Final answer:
Codes of stimulus intensity in endocrine and neural control differ because endocrine control relies on hormonal signaling for sustained, systemic responses, while neural control uses rapid, localized neurotransmitter signaling for immediate action, such as the fight-or-flight response.
Step-by-step explanation:
The codes of stimulus intensity for endocrine (E) and neural (N) control have distinct characteristics due to the different ways these systems operate. The endocrine system relies on chemical signaling through hormones, which are secreted into the bloodstream and travel throughout the body to act on target cells. These hormonal signals can be triggered by changes in extracellular fluid levels, ion levels, or even by other hormones. The neural control primarily uses neurotransmitters for rapid communication within localized areas, and it can directly stimulate glands to release hormones through neural stimuli.
The endocrine signaling is relatively slow and can sustain responses for a longer duration, making them suitable for ongoing processes such as growth, metabolism, and reproduction. In contrast, neural stimuli allow for quick, short-lived responses like the fight-or-flight reaction, where the nervous system stimulates the adrenal medulla to release epinephrine and norepinephrine in response to stress. This action occurs within seconds, demonstrating the rapid nature of neural communication.
The hypothalamic-pituitary axis exemplifies the coordination between the endocrine and nervous systems. The hypothalamus receives input from the nervous system and can both secrete hormones directly into the bloodstream and regulate anterior pituitary-controlled hormones, highlighting the interplay of both forms of stimulus intensity.