Astanga Hrudaya
रसात्मकं वहन्त्योजस्तन्निबद्धं हि चेष्टितम्। स्थूलमूलाः सुसूक्ष्माग्राः पत्ररेखाप्रतानवत्॥१९॥
they transport the rasa (first fluid tissue) and ojas (essence of tissues) to the whole body; on them all the activities of the body depend they are big at their roots and very small at tips,
english translation