Breathing provides life-sustaining oxygen and rids the body of the gaseous waste product carbon dioxide. The respiratory control center in the brain stem receives various types of input from sensors in the body that influence the breathing rate. Factors that affect breathing rate can cause temporary or sustained changes in the pattern and rate of respiration.
Blood Carbon Dioxide Content
The blood carbon dioxide content strongly influences the breathing rate. Sensors in certain arteries of the body and in the brain continuously monitor carbon dioxide levels in the blood, sending input to the respiratory control center, notes the reference text "Human Physiology." The respiratory rate increases as carbon dioxide levels rise. Conversely, decreased carbon dioxide levels lead to a slowed breathing rate. The system of detection and correction of carbon dioxide levels through adjustments in the breathing rate proves exquisitely sensitive, responding to relatively small changes in blood carbon dioxide content.
Blood pH
The sensors that monitor the blood carbon dioxide content also detect shifts in blood pH--a measure of the acidity or alkalinity of the blood. Increasing acid levels in the blood lead to an increased respiratory rate. Diabetic ketoacidosis serves as an example of the influence of blood pH on the respiratory rate. With this condition, excessive fat breakdown leads to an accumulation of acidic chemicals known as ketones in the blood. The ketones cause a drop in blood pH and rapid, deep breathing, a characteristic symptom of diabetic ketoacidosis, notes the Merck Manual for Healthcare Professionals.
Blood Oxygen Content
Substantially low blood oxygen content increases the respiratory rate. This mechanism, however, proves secondary to the influence of the carbon dioxide and pH levels under normal circumstances, notes the reference text "Human Physiology."
Epinephrine
Epinephrine, also known as adrenalin, causes an increase in the respiratory rate. The release of epinephrine associated with exercise contributes to the increased breathing rate that occurs with physical exertion.
Respiratory Control Center Damage
The respiratory control center of the brain stem maintains automatic breathing. Damage to this area of the brain can have catastrophic effects, potentially leading to respiratory arrest. Head injuries and associated brain swelling commonly cause elevated pressure within the skull, explains MedlinePlus from the National Institutes of Health. The increased pressure may force the brain stem through the narrow opening at the base of the skull, damaging the respiratory control center and potentially causing death.
Narcotics
Prescription and illicit narcotics decrease the respiratory rate. When taken as directed, prescription narcotics do not typically cause a medically significant decrease in the breathing rate. If taken in amounts greater than prescribed or combined with alcohol, however, narcotics can cause severe respiratory depression. The Merck Manual for Healthcare Professionals reports that narcotic overdose commonly causes a markedly decreased respiratory rate or cessation of breathing.
