SA Node
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| Heart conduction system, with the sinoatrial node labeled at the top right. | |
| Latin | nodus sinuatrialis |
|---|---|
| Precursor | Cardiac mesoderm |
| System | Cardiovascular system |
The sinoatrial node (SA node), also known as the sinus node, is a group of specialized cardiac muscle cells located in the right atrium of the heart. It is the primary pacemaker of the heart, responsible for initiating the electrical impulses that dictate the heart's rhythm.
Structure[edit | edit source]
The SA node is a small, ellipsoid structure situated in the upper wall of the right atrium, near the entrance of the superior vena cava. It is composed of pacemaker cells that have the unique ability to generate spontaneous electrical activity. These cells are smaller than typical cardiac muscle cells and have fewer contractile fibers.
Function[edit | edit source]
The primary function of the SA node is to generate electrical impulses that propagate throughout the heart, initiating the heartbeat. The electrical activity of the SA node is influenced by the autonomic nervous system:
- The sympathetic nervous system increases the rate of impulse generation, thereby increasing heart rate.
- The parasympathetic nervous system, primarily through the vagus nerve, decreases the rate of impulse generation, thereby decreasing heart rate.
The SA node sets the pace for the heart under normal conditions, typically generating impulses at a rate of 60 to 100 beats per minute in a resting adult.
Clinical Significance[edit | edit source]
Dysfunction of the SA node can lead to various cardiac arrhythmias. Common conditions include:
- Sick sinus syndrome: A collection of heart rhythm disorders due to malfunction of the SA node, leading to bradycardia, tachycardia, or a combination of both.
- Sinus bradycardia: A slower than normal heart rate, which can be normal in athletes but may indicate SA node dysfunction in others.
- Sinus tachycardia: A faster than normal heart rate, which can occur due to increased sympathetic stimulation or other factors.
Also see[edit | edit source]
Cardiovascular disease A-Z
Most common cardiac diseases
- Cardiac arrhythmia
- Cardiogenetic disorders
- Cardiomegaly
- Cardiomyopathy
- Cardiopulmonary resuscitation
- Chronic rheumatic heart diseases
- Congenital heart defects
- Heart neoplasia
- Ischemic heart diseases
- Pericardial disorders
- Syndromes affecting the heart
- Valvular heart disease
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
A[edit source]
- Accelerated idioventricular rhythm
- Acute decompensated heart failure
- Arteriosclerotic heart disease
- Athletic heart syndrome
- Atrial flutter
- Atrioventricular fistula
- Cardiovascular disease in Australia
- Autoimmune heart disease
B[edit source]
C[edit source]
- Ebb Cade
- Cardiac allograft vasculopathy
- Cardiac amyloidosis
- Cardiac asthma
- Cardiac tamponade
- Cardiogenic shock
- Cardiogeriatrics
- Cardiorenal syndrome
- Cardiotoxicity
- Carditis
- Coronary artery aneurysm
- Coronary artery anomaly
- Coronary artery disease
- Spontaneous coronary artery dissection
- Coronary artery ectasia
- Coronary occlusion
- Coronary steal
- Coronary thrombosis
- Coronary vasospasm
- Cœur en sabot
- Coxsackievirus-induced cardiomyopathy
D[edit source]
E[edit source]
H[edit source]
- Heart attack
- Heart failure
- Heart failure with preserved ejection fraction
- Heart to Heart (1949 film)
- High-output heart failure
- Hyperdynamic precordium
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
I[edit source]
- Idiopathic giant-cell myocarditis
- Interventricular dyssynchrony
- Intraventricular dyssynchrony
- Isolated atrial amyloidosis
K[edit source]
L[edit source]
M[edit source]
- Mydicar
- Myocardial bridge
- Myocardial disarray
- Myocardial rupture
- Myocardial scarring
- Myocardial stunning
- Myocarditis
N[edit source]
O[edit source]
P[edit source]
- Papillary fibroelastoma
- Pathophysiology of heart failure
- Postpericardiotomy syndrome
- Pulmonary vein stenosis
R[edit source]
S[edit source]
- Saturated fat and cardiovascular disease
- SCAR-Fc
- Shone's syndrome
- Strain pattern
- Subacute bacterial endocarditis
- Sudden cardiac death of athletes
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
T[edit source]
V[edit source]
W[edit source]
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