinephrine
- Glutamine
- Norepinephrine
Answer: A. When blood pressure increases, baroreceptors activate parasympathetic (vagal) output to the heart. The vagus nerve releases acetylcholine at the SA node, which binds to M2 muscarinic receptors, causing bradycardia and reduced cardiac output to lower blood pressure. --- ---
Which of the following is the neurotransmitter agent normally released in the sinoatrial node (SAN) of the heart in response to an increase in blood pressure?
- Norepinephrine
- Epinephrine
- Acetylcholine
- Dopamine
Answer: C. Increased BP triggers the baroreceptor reflex, leading to parasympathetic (vagal) release of Acetylcholine to slow the heart rate.
Which of the following is the neurotransmitter agent normally released in the sinoatrial node (SAN) of the heart in response to an increase in blood pressure via the baroreceptor reflex?
- Norepinephrine
- Acetylcholine
- Dopamine
- Epinephrine
Answer: B. The baroreceptor reflex responds to high BP by increasing parasympathetic tone, releasing Acetylcholine to slow the heart rate.