Conduction system of heart regulation by the autonomic nervous system
The autonomic nervous system (ANS) plays an important role in regulating the conduction system of the heart. The ANS is a division of the nervous system that controls many of the body’s automatic functions, including heart rate and rhythm. The ANS has two main branches: the sympathetic nervous system and the parasympathetic nervous system, which have opposite effects on the heart’s conduction system.
- Sympathetic nervous system: The sympathetic nervous system is activated during times of stress or physical activity, and it increases heart rate and the strength of heart contractions. It does this by releasing the hormone adrenaline (also known as epinephrine) and activating the SA node and other parts of the conduction system. This leads to a faster heart rate and more forceful contractions, allowing the heart to pump more blood to meet the body’s increased demand.
- Parasympathetic nervous system: The parasympathetic nervous system is activated during times of relaxation or rest, and it has the opposite effect on the heart than the sympathetic nervous system. It slows down heart rate and decreases the strength of heart contractions by releasing the neurotransmitter acetylcholine, which acts on the SA node and other parts of the conduction system. This leads to a slower heart rate and weaker contractions, conserving energy and allowing the body to rest.
The balance between the sympathetic and parasympathetic nervous systems is important for maintaining a normal heart rate and rhythm. When this balance is disrupted, it can lead to abnormal heart rhythms and other cardiac problems. For example, an overactive sympathetic nervous system can cause a rapid heart rate, while an overactive parasympathetic nervous system can cause a slow heart rate.
In summary, the autonomic nervous system plays a crucial role in regulating the conduction system of the heart. The sympathetic and parasympathetic branches of the ANS have opposite effects on the heart’s conduction system, and their balance is important for maintaining a normal heart rate and rhythm.