Brenda and her friend are relaxing in a paddleboat, slowly working the paddles with their legs to move the boat. Which organelles in the muscle cells of Brenda’s legs enable Brenda to have the energy for this activity?

yes? sounds right, but you didn’t ask a question.

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.