The body's involuntary control of respiration is mediated by the brain's respiratory center located in the brainstem, particularly in the medulla oblongata and pons. The respiratory center regulates the rhythmic, alternating cycles of inspiration and expiration. Comparative brain sizes In animals, the brain, or encephalon (Greek for in the head), is the control center of the central nervous system. ... The brain stem is the stalk of the brain below the cerebral hemispheres. ... Position of medulla oblangata in the human brain The medulla oblongata is the lower portion of the brainstem. ... Position of the pons in the human brain The pons (sometimes pons Varolii after Costanzo Varolio) is a knob on the brain stem. ... There are several meanings of the word inspiration: The stimulating influence upon the intellect or emotions leading to creativity. ... Exhalation is the movement of air out of the bronchial tubes, through the airways, to the external environment during breathing. ...

From within the medulla, graded action potentials are discharged in a cyclic pattern, and act to excite respiratory muscles. Bilaterally paired aggregations of neurons called the dorsal respiratory group and the ventral respiratory group, act in inspiration and expiration (respectively), are mutually inhibitory and act with symmetry (facilitated by cross communication). The dorsal respiratory group is active during inspiration although they are not the source of rhythmic respiration. The ventral respiratory group is involved in inspiration and expiration; these neurons play an important role in respiratory muscle contraction. The Pre-Botzinger Complex is the an essential site for the generation of the respiratory rhythm. The exact mechanism of the rhythm remains controversial. Drawing by Santiago Ramón y Cajal of cells in the pigeon cerebellum. ... The dorsal repiratory group is found in many types of fish and marine mammals. ...

Receptors play important roles in the regulation of respiration; central and peripheral chemoreceptors, and mechanoreceptors. In a sensory system, a sensory receptor is a structure that recognizes a stimulus in the internal or external environment of an organism. ... A Chemosensor, also known as chemoreceptor, is a cell or group of cells that transduce a chemical signal into an action potential. ... A mechanoreceptor is a sensory receptor that responds to mechanical pressure or distortion. ...

Central chemoreceptors of the central nervous system, located on the ventrolateral medullary surface, are sensitive to the pH of their environment. These act to detect a change in pH of the cerebral spinal fluid. An increase in carbon dioxide tension of the arteries will indirectly cause the blood to become more acidic; the cerebral spinal fluid pH is closely comparable to the plasma pH, as carbon dioxide easily diffuses across the blood/brain barrier. The detection of variation in the arterial carbon dioxide tension acts as a quick-response-system, useful in short term regulation. This system utilizes a negative feedback system, therefore if the pH of the cerebral spinal fluid does not compare to an ideal “set” level, then the receptor will send an error signal to the effectors and appropriate action may be executed. PH or ph or pH or Ph may be: pH, a measure of acidity (chemistry) Ph, a phenyl ring (organic chemistry) PH, the ISO country code of the Philippines (see . ... Blood plasma is the liquid component of blood, in which the blood cells are suspended. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ...

Peripheral chemoreceptors act most importantly to detect variation of the oxygen in the arterial blood, in addition to detecting arterial carbon dioxide and pH. These nodes, called aortic and carotid bodies, are located on the arch of the aorta and on the common carotid artery, respectively. A continual signal is sent, via cranial nerves IX and X, from the peripheral chemoreceptors. With a decrease in arterial oxygen tension, the signal intensifies, calling for an increase in respiration. General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... The largest artery in the human body, the aorta originates from the left ventricle of the heart and brings oxygenated blood to all parts of the body in the systemic circulation. ... In human anatomy, the carotid artery is a major artery of the head and neck. ...

Mechanoreceptors are located in the airways and parenchyma, and are responsible for a variety of reflex responses. These include the Hering-Breuer reflex that terminates inspiration to prevent over inflation of the lungs, and the reflex responses of coughing, airway constriction, and hyperventilation. The upper airway receptors are responsible for reflex responses such as, sneezing, bradycardia, coughing, closure of glottis, and hiccups. The spinal cord reflex responses include the activation of additional respiratory muscles as compensation, gasping response, hypoventilation, and an increase in breathing frequency and volume. For the aerial route, see Airway (aviation). ... The parenchyma are the functional parts of an organ in the body (i. ... In medicine, hyperventilation (or hyperpnea) is the state of breathing faster or deeper (hyper) than necessary, and thereby reducing the carbon dioxide concentration of the blood below normal. ... A sneeze is the semi-autonomous, convulsive expulsion of air from the nose. ... Bradycardia, as applied in adult medicine, is defined as a heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min [1]. It is also less commonly known as brachycardia. ... The space between the vocal cords is called the glottis. ... A hiccup is an involuntary spasm of the diaphragm. ... Cross-section through cervical spinal cord. ...

In addition to involuntary control of respiration by the respiratory center, respiration can be affected by conditions such as emotional state, via input from the limbic system, or temperature, via the hypothalamus. Voluntary control of respiration is provided via the cerebral cortex, although chemoreceptor reflex is capable of overriding conscious control. The limbic system is a group of brain structures that are involved in various emotions such as aggression, fear, pleasure and also in the formation of memory. ... Temperature is the physical property of a system which underlies the common notions of hot and cold; the material with the higher temperature is said to be hotter. ... In the anatomy of mammals, the hypothalamus is a region of the brain located below the thalamus, forming the major portion of the ventral region of the diencephalon and functioning to regulate certain metabolic processes and other autonomic activities. ... Location of the cerebral cortex Slice of the cerebral cortex, ca. ...

References

• Paul, Anthony D., et al., Neuronal Connections of a Ventral Brainstem Respiratory Chemosensitive Area: “Ventral Brainstem Mechanisms and Control of Respiration and Blood Pressure” [1]
   
• Rabbany, Sina Y., “Breathing Coordination”, Hofstra University [2]
   
• Webber, Charles L., Jr., Ph.D, Pulmonary Curriculum Function:“Neural Control of Breathing”, Stritch School of Medicine, Loyola University-Chicago [3]
   
• Rhoades, Rodney, Ph.D., Pflanzer, Richard, Ph.D, (2003) Human Physiology, 4th ed., Thompson Learning, Inc: Brooks/Cole, pp. 672-676