BIO66 Chapter 9 - The Autonomic Nervous System

Somatic Nervous System

Voluntary - at will, conscious; Excitatory; Movement, muscle cell excitation.

Autonomic Nervous System

Regulates activity of cardiac muscle, smooth muscle, and glands (visceral organs & blood vessels); Excitatory or inhibitory.

Has 2 subdivisions: Sympathetic & Parasympathetic

Parasympathetic Nervous System

"Rest & digest"; LONG PREganglionic neurons; VERY SHORT (or within the organ itself) POSTganglionic neurons; Slowed heart rate; Dilation of visceral organ blood vessels; Increased digestive activity.

Sympathetic Nervous System

"Fight or flight" reaction; SHORT PREganglionic neurons; LONG POSTganglionic neurons; Prepares body for intense physical activity in emergency: Increased heart rate, Increased blood glucose concentration, Increased blood flow to skeletal muscles, Pupil dilation.

Preganglionic neurons

Have cell bodies in the CNS.

Postganglionic neurons

Have cell bodies in the autonomic ganglia.

Norepinephrine (NE)

A catecholamine involved in the sympathetic nervous system; regulates alertness, arousal, and stress response, playing a role in attention and mood regulation

Epinephrine (E)

A catecholamine involved in the sympathetic nervous system; also known as adrenaline; increasing heart rate and energy availability

Acetylcholine (Ach)

A neurotransmitter involved in BOTH the sympathetic and parasympathetic nervous systems; involved of muscle contraction, memory, learning, and ANS regulation

Sympathetic Division

Associated with emergency responses

Parasympathetic Division

Associated with rest and digest functions.

Cardiac muscle

Muscle regulated by the autonomic nervous system; striated, involuntary

Smooth muscle

Muscle regulated by the autonomic nervous system; non-striated, involuntary

What does the Autonomic System Regulate?

glands, cardiac muscle, smooth muscle, blood vessels, visceral organs

What are the two major divisions of the autonomic nervous system (ANS)?

The sympathetic nervous system and the parasympathetic nervous system.

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

The autonomic nervous system (ANS) controls INVOLUNTARY functions (cardiac muscle, smooth muscle, glands), whereas the somatic nervous system controls VOLUNTARY movements of skeletal muscles.

What types of muscles and organs does the autonomic nervous system regulate?

The ANS regulates cardiac muscle, smooth muscle, and glands (such as those in visceral organs and blood vessels).

What is the main function of the autonomic nervous system?

It regulates involuntary physiological functions such as heart rate, digestion, respiration, and glandular activity.

What is the difference between preganglionic and postganglionic neurons?

Preganglionic neurons have their cell bodies in the CNS and synapse with postganglionic neurons.

Postganglionic neurons have their cell bodies in autonomic ganglia and extend to the target organs.

What is the main function of the sympathetic nervous system?

It prepares the body for fight-or-flight responses, increasing alertness and energy in emergency situations.

Which neurotransmitters are associated with the sympathetic nervous system?

Norepinephrine (NE) and epinephrine (E). Acetylcholine (ACh) is also involved in preganglionic signaling.

What are the physiological effects of the sympathetic nervous system during a fight-or-flight response?

Increased heart rate, increased blood glucose, increased blood flow to skeletal muscles, and pupil dilation.

How do the lengths of sympathetic preganglionic and postganglionic neurons compare?

Sympathetic neurons have short preganglionic neurons and long postganglionic neurons.

How does norepinephrine affect alertness and mood regulation?

Norepinephrine helps regulate alertness, arousal, and stress responses and plays a role in mood regulation.

What role does epinephrine play in the body's response to stress?

Epinephrine (adrenaline) increases heart rate, enhances energy availability, and triggers fight-or-flight responses.

What is the primary function of the parasympathetic nervous system?

It promotes rest-and-digest functions, conserving energy and maintaining homeostasis.

Which neurotransmitter is most associated with the parasympathetic nervous system?

Acetylcholine (ACh).

How do parasympathetic preganglionic and postganglionic neuron lengths compare?

Parasympathetic neurons have long preganglionic neurons and short postganglionic neurons (often located within or near the target organ).

How does the parasympathetic nervous system affect heart rate and digestion?

It slows heart rate and increases digestive activity.

Why is the parasympathetic nervous system referred to as "rest and digest"?

Because it conserves energy, lowers heart rate, and stimulates digestion and other maintenance functions when the body is at rest.#