0317 - Autonomic Nervous System - EG Flashcards
List some characteristics of the autonomic nervous system.
- operates subconsciously - is involuntary - modulates functions essential for maintaining life. - controlled by the hypothalamus. - has two main subdivisions: sympathetic and parasympathetic, which have complementary roles
What is the coin of phrase to describe the activity of the sympathetic nervous system? List some functions of the sympathetic nervous system.
“all or none” crisis response and the Four “f’s” - flight, fright, fight, and reproduction. accelerates the heart, relaxes airways, inhibits digestion, stimulates glucose release, inhibits salivation (dry mouth), promotes sweating (palms), dilates pupil, elevates upper eyelid, relaxes bladder to retain urine, stimulates orgasm, stimulates secretion of adrenaline/noradrenaline from adrenal medulla.
What is the coin of phrase to describe the activity of the parasympathetic nervous system? List some functions of the parasympathetic nervous system.
“rest and digest”slows the heart, constricts airways, stimulates digestion and defecation, stimulates salivation, inhibits sweat glands, constricts pupil, stimulates bladder for urination, stimulates sexual arousal.
What is the limbic system?
part of the brain that registers environmental cues - includes olfactory and hippocampal pathways, as well as emotional input, to directly influence the hypothalamus.
What is the main integration centre of the ANS?
the hypothalamus, integrates information from the limbic system, cerebral cortex, reticular formation of the brainstem, and spinal cord.
Were do the parasympathetic nerves arise from? The sympathetic nerves?
Parasympathetic is “craniosacral” from cranial nerves 3, 7, 9, and 10 as well as sacral 2-4. Sympathetic is “thoracolumbar” from T1 to L2.
How are the nerves of the ANS structured in comparison to the nerves of the somatic NS?
Nerves of the ANS have 2 cells to create a path between the CNS and effector target, a preganglionic neuron and a postganglionic neuron, whereas in the somatic nervous system there is only 1 cell between the CNS and effector target.
What neurotransmitter is released by pre-ganglionic neurones of the sympathetic and parasympathetic NS? What is the receptor?
Preganglionic neurons of both sympathetic and parasympathetic NS release acetylcholine which is the ligand for a nicotinic receptor on the post-synaptic membrane of postganglionic nerves and cells of the adrenal medulla.
What neurotransmitter is released by post-ganglionic neurones of the sympathetic and parasympathetic NS? What is the receptor?
The postganglionic neuron of the sympathetic NS releases noradrenaline to a adrenergic receptor (alpha and beta subtypes) on effector cell.The postganglionic neuron of the parasympathetic NS releases acetylcholine to be detected by a muscarinic receptor on effector cell.
What is the difference in activity of ACh as a neurotransmitter within the somatic NS to the ANS?
In the somatic ACh is always excitatory, and the ANS is excitatory in ganglion or in adrenal medulla, but in its parasympathetic postganglionic effect is either excitatory or inhibitory dependent on the post-synaptic receptor subtype.
Where do the cell bodies of sympathetic fibres lie within the spinal cord?
The lateral horn.
Describe the pathway options of a preganglionic neuron of the sympathetic NS as it leaves the spinal cord.
From the lateral horn leaves via the ventral motor root, mixes with other nerves in the ventral primary ramus, and exits into the white ramus communicans to enter the paravertebral ganglion. Can then either (1) synapse here at the level it has left the spinal cord, or (2) travel up/down the paravertebral chain to synapse in another division/level of the sympathetic chain, or exit without synapsing via the grey ramus communicans where other postganglionic will exit and (3) travel via to synapse at a pre-ganglionic ganglia such as the celiac ganglion (become greater splanchnic n), superior mesenteric ganglion (lesser splanchnic n), or inferior mesenteric ganglion (least splanchnic n), or travel to (4) synapse at the adrenal medulla.
What is the lowest ganglia of the paravertebral chain?
Ganglion impar
What are the three superior ganglia of the sympathetic NS?
the superior, middle, and inferior or “stellate” (to lungs and heart);
What is the ANS function of the adrenal gland?
Releases adrenalin and noradrenalin into the bloodstream to heighten and prolong sympathetic activation, by reaching cells not directly innervated.
