The heart is a muscular organ about the size of a closed fist that functions
as the body's circulatory pump. It takes in deoxygenated blood through
the veins and delivers it to the lungs for oxygenation before pumping it
into the various arteries (which provide oxygen and nutrients to body
tissues by transporting the blood throughout the body). The heart is
located in the thoracic cavity medial to the lungs and posterior to the
sternum.

The brain is one of the most complex and magnificent organs in the human
body. Our brain gives us awareness of ourselves and of our environment,
processing a constant stream of sensory data. It controls our muscle
movements, the secretions of our glands, and even our breathing and
internal temperature. Every creative thought, feeling, and plan is developed
by our brain. The brain's neurons record the memory of every event in
our lives. In fact, the human brain is so complicated that it remains an
exciting frontier in the study of the body; doctors, psychologists, and
scientists are continually endeavoring to learn exactly how the many
structures of the brain work together intricately to create our
powerful human mind.