Autonomic NS and Visceral Reflexes Flashcards
General Actions of the Autonomic Nervous System
Involuntary control of glands, cardiac muscle, and smooth muscle
Responsible for visceral reflexes
What is another name for the
Autonomic Nervous System?
What does it contrast?
Visceral Motor System (unconscious control)
Contrasts the Somatic Nervous System (conscious control)
What are Visceral Reflexes?
Unconscious, automatic, sterotyped responses to stimulation of viscera effectors to stimuli
ex. A rise in blood pressure triggers a reflexive decrease in heart rate
What are the two sub-divisions of the Autonomic Nervous System?
Sympathetic Division: (Battle-mode)
Parasympathetic Division: (Rest and Digest mode)
What is the Sympathetic Division and what does it do?
- “fight or flight” responses for increased physical activity
- Increases heart rate and pumps more blood to skeletal muscles
- Reduces blood flow to skin and GI tract
Describe the Parasympathetic Division
- “Rest and Digest” responses with calming effect
- Decreases heart rate
- Simulates digestive and waste elimination
What is the Autonomic Tone?
Balanced activity of both sympathetic and parasympathetic division
(will shift according to body’s needs)
2 Neural Pathways of the Autonomic System
Preganglionic Fibers:
- Neurosoma in brainstem or spinalcord
- Axon terminates in ganglion
Postganglionic Fibers:
- Neurosoma in ganglion
- Axon extends to target area
Comparison of Somatic and Autonomic NS
Effectors
Somatic: Skeletal Muscle
Autonomic: Glands, smooth, and cardiac muscle
Comparison of Somatic and Autonomic NS
Type of Control
Somatic: voluntary
Autonomic: involuntary
Comparison of Somatic and Autonomic NS
Efferent Pathways
Somatic:
One nerve fiber from CNS to effector, no ganglia
Autonomic:
Two nerve fibers from CNS to effector, synapse at a ganglion
Comparison of Somatic and Autonomic NS
Distal Nerve Endings
Somatic: Neuromuscular junctions
Autonomic: Varicosities (enlarged veins)
Comparison of Somatic and Autonomic NS
Effect on target cells
Somatic: Always excitatory
Autonomic: Excitatory or Inhibitory
Comparison of Somatic and Autonomic NS
Effect on Denervation
Somatic: Flaccid Paralysis
Autonomic: Denervation Hypersensitivity
Describe the Sympathetic process in the Thoracolumbar Division
Arises from thoracic and lumbar regions
Preganglionic fibers exit out of spinal cord via spinal nerves (T1 to L2) and attach to Sympathetic Chain Ganglia
Post-ganglionic fibers branch exit of Sympathetic Chain Ganglia to Cervical and Coccygeal areas (above T1 and below L2)
Describe the Preganglionic and Postganglionic fibers in the Sympathetic Division
Preganglionic fibers:
Enter ganglia through white communicating rami
Postganglionic Fibers: Unmyelinated
Leave ganglia by various routs including gray communicating rami
Sympathetic Postganglionic Fibers Pathways
Spinal Nerve Route
Supports sweat glands, arrector muscles, and blood vessels of skin and skeletal muscles
Sympathetic Postganglionic Fibers Pathways
Sympathetic Nerve Route
Supports iris, salivary glands, lungs, heart, thoracic blood vessels, esophagus
(supports mainly thoracic organs and some cranial organs)
Sympathetic Postganglionic Fibers Pathways
Splanchic Nerve Route
Supports liver, spleen, adrenal glands, stomatch, intestines, kidenys, urinary bladder, reproductive organs
(Supports abdominal and pelvic organs)
Where are the Adrenal Glands?
Superior to each kidney (kidney hats)
Adrenal Cortex
- Outer layer of the Adrenal Glands
- Secretes steriod hormones
Adrenal Medulla
- Inner part of the Adrenal Glands
- Modified Sympathetic Ganglion
- Secretes epinephrine and norepinephrine
Describe the Parasympathetic Process in the Cranial Sacral Division
Arises from Cranial and Sacral Regions
Preganglionic Fibers exit out of pons, medulla oblongata, S2 to S4 of spinal cord and reach over to their target organs and 4 cranial ganglions
(Have long Preganglionic Fibers and short Postganglionic Fibers)
Name the 4 Cranial Nerves and their functions
Oculomotor Nerve (III): Controls lens and pupils
Facial Nerves (IV): Controls tear, salivary, and nasal glands
Glossopharyngeal Nerve (IX): Controls salivary glands
Vagus Nerve (X): provides branches for heart, lungs, esophagus, and other organs
(Vagus nerve contains 90% of parasympathetic preganglionic fibers)S
