16. The Autonomic Nervous System Flashcards
Define efferent, in terms of neurones.
Neurone that carried signals from the brain or spinal cord to the periphery using motoneurone or autonomic neurones.
Define ganglion, in terms of neurones.
Collection of neuronal cell bodies in the peripheral nervous system.
What’s the difference between pre-ganglionic neurone and post-ganglionic neuron?
Neurone immediately proximal to the ganglion in pre and immediately distal to the ganglion in post.
What is the effector in the nervous system?
The target organ thorough which the nervous system exerts its actions.
What are the three sections of the nervous system according to the region?
Brain, spinal cord and nerves.
What are the two sections of the nervous system according to anatomical overview?
Grey matter and white matter.
What are the two sections of the nervous system according to general anatomical classification?
Central nervous system and peripheral nervous system, although they are not independent of one another.
What is the CNS characterised by?
Encasement of the cranium and vertebral column which are suspended in cerebrospinal fluid and are responsible for the sophisticated functions of the nervous system.
What five things make up the PNS?
Axons of cranial nerves, axons of spinal nerves, ganglia, nerve plexuses and enteric nervous system.
How can the nervous system be classified according to direction of signalling?
Afferent and efferent.
How can the efferent nervous system be classified by function?
Somatic and autonomic nervous systems.
What are the three classifications of the autonomic nervous system?
Sympathetic, parasympathetic and enteric.
What is the effector organ if the somatic nervous system?
Skeletal muscle.
When do somatic efferents get fully developed?
By puberty.
What is the layout of the somatic nervous system?
One neurone carries output and the efferent neurone terminates directly on the effector organ.
What came first, somatic or autonomic control?
Autonomic.
How does the autonomic nervous system control functions?
By the continuous output in two opposing systems.
What are the two general actions of the autonomic nervous system?
Constancy - establishes and maintains homeostasis of internal environments in the body through regulation of various systems of the body.
Intermittent change in bias - promotes excretory mechanism of the body as and when necessary and appropriate.
What are the effector organs of the autonomic nervous system?
Visceral organs, smooth muscle, secretory glands and cardiac muscle.
What is the general layout of the autonomic nervous system?
2 neurones in a pathway. One cell body in the CNS and one in the PNS.
What does over activity of the parasympathetic nervous system lead to?
Over activity leading to dilated blood vessels and shortage of substrate to the brain.
What does over activity of the sympathetic nervous system lead to?
Constriction of blood vessels and profound problems, e.g. shortage of substrate to tissues of the body.
What is the consequence of activity in the sympathetic nervous system?
Expenditure of energy, diversion of blood to muscles and heart, increase in heart rate, increase in blood pressure and reduced blood flor to GIT and skin.
Where can a sympathetic neurone synapse?
In chain at a level corresponding to level of origin, at a different level to origin or in paravertebral chain.
What are the two classes of adrenoceptors?
a and B receptors. Both can exercise presynaptic inhibition of the other.
What happens when the parasympathetic nervous system is active?
Reduces the heart rate, promotes digestion and other bodily functions and promotes sleep.
Define afferent.
Carried incoming signals from the periphery to the CNS using sensory neurones.
