Sympathetic nervous system

Definition

The sympathetic nervous system is a part of the autonomic nervous system responsible for the body's 'fight or flight' response. It prepares the body to react to stressful situations by increasing heart rate, redirecting blood flow to muscles, and releasing energy stores, which are essential for survival during emergencies. This system plays a critical role in regulating processes such as glomerular filtration and overall homeostasis across various organ systems.

5 Must Know Facts For Your Next Test

1. The sympathetic nervous system triggers the release of adrenaline (epinephrine) from the adrenal glands, which enhances the body's ability to respond quickly to stressors.
2. During sympathetic activation, renal blood flow decreases as blood is redirected away from the kidneys to support muscles and critical organs for immediate survival.
3. This system increases glomerular filtration rate during stressful situations by promoting renal perfusion initially but can lead to reduced function over prolonged stress.
4. The sympathetic nervous system can influence tubular reabsorption processes in the kidneys by regulating the release of hormones like renin and angiotensin, impacting blood pressure.
5. Long-term activation of the sympathetic nervous system can lead to health issues such as hypertension and kidney damage due to its effects on vascular resistance and fluid balance.

Review Questions

• How does the sympathetic nervous system impact renal function during stress?
  • During stress, the sympathetic nervous system decreases renal blood flow as it prioritizes blood supply to essential muscles and organs. This can initially increase glomerular filtration rate due to heightened adrenaline levels, but prolonged activation may ultimately impair kidney function due to reduced perfusion. Therefore, while the body prepares for immediate threats, renal processes may suffer if stress is sustained.
• Discuss how the sympathetic nervous system interacts with other organ systems to maintain homeostasis during a stressful event.
  • The sympathetic nervous system interacts with multiple organ systems to maintain homeostasis during stress by coordinating responses that prepare the body for action. For example, it elevates heart rate and respiratory rate while redirecting blood flow away from non-essential systems like digestion. This integrated response helps ensure that energy is available for immediate use in critical areas such as muscles while maintaining basic life-supporting functions in other systems.
• Evaluate the long-term consequences of persistent sympathetic nervous system activation on overall health.
  • Persistent activation of the sympathetic nervous system can lead to significant long-term health issues such as chronic hypertension and cardiovascular disease. The continuous release of stress hormones may cause structural changes in blood vessels and elevate risks for kidney dysfunction. This ongoing state of 'fight or flight' can disrupt homeostasis across organ systems, leading to metabolic disorders, weakened immune responses, and other chronic conditions that detrimentally affect quality of life.

Related terms

Parasympathetic Nervous System: The component of the autonomic nervous system that promotes the 'rest and digest' response, counteracting the effects of the sympathetic nervous system.

Autonomic Nervous System: A division of the peripheral nervous system that controls involuntary bodily functions, including heart rate, digestion, and respiratory rate.

Homeostasis: The state of steady internal conditions maintained by living organisms, involving multiple organ systems working together to regulate variables like temperature, pH, and electrolyte balance.