The visceral system of the Peripheral Nervous System is known as the Autonomic Nervous System. The sensory (afferent) and motor (efferent) nerves connecting the body's surface with the central nervous system constitute the peripheral nervous system. In other words, the rest of the nervous system, other than the brain's Autonomic Nervous system.
The nerve fibres of the Autonomic Nervous System are connected with blood vessels, endocrine glands, heart, lungs, stomach, intestines, in and bladders etc. The Autonomic Nervous System is controlled by the old brain and is not under the functional control of the cortex. The synapse of the system is situated outside of both the spinal column and central nervous system.
{tocify} $title={Table of Contents}
Physiologists have discovered two divisions of the autonomic nervous system, i.e., sympathetic division and parasympathetic division. These two divisions never function together. Either of the two functions at a time.
Read: Emotion in Psychology
Read: Physical Changes during Emotion (External & Internal)
Read: Theories of Emotion: Evolutionary, Cannon-Bard, James-Lange and Schachter-Singer Theory
$ads={2}
The Sympathetic Nervous System
The spinal nerves emerge from the middle portions of the spinal cord. These spinal nerves emerging on both the sides of the spinal cord run a series of ganglia. Ganglia are the nerve centres present on both sides of the spinal cord. These nerve fibres run up and down the body synapse with the effector neurons that go into muscles, glands, skin, and viscera. These fibres form thoracolumbar segments of the spinal column and finally reach organs from the head to toes - all body parts. This part of the autonomic system is called the sympathetic nervous division because they make the visceral organs function in 'sympathy' during emergency conditions of serious effort or exercise, states of fear and anger.
$ads={2}
Functions of Sympathetic division
The sympathetic division acts in three significant events, such as during (a) excitement, an emotion of fear, anger and elation, (b) violent exercise and bodily activities and (c) extreme cold when the life is endangered.
Owing to the function of the sympathetic division during emotions such as anger and rage, the medulla of the adrenal gland pours an excess amount of its "adrenaline" secretion into the bloodstream. This secretion in the bloodstream is associated with intense emotional experiences. This leads to the release of stored sugar from the liver into the blood.
There are chemical changes in the blood, a result of which the blood clots easily and quickly. Blood pressure increases and pulse beats become rapid and vigorous. The passages of the lungs enlarge, and more air is admitted due to heavy breathing. The pupils of the eyes are dilated, and thus more light enters the eyes. Heavy sweating occurs throughout the body. Palms and hands are complete with sweating. The temperature of the skin sometimes rises and at times falls several degrees.
$ads={1}
The adrenal medulla also secretes another hormone called "noradrenaline", which constricts the blood vessels at the skin's surface. Blood is channelised from the stomach and sex organs to the motor organs, such as the muscles and arms. The digestive functions come to a stop. There is a cessation of digestive juices due to the inhibitive function of the sympathetic division. The blood from these is diverted to the muscles. Hairs stand on their roots. The adrenaline secreted from adrenal glands expedites the actions and reinforces emergency-facing processes. There is evidence that the thyroids and pituitary glands also secrete hormones during emotion.
The stomach's maximum visceral changes during joy, whereas in fear and anger, the adrenal functions vigorously. During sorrow, the gall bladder becomes most active. These glandular responses in emotion are adaptive in nature, which means individuals can cope physically with an emergency situation.
$ads={2}
The visceral activities, as well as the neural activities, involve emotion. Almost the total nervous system is involved in emotional response. Electrical responses are also closely associated with the visceral and the activities during emotion. The electrical reactions, such as galvanic responses and brain potentials, undergo changes during emotion. The autonomic actions energising sweat glands lead to perspiration, which produces changes in the electrical properties of the skin. The tissues of the skin generate electromotive force, and the skin's electrical resistance is changed.
$ads={1}
The Parasympathetic Nervous System
From the two end segments of the spinal cord, i.e., from the upper and the lower segments, the nerves of the parasympathetic division emerge on both sides. The upper division of the spinal column is called the cranial part, and the lower segment is called the sacral part. These nerves then pass the rough series of ganglia and reach the structures of the visceral organs having synapses outside the central nervous system.
Thus, the parasympathetic division of the autonomic nervous system is situated above and below the sympathetic division. Therefore, this division is known as the "craniosacral division' of the autonomic nervous system. Parasympathetic nerves like the sympathetic division reach almost all the body's organs from head to toes. When sympathetic division is active, the parasympathetic division takes a rest and vice-versa. Whether a particular division accelerates or inhabits a specific organ or system depends on the organism's welfare at that moment, depending on the situation.
$ads={2}
Functions of Parasympathetic division
The parasympathetic division is involved in the ordinary vital ions of life. The parasympathetic division maintains the ordinary processes of life. Protection of the eyes from the bright light is the work of this division. The constrictions of the pupils of the eyes are done by this division. It adjusts the lens of the eye for a new vision.
The construction of food, digestion, and excretion is done by parasympathetic. During sexual union, more blood supply to the sex, organs are made is division. It meets the physiological demands of the body to maintain. It stores energy in abundance for future use by the sympathetic division during an emergency.
But owing to prolonged emotion, if both the divisions of the Autonomic nervous system become overactive, that may lead to organic pathology, parasympathetic overactivity may lead to peptic ulcer, backache, headache etc. The sympathetic overactivity may lead to psychosomatic diseases, such as asthma, tuberculosis, migraine, etc., for which physicians prescribe psychosomatic medicines.