Which of the following statements is correct about the nodes of Ranvier?

The energy required during the transmission of a nerve impulse is provided by:

Which of the following statements are correct?
$I$. Dendrites are long fibres with branched distal ends.
$II$. Axons are short fibres which arise from the cell body.
$III$. The cell body of a neuron contains cytoplasm,a nucleus with cell organelles,and Nissl's granules.
$IV$. Dendrites transmit nerve impulses away from the cell body to a synapse.
The correct option is:

Four healthy people in their twenties were involved in injuries resulting in damage and death of a few cells of the following types. Which of these cells are least likely to be replaced by new cells?

The gap between two adjacent myelin sheaths is called ........

What does a neuron consist of?