Autonomic Nervous System Flashcards

A set of vocabulary flashcards covering key Autonomic Nervous System concepts from the notes.

Autonomic Nervous System (ANS)

-innervates which muscles?

-voluntary or involuntary

Innervates smooth muscle, cardiac muscle, and glands; operates involuntarily to adjust organ activities for bodily function.

2 divisions of the nervous system?

CNS and PNS

CNS divisions?

Brain and spinal cord

PNS divisions?

Motor neurons and Sensory Neurons

-motor neurons

1) Somatic nervous system (VOLUNRARY)

2) Autonomic Nervous System (involuntary)

Autonomic nervous system divisions

Sympathetic and parasympathetic

Dual Innervation

Two divisions (sympathetic and parasympathetic) innervate the same organs with opposite effects to regulate function.

Sympathetic nervous system examples

Mobilizes the body for activity (fight or flight); activated by the 4 E’s; increases heart rate, sweating, pupil dilation; directs blood to skeletal muscles and heart; bronchioles dilate; liver releases glucose.

Parasympathetic nervous system

Conserves energy (rest & digest); calms organs; promotes digestion, diuresis, defecation; lowers BP/HR/RR; GI activity high; pupils constricted; majority of parasympathetic fibers via the vagus nerve (CN X, ~90%).

4 E’s

Exercise, Excitement, Emergency, Embarrassment; triggers sympathetic activation.

3 D’s

Digestion, Diuresis, Defecation; promoted by parasympathetic activity.

Vagus nerve (CN X)

Comprises ~90% of parasympathetic nerve fibers; major conduit for parasympathetic signals to thorax and abdomen.

Pupillary response (parasympathetic vs sympathetic)

Parasympathetic constricts pupils; Sympathetic dilates pupils.

Bronchioles (sympathetic effect)

Dilates airways to improve airflow during stress.

Bronchioles (parasympathetic effect)

Constricts airways during rest.

Heart rate control

Sympathetic accelerates heartbeat; Parasympathetic slows heartbeat.

Blood flow during activity

Sympathetic activation directs blood to skeletal muscles and heart; vasodilation in those tissues.

Glycogen to glucose conversion

Sympathetic stimulation converts glycogen to glucose in the liver to supply energy.

Neurons originate where?

spinal cord or brain stem

How many neurons needed for each pathway in divisions?

2 neurons needed for each

pathway in ANS (both

divisions)

• Neuron 1: spinal

cord/brainstem → ganglion

(preganglionic neuron)

• Neuron 2: ganglion → effector

(postganglionic neuron

Preganglionic neuron

Originates in spinal cord or brainstem and synapses in a ganglion.

Postganglionic neuron

Synapses in a ganglion and transmits signal to the effector organ.

Ganglia

Clusters of neurosomas; synaptic relay points in ANS; two neurons per pathway (preganglionic and postganglionic).

Parasympathetic neurotransmitter

Acetylcholine (ACh) released from both preganglionic and postganglionic fibers; cholinergic.

Sympathetic neurotransmitters

Acetylcholine (ACh) from preganglionic to ganglion; Norepinephrine (NE) from postganglionic to effector; adrenergic fibers.

Adrenergic vs Cholinergic

Adrenergic receptors respond to NE/epinephrine; Cholinergic receptors respond to ACh.

Sympathetic hormones

Epinephrine and norepinephrine released from adrenal medulla into bloodstream; triggered by preganglionic ACh.

Parasympathetic neurotransmitter (ACh)

ACh released from both preganglionic and postganglionic fibers; cholinergic signaling.

Visceral (Autonomic) reflexes

Unconscious, automatic responses; receptor → afferent → integrating center (brainstem/hypothalamus/spinal cord) → efferent → effector.

Antagonistic control

Regulators have opposite effects on a system; allows precise control; different receptors explain varied responses.

Dual Innervation tone

Sympathetic tone and Parasympathetic tone describe baseline activity; usually one dominates to prevent haywire activity.

Origins of neurons (sympathetic vs parasympathetic)

Sympathetic: thoracolumbar (thoracic & lumbar). Parasympathetic: craniosacral (brainstem and sacral spine).

Ganglia

Ganglia (clusters of neurosomas) = synaptic connection points between neurons

Paravertebral ganglia

Sympathetic chain ganglia adjacent to the spinal cord; site of preganglionic to postganglionic synapse.

Collateral ganglia

Prevertebral ganglia in front of the vertebral column; receive preganglionic input to postganglionic neurons targeting abdominal organs.

Chronic stress effects

Chronic sympathetic overactivity can raise blood pressure, cause digestive problems, and suppress the immune system; parasympathetic activation mitigates these effects.

Physiological sigh

Breathing technique: double inhale with a small top-inhale, followed by a slow exhale; used to reduce sympathetic arousal.