Autonomic Nervous System Review Flashcards
2 main neurotransmitters of autonomic nervous system
Ach, NE
type of autonomic innervation: adrenal medulla
sympathetic only
type of autonomic innervation: most sweat glands
sympathetic only
type of autonomic innervation: blood vessels
although they do have cholinergic receptors on endothelium of BV, but only innervated by SNS
dominant basal tone: cardiac
parasympathetic
dominant basal tone: bronchial smooth muscle
parasympathetic
dominant basal tone: GI tract
parasympathetic
dominant basal tone: urinary tract
parasympathetic
dominant basal tone: salivary glands
parasympathetic
dominant basal tone: most sweat glands
sympathetic
dominant basal tone: arterioles/veins
sympathetic
how many ganglion in somatic nervous system
1
postganglionic receptor and neurotransmitter in PSNS
Ach, mAchR (cholinergic)
postganglionic receptor and neurotransmitter in SNS
NE, adrenergic receptors (alpha, beta)
postganglionic receptor and neurotransmitter in sweat glands
Ach, mAchR (cholinergic) (even though its a part of the SNS)
postsynaptic neurotransmitters in adrenal medulla
80% epi, 20% NE
adrenal medulla innervation, number of neurons, type of postsynaptic cells, neurotransmitters
sympathetic innervation, only 1 neuron, postsynaptic neuroendocrine cells, secrete epi/norepi into blood, mimics sympathetic stimulation
anatomical origin of SNS
T1-T12, L1-L5
anatomical origin of PSNS
CN 3, 7, 9, 10 (90% vagus nerve), S2-S4
location of sympathetic ganglia
sympathetic chain of paravertebral column
location of PSNS ganglia
target organ
receptor on postganglionic neuron of SNS and PSNS
nAchR
receptor on target tissue of SNS and exceptions
adrenergic, sweat glands, adrenal medulla
receptor on target tissue of PSNS
mAchR
steps of neurotransmission
- synthesis
- storage in vesicles
- release r/t AP (vesicles fuse with nerve terminal)
- action at receiving tissue
- termination (reuptake via transporter, enzyme degradation, diffusion)
steps of cholinergic neurotransmission
- synthesis from choline, acetyl-CoA
- storage in vesicles
- action potential triggers Ca++ entry, Ca++ interacts with SNARE protein on vescicle –>fusion of vesicle and opening –> release of Ach
- binding to receptor
- termination of action. primary mechanism: enzyme degradation via AchE
- recycle choline via reuptake
ligand gated ion channel
fast response, binds and channels open so ions can pass through ex) nAchR and GABA
GPCR
connected to g protein, most common receptor that drugs act on
transmembrane with linked enzymatic domain
when drug binds, enzyme activates ex) oncology medications
intracellular receptor
receptor either in cytosol or nucleus, drug has to be lipophilic. effects transcription and increases or decreases amount of protein synthesis ex)cortisol, sex hormones
muscarinic cholinergic receptor specs
- it is a GPCR
- there are 5 subtypes with 2 subgroups
- diverse cellular responses, not very selective
- autonomic effector tissues: heart, endothelium, smooth muscle, glands, CNS
nicotinic cholinergic receptor specs
- ligand gated ion channel (Na/K)
- 2 major subtypes: NicN, NicM
- location: autonomic ganglia, skeletal muscle innervated by somatic nerves, CNS
- Ach binds, conformational change, channel opens and positively charged ions pull through channel
- depol of postsynaptic cells
where are M1 receptors
CNS
where are M2 receptors
heart
where are M3 receptors
smooth muscle, glands, endothelium, eye (circular, ciliary muscle)
where are M4 receptors
CNS
where are M5 receptors
CNS
where are NicN receptors
ANS ganglia, adrenal medulla, CNS
where are NicM receptors
skeletal NMJ
characteristics of cholinergic receptors
- selective distribution
- receptor type: muscarinic (GPCR),
- nicotinic (Nic) (ligand gated ion channel)
muscarinic ligands
Ach, muscarine
nicotinic ligands
Ach, nicotine
acetylcholine neurotransmitter sites
NMJ, autonomic ganglia, at effector junction of postganglionic parasympathetic neurons, CNS
stages of adrenergic neurotransmission
- synthesis of NE (catecholamines) from amino acid tyrosine
- uptake/storage of vesicles
- release with action potential
- receptor binding
- termination of action- reuptake via NE transporter. also, enzymatic metabolism, especially via MAO in neurotransmitter terminal. important drug target)
alpha adrenergic receptor specs
type of receptor
ligands
subtypes
- GPCR
- ligands: NE, epi, DA
- 2 subtypes of a1 and a2
way a1 receptor works
excitatory. increased calcium activated calmodulin. increases actin-myosin interaction. smooth muscle contraction occurs
way a2 receptor works
inhibitory. decreased cAMP production. decreased NE release
beta adrenergic receptor specs subtypes type of receptor activation pathway autonomic effector tissues
- B1, B2, B3
- GPCR
- activation of adenyl cyclase, increased cAMP production, increased kinase activation or phosphorylation.
