We breathe with the intelligence of the endocrine system, beginning with the thymus gland. The thymus gland is in association with t-cells, immunity and the energy of the heart. It is the most robust when we are children. We also do a kidney twist breath - to help balance the hormones of the adrenals. The pineal gland is also discussed post nadi shodana into "handless nadi shodana" - helpful for meditation.