Define homeostasis.

Define homeostasis.

• A. Balance between SNS/PNS (relaxed)
• B. Endocrine balance
• C. Constant heart rate
• D. Unchanging brain activity

Answer: (A)

Homeostasis is the body's ongoing ability to keep internal conditions stable by dialing regulatory processes up or down as needed. A central mechanism is the autonomic nervous system balancing its two branches: the sympathetic (fight-or-flight) and the parasympathetic (rest-and-digest) systems. When something nudges the internal environment away from the desired state, these branches adjust heart rate, digestion, temperature, and other functions to bring conditions back toward the set point. It’s a dynamic, not rigid, balance—adjusting as the body encounters stress, different activities, or environmental changes. Relating this to the options, the best description highlights that steady regulation comes from the interplay of SNS and PNS rather than a single rigid condition. The endocrine system participates in regulation, but homeostasis isn’t limited to an endocrine balance. A constant heart rate isn’t necessary, since heart rate should rise or fall with activity and demand. Brain activity also changes with tasks and states of arousal, so it isn’t unchanging.

Homeostasis is the body's ongoing ability to keep internal conditions stable by dialing regulatory processes up or down as needed. A central mechanism is the autonomic nervous system balancing its two branches: the sympathetic (fight-or-flight) and the parasympathetic (rest-and-digest) systems. When something nudges the internal environment away from the desired state, these branches adjust heart rate, digestion, temperature, and other functions to bring conditions back toward the set point. It’s a dynamic, not rigid, balance—adjusting as the body encounters stress, different activities, or environmental changes.

Relating this to the options, the best description highlights that steady regulation comes from the interplay of SNS and PNS rather than a single rigid condition. The endocrine system participates in regulation, but homeostasis isn’t limited to an endocrine balance. A constant heart rate isn’t necessary, since heart rate should rise or fall with activity and demand. Brain activity also changes with tasks and states of arousal, so it isn’t unchanging.