- autonomic effector tissues. heart, kidney, liver, smooth muscle, skeletal muscle, fat cells.
how to terminate action of NE
reuptake back into presynaptic neuron, diffusion, metabolism (minor role)
noradrenegic receptors
- GPCR
- negative feedback limits response
- alpha 1
- alpha 2
- beta 1, beta 2, beta 3
dopamine catecholamine specs
precursor of norepinephrine, epi, at effector junction. sympathetic, renal vascular smooth muscle
dopamine termination of action
neuronal reuptake by DA transporter, MAO brerakdown
dopamine receptors action via GPCR
cAMP is second messenger. D1 class (D1, D5) increases cAMP. D2 class (D2, D3, D4) decreases cAMP production.
low, intermediate, and high dose dopamine
low dose- vasodilation (D1) intermediate dose (and inotrope) B1 high dose-vasoconstriction (a1)
other neurotransmitters in autonomic, enteric, and NANC neurons
NO vasoactive intestinal peptide (VIP) calcitonin gene related peptide (GCRP) neuropeptide Y (NPY) substance P serotonin others
ANS stimulation of SA node
SNS increases heart rate via B1 receptor
PSNS decreases heart rate via M2 receptor
ANS stimulation of contractility
SNS increases contractility of B1
PSNS decreases contractility via M2
ANS stimulation of bronchiolar smooth muscle
SNS dilates via B2
PSNS constricts via M3
ANS stimulation of kidney
SNS induces renin release via B1
ANS stimulation of liver
SNS stimulated glucagon release via B2
ANS stimulation of vascular smooth muscle: skin, splanchnic
SNS constricts via A1
ANS stimulation of skeletal muscle
SNS vasodilator via B2
ANS stimulation of GI walls
SNS relaxes via B2
PSNS contracts via M3
ANS stimulation of GI sphincters
SNS contracts via A1
PSNS dilates via M3
ANS stimulations of GI secretions
PSNS increases secretions via M3
ANS stimulation of urinary bladder wall
SNS relaxes via B2
PSNS contracts via M3
ANS stimulation of urinary bladder sphincter
SNS contracts via A1
PSNS relaxes via M3
ANS stimulation of uterine smooth muscle
SNS relaxes via B2
PSNS super minor contraction via M3
ANS stimulation of reproductive system
SNS incites ejaculation via A1
PSNS erection via M3
ANS stimulation of adrenal medulla
SNS release of NE and Epi via nicotinic receptor
ANS stimulation via pilomotor smooth muscle
SNS contracts via A1
ANS stimulation via sweat glands- thermoregulatory
SNS increases sweat via muscarinic receptor
ANS stimulation via sweat glands (apocrine/stress)
SNS increases sweat via a1 receptor
ANS stimulation via fat cells
SNS lipolysis via B3
eNOS
endothelial nitric oxide synthase; enzyme that makes nitric oxide from L-arginine
PDE5
phosphpdiesterase 5; the enzyme that breaks down he 2nd messenger (cGMP)
iris effects, SNS, PSNS
pupillary control, SNS a1 mydriasis, PSNS M3 miosis
ciliary muscle effects, SNS, PSNS
focuses lens
SNS: none
PSNS: accommodate near vision (M3), increase outflow of aqueous humor
ciliary body effects, SNS, PSNS
aqueous humor production
SNS increase secretion of aqueous humor via epithelium (B1)
aqueous humor effects, PSNS, SNS
intraocular pressure
increases IOP SNS
decreases IOP PSNS
adrenergic
describes neurons or receptors that use NE, or drugs that mimic sympathetic nerve stimulation
alpha adrenergic terminology
adrenergic receptor activated by NT NE
beta adrenergic terminology
adrenergic receptor activated by NT NE
catecholamine terminology
molecule class that contains a catechol and amine group. includes NE, epi, dopa
cholinergic terminology
describes neurons receptors that use Ach, orr drugs that mimic PSNS nerve stimulation
epinephrine terminology
adrenalin, produced in adrenal medulla, also NT in CNS
muscarinic receptor terminology
cholinergic receptor of PSNS, name derived from muscarine, a natural receptor agonist substance from mushrooms
nicotinic receptor terminology
cholinergic receptor, deprived from nicotine, a natural receptor agonist, 2 distinct types in periphery. NMJ and autonomic ganglia types
NE terminology
noradrenalin; NT at sympathetic effector tissues in periphery, some produced in adrenal medulla, also NT in CNS
preganglionic terrminology
situated before a ganglion
postganglionic terminology
situated after a ganglion