Autonomic Nervous System

Sympathetic & Parasympathetic Divisions

Unit 12 Synopsis

In this unit, we will delve deeper into the autonomic nervous system, the parasympathetic and sympathetic systems, and reflexes. We will do the lab to explore ANS responses to stressful situations.

Deception Detection

Para-

Near

splanch-

viscera

Post-

After

Auto-

Self

Pre-

Before

Ram(i)-

Branch

-nomos

law, govern

Affixes

Overview

The autonomic nervous system has involuntary control of the body.

Controls mechanisms such as cardiac and smooth muscle tissue in the gastrointestinal tract.

Effector organs include glands, smooth, and cardiac muscle
Broken down into:
- parasympathetic and sympathetic nervous systems

Composed of ganglia that serve as centers between the
- Preganglionic neurons: transmit signals from the CNS to the ganglion
- Postganglionic neurons: transmit signals from ganglia to effects

Physiology

NT

ACh: includes all preganglionic axons and parasympathetic postganglionic axons; released by cholinergic axons

Norepinephrine: includes most sympathetic postganglionic axons; released by adrenergic axons. Effectors break down slower than ACh therefore effects last longer.

Receptors

Cholinergic: nicotinic and muscarinic

Adrenergic: respond to epinephrine and norepinephrine

Parasympathetic Nervous System
(Craniosacral division)

"Rest and Digest"

Functions

Allows the body to perform normal daily functions, such as digestion, reproduction, waste excretion, and fight infections
SLUDD: salivation, lacrimation, urination, digestion, defecation
Decrease heart rate, bronchoconstriction (decrease airway diameter), constriction of pupil

Anatomy

Ganglia are found away from the spine, near or in the effector organs
There are 5 pairs of terminal ganglia.
Craniosacral location: originate from the base of the brain and slightly superior to the coccyx.

Cranial nerves

I. Olfactory (sensory)

II. Optic (sensory)

III. Oculomotor (motor)

IV. Trochlear - controls single muscle of the eye (cross eyes) (motor)

V. Trigeminal - innervates face and jaw muscles (both)

VI. Abducens - stimulates some eye muscles (motor)

VII. Facial - enable facial expressions (both)

VIII. Auditory (sensory)

IX. Glossopharyngeal - tongue and pharynx (both)

X. Vagus - digestion, heart rate, respiration, reflex actions (coughing, sneezing, swallowing) (both)

XI. Spinal accessory - move head and shoulders (motor)

XII. Hypoglossal - swallow and talk (motor)

Sympathetic Nervous System
(Thoracolumbar division)

"Fight or flight"

Functions

Stimulates heart rate, intestinal sphincter constriction, urinary bladder relaxation, dilation of pupils, and sweat secretion.
Inhibits: stomach and intestinal movements, and bronchial muscles

Anatomy

Ganglia are lateral to the ventral surface of spinal cord from second cervical vertebra to coccyx
White ramus communicans - preganglionic neuron axons have a small diameter and myelin sheath
Usually synapse with multiple postganglionic neurons
Routes of exit for sympathetic axons
- Spinal nerves: innervate sweat glands, smooth muscle in blood vessels in skin and bones, and arrector pili
- Sympathetic nerves: innervate cardiac muscle, smooth muscle of esophagus and lungs
- Splanchnic nerves: innervate abdominopelvic structures
- Innervation of adrenal medulla