Chapter 15: Autonomic Nervous System Flashcards
Somatic Nervous System
Consists of:
Somatic motor neurons that innervate (or excitation) the skeletal muscles of the body.
Autonomic Nervous System
Part of the nervous system that regulates cardiac muscle, smooth muscle and glands.
Motor neurons excite and inhibit ongoing activities in the cardiac muscle, smooth muscle and gland tissue.
Visceral Effectors
Tissue: Cardiac muscle, smooth muscle and glands that is associated with visceral of the body.
Biofeedback
Monitoring device that displays information about the bodies function such as: HR, BP and enchants the ability to learn conscious control.
The ANS is somewhat dependent on higher centers.
Interoceptors
Sensory receptors located in blood vessels, visceral organs, muscle and nervous system that monitors conditions in the internal environment.
2 Main Branches of ANS
- Sympathetic nervous system: promotes fight or flight
- Parasympathetic nervous system: promotes rest and digest
Duel Innervation
Arrangement of the ANS branches where most organs receive nerves from both divisions.
3rd Division of ANS
Enteric Nervous System.
Operates involuntary but can be regulated by other divisions of ANS.
Contains: sensory neurons, interneurons, motor neurons that extend most of the length of the GI tract.
Can integrate information from sensory neurons while providing uncut to motor neurons .
Autonomic Ganglion
Collection of neuronal cell bodies in the CNS.
2 major groups:
1. Sympathetic ganglia
2. Parasympathetic ganglia
Chromaffin Cells
Specialized cells in adrenal medulla. In some autonomic pathways, the first motor neuron will extend to this type of cell.
With stimulation by sympathetic Preganglionic neurons, these cell release a mixture of catecholamines hormones: about 80% epinephrine, 20% norepinephrine and a trace of dopamine. These hormones circulate throughout the body.
Sensory Input SNS
From somatic senses and special senses
Sensory Input ANS
Mainly from interoceptors, some from somatic senses and special senses.
Control of Motor Input SNS
Voluntary control from cerebral cortex
contributions from basal ganglia, cerebellum, brain stem and spinal cord.
Control of Motor Output ANS
Involuntary control from hypothalamus, limbic system, brain stem and spinal cord.
Motor Neuron Pathway
One neuron pathway: somatic motor neuron extending from CNS synapse directly with effector,
Motor Neuron Pathway ANS
Usually 2 pathways
1. Preganglionic neurons extending from CNS synapse with in autonomic ganglion and extending from ganglion synapse with visceral effector.
2. Preganglionic neurons may extend from CNS to synapse with chromaffin cells of adrenal medulla.
Neurotransmitter and Hormones SNS
All somatic motor neurons release only ACh.
Neurotransmitters and Hormones ANS
All sympathetic and parasympathetic Preganglionic neurons release ACh.
Effectors SNS
Skeletal Muscle
Effectors ANS
Smooth muscle, cardiac muscle and glands
Responses SNS
Contraction of skeletal muscle
Responses ANS
Contraction or relaxation of smooth muscle.
Increased or decreased rate and force of contraction of cardiac muslce
Increased or decreased secretions of glands.
Preganglionic Neurons of Sympathetic Division
Axons are known as : thoracolumbar outflow
Neurons have their cell bodies in the lateral horns of the gray matter in the 12 thoracic segments and the first 2 lumbar segments of the spinal cord.
An axon may synapse with ganglion it reaches first.
An axon may travel to a higher or lower ganglion before synapsing with postganglionic neurons.
The axons of incoming neurons pass up or down from ganglion to ganglion in the sympathetic trunk.
Preganglionic Neurons Parasympathetic Division
Axons here are known as : craniosacral outflow
There are no autonomic nerve cell bodies in the cervical segment of spinal cord.
Neurons are located in the nuclei of 4 cranial nerves in brainstem III, VII, IX, X and in gray matter of the 2nd to 4th sacral segments of the spinal cord.
Axons of parasympathetic Divison pass to terminal ganglia near or within a visceral effector.
Parasympathetic Divison of ANS
Also known as craniosacral division
Distributed is limited mainly to head and viscera of thorax, abd, pelvis and some blood vessels.
White and gray rami are not present.
Consists of 2 motor neurons.
Neurotransmitter Preganglionic neurons releases ACh
Rest and digest effects
Muscarinic ACh receptors result in decreased HR and force of contractions.