Autonomic Nervous System – Practice Flashcards

200 question-and-answer flashcards covering anatomy, physiology, neurotransmitters, divisions, control centers, and functions of the autonomic nervous system.

What two main divisions make up the autonomic nervous system (ANS)?

The sympathetic division and the parasympathetic division.

Which branch of the nervous system provides voluntary control of skeletal muscles?

The somatic nervous system.

Which branch of the nervous system innervates glands, smooth muscle, and cardiac muscle?

The autonomic nervous system (ANS).

What is the primary functional slogan for the sympathetic division?

"Fight or flight."

What is the primary functional slogan for the parasympathetic division?

"Rest and digest."

Where are preganglionic neuron cell bodies of the sympathetic division located?

In the lateral gray horns of spinal cord segments T1–L2 (thoracolumbar region).

Where are preganglionic neuron cell bodies of the parasympathetic division located?

In the brainstem nuclei and the sacral spinal cord segments S2–S4 (craniosacral region).

How many neurons are in the efferent pathway of the autonomic nervous system?

A two-neuron chain (preganglionic neuron and postganglionic neuron).

What neurotransmitter is released by all somatic motor neurons?

Acetylcholine (ACh).

Is the effect of acetylcholine on skeletal muscle always stimulatory or inhibitory?

Always stimulatory.

Which neurotransmitters can be released by postganglionic autonomic neurons?

Acetylcholine (ACh) or norepinephrine (NE).

What term describes neurons that release acetylcholine?

Cholinergic fibers.

What term describes neurons that release norepinephrine?

Adrenergic fibers.

Are parasympathetic preganglionic fibers long or short?

Long.

Are parasympathetic postganglionic fibers long or short?

Short.

Are sympathetic preganglionic fibers long or short?

Short.

Are sympathetic postganglionic fibers long or short?

Long.

Where are parasympathetic ganglia typically located?

In or near the walls of visceral effector organs.

Where are sympathetic ganglia typically located?

Close to the spinal cord in the sympathetic trunk or collateral ganglia.

What cranial nerve carries about 90 % of all preganglionic parasympathetic fibers?

The vagus nerve (cranial nerve X).

Which two autonomic divisions exhibit antagonistic control over the heart?

The sympathetic and parasympathetic divisions.

What is dual innervation?

The phenomenon where most visceral organs receive nerve fibers from both sympathetic and parasympathetic divisions.

Name an organ that receives only sympathetic innervation.

Most blood vessels (also acceptable: sweat glands or arrector pili muscles).

What is sympathetic tone?

The continuous partial constriction of blood vessels maintained by sympathetic nerve activity.

How does increased sympathetic activity affect blood vessel diameter?

It causes vasoconstriction.

How does decreased sympathetic activity affect blood vessel diameter?

It causes vasodilation.

Which division of the ANS increases heart rate?

The sympathetic division.

Which division of the ANS decreases heart rate?

The parasympathetic division.

Which division of the ANS dilates the pupils?

The sympathetic division.

Which division of the ANS constricts the pupils?

The parasympathetic division.

What is the overall metabolic effect of sympathetic stimulation on the liver?

It triggers the liver to release glucose into the bloodstream.

What autonomic effect occurs on respiratory bronchioles during sympathetic activation?

Bronchodilation (airway dilation).

Which neurotransmitter has longer-lasting effects in the body, ACh or NE?

Norepinephrine (NE).

Why are parasympathetic effects generally short-lived?

Because acetylcholine is rapidly broken down by acetylcholinesterase.

Which endocrine organ releases epinephrine and norepinephrine into the blood during sympathetic activation?

The adrenal medulla.

What name is given to parasympathetic ganglia that lie within the target organ wall?

Intramural ganglia.

What name is given to parasympathetic ganglia that lie very close to the target organ?

Terminal ganglia.

Which cranial nerve carries parasympathetic fibers to the eye for pupillary constriction and lens bulging?

The oculomotor nerve (cranial nerve III).

Which cranial nerve carries parasympathetic fibers to the nasal and lacrimal glands?

The facial nerve (cranial nerve VII).

Which cranial nerve carries parasympathetic fibers to the parotid salivary glands?

The glossopharyngeal nerve (cranial nerve IX).

Which spinal cord segments give rise to parasympathetic sacral outflow?

S2–S4.

The cell bodies of sympathetic preganglionic neurons reside in which specific spinal cord structure?

The lateral gray horns.

What structure does a sympathetic preganglionic axon use to enter the sympathetic trunk?

The white ramus communicans.

What structure does a sympathetic postganglionic axon use to re-enter a spinal nerve?

The gray ramus communicans.

Which term describes a chain of paravertebral ganglia located on each side of the vertebral column?

The sympathetic trunk (or sympathetic chain).

What are splanchnic nerves?

Sympathetic preganglionic fibers that pass through the sympathetic trunk without synapsing and form nerves to collateral ganglia in the abdomen or pelvis.

Which autonomic division stimulates sweat gland secretion?

The sympathetic division.

Which autonomic division stimulates increased digestive glandular activity?

The parasympathetic division.

What brain region is considered the main integrative center of autonomic nervous activity?

The hypothalamus.

Which part of the brain stem contains centers that regulate heart rate and blood vessel diameter?

The medulla oblongata.

Which midbrain structure controls the pupillary light reflex?

