Lecture 4. Pharmacology of the Peripheral Nervous System: Form and Function Flashcards
What makes up the central nervous system?
Brain & spinal cord
What makes up the peripheral nervous system?
All nerves outside the brain and spinal cord
What do afferent fibres carry?
Sensory information to the CNS
What do efferent fibres carry?
Signals from the CNS to the periphery
What does the ventral horn contain?
Somatic motor neurones
What does the lateral horn contain?
Spinal preganglionic neurones of autonomic nerve system
What is the active zone of a synapse?
Where neurotransmitter is released
How large are synaptic vesicles?
~40nm
What neurotransmitter is released from a synapse found in the somatic nervous system and where does it release the neurotransmitter?
Acetylcholine, into the skeletal muscle
What are preganglionic neurones?
Neurones that arise in the brain stem or lateral horn of the spinal cord and synapse with the postganglionic neurones
What are postganglionic neurones?
The cell bodies of which are contained within an autonomic ganglion (a collection of nerve cell bodies) that lies outside the CNS. The nerve endings of postganglionic neurones synapse with their effector cells in tissues that include visceral smooth muscle, cardiac muscle, vascular smooth muscle and exocrine glands
What neurotransmitter is released from all parasympathetic postganglionic neurones at the neuroeffector junction?
Acetylcholine
What is the neurotransmitter released from the majority of the postganglionic neurones of the sympathetic system?
Noradrenaline
What cells releases adrenaline?
Chromaffin cells of adrenal medulla
How can synapses be classified?
According to the transmitter released from the presynaptic neurone
What does cholinergic mean?
Transmission where the presynaptic neurone synthesises and releases acetylcholine (ACh)
What are cholinoceptors?
Receptors upon which ACh acts
What are nicotinic cholinoceptors (nAChR)?
Activated by ACh or the tobacco alkaloid nicotine but not by muscarine
What are muscarinic cholinoceptors (mAChR)?
Activated by ACh or the fungal alkaloid muscarine but not by nicotine
What does noradrenergic mean?
Transmission where synapses where the transmitter is noradrenaline
What are the two classes of adrenorecptor in the nervous system?
α-adrenoceptors and β-adrenoceptors
What type of channel and receptor are nicotinic cholinoceptors?
Ligand-gated ion channels - ionotropic receptors
What type of channel and receptor are muscarinic cholinoceptors and all subtypes of adrenoceptor?
G-protein-coupled receptors - metabotropic receptors
How many acetylcholine muscarinic receptors are there?
5
What activated GIRK channels?
β and γ subunits
What does the PNS regulate?
The activity of all peripheral organs through coordination with the CNS
What are the major divisions of the PNS?
Somatic nervous system - serves skeletal muscle
Enteric nervous system - serves the gut
Autonomic nervous systems - serves all other organs
What two systems are found in the autonomic nervous systems?
Sympathetic and parasympathetic nervous systems
What is the sympathetic nervous system predominantly concerned with?
“Fight or flight” response
What is the parasympathetic nervous system predominantly concerned with?
“Rest and digest” function
