DYNAMICS OF BREATHING:-The most basic unit of life, can teach you an enormous about yoga. In fact, the most essential yogic concepts can derived from observing the cell’s form & function. This chapter explores breath from a yogic perspective, using the cell as a tsarting point. Yoga Lessons from a cell:- cells are the smallest buliding blocks of life, from single-celled plants to multitrillion-celled animals. The human body, which is made up of roughly 100 trillion cells, begins as a single, newly fertillzed cell. A cell consists of three parts: the cell membrane, the nucleus, & the cytoplasm. The membrane separated the cell’s external environment, which conatins nutrients that the cell requires, from its internal environment, which consisst of the cytoplasm & the nucleus. Nutrients have to get through the membrane, & once inside, the cell metabolizes these nutrients & turns them into the energy that fuels its its life functions. As a result of this metabolic activity, waste gets generated that must somehow get back out through the membrane. Any impairment in the membrane’s ability to let nutrients in or waste out will result in the death of the cell via starvation or toxicity. This observation that living things take in nutrients provides a good basis for understanding the term prana, which refers to what nourishes a living thing. Prana refers not noly to what is brought in as nourishment but also to the action that brings it in. YOGA & THE SPINE:- The central nervous system, with its complex sensory & motor functions, allows for an enormous amount of flexibility in a vertebrate’s survival activival activies. As these syatems evolved over millions of years & became more crucial to the survival of our early ancestors, they required the corresponding development of a protective structure that allows for free movement but is stable enough to offer protection to these vital yet delicate tissues. That structure, the skeletal spine, is perhaps nature’s most elegant & intricate solution to the dual demands of sthira & sukha. The human spine is unique among all mammals in that it exhibits both primary & secondary curves. The primary curve of the spine comprises the kyphotic thoracic &sacral curves; the secondary, lordotic curves are present in the cervical & lumbar regions (see figure 2.1). Only a true biped requires both pairs of curves; tree-swinging & knuckle-walking primates have some cervical curve, but no lumbar lordosis, which is why they can’t walk comfortably on two legs for long.