What major physical changes occur in the metamorphosis from the tadpole stage to the adult stage that enable the adult frog to survive on land?

At birth, a tadpole is essentially a head with eyes and a tail. Many internal changes must occur before a tadpole is ready to be a land dwelling frog. As a tadpole grows, she will develop bones. The tadpole must also grow some new internal organs, the most important of which are the lungs, and a fully grown heart.