F3. Autonomic Nervous System Flashcards
what does the central nervous system include?
brain and spinalcord
sensory nerves?
travel to the spinal cord from periphery (e.g. skin) - afferent fibres
motor nerves?
travel away from the spinal cord to the muscle: somatic efferent system. Voluntary control of skeletal muscle
autonomic nerves?
– unconscious physiological control of organ systems
drug targets of CNS?
Drugs for CNS disorders, pain relief
Drug targets for peripheral nervous sytem?
sensory nerves- pain relief, local anaesthetics
motor nerves- Muscle weakness (myasthenia gravis) Muscle paralysis during operations
autonomic system- Many common drugs
Cardiovascular, GI, respiratory, urinary tract, OTCs
Divisions of the autonomic system?
sympatheic nervous system (prepares for activity), parasympathatic nervous system (stimulates visceral processes). They usually work together, not opposing actions
the enteric nervous system?
Local neuronal network co-ordinating the GI tract, with input from PNS and SNS
Describe how the sympathetic and parasympathetic uses two neurone?
the first neurone makes connection ( a synapse) with the second, in a group of nerve cell bodies known as ganglion.
-preganglionic neuron fromCNS
-post ganglionic neuron innervates the target tissue (ONE NOTE)
how is adrenaline released?
subset of pre ganglionic SNS fibres synapse with the adrenal medulla- releases adrenaline into circulation (ONE NOTE)
what are the spinal cord division? (top to bottom)
medullary, cervical, thoracic, lumbar, sacral (one note)
Describe somatic motor efferent neurone
single motor neurone innervating voluntary skeletal muscle
what kind of muscle does the somatic nervous system innervate?
skeletal muscle for deliberate motion
what kind of muscle does the autonomic nervous system innervate?
smooth and cardiac muscle for involuntary motion
Describe neurones in the somatic nervous system
-heavily myelinated
-singular
-acetylcholine
-triggers a stimulatory response
Describe neurones in the autonomic nervous system
-lightly or non-myelinated
-two neurone chain: preganglionic and postganglionic
-triggers a stimulatory or inhibitory response
Describe the sympathetic nervous system anatomy
-fibres originate in the thoracic and lumbar region
-synapse in paired (two sets) paravertebral ganglia: bilateral connections to periphery (e.g blood vessels)
-synapse in unpaired (one set, midline) prevertebral ganglia
-synapse in adrenal medulla (preganglionic neurone straight to adrenal medulla)
-ganglia near spinal cord
ONE NOTE
What does the sympathetic nervous system trigger?
-dilates pupil (more light)
-inhibits salivation
-relaxes bronchi
-accelerates heart beat
-inhibits peristalsis and secretion
-stimulates glucose production and release
-secretion of adrenaline and noradrenaline
-inhibits bladder contraction
-stimulates orgasm
-blood vessels constrict and relax to direct blood to working muscles (vascular shunt)
Describe the length of neurones in the sympathetic nervous system
-short preganglionic neurones
-long postganglionic neurones
Describe neurone lengths in the parasympathetic nervous system
-long preganglionic neurones
-short postganglionic neurones
parasympathetic ganglia are located in or close to target organs
Describe the parasympathetic nervous system anatomy
-fibres originate in the medulla (brain) and sacral region
-parasympathetic ganglia are located in or close to target organs
-the vagus (10th cranial nerve, X) provides parasympathetic innervation of heart, lungs, pancreas and GI tract
What responses does the parasympathetic system trigger?
-constricts pupils
-stimulates saliva flow
-constricts bronchi
-slows heartbeat
-stimulates peristalsis and secretion
-stimulates bile release
-contracts bladder
what are the opposing actions between the PNS and SNS?
heart rate, airway tone, GI motility
what are single system controls in the PNS and SNS?
liver (sympathetic), GI secretion (parasympathetic)
what are coordinated effects between the PNS and SNS?
salivary secretion of fluid (parasympathetic) and enzymes (sympathetic)
what neurotransmitters and hormone is involved in the ANS?
-neurotransmitter: acetylcholine and noradrenaline
-hormone: adrenaline
-these are all biogenic amine due to structure (one note)
what are the two acetylcholine (ACh) receptors?
-nicotinic receptors, ligand gated ion channels, “fast for PNS and SNS” (2 subtypes)
-muscarinic receptors, Gprotein coupled receptors- “flexible” (5 subtypes)
what does noradrenaline and adrenaline bind to?
adrenoreceptors which are G protein coupled receptors. There are 5 subtypes (a1, a2, B1, B2, B3
how does acetylcholine work in parasympathetic neurones?
-In postganglionic parasympathetic neurones- ACh activates muscarinic receptors on targets ONE NOTE
-Acetylcholine is the main neurotransmitter in the parasympathetic nervous system
Describe noradrenaline and adrenaline in the sympathetic nervous system
-NA and adrenaline are the main mediators
-most postganglionic sympathetic neurones transmit noradrenaline, activating adrenoreceptors
-tissue adrenoreceptors are activated by noradrenaline or circulating adrenaline
-sympathetic innervation of sweat glands uses acetylcholine/ muscarinic receptors
what main receptor is involved in the heart?
B1- AR
what main receptor is involved blood vessels?
a1- AR
B2- AR
what main receptor is involved in the lungs?
B2- AR
Describe salbutamol
selective for B2-adrenoreceptors in the lung over B1-adrenoreceptors in the heart
what are the two divisions of the peripheral nervous system?
-sensory or afferent division (to CNS)
-motor or efferent division (from CNS)
Describe the somatic nervous system
-innervates skeletal muscle for deliberate motion
-heavily myelinated and singular neurones
-acetylcholine
-stimulatory response
Describe the autonomic nervous system
-innervates smooth and cardiac muscle for involuntary motion
-lightly or non myelinated two neurone chain (preganglionic and postganglionic)
-acetylcholine or norepineprine
-stimulatory or inhibitory response
Describe muscarinic receptors
-mainly found in the parasympathetic nervous system on the surfaces of smooth muscles, cardiac muscles and glands
-G protein coupled receptor
-function: regulate involuntary processes
Describe nicotinic receptors
-found in the autonomic ganglia, the neuromuscular junction (where nerves meet muscles) and the central nervous system
-ligand gated ion channel
-function: stimulate muscle contractions and transmit signals between neurones
what are the differences between adrenergic receptors and muscarinic receptors?
-adrenoreceptors respond to adrenaline and noradrenaline
-muscarinic receptors respond to acetylcholine
-adrenoreceptors found in sympathetic nervous system
-muscarinic receptors found in parasympathetic nervous system
-both G coupled protein receptors
when is acetylcholine used in the sympathetic pathway?
in control of sweat glands and blood vessels
