Which of the following statements are correct for regulation of cardiac activity?

(i) A special neural center in the medulla oblongata can moderate the cardiac function through autonomic nervous system.

(ii) Neural signals through the sympathetic nerves can increase the rate of heart beat, the strength of ventricular contraction and thereby the cardiac output.

(iii) Parasympathetic neural signals decrease the rate of heart beat, speed of conduction of action potential and thereby the cardiac output.

(iv) Adrenal medullary hormones can also increase the cardiac output.

(v) Adrenalin or epinephrine increase heartbeat.

(vi) Acetylcholine decrease heartbeat.