Autonomic Nervous System - Sympathetic Division Functions

Autonomic Nervous System - Sympathetic Division

The autonomic nervous system is part of the peripheral nervous system responsible for controlling involuntary functions such as heart rate, blood pressure, digestion, glands, and metabolism. It consists of two divisions: the sympathetic division (also known as the thoracolumbar outflow) and the parasympathetic division (also called the craniosacral outflow). In this article, we will focus on the sympathetic division.

Functions of the Sympathetic Division

Activating the Body

The sympathetic division is responsible for preparing the body for strenuous physical activity by increasing heart rate, respiration rate, and blood flow to skeletal muscles. This helps deliver oxygen and nutrients to working muscle tissue during intense exercise.

Regulating Metabolic Rate

By increasing metabolic rate, the sympathetic division controls the body's response to stressors like cold temperatures, fear, or fasting, which can increase energy expenditure and promote fat loss.

Impacting Digestion

During high metabolic states, the parasympathetic nervous system inhibits digestive processes while the sympathetic nervous system stimulates them. Consequently, food consumption increases and digestive function slows down when the body needs more resources to deal with stress.

Peripheral Vascular Response

The vasoconstriction mediated by the sympathetic division maintains normal blood pressure, diverts blood flow away from internal organs to essential areas, and provides the necessary oxygen to maintain muscular contraction.

Facilitating Thermoregulation

The sympathetic division can facilitate thermogenesis through non-shivering heat production in brown fat by stimulating the release of norepinephrine, which induces lipolysis and generates heat via uncoupling protein 1 (UCP1)(6).

Key Players in the Sympathetic Division

Neurotransmitters

Neurotransmitter acetylcholine plays a key role in the parasympathetic nervous system, while norepinephrine is the primary neurotransmitter used by the sympathetic nervous system. Other important neurotransmitters in the sympathetic division include dopamine, serotonin, histamine, and many others.

Innervation

The sympathetic division is innervated by a number of spinal nerve roots, with the greatest number of fibers in the first thoracic and second, third, and fourth lumbar roots.

Autonomic Nervous System - Sympathetic Division: What You Need to Remember

The sympathetic division of the autonomic nervous system is vital for activating the body, regulating metabolic rate, impacting digestion, facilitating peripheral vascular response, and aiding in thermoregulation. It uses neurotransmitters like norepinephrine and is innervated by spinal nerve roots, primarily the first thoracic and second to fourth lumbar roots.

In summary, the sympathetic division is a crucial part of the autonomic nervous system, ensuring that our bodies are prepared to handle physical stress and function effectively in various situations.

Explore the functions and key players of the sympathetic division of the autonomic nervous system. Learn how it activates the body, regulates metabolic rate, impacts digestion, facilitates peripheral vascular response, and aids in thermoregulation. Understand the role of neurotransmitters like norepinephrine and the innervation of the sympathetic division.