Human Heart and Circulation Theory in Vedas

William Harvey first invented the theory of circulation. It was one of the greatest medical theory of all the time. He introduced the function of heart and the circulation of blood. In Shatapatha, it is discussed that the Aryans have discussed the same theory long before and it is in Vedas. Let's discuss the Vedic verses which explain the functioning of Heart. 

Blood Circulation in Vedas
Atharvaveda 10.2.26
मूर्धानमस्य संसीव्याथर्वा हृदयं च यत् Ι
मस्तिष्कादूर्ध्वः प्रैरयत् पवमानोऽधि शीर्षतःΙΙ
उसके सर और हृदय को प्रजापति ने आपस में जोड़ा Ι तत्पश्चात ऊर्ध्व पवमान ने इसके मस्तिष्क और शीर्षभाग को प्रेरित किया Ι              

Atharvaveda 10.9.15
यस्ते क्लोमा यदृधदयं पुरीतत् सहकण्ठिका Ι
आमिक्षां दुह्रतां दात्रे क्षीरं सर्पिरथो मधु ΙΙ      
तेरे जो हृदय, फेफड़े, मलाशय था कंठ भाग हैं, वः डाटा के निमित्त दुग्ध, दधि, दृत था मधु आदि प्रदान करें Ι       

In Vedas, the term Hridaya is used for Heart. Hridaya = Hri + da + yam where Hri means taking over, da means giving and yam means circulation i.e. taking over the blood from all the body parts to purify it and then circulates back to the body parts after purification.