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The sympathetic nervous system's primary process is to stimulate the body's fight or flight response. It is, however, constantly active at a basic level to maintain homeostasis. [4] The sympathetic nervous system is described as being antagonistic to the parasympathetic nervous system. The latter stimulates the body to "feed and breed" and to ...
Rate dependence of the action potential is a fundamental property of cardiac cells and alterations can lead to severe cardiac diseases including cardiac arrhythmia and sometimes sudden death. [3] Action potential activity within the heart can be recorded to produce an electrocardiogram (ECG). This is a series of upward and downward spikes ...
Sympathomimetic drugs (also known as adrenergic drugs and adrenergic amines) are stimulant compounds which mimic the effects of endogenous agonists of the sympathetic nervous system. Examples of sympathomimetic effects include increases in heart rate, force of cardiac contraction, and blood pressure. [1] The primary endogenous agonists of the ...
Paroxysmal sympathetic hyperactivity (PSH) is a syndrome that causes episodes of increased activity of the sympathetic nervous system. Hyperactivity of the sympathetic nervous system can manifest as increased heart rate, increased respiration, increased blood pressure, diaphoresis, and hyperthermia. [1] Previously, this syndrome has been ...
The M2 muscarinic receptors are located in the heart, and act to bring the heart back to normal after the actions of the sympathetic nervous system: slowing down the heart rate, reducing contractile forces of the atrial cardiac muscle, and reducing conduction velocity of the sinoatrial node and atrioventricular node. They have a minimal effect ...
Myocardial contractility. Myocardial contractility represents the innate ability of the heart muscle (cardiac muscle or myocardium) to contract. It is the maximum attainable value for the force of contraction of a given heart. The ability to produce changes in force during contraction result from incremental degrees of binding between different ...
The sympathetic effects of norepinephrine include: In the eyes, an increase in production of tears, making the eyes more moist, [19] and pupil dilation through contraction of the iris dilator. In the heart, an increase in the amount of blood pumped. [20] In brown adipose tissue, an increase in calories burned to generate body heat ...
By coupling sympathetic inhibition and parasympathetic activation, the baroreflex maximizes blood pressure reduction. Sympathetic inhibition leads to a drop in peripheral resistance, while parasympathetic activation leads to a depressed heart rate (reflex bradycardia) and contractility. The combined effects will dramatically decrease blood ...