autonomic nervous system Flashcards
Autonomic nervious system graph
–> direction
{Higher brain centres: [Brain stem nuclei];
Brain stem nuclei: [Visceral afferents, Parasympathetic efferents, Sympathetic efferents];
Visceral afferents: [ENS];
Parasympathetic efferents: [ENS];
Sympathetic efferents: [ENS];
Enteric Nervous system (ENS): [Sensory neurones, Interneurons, Motor neurones]}
Walter Cannon
noticed autonomic nervous system
coined the term Homeostasis and fight or flight
Autonomic Nervous System
- Control smooth muscles, exocrine and endocrine secretions, and metabolic processes
- systems often drive organs in opposite directions
- Systems cooperate to maintain homeostasis
- flight or fight/ rest and digest are extremes
- if one system is inhibited, the other will dominate which can lead to threatening consequences
- Activation depends on experience, context, basal level
Parasympathetic receptors
Preganglion: Nicotinic
PostGanglion: muscarinic
Sympathetic receptors
PreGanglion: Nicotinic
PostGanglion: Adrenergic
Parasympathetic preganglion cell body locations
Medulla(III, VII, IX, X) and sacral spinal cord
-long axon
Sympathetic PreGanglioinic cell body locations
Thoracic and Lumbar Spinal cord
-shorter axon
Parasympathetic PostGanglionic Cell body locations
In Ganglia near innervated organ or tissue
-short axon
Sympathetic postganglionic cell body locations
Paravertebral chain ganglia or abdominal ganglia
-longer axon
Parasympathetic neurotransmitters
AcetylCholine
- nicotinic receptors preganglion
- muscarinic receptors postganglion
Sympathetic Neurotransmitters
Acetylcholine
- muscarinic for sweat glands postganglion
- nicotinic for all preganglion
- goes to adrenal medulla nicotinic receptors to stimulate epinephrine and norepinephrine release into blood stream
NorEpinephrine
- Alpha Beta receptors for cardiac and smooth muscle, gland cells, nerve terminals
- -postganglion
Nicotinic receptors
pre and post for parasympathetic and sympathetic
cholinergic
2 alpha and 3 beta subunits
needs 2 ACh molecules
sodium ion channel
muscarinic receptors
cholinergic post tissue for parasympathetic metabotropic -deactivates adenylyl cyclase (inhibits cAMP) -Activates Phospholipase C -Opens K+ channels
alpha and beta receptors
noradrenergic metabotropic -activates adenylyl cyclase with g protein and GTP --uses ATP to make cyclic AMP ---adds to Protein Kinase ----phosphorylates Enzymes -----cellular response
Beta receptor subtypes
1, 2, 3
Alpha receptor subtypes
1, 2
muscarinic receptor subtypes
M1, M2, M3, M4, M5
sympathetic heart activation
- Beta1 is the predominant receptor subtype
- Activates cAMP System
- Increases heart rate
- Increases force of contraction
Autonomic control of bladder
Beta2- Relaxes Bladder Muscle
Alpha1- Contracts Sphincter Muscle
M3 - Contracts Bladder Muscle
M1- Relaxes Sphincter Muscle
Adrenal Gland
resides on kidney sympathetic activation Epinephrine 80 % Norepinephrine 20% Boosts and coordinates sympathetic nervous system response
Catecholamine synthesis
Tyrosine
–Tyrosine hydroxylase(TH)
DOPA –Aromatic Amino acid decarboxylase (AADC)
Dopamine
Dopamine beta-Hydroxylase (DBH)
Norepinephrine
Epinephrine synthesis
Norepinephrine
phenylethanolamine N-methyltranserase
epinephrine
Dopaminergic Synapse
- Stored in Synaptic vesicles
- Storage is Reserpine sensitive (Blocks VMAT)
- Release regulated by calcium influx
- Removal from synapse by Reuptake (DAT) and Degradation by MAO and COMT
- Metabotropic receptors: D1, D2, D3, D4
- Release Regulated by D2 Autoreceptors
Reserpine
inhibits vesicularization of monoamines
MAO
degrades free monoamines
Depletes brain of monAmines
Decreases blood pressure
Precipitates depression
Dopamine Degradation
CoMT then MAO
Dopamine -Catechol-O-methyltransferase (COMT)
- 3-Methoxytyramine (3-MT)
- Monoamine Oxidase (MAO) Aldehyde dehydrogenase
- Homovanillic acid (HVA)
Dopamine degradation MAO then COMT
Dopamine Monoamine oxidase(MAO) -3,4-dihydroxyphenyl-acetic acid (DOPAC) catchol-O-methyltranserase (COMT) -Homovanillic acid
Homovanillic acid (HVA)
easier to detect than dopamine.
dopamine measurement
spinal tap, MAO, COMT, get that stuff, then youve got a decent idea of how much dopamine
-more direct than Homovanillic acid measurement (metabolite)
Major Dopaminergic Pathways
Nigrostriatal
Mesolimbic
Mesocortical
Tuberoinfundibular
Nigrostriatal Pathway (DA)
substantia nigra to striatum movement
-associated with parkinsons
DA cell bodies are in the substantia nigra
Mesocortical pathway (DA)
Ventral Tegmental Area to Cortex
- thinking
- disfunction associated with disfunction’
Tuberoinfundibular Pathway (DA)
Arcuate Nucleus (A12) - Median Eminence - Anterior Pituitary - DA Inhibits Prolactin release
Noradrenergic Synapse
- Stored in Synaptic Vesicles
- Storage is Reserpine Sensitive (Blocks VMAT)
- Release caused by calcium influx
- Removal from synapse by reuptake (NET) and Degradation by MAO and COMT
- Metabotropic Receptors: Alpha and Beta
- Release Regulated by Alpha2 autoreceptors
Norepinephrine degradation
COMT then MAO
Norepinephrine -COMT Normetanephrine -MAO VanillylMandelic acid (VMA)
NorEpinephrine degradation
MAO then COMT
Norepinephrine -MAO Dihydroxymandelic acid -COMT Vanillylmandelic acid (VMA)
epinephrine degradation
COMT then MAO
Epinephrine -COMT Metanephrine -MAO VMA
epinephrine degradation
MAO then COMT
Epinephrine -MAO Dihydroxymandelic acid -COMT VMA
Noradrenergic pathway
NE cell bodies are in the cerebellum
