Like other muscles, it needs oxygen and nutrients to function. The heart receives its oxygen and nutrients from blood pumped from a large blood vessel called the aorta, through smaller blood vessels called arteries (coronary arteries), then through even smaller vessels called arterioles and capillaries.ike other muscles, it needs oxygen and nutrients to function. The heart receives its oxygen and nutrients from blood pumped from a large blood vessel called the aorta, through smaller blood vessels called arteries (coronary arteries), then through even smaller vessels called arterioles and capillaries.
What is PDF? Portable Document Format (PDF) is a file format used to present and exchange documents reliably, independent of software, hardware, or operating system. Invented by Adobe, PDF is now an open standard maintained by the International Organization for Standardization (ISO).
PDF files are cross-platform files, which means they are able to be read on both Mac and Windows operating systems, as well as the new Android platform found in many of today's cell phones. Many of today's eBook publishers use PDF format for publishing.