Answer:
Blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. As the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.
Sit-ups I hear is hard on the back, I don't think people like these now a days.
Leg extensions as apposed to squats for quads I've heard about being bad for knees as well.
For the first question, it is true.
Ok............////::..:/.:/./..//:....
