atria
The atria form the smaller part of the heart, while the ventricles form the larger part of the heart.
the atria
The word heart is a noun. The plural form is hearts.
The epicardium is the outermost layer of the heart wall and is part of the pericardium, which is the sac that surrounds the heart. It is a protective layer that helps lubricate and protect the heart.
The smaller part of the cell
so there are veins that connect the lungs and the heart and blood vessels carry blood form any direction in and out of the pumping heart
smaller
Tissues are formed together and then they form organs. The brain is a very good example of this, and also the heart. You could not say tissues are actual organelles, but they form them when they group together.
The organs that form part of the circulatory system are the heart, blood vessels, and blood. The heart pumps blood through the blood vessels, supplying oxygen and nutrients to the body's tissues and removing waste products.
You have an aorta, which comes out from the heart. This comes down to your lower abdomen. It gives branches on the way to your head and brain, to your upper limbs, to various abdominal organs. Now it has to divide to two legs. That only means that you need smaller branches to various parts of the body. You have smaller and smaller arteries to reach every part of your body. No body probably knows about, how they go to each and every part of the body to supply the blood.
The Heart is part of the circulatory system.
Females tend to be smaller in stature than men and, barring disease, don't require as large a heart to pump blood to a smaller sized body.