The autonomic nervous system affects:

Parasympathetic nerves increase the mobility in

What are the histiocytes of the brain?

Which system is responsible for the conservation of energy?

Contraction of involuntary muscles, secretion of digestive glands and rate of heart beats are under the control of

Select the correct option:
$(1)$ The cell body contains typical cell organelles and Nissl's granules / neurotransmitters.
$(2)$ The nervous system of Hydra is composed of a nerve net / ganglia.