Heart is innervated by

The strength of ventricular contraction increases when $SAN$ is stimulated by

Cardiac activities of the heart are regulated by:
$A.$ Nodal tissue
$B.$ $A$ special neural centre in the medulla oblongata
$C.$ Adrenal medullary hormones
$D.$ Adrenal cortical hormones
Choose the correct answer from the options given below:

Stimulation of the vagus nerve will make the heart beat

If the sympathetic nerve to the heart is cut off,the heart beat will

Heart rate is increased by all the following except: