The purines in dna are
a. thymine and cytosine
b. thymine and guanine
c. adenine and guanine
d. adenine and cytosine

your body is trying to warm itself up. or more precisely, sensors in your skin send messages to your brain to generate heat to your body.

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.