Hjärtfrekvensreglering

Hjärtfrekvensreglering describes the body's mechanisms for controlling the rate at which the heart beats. This regulation is crucial for ensuring that the heart can adequately supply the body with oxygenated blood under varying physiological conditions. The primary driver of heart rate control is the autonomic nervous system, which comprises the sympathetic and parasympathetic branches.

The sympathetic nervous system, activated during stress or physical exertion, releases neurotransmitters like norepinephrine that increase heart rate and contractility. Conversely, the parasympathetic nervous system, primarily via the vagus nerve, releases acetylcholine, which slows the heart rate. Hormones, such as adrenaline (epinephrine) and thyroid hormones, also play a role in modulating heart rate.

The sinoatrial (SA) node, located in the right atrium, acts as the heart's natural pacemaker, initiating electrical impulses that trigger each heartbeat. The SA node's firing rate is influenced by the autonomic nervous system and hormonal signals. Other factors like body temperature, electrolyte balance, and certain medications can also affect heart rate.

Abnormalities in heart rate regulation can lead to various cardiac conditions, including bradycardia (slow heart rate) and tachycardia (fast heart rate). Medical interventions often aim to restore a normal heart rhythm and rate through pharmacological or device-based therapies, such as pacemakers. Understanding hjärtfrekvensreglering is fundamental to comprehending cardiovascular physiology and managing heart health.