The midbrain (specifically nuclei controlling cranial nerve III).

Name two visceral reflexes controlled at the spinal cord level that can be consciously overridden.

Defecation and micturition reflexes.

Which division of the ANS dominates under non-stressful conditions?

The parasympathetic division.

Which division of the ANS is dominant during exercise?

The sympathetic division.

What is the effect of sympathetic stimulation on salivation?

It decreases salivation.

What is the effect of parasympathetic stimulation on salivation?

It increases salivation.

How does sympathetic activity affect blood flow distribution?

It shunts blood toward skeletal muscles, heart, and brain and away from digestive organs and skin.

What effect does sympathetic stimulation have on sweating?

It increases sweat production to aid cooling.

How does parasympathetic activity influence pupil size?

It constricts the pupils (miosis).

Which autonomic division increases blood clotting ability?

The sympathetic division.

What is the term for nerve fibers that stimulate arrector pili muscles?

Sympathetic postganglionic fibers (cholinergic in this special case).

Which specific receptor type determines whether NE causes excitation or inhibition in a target organ?

The type of adrenergic receptor present (α or β subtypes).

What are the two main chemical classes of autonomic neurotransmitter receptors?

Cholinergic receptors and adrenergic receptors.

Which enzyme degrades acetylcholine in the synaptic cleft?

Acetylcholinesterase.

Why can sympathetic effects be body-wide and long-lasting?

Because NE is inactivated slowly and adrenal medullary hormones circulate in the blood for prolonged periods.

Which autonomic division stimulates liver glycogenolysis (glucose release)?

The sympathetic division.

Which autonomic division promotes energy storage (glycogenesis) in the liver?

The parasympathetic division.

Which division of the ANS decreases urinary output by constricting renal blood vessels?

The sympathetic division.

Which division of the ANS stimulates bladder contraction leading to urination?

The parasympathetic division.

What cardiovascular parameter is chiefly regulated by sympathetic tone?

Systemic blood pressure.

Which autonomic division increases respiratory rate and bronchiole diameter?

The sympathetic division.

Which autonomic division predominates in controlling gastrointestinal motility and secretions?

The parasympathetic division.

What effect does parasympathetic stimulation have on heart contractility?

It has little direct effect on contractility but slows heart rate; overall cardiac output decreases.

How do sympathetic impulses affect the adrenal medulla?

They stimulate the adrenal medulla to secrete epinephrine and norepinephrine.

Which division of the ANS causes hair to stand on end (piloerection)?

The sympathetic division.

Which autonomic division would be primarily responsible for decreased immune system activity during stress?

The sympathetic division.

What term describes a persistent, background level of sympathetic activity?

Sympathetic tone.

Which cranial nerve carries parasympathetic fibers that control lacrimal gland secretion?

The facial nerve (cranial nerve VII).

What is the functional result of sympathetic stimulation on the digestive tract sphincters?

Sphincters contract, slowing or stopping passage of intestinal contents.

Which autonomic division initiates erection of the penis and clitoris?

The parasympathetic division (via sacral outflow).

Which autonomic division triggers ejaculation and vaginal contractions?

The sympathetic division.

What central nervous system structure links emotional states to autonomic responses?

The limbic system acting through the hypothalamus.

How many sympathetic trunks run alongside the vertebral column?

Two, one on each side.

What does the term "thoracolumbar outflow" refer to?

The origin of sympathetic preganglionic fibers from thoracic and lumbar spinal segments (T1–L2).

What does the term "craniosacral outflow" refer to?

The origin of parasympathetic preganglionic fibers from cranial nerves and sacral spinal cord segments S2–S4.

Which autonomic division uses terminal ganglia?

The parasympathetic division.

Which autonomic division uses collateral (pre-vertebral) ganglia such as the celiac or superior mesenteric?

The sympathetic division.

What effect does sympathetic stimulation have on blood glucose levels?

It elevates blood glucose levels.

What is an example of a sympathetic collateral ganglion?

The celiac ganglion (also acceptable: superior mesenteric or inferior mesenteric ganglion).

Which portion of the ANS can be consciously influenced via biofeedback and meditation, though indirectly?

Both divisions can be influenced indirectly through cerebral cortex modulation of hypothalamic centers.

Name a physiologic parameter controlled by hypothalamic autonomic centers.

Body temperature (also acceptable: water balance, blood pressure, heart activity, endocrine function).

What is the role of the medullary cardiovascular center?

To regulate heart rate and blood vessel diameter.

Which autonomic division typically dominates the ciliary muscle for near vision accommodation?

The parasympathetic division.

What effect does sympathetic activation have on the ciliary muscle?

It relaxes the ciliary muscle, favoring far vision.

Which autonomic division promotes glycogen synthesis after a meal?

The parasympathetic division.

Which division of the ANS enhances mental alertness during stress?

The sympathetic division.

How is body temperature lowered by sympathetic activation?

Through increased sweating and vasodilation of skin vessels (in humans, mostly sweating).

What is a primary effect of parasympathetic stimulation on the lungs?

Bronchoconstriction and increased bronchial secretions.

What cortical area can modulate ANS activity via the limbic system?

The cerebral cortex, especially parts of the frontal lobe and association areas.

How does the ANS help restore homeostasis after exercise?

Parasympathetic activity increases and sympathetic activity decreases, lowering heart rate, restoring digestion, and conserving energy.