Week 6 // Autonomic Nervous System Flashcards
What is a sensory neuron?
Sensory neurons are related to touch, pain, temperature, and proprioception (sense of self position), sight, hearing, taste, smell and equilibrium.
What is a motor neuron?
Motor neurons innervate skeletal muscles
What is the somatic nervous system?
The somatic nervous system includes sensory and motor neurons. Sensory neurons are related to touch, pain, temperature, and proprioception (sense of self position), sight, hearing, taste, smell and equilibrium. Motor neurons innervate skeletal muscles
What is the autonomic nervous system?
The autonomic nervous system receives input from sensory receptors located in organs, blood vessels, muscles and the nervous system.
The axon of the somatic motor neuron
The axon of a single, myelinated somatic motor neuron extends from the central nervous system to the skeletal muscle fiber it innervates
Spinal cord —- somatic motor —–effector (skeletal muscle)
The axon of the somatic motor neuron
The axon of a single, myelinated somatic motor neuron extends from the central nervous system to the skeletal muscle fiber it innervates
Spinal cord —- somatic motor —–effector (skeletal muscle)
UNMyELATED *
Most autonomic motor pathways consist of two motor neurons in series.
A preganglionic neuron has its cell body in the central nervous system and the axon extends to an autonomic ganglion.
A postganglionic neuron has its unmyelinated axon extending from the ganglion to the effector
autonomic ganglion
neurotransmitter
effectors can be
smooth muscles, cardiac muscles, glands
somatic neuron pathway axon has how many neurons?
one neuron
autonomic nervous system has
two neuron - post-ganlioonic pre ganglionic (release neuron transmitter directly to gland)
The autonomic nervous system is divided into two divisions *
The sympathetic nervous system is often referred to as the fight-or-flight division because its stimulation leads to increased alertness and metabolism to be ready for an emergency.
The parasympathetic nervous system is often referred to as the *
The parasympathetic nervous system is referred to as the rest-and-digest division as its stimulation slows down most body activity.
control of motor output ANS and somatic
Control of motor output Somatic
Fight or flight
Voluntary control from cerebral cortex, with contributions from corpus striatum, cerebellum, brainstem, and spinal cord.
Control of motor output ANS
rest and digest
Involuntary control from hypothalamus, limbic system, brainstem, and spinal cord; limited control from cerebral cortex.
preganglionic
Each division of the autonomic nervous system has two motor neurons: First is the The preganglionic (cell body in the brain or spinal cord)
postganglionic
Each division of the autonomic nervous system has two motor neurons: postganglionic (cell body and dendrites located in an autonomic ganglion where it synapses with preganglionic axons)
where are the preganglion neurons? Dont need to remember
In the sympathetic division, the cell bodies of preganglionic neurons are in the lateral horns of the gray matter in the 12 thoracic and first 2 or 3 lumbar segments
two type of Autonomic ganglia *
There are two types of autonomic ganglia:
Sympathetic
Parasympathetic
Sympathetic trunk ganglia
Lie in a vertical row on either side of the vertebral column
Prevertebral ganglia
Lie anterior to the vertebral column and close to the large abdominal arteries
After axons of sympathetic preganglionic neurons enter sympathetic trunk ganglia, they may connect with postganglionic neurons in one of 4 ways. (photo round circle middle) (no worry)
- An axon may synapse with postganglionic neurons in the first ganglion it reaches.
- An axon may ascend or descend to a higher or lower ganglion before synapsing with postganglionic neurons.
- An axon may continue, without synapsing, through the sympathetic trunk ganglion to end at a prevertebral ganglion and synapse with postganglionic neurons.
- An axon may also pass, without synapsing, through the sympathetic trunk ganglion and a prevertebral ganglion and then extend to the adrenal medullae.
abdomen autonomic plexus (not tested)
The abdomen and pelvis contain major autonomic plexuses which are often named after the artery along which they are distributed
These include the celiac (solar) plexus, the superior mesenteric plexus, the inferior mesenteric plexus, the renal plexus and the hypogastric plexus
sympathetic trunk ganglion *
Cell bodies of the sympathetic preganglionic neurons are part of the lateral gray horns of all thoracic segments and of the first two lumbar segments of the spinal cord
The paired sympathetic trunk ganglia are anterior and lateral to the vertebral column
Usually, there are 2 cervical, 11 or 12 thoracic, 4 or 5 lumbar, 4 or 5 sacral sympathetic trunk ganglia and 1 coccygeal ganglion
Cell bodies of the parasympathetic preganglionic neurons are located in (not tested)
nuclei in the brain stem and in the lateral gray matter of the 2nd through 4th sacral segments of the spinal cord
Cranial parasympathetic outflow extends from the brain stem in 4 cranial nerves
Sacral parasympathetic outflow extends from the 2nd through 4th sacral spinal nerves
When sympathetic input increases,
parasympathetic input decreases and vice versa
parasympathetic input increases
sympathetic input decrease (balanced by hypothalamus)
Functions such as heart rate and force of ventricular contraction, blood pressure and blood vessel diameter are controlled by autonomic reflexes that occur when nerve impulses pass through *
an autonomic reflex arc
When parasympathetic input increases
sympathetic input decrease (balanced by hypothalamus)
Autonomic Dysreflexia
Exaggerated response of the sympathetic nervous system occurring in 85% of individuals with spinal cord injury at or above T6.
If untreated, can cause seizures, stroke or heart attack.
Raynaud’s Phenomena
Occurs due to excessive sympathetic stimulation of smooth muscle in arterioles of digits.
Vasoconstriction leads to numbness and ischemia in digits.
