How much is the weight of an adult human brain in grams (in $\text{ g}$)?

Which part of the brain regulates and controls involuntary actions?

Which of the following statements are true about the brain?
$(i)$ The main thinking part of the brain is the hindbrain.
$(ii)$ Centres of hearing,smell,memory,sight,etc.,are located in the forebrain.
$(iii)$ Involuntary actions like salivation,vomiting,and blood pressure are controlled by the medulla in the hindbrain.
$(iv)$ Cerebellum does not control posture and balance of the body.

Spinal cord originates from:

$(a)$ Name the part of the brain which controls:
$(i)$ voluntary actions,
$(ii)$ involuntary actions.
$(b)$ What is the significance of the peripheral nervous system? Name the components of this nervous system and distinguish between the origin of the two.

What constitutes the central and peripheral nervous systems? How are the components of the central nervous system protected?