The human heart is a muscular organ that plays an essential role in pumping blood throughout the body. It is located in the chest, between and slightly left of center, and weighs about 10-12 ounces (300 grams). The heart has four chambers: two atria on top and two ventricles below. Blood low in oxygen returns to the right side of the heart while blood high in oxygen goes to the left side, then pumps out through arteries to deliver oxygen throughout the body.
The phrase "human heart" can also be used metaphorically to refer to a person's emotional or moral center - their deepest feelings and values that drive their behavior and actions. In this sense, it refers to the innermost nature of an individual, often associated with love, compassion, courage, loyalty, and other positive qualities.