What is the autonomic nervous system and what does it control?

The autonomic nervous system (ANS) is the part of the nervous system that controls involuntary functions, such as those of smooth muscle, cardiac muscle, and glands. It operates without conscious effort to regulate essential bodily processes.

How does the autonomic nervous system differ from the somatic nervous system?

The ANS differs from the somatic nervous system in its efferent pathway: it uses a two-neuron relay system (preganglionic and postganglionic neurons) to reach target organs, while the somatic motor pathway involves a single motor neuron directly innervating skeletal muscle.

What are the main subdivisions of the autonomic nervous system and their roles?

The ANS has two main subdivisions: the sympathetic nervous system, which prepares the body for "fight or flight" by increasing heart rate and blood pressure, and the parasympathetic nervous system, which promotes "rest and digest" by slowing heart rate and stimulating digestion.

What neurotransmitters are used in the autonomic nervous system?

The ANS uses specific neurotransmitters: acetylcholine (ACh) is released by all preganglionic neurons and postganglionic parasympathetic neurons, while norepinephrine (NE) is released by most postganglionic sympathetic neurons, with exceptions like sweat glands using ACh.

What is referred pain and how does it relate to the autonomic nervous system?

Referred pain is perceived at a site distant from the affected organ but within the same spinal segment innervation, often due to autonomic sensory pathways. Examples include heart pain felt in the arm or gallbladder pain in the shoulder.

What are the functions of the afferent component in the autonomic nervous system?

The afferent component of the ANS handles sensory input for visceral reflexes, sensations like hunger and nausea, and visceral pain caused by factors such as organ stretching or ischemia.

Where do the sympathetic and parasympathetic systems originate in the body?

The sympathetic system originates from thoracolumbar segments (T1–L2) of the spinal cord. The parasympathetic system has craniosacral outflow, with parts from cranial nerves III, VII, IX, and X, and sacral segments S2–S4.

Autonomic Nervous System – Sympathetic vs Parasympathetic

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