this regularity depends on a complex interplay of chemical and neural control systems that operate automatically to reset the rate and depth of breathing as changes occur in posture and activity , to adjust the level of ventilation so that changes in gas tensions and ph in the blood and in the brain intersitial fluid are exceedingly modest despite wide swings in metabolic rate and in environmental conditions , and to coordinate ventilation and circulation so that the requirements of individual tissues for o2 delivery and co2 removal are satisfied .
C0006104
brain
C0242428
satisfied