ST8: Autonomic Nervous System Flashcards
prevertebral ganglia
celiac superior mesenteric aortico-renal inferior mesenteric hypogastric
the cell body of each preganglionic neuron lies in the ___ of spinal cord; its fibers passes through a ____ of the cord into the corresponding spinal nerve
intermediolateral horn
ventral root
- The sympathetic pathways that originate in the different segments of the spinal cord are not necessarily distributed to the same part of the body as the somatic spinal nerve fibers from the same segments.
- Instead, the sympathetic fibers from cord segment T1 generally pass up the sympathetic chain to terminate in the ___
- from T2 to terminate in the ____;
- from T3, T4, T5, and T6 into the ____;
- from T7, T8, T9, T10, and T11 into the ____;
- from T12, L1, and L2 into the ____.
- head
- neck
- thorax
- abdomen
- legs
parasympathetic fibers leave the CNS through ____; additional parasympathetic fibers leave the lowermost part of the spinal cord through the second and third sacral spinal nerves and occasionally the first and fourth sacral nerves
CN 3, 7, 9, 10
About 75 percent of all parasympathetic nerve fibers are in the ____, passing to the entire thoracic and abdominal regions of the body.
vagus nerves (cranial nerve X)
- Parasympathetic fibers in the third cranial nerve go to the ___. 2. Fibers from the seventh cranial nerve pass to the ____
- Fibers from the ninth cranial nerve go to the ___.
- pupillary sphincter and ciliary muscle of the eye
- lacrimal, nasal, and submandibular glands
- parotid gland
The sympathetic and parasympathetic nerve fibers secrete mainly one or the other of two synaptic transmitter substances, ____.
acetylcholine or norepinephrine
The fibers that secrete acetylcholine are said to be ___. Those that secrete norepinephrine are said to be ____
cholinergic
adrenergic
All preganglionic neurons are ___ in both the sympathetic and the parasympathetic nervous systems.
cholinergic
Either all or almost all of the postganglionic neurons of the parasympathetic system are also ____.
cholinergic
most of the postganglionic sympathetic neurons are ___
adrenergic
____ is called a parasympathetic transmitter and ____ is called a sympathetic transmitter
acetylcholine
norepinephrine
- Once acetylcholine is secreted into a tissue by a cholinergic nerve ending, it persists in the tissue for a few seconds while it performs its nerve signal transmitter function.
- Then it is split into an ____, catalyzed by the enzyme ___ that is bound with collagen and glycosaminoglycans in the local connective tissue.
- The choline that is formed is then transported back into the terminal nerve ending, where it is used again and again for synthesis of new acetylcholine.
- acetate ion and choline; acetylcholinesterase
After secretion of norepinephrine by the terminal nerve endings, it is removed from the secretory site in three ways:
- reuptake into the adrenergic nerve endings by an active transport process, accounting for removal of 50 to 80% of the secreted norepinephrine
- diffusion away from the nerve endings into the surrounding body fluids and then into the blood, accounting for removal of most of the remaining norepinephrine
- destruction of small amounts by tissue enzymes (one of these enzymes is ____, which is found in the nerve endings, and another is ____, which is present diffusely in the tissues).
- monoamine oxidase; catechol-O-methyl transferase
acetylcholine mainly activates 2 types of receptors
- muscarinic
2. nicotinic
receptors that use G proteins as their signaling mechanism, are found on all effector cells that are stimulated by the postganglionic cholinergic neurons of either the parasympathetic nervous system or the sympathetic system
muscarinic receptors
