ANS Basics
This part of the body's nervous system innervates smooth muscle, cardiac muscle, and glands.
What is the autonomic nervous system?
This division of the ANS is known as the "rest and digest" system.
What is the parasympathetic division?
The two major neurotransmitters used by the ANS.
What are acetylcholine (ACh) and norepinephrine (NE)?
Preganglionic sympathetic neurons exit the spinal cord through these structures.
What are white rami communicantes?
This division typically increases heart rate and respiratory rate.
What is the sympathetic division?
The ANS operates mostly under this type of control.
What is involuntary (or subconscious) control?
This division mobilizes the body during activity and is called the "fight or flight" response.
What is the sympathetic division?
Adrenergic receptors respond to these substances.
What are norepinephrine and epinephrine?
This structure runs alongside the spinal cord and contains sympathetic ganglia.
What is the sympathetic trunk (or chain)?
Sympathetic tone refers to the baseline constriction of these.
What are blood vessels?
The ANS differs from the somatic nervous system in these three main ways.
What are effectors, efferent pathways and ganglia, and neurotransmitter effects?
All visceral organs are served by both the parasympathetic and sympathetic divisions, but they cause opposite effects. What is this phenomenon called?
What is dual innervation?
These cholinergic receptors can be excitatory or inhibitory, depending on the organ.
What are muscarinic receptors?
In this unique pathway, sympathetic preganglionic neurons bypass synapsing and directly stimulate the adrenal medulla.
What is the adrenal medulla pathway?
This type of reflex arc involves smooth muscle or glands instead of skeletal muscle.
What is a visceral reflex arc?
The somatic motor system uses this neurotransmitter, which is always stimulatory.
What is acetylcholine (ACh)?
Sympathetic fibers originate from these spinal cord regions.
What are the thoracic and lumbar regions?
These receptors are found on all postganglionic neurons and are always stimulatory.
What are nicotinic receptors?
What are terminal (intermural) ganglia?
The main integrative center of the ANS in the brain.
What is the hypothalamus?
What are somatic and autonomic fibers?
Parasympathetic ganglia are found in or near these.
What are visceral effector organs?
Norepinephrine binding to these receptors on the heart increases heart rate.
What are beta-1 (B1) adrenergic receptors?
Parasympathetic outflow arises from these two main regions.
What are the brainstem and sacral spinal cord?
This condition, often linked to overactive sympathetic activity, results in high blood pressure.
What is hypertension?