The Heart sends Blood all over the body.
The Heart belongs to Fire energy within the 5 organs' energy. (Liver=Wood, Spleen=Earth, Lung=Metal, Kidney=Water)
Heart energy is Fire energy, which means Heart energy is hot. So Heart energy is the strongest Yang energy within 5 organs' energy.

The Heart repeats the movement of contraction all day without any rest and generates heat which is necessary for the whole body. So in the case of menopausal disorders, when the Heart energy stagnates, we experience heat rising suddenly from the chest, causing a hot flash, palpitations, and profuse sweating.

In Western medicine, our mental activity is regarded as controlled by the brain, but in Eastern medicine, it is regarded as controlled by Heart. So when we have some trouble in our mind, we feel tightness in our chest, or when we are nervous, our heart rate gets faster. Mental disorders, hallucinations and auditory hallucinations are considered to be Heart energy problems.

As the Liver controls the eyes, the Heart controls the tongue.
If there is dysfunction of the brain, speech becomes unclear, so it is important to move the tongue a lot for preventing senile dementia.

The organ which has strong relationship to the Heart and also has Fire energy is the Small Intestine. So if there is a problem in the Small Intestine, the tongue gets some pimples or gets rough. Recently there is a doctor who states that the heart is in the Small Intestine.