Question

Define nervous system and endocrine system.

Answer 1

The nervous system responds to stimuli by sending electrical action potentials along neurons, which in turn transmit these action potentials to their target cells using neurotransmitters, the chemical messenger of the nervous system. This response to stimuli is near instantaneous.

Hormones are synthesized at a distance from their target cells, and travel through the bloodstream or intercellular fluid until they reach these cells. Upon reaching their target cell, the hormones act on the cell to increase or decrease the expression of specific genes.

This process takes significantly longer, as hormones must first be synthesized, transported to their target cell, and enter or signal the cell. Then, the target cell must go through the process of transcription, translation, and protein synthesis before the intended action of the hormone is seen.

Although hormones act more slowly than a nervous impulse, their effects are long lasting. Additionally, target cells can respond to minute quantities of hormones and are sensitive to subtle changes in hormone concentration.
The nervous and endocrine systems work together to maintain homeostasis.
The nervous system responds rapidly to short-term changes by sending electrical impulses.
The endocrine system brings about longer-term adaptations by sending out chemical messengers (hormones) into the bloodstream.