Autonomic Nervous System (ANS) (How innervation affects or does not affect…
Autonomic Nervous System (ANS)
Parasympathetic nervous system
Active when you are at rest or digesting.
Nerves originate in the cranial and sacral regions.
Ganglia in or close to visceral organ served; therefore, these have long preganglionic axons and short postganglionic axons.
All axons, preganglionic and postganglionic release Ach.
LImited branching of fibers.
Sympathetic nervous system
Active when you are excited, scared, exercising or embarrassed. Known as the "flight or fight" response.
Originates at the thoracic and lumbar region
Ganglia are close to the CNS along the vertebral column; therefore, they have short preganglionic axons and long postganglionic axons.
All preganglionic axons release ACh while most postganglionic axons release norepinephrine.
Fibers branch profusely.
Compare and contrast Autonomic and Somatic Nervous Systems- Both are part of the motor division of the peripheral nervous system. Mainly differ in innervation; somatic targets skeletal muscle and have one neuron pathways, synapse are at neuromuscular junctions. Autonomic targets smooth and cardiac muscle and glands with two neuron pathways. Synapse are in ganglion. Both Somatic motor division and sypathetic division release the neurotransmitter acetylcholine. The parasympathetic division releases norepinephrine.
How innervation affects or does not affect major structures in the body.
Sympathetic-increases heart rate and force of contraction. Affects the SA node.
Parasympathetic-decreases heart rate.
Airways of the lungs
Sympathetic-decrease activity of glands and smooth muscle. Constrict sphincters.
Parasympathetic- increases activity of glands and smooth muscle. Relaxes sphincters.
Accessory digestive organs (salivary glands and liver)
Sympathetic-decrease activity of the salivary glands and signal the liver to release glucose.
Parasympathetic-increases activity of the salivary glands. No effect on the liver.
Iris of the eye
Sympathetic-dilates the pupil
Parasympathetic-constricts the pupil
Lens of the eye
Sympathetic- change lense for distance vision using the capillary body
Parasympathetic-changes lens for near vision.
Sympathetic-constrict some blood vessels to increase blood pressure. Abdominal organs and skin dilate vessels to brain, skeletal muscles and the ehart.
Parasympathetic-little to no effect on systemic blood vessels. May have vasoconstriction of coronary vessels.
Sympathetic-secretes epinephrine and some norepinephrine enter the blood stream and enhance the sympathetic response to a threat.