Autonomic Nervous System: Divisions, Functions, Anatomy, Function, Disorders

The autonomic nervous system (ANS) is a vital part of the human nervous system that controls involuntary functions like heart rate, digestion, respiration, and glandular activities. It is divided into the sympathetic and parasympathetic divisions, which work together to maintain homeostasis. The ANS ensures smooth coordination of the body's internal organs, adapting to changing needs without conscious effort. In this article, the autonomic nervous system (ans), structure of the autonomic nervous system, autonomic nervous system functions, and disorders of the autonomic nervous system are discussed. Autonomic Nervous System is a topic of the chapter Neural Control and Coordination in Biology.

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This Story also Contains

1. What is the Autonomic Nervous System (ANS)?
2. Structure of the Autonomic Nervous System
3. Autonomic Nervous System Functions
4. Disorders of the Autonomic Nervous System

What is the Autonomic Nervous System (ANS)?

The autonomic nervous system is one of the crucial subdivisions of the PNS. It governs such involuntary activities as heartbeat, blood pressure, digestion rate, and respiratory rate. It runs beneath conscious awareness to maintain homeostasis and to respond to stress.

Two main branches that constitute the ANS are the sympathetic nervous system, which prepares the body for situations concerning 'fight or flight', and the parasympathetic nervous system, leading to 'rest and digest'. These two systems ensure that the body adjusts to various demands but stays balanced within itself.

The autonomic nervous system plays an essential role in homeostasis because it controls most of the fundamental, vital activities in the body subconsciously. It provides prompt responses to stressors and thus maintains survival and optimal organ functions by distributing energy to sustain life processes like circulation, respiration, and digestion.

Structure of the Autonomic Nervous System

The ANS is complex in terms of the anatomical basis of its multiple components and pathways through which it exercises its control over bodily functions. There are two main divisions, along with various neurons and ganglia, that function together to transmit signals.

Division of the ANS

• Sympathetic nervous system: This prepares the body for intense physical activity and stress.

• Parasympathetic Nervous System: Anabolic predominance for rest and recovery.

The Components of the ANS

• Preganglionic Neurons: Those originating in the central nervous system that convey the signal to the autonomic ganglia.

• Postganglionic Neurons: Receives signals from preganglionic neurons and innervates target organs.

Anatomy of Autonomic Ganglia

• Found in various parts of the body; serve as relay stations for nerve impulses.

• Enable nerve impulses from the CNS to reach the target organs.

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Autonomic Nervous System Functions

The ANS is responsible for maintaining homeostasis and bringing about an appropriate response to stimuli.

Sympathetic division

• Through vasoconstriction, it redirects blood flow away from the gastrointestinal system and skin.
• Peristalsis is inhibited by it.
• It improves blood flow to the skeletal muscles and lungs.
• By using epinephrine to dilate the bronchioles, it permits increased oxygen exchange in the alveoli.
• It increases heart rate and contracts cardiac cells to improve blood flow in the skeletal muscles.
• It improves eye vision by relaxing the ciliary muscles and dilation of the pupils.
• It dilates the heart's coronary arteries.
• The intestinal and urinary sphincters are constricted.
• It facilitates orgasm stimulation.

Parasympathetic division

• By widening the blood arteries, it enhances the flow of blood to the gastrointestinal system.

• When oxygen is not required, it constricts the bronchioles.

• The heart is parasympathetically controlled by the vagus nerves in the cardiac branches

• It allows for closer vision by constricting the pupil and contracting the ciliary muscles.

• By activating the salivary glands, it speeds up peristalsis and improves nutrient absorption.

• They participate in the erection of genital tissues and increase sexual desire.

Enteric Nervous System

• It detects alterations in the gut's chemistry and mechanics.

• It controls the gut's secretions.

• It alters the movements of the peristaltic

Disorders of the Autonomic Nervous System

Several disorders and diseases are associated with the ANS; they cause severe health complications.

Dysautonomia

• Genetic inheritance, autoimmune diseases, or injury; major symptoms: fainting, unstable blood pressure, and digestive problems

• Diagnosed by autonomic function tests; medicines and changes in lifestyle for treatment.

Other Disorders of the ANS

• Postural Orthostatic Tachycardia Syndrome (POTS): Rapid heartbeat upon standing.

• Autonomic Neuropathy: It is the damage to autonomic nerves and it is usually seen in the case of Diabetes.

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