ANS Flashcards
What are some differences between PNS and somatic?
PNS has two neurons, one myelinated preganglionic that secretes ACh and an unmyelinated post ganglionic that secretes either ACh or NE. Somatic or voluntary muscle is myelinated all the way and secretes ACh causing contraction
What allows precise control over organs?
innervation by both sympathetic and parasympathetic neurons allows regulation of visceral activities such as cardiac function, BP, circulation, digestion, thermoregulation, and pupil size
What are some effects of sympathetic stimulation?
Increased HR, vasoconstriction, decreased digestion, filling (relaxation) of bladder, bronchiodilation
What are some effects of parasympathetic?
decreased rate of contraction, constrict bronchioles, mucus secretion, peeing/pooping
What are some differences in structure of parasympathetic and sympathetic nervous system?
Parasympathetic has long preganglionic, PANS is localized with only one preganglion synapsing with few postganglion, SANs is widespread where one preganglion synapses with many effectors, and both neurons release ACh. The sympathetic preganglionic nerve is short and post ganglion releases NE (only secrete ACh for sweat)
Where do sweat glands on receive innervation from?
SANS
How do you make ACh vs NE?
acetyl CoA + choline = Ach, ACh is destroyed at CT by Ach-esterase. Tyrosine>DOPA>dopamine>vesicular transport>NE to synaptic space. NE binds to adrenergic recptor and can diffuse, be metabolized COMT/MAO, and reuptaked
What’s rate limiting step of making catecholamines?
tyrosine hydroxylase
Where does sympathetic and parasympathetic emerge from?
sympathetic is from T1-L2 and parasympathetic is cranial and sacral
Lies aling either side of the spinal cord; sympathetic ganglion chain….
sympathetic trunk
This organ has no post ganglioninc fibers…
adrenal medulla
True/False: Most hormones released into the blood are NE?
False, 80% is epinephrine
What does preganglionic always release?
Always releases ACh to muscarinic receptor which increases depolarization
found on postganglionic cell bodies of all autonomic ganglia and at adrenal medulla; also subtype at NMJ in skeletal muscles; ligand gated
Nicotinic receptor
found on all postganglionic PANS effector cell membranes and on those “exception” tissues (sweat glands) of SANS; GPCR coupled
Muscarinic receptors
What does atenolol do in cardiac?
When NE binds to B1, it causes lots of contraction, but with atenolol cAMP levels decrease to AMP via phosphodiesterase
How can norepinephrine act on the smooth muscle, and cause opposite effects? How does smooth muscle contract in some places & relax in other places?
Alpha 1 receptors on smooth muscle of arterioles vs B2 receptors on smooth muscle in bronchioles and arterioles cause different affects. Alpha 1 has more calcium available for contraction, while B2 has less calcium available for contraction so it relaxes.
Receptor that increases heart rate and force of contraction
B1
receptor that causes vasoconstriction (arterioles)
A1
Receptor that causes dilation of bronchioles and inhibits mucus secretion
B2
Receptor that decreases motility of GI, causes contraction of sphincters, and inhibits digestion
A1
Receptor that causes relaxation of bladder
B2
Receptor that causes dilation of pupil
B2 and A1
Receptor for causing glycogenolysis and dilation of arterioles of skeletal muscle
B2
Receptor that causes lipolysis
B1 and B2
Receptor that decreases rate and force of contraction? (can also relax sphincters)
M2
Receptor that dilates vessels of penis and cilitoris, constricts bronchioles, stimulates mucus secretion, increase motility, relax sphincters, stimulates digestion, and constricts pupils
M3
How does a pupil dilate?
NE or EP binds to A1 or B2 receptor on pupil. The dilator muscle needs to contract so the circular muscle can relax.
What kind of GPCR does A1 and B2 work in conjunction with?
A1 works with Gq and B2 works with Gs
What types of receptors are muscarinic and nicotininc?
Muscarinic are GPCR (Gq or Gi) and Nicotinic are ligand gated ion channels
What are the adr. receptors associated G proteins?
A1 - Gq, A2 - Gi, B1-B3 - Gs, and D1 - Gs
What are cholinergic receptors and their associated proteins?
M1 - Gq, M2 - Gi, M3 - Gq, M4 - Gi, M5 - Gq, Nn and Nm have increased cation permeability
What is rate limiting and second step to catecholamine synthesis?
tyrosine hydroxylase and dopa decarboxylase
What two enzymes break down catecholamines?
COMT in chromaffin cells and MAO
What’s antagonist to Alpha receptors?
Prazosin
What’s antagonist to B1 receptors?
atenolol
What’s antagonist to B2 receptors?
propranolol
What’s antagonist to muscarinic receptors?
atropine
What’s antagonist to nicotinic receptors?
pancuronium
What is an antagonist to D1 receptor?
D-tetrahydropalmatine
What happens when you get excessive muscarinic and nicotinic stimulations?
Muscarinic = Diarrhea, Urination, Miosis, Bradycardia, Bronchoconstriction, Excitation, Emesis, Lacrimation, Salivation, and Sweating. Treat with Atropine and Pralidoxime
Nicotinic = SK muscle excitation, paralysis
