Autonomic Nervous System

Autonomic Nervous System

The autonomic nervous system (ANS) is a pathway in your body that controls automatic responses. It helps regulate like blood, digestion, and arousalS parts work differently and are different places. It's not the same as the part of your body that controls voluntary actions. The ANS is part of the central nervous system (CNS). The parasympathetic nervous system (PNS) helps keep your body balanced and relaxed. The sympathetic nervous system (SNS) helps your body react to stressful situations. The PNS works slowly, but the SNS works quickly.

Sympathetic and parasympathetic nervous systems

What is the difference between the autonomic and the somatic nervous system?

The peripheral nervous system has two parts: the somatic and autonomic systems. The somatic system controls voluntary movements, like moving your fingers or speaking. It uses motor neurons with thick myelination and strong synapses to communicate your On the other the aut involuntary movements, like heart rate and digestion. It uses two less myelinated neurons and ganglions to send signals. This system is independent of voluntary control and is regulated by the hypothalamus.

What is the function of the autonomic nervous system?

The autonomic nervous system is responsible for involuntary processes in the body. It has three divisions, each with distinct functions. The sympathetic nervous system is activated when the body perceives danger it to fight or flee. It's a stress response that mobilises the body's resources through hormones and physical changes. The parasympathetic nervous system returns the body to a state of balance after the sympathetic nervous system's activation. It regulates digestion, urination, and conserves energy. The enteric nervous system is a network of neurons in the gastrointestinal tract lining, also called the "second brain." The sympathetic and parasympathetic nervous systems are antagonistic, meaning they function as opposites.

How does the autonomic nervous system control the heart rate?

The heart has its pacemaker, the sinoatrial node, which keeps a steady resting heart rate of around 70 bpm for humans. Unlike other muscles, the heart doesn't rely on impulses from the nervous system to keep pumping. However, the autonomic nervous system can modify the heart rate depending on the body's needs. When more oxygen is required, such as when fleeing from a threat, the heart rate increases. Conversely, when the body is safe and relaxed, the heart rate decreases. Understanding how the heart works without autonomic influence is important in understanding how the autonomic system controls heart rate.

Heart rate without influence by the autonomic nervous system

The heart rate is controlled by the sinoatrial node (SAN), a group of cells on the right side of the heart that controls the heart rhythm by sending impulses to the cardiac muscle. The heart's chambers contract in sequence in response to stimulus sent by the SAN.

The atrioventricular node (AVN) acts as a gate for the electrical impulse between the atria and ventricle.

The sequence triggered by one excitatory wave starting from the SAN goes as follows:

The SAN sends an electrical impulse to the atria, making them contract. The electrical impulse enters the AVN; there's a short delay (PAUSE!).The AVN sends an impulse to another structure called the bundle of His, using a pathway made up of specialised muscles called the Purkinje fibre. The bundle of His carries the impulse to the base of the ventricles. Once at the bottom, the impulse is released from the main bundle of His into all the small branches coming out of it, making all the ventricles contract upwards at once.

Influence of the autonomic nervous system on the heart rate

The regulation of heart rate is a complex process that involves various mechanisms working together to maintain a steady rhythm. The SAN is responsible for initiating the electrical impulses that cause the heart to beat, while the AVN acts as a gatekeeper to ensure that the impulses are transmitted in the correct sequence. The autonomic nervous system plays a crucial role in controlling heart rate by modifying the impulses sent by the SAN.

Chemoreceptors and baroreceptors are sensory cells that detect changes in blood chemistry and pressure, respectively. When the chemoreceptors sense a decrease in pH levels due to high levels of carbon dioxide, they send signals to the medulla oblongata to increase heart rate via the sympathetic nervous system. This results in more blood being sent to the lungs to absorb oxygen and remove carbon dioxide. On the other hand, baroreceptors sense changes in blood pressure and can activate the parasympath heart the heart rate pressure low.

Overall, the complex interplay between the SAN, AVN, and the autonomic nervous system allows the heart to respond quickly and efficiently to changes in the body's needs, ensuring that oxygen and nutrients are delivered to the tissues and organs that need them most.


Autonomic Nervous System - Key takeaways The autonomic nervous system is a neural pathway part of the peripheral nervous system that regulates automatic responses to stimuli. The autonomic system regulates the heart rate, respiratory rate, blood pressure, digestion and arousal. There are three subdivisions of the autonomic nervous system - the parasympathetic nervous system (rest and digest), the sympathetic nervous system (fight or flight) and the enteric system (lines the gastrointestinal tract).The heart rate is controlled independently by a pacemaker called the sinoatrial node (SAN). The sympathetic nervous system can influence the heart rate, which raises it or the parasympathetic nervous system, which lowers it. The mechanism by which the autonomic nervous system senses the need to adjust the heart rate is either chemoreceptors,  which sense pH levels in the blood, or baroreceptors, which sense low and high blood pressure.

Autonomic Nervous System

What is the difference between the somatic and autonomic nervous system?

The somatic nervous system controls the senses and voluntary movement, whereas the autonomic nervous system controls involuntary responses.

What is included in the autonomic nervous system?

The autonomic nervous system includes the parasympathetic and sympathetic nervous system.

What triggers the autonomic nervous system?

The autonomic nervous system is divided into two parts: the sympathetic nervous system, also known as the fight-or-flight system, and the parasympathetic, also known as the rest and digest system. The fight-or-flight response is triggered by perceived danger or changes in the body. The parasympathetic nervous system is triggered by stimuli that signal rest and relaxation such as calming sounds, relaxing scents, and a sustained quiet environment.

What are the 3 divisions of the autonomic nervous system?

Sympathetic, parasympathetic and enteric nervous systems.

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