Which part of the brain controls the involuntary action of the heartbeat?

Which of the following statements are true?
$(i)$ Sudden action in response to something in the environment is called reflex action.
$(ii)$ Sensory neurons carry signals from spinal cord to muscles.
$(iii)$ Motor neurons carry signals from receptors to spinal cord.
$(iv)$ The path through which signals are transmitted from a receptor to a muscle or a gland is called reflex arc.

In which lobe of the cerebrum are the centers for temperature,smell,and touch located?

The junction between two neurons is called:

Where does the spinal cord originate from?

$A$ protective and an insulating sheath of myelin found around the axon is made up of ..........