ABSTRACT
Breathing takes place secondary to the contraction and relaxation of the respiratory muscles, which occurs automatically without conscious effort. This action is dependent on an intact nervous system relaying impulses from the rhythm generator and the respiratory centers in the brainstem, via the spinal cord and phrenic nerve to the muscles of respiration. • Breathing is constantly adjusted to match changes in metabolic demands, e.g. increased
metabolism, exercise or breathing at altitude. • How effective an adaptive change in breathing pattern is, will depend on the mechanical
properties of the thorax and the efficiency of gas exchange by the lungs. • Breathing is regularly modified to accommodate many activities, e.g. speech, voluntary
movement and exercise, swallowing and coughing. • Breathing pattern can be influenced by voluntary cortical control during wakefulness. • Various diseases and pharmacological agents can influence the control of breathing.
