THE NERVOUS SYSTEM & THE RESPIRATORY REGULATION MECHANISM
The nervous system controls the flow of air into and out of the lungs. The nervous system ensures that the unconscious breathing process is carried out in a regular pattern and rate.
The respiratory centre: The respiratory process begins in this centre located in the brain stem. The centre is made up of a cluster of nerve cells. Simultaneous signals are dispatched by these cells to rib muscles, the diaphragm, and those muscles that are involved in inhalation. The diaphragm: It is a dome-shaped muscle. This large tissue lies just under the lungs. When a nervous impulse stimulates the diaphragm, it flattens. When the diaphragm makes a downward movement, the stomach cavity volume gets expanded. The cavity consists of the thoracic cavity which includes the lungs. And as the rib muscles get stimulated, they too contract. As a result, the rib cage is pulled up and out. This movement further expands the thoracic cavity. Such expanded volume causes air to rush into the thoracic cavity and then to the lungs. The fast and brief nervous stimulation also aids the exhalation process. This exhalation process takes place as the nervous stimulation ceases. As a consequence thereof, the rib muscles and the diaphragm and relax propelling the exhalation stage.
RATE OF SIGNALS
Generally, the respiratory center gives out 12 to 20 signals every minute. This means that a normal person breathes 12 to 20 times within 60 seconds. The newborn babies breathe approximately 30 to 50 times in a minute.
CONSCIOUS ALTERATION OF THE RESPIRATORY SYSTEM
Conscious actions can control the rhythm of the respiratory system. In fact, many yogic exercises underline the need for a person to exercise regular control of the complex respiratory system via conscious efforts. This conscious act helps the person concerned to strengthen his physical constitution and also the mental outlook.
Such conscious alteration or temporary abatement of the respiratory system is done by holding or controlling the breath. Several parts of the nervous system come into play in such an act. The portion of the brain aiding the thinking process (cerebral cortex) has a major role to play. It sends signals to the rib muscles and the diaphragm for temporarily overriding the respiratory center signals. A person can avoid inhaling noxious fumes by holding his breath. However, a person cannot hold his breath for an indefinite period.
WHAT HAPPENS WHEN THERE IS NO EXHALATION
When exhalation does not take place, our blood builds up a dangerous buffer stock of carbon dioxide. This accumulation makes the blood more acidic. Hiked acidity conflicts with the enzyme activity. The enzymes are specialized proteins participating in almost all biochemical reactions within our body.
Chemoreceptors: Special receptors called chemoreceptors prevent the blood from getting too acidic. The chemoreceptors monitor the blood. The chemoreceptors are located in the neck blood vessels and the brainstem.
When acid builds up in the blood, these chemoreceptors dispatch nervous signals to the respiratory center. The centre then overrides the cerebral cortex signals. This forces the person to exhale and resume breathing. Exhalations bring back the normal level of the blood acid after throwing out the carbon dioxide. Immediately inhalation brings in oxygen.
WHAT PREVENTS OVER-INHALATION?
Specialized cells called the stretch receptors prevent the possibility of over-inhalation. These stretch cells are located in the lungs. The stretch receptors measure the volume of air within our lungs. The moment inhalation crosses the danger level, these stretch receptors flicks out signals to the respiratory center. The centre immediately shuts down the inhalation muscles and stops the air intake process.
THE NERVOUS SYSTEM
The nervous system is constituted of two processes. They are the central and the peripheral nervous systems. The central nervous system includes the brain and the spinal cord.
THE CENTRAL NERVOUS SYSTEM
The central nervous system processes and coordinates the incoming sensory information and the outgoing motor commands. The central nervous system is also the seat of complex brain functions such as emotion, learning, memory, and intelligence.
THE PERIPHERAL NERVOUS SYSTEM
The peripheral nervous system includes all neural tissue beyond the central nervous system. The peripheral nervous system provides sensory information to the central nervous system. The peripheral nervous system also carries motor commands to the body’s tissues.
The somatic nervous system: Voluntary motor commands, such as moving the muscles for walking or talking, are controlled by the somatic nervous system.
The autonomic nervous system: determines the involuntary motor commands, such as digestion and heart beat. The autonomic nervous system is further divided into two systems, viz. , the sympathetic nervous system and the parasympathetic nervous system.
The sympathetic nervous system: The sympathetic nervous system is also called the “flight or fight" system. It increases prepares our body for quick responses to unusual situations, activates alertness, and stimulates tissue.
The parasympathetic nervous system: The parasympathetic nervous system has just the opposite function. The parasympathetic nervous system is called the “repose and rest" system. It conserves controls the sedentary activities like digestion and also preserves our energy.
Therefore, the Nervous System refers to those elements that are concerned with the reception of stimuli, the transmission of nerve impulses, or the activation of muscle mechanisms in an animal organism.
Nilutpal Gogoi is a writer and a freelance journalist having more than 18 years of service in several audio-visual and print media reputed organizations in North East India. He has published more than 1000 articles and a popular adventure book for children.
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