At this stage your baby's heart beats at approximately 140 beats per minute, so at least twice as fast as your own. The heart and its internal electrical conducting system are structurally complete but its external nerve supply is still quite immature. The nerves to the heart influence its rhythm, gradually slowing the rate as the pregnancy advances.
The heart is tiny and to maintain an adequate output the heart is unable to increase the amount of blood it pumps with each beat (as we can), but instead increases the number of times it beats each minute.
The abdominal cavity is large enough to hold the intestines. Whereas before they were bulging outside of your baby's body, they now fit into her abdominal cavity. Having started to rotate while outside the body, the bowel completes its final rotation in the abdominal cavity. Once inside, the bowel position remains fixed, and its diameter increases as the loops of bowel become hollow.