Editing Human brain (section)

===Regulation===
[[Autonomic nervous system|Autonomic]] functions of the brain include the regulation, or [[Neuroscience of rhythm|rhythmic control]] of the [[heart rate]] and [[respiratory rate|rate of breathing]], and maintaining [[homeostasis]].

[[Blood pressure]] and [[heart rate]] are influenced by the [[vasomotor center|vasomotor centre]] of the medulla, which causes arteries and veins to be somewhat constricted at rest. It does this by influencing the [[sympathetic nervous system|sympathetic]] and [[parasympathetic nervous system]]s via the [[vagus nerve]].{{sfn|Guyton & Hall|2011|pp=202–203}} Information about blood pressure is generated by [[baroreceptor]]s in [[aortic body|aortic bodies]] in the [[aortic arch]], and passed to the brain along the [[general visceral afferent fibers|afferent fibres]] of the vagus nerve. Information about the pressure changes in the [[carotid sinus]] comes from [[carotid body|carotid bodies]] located near the [[common carotid artery|carotid artery]] and this is passed via a [[Hering's nerve|nerve]] joining with the [[glossopharyngeal nerve]]. This information travels up to the [[solitary nucleus]] in the medulla. Signals from here influence the vasomotor centre to adjust vein and artery constriction accordingly.{{sfn|Guyton & Hall|2011|pp=205–208}}

The brain controls the [[respiratory rate|rate of breathing]], mainly by [[respiratory center|respiratory centre]]s in the medulla and pons.{{sfn|Guyton & Hall|2011|pp=505–509}} The respiratory centres control [[respiration (physiology)|respiration]], by generating motor signals that are passed down the spinal cord, along the [[phrenic nerve]] to the [[Thoracic diaphragm|diaphragm]] and other [[muscles of respiration]]. This is a [[spinal nerve|mixed nerve]] that carries sensory information back to the centres. There are four respiratory centres, three with a more clearly defined function, and an apneustic centre with a less clear function. In the medulla a dorsal respiratory group causes the desire to [[inhalation|breathe in]] and receives sensory information directly from the body. Also in the medulla, the ventral respiratory group influences [[exhalation|breathing out]] during exertion. In the pons the [[pneumotaxic center|pneumotaxic centre]] influences the duration of each breath,{{sfn|Guyton & Hall|2011|pp=505–509}} and the [[apneustic center|apneustic centre]] seems to have an influence on inhalation. The respiratory centres directly senses blood [[carbon dioxide]] and [[pH]]. Information about blood [[oxygen]], [[carbon dioxide]] and pH levels are also sensed on the walls of arteries in the [[peripheral chemoreceptor]]s of the aortic and carotid bodies. This information is passed via the vagus and glossopharyngeal nerves to the respiratory centres. High carbon dioxide, an acidic pH, or low oxygen stimulate the respiratory centres.{{sfn|Guyton & Hall|2011|pp=505–509}} The desire to breathe in is also affected by [[pulmonary stretch receptor]]s in the lungs which, when activated, prevent the lungs from overinflating by transmitting information to the respiratory centres via the vagus nerve.{{sfn|Guyton & Hall|2011|pp=505–509}}

The [[hypothalamus]] in the [[diencephalon]], is involved in regulating many functions of the body. Functions include [[neuroendocrine]] regulation, regulation of the [[circadian rhythm]], control of the [[autonomic nervous system]], and the regulation of fluid, and food intake. The circadian rhythm is controlled by two main cell groups in the hypothalamus. The anterior hypothalamus includes the [[suprachiasmatic nucleus]] and the [[ventrolateral preoptic nucleus]] which through gene expression cycles, generates a roughly 24 hour [[circadian clock]]. In the [[circadian clock|circadian day]] an [[ultradian rhythm]] takes control of the sleeping pattern. [[Sleep]] is an essential requirement for the body and brain and allows the closing down and resting of the body's systems. There are also findings that suggest that the daily build-up of toxins in the brain are removed during sleep.<ref name="sleep">{{cite web |title=Brain Basics: Understanding Sleep {{!}} National Institute of Neurological Disorders and Stroke |url=https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Understanding-Sleep |website=www.ninds.nih.gov |url-status=live |archive-url=https://web.archive.org/web/20171222044016/https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Understanding-Sleep |archive-date=December 22, 2017  }}</ref> Whilst awake the brain consumes a fifth of the body's total energy needs. [[Neuroscience of sleep|Sleep]] necessarily reduces this use and gives time for the restoration of energy-giving [[Adenosine triphosphate|ATP]]. The effects of [[sleep deprivation]] show the absolute need for sleep.{{sfn|Guyton & Hall|2011|p=723}}

The [[lateral hypothalamus]] contains [[orexin]]ergic neurons that control [[appetite]] and [[arousal]] through their projections to the [[ascending reticular activating system]].<ref name=Davis>{{ cite book | chapter=24. Orexigenic Hypothalamic Peptides Behavior and Feeding – 24.5 Orexin | chapter-url=https://books.google.com/books?id=KuAEPOPbW6MC&pg=PA361 | pages=361–362 |last1=Davis |first1=J.F. |last2=Choi |first2=D.L. |last3=Benoit |first3=S.C. | title=Handbook of Behavior, Food and Nutrition |editor1-last=Preedy |editor1-first= V.R. |editor2-last=Watson |editor2-first=R.R. |editor3-last=Martin |editor3-first=C.R. | publisher=Springer | year=2011 | isbn=978-0-387-92271-3 }}</ref>{{sfn|Squire|2013|p=800}} The hypothalamus controls the [[pituitary gland]] through the release of peptides such as [[oxytocin]], and [[vasopressin]], as well as [[dopamine]] into the [[median eminence]]. Through the autonomic projections, the hypothalamus is involved in regulating functions such as blood pressure, heart rate, breathing, sweating, and other homeostatic mechanisms.{{sfn|Squire|2013|p=803}} The hypothalamus also plays a role in thermal regulation, and when stimulated by the immune system, is capable of generating a [[fever]]. The hypothalamus is influenced by the kidneys: when blood pressure falls, the [[renin]] released by the kidneys stimulates a need to drink. The hypothalamus also regulates food intake through autonomic signals, and hormone release by the digestive system.{{sfn|Squire|2013|p=805}}