Pharm 3 Lecture Flashcards
What are the 2 components of the PNS?
Efferent Division
Afferent Division
What are the 2 components of the Efferent Division?
Autonomic System
Somatic System
What are the 3 components of the Autonomic System?
Enteric
Parasympathetic
Sympathetic
Afferent Nerves
Carry sensory information form parts of the body to the brain for processing; reflex signaling arcs such as carotid bodies
Efferent Nerves
Carry impulses away from the brain and spinal cord; also known as motor nerves
“Exits brain”
Autonomic Nervous System
Involuntary or automatic response of the PNS. Regulates the cardiopulmonary and digestive systems; divided into sympathetic and parasympathetic
Use feedback arcs, works with endocrine system; ANS uses electrical impulses and neurotransmitters; Endocrine uses hormones
Somatic Nervous System
Controls skeletal muscles during voluntary movement and is under conscious control
One junction system; stimulus via single nerve axon to synapse (NMJ); neurotransmitter pass signal to brain
What is the neurotransmitter substance found in the somatic system?
Ach
Ganglia
clusters of nerve cell bodies lying outside the CNS; journeys from the brain to the first junction or synapse
What are the neuroeffector transmitters for sympathetic and parasympathetic branches?
Parasympathetic- ACh
Sympathetic- NE
Carotid Bodies Reflex Arc
Detects pressure changes, relaying that information to the brain to maintain homeostasis
2 Parts of ENS
Myenteric Plexus (Plexus of Auerbach) Submucous Plexus (Plexus of Meissner)
Enteric Nervous System
Semiautonomous part of ANS in the GI tract; send sensory input to parasympathetic and sympathetic nervous system and receives motor output from them
What are sweat glands controlled by?
Sympathetic; neuroeffector transmitter is ACh (doesn’t follow trend)
Is SNS or PNS more focused?
Normally work in opposition of each other; but SNS is much broader and PNS is much more narrowly focused
How is blood pressure controlled?
Almost exclusively by SNS
Cholinergic
release ACh
Which neurons are cholinergic?
All preganglionic neurons
Parasympathetic postganglionic
Somatic neurons
Adrenergic
release NE
What neurotransmitters help modulate synaptic transmission?
ATP, vasoactive intestinal peptide, enkephalins, neurotensin, somatostatin, neuropeptide Y, substance P
Cholinergic Neuron Receptor Types
Nicotinic
Muscarinic
Adrenergic Neuron Receptor Types
Alpha adrenergic
Beta adrenergic
Dopaminergic adrenergic
What are the most primitive parts of the brain?
Medulla Oblongata
Midbrain
What is the #1 cardiovascular variable your body seeks to auto-regulate?
Mean Arterial Pressure
What is IV norepinephrine called?
Noradrenaline
Chronotrope
heart rate
Ionotrope
contractility
Baroreceptors
detect MAP, located in aortic arch and carotid sinus
Net Effect of Levophed
Increase SVR
Decrease HR
even though the drug has direct positive chronotropic effects
Parasympathetic Response (Vasomotor Center)
Increase Peripheral vascular resistance
Decrease heart rate
Sympathetic Response (vasomotor center)
Increase heart rate
increase contractile force
increase venous tone
Autoreceptor
presynaptic neuron is inhibited by the chemical it produces (such as norepinephrine)
Heteroreceptor
presynpatic neuron is inhibited by chemicals that are released by neurons with which it has a synapse (and which that presynaptic neuron doesn’t produce)
Presynaptic Autonomic Feedback
Autoreceptors; heteroreceptors
Postsynaptic Autonomic Feedback
Up-regulation and down-regulation at the receptor level in response to previous neuronal activity; modulation of the primary transmitter-receptor event by events evoked by the same or other transmitters acting on different postsynaptic receptors
Where are muscarinic receptors located?
Effector Postsynaptic cells of the PNS
Parasympathomimetic
muscarinic activation; mimics the effects of the PNS
Where are nicotinic receptors located?
NMJ and at the ganglia of the ANS; not specific for the PNS
Six Steps of Cholinergic Neuotransmission
- Synthesis of Acetylcholine
- Uptake into storage vesicles
- Release of neurotransmitter
- Binding to the receptor
- Degradation of Ach
- Recycling of choline
What inhibits transport of choline?
Hemicholinium
What blocks the release of Ach?
Blocked by botulinum toxin
What does spider venom cause?
Release of Ach
How is choline transported into the cholinergic neuron?
It has to be transported actively; has a strong positive charge that makes it unable to diffuse through the membranes
What is the rate limiting step in the synthesis of ACh?
Uptake of Choline
Varicosities
vesicles that look like beads on the presynaptic nerve terminal; contain ATP, ACh, as well as other co-transmitters that also act as signal regulators
How to get rid of ACh?
ACh is very rapidly hydrolized via acetylcholinesterase in the synaptic cleft.
How is choline recycled?
Sodium-coupled reaction allows choline to re-penetrate the presynaptic cell membrane
Most ____________ agonists have some ________action.
Muscarinic; nicotinic
All ___________ agonists have some ___________ action.
nicotinic; muscarinic
Most useful pharmaceutical applications are those utilizing ___________ agonists.
Muscarinic
Primary Nicotinic Agonists
Direct acting
Arencline tartrate and Nicotine
Carbachol (also used for its muscarinic effects)
Primary Muscarinic Agonists
Direct acting
Bethanechol
Cevimeline (dry mouth)
Pilocarpine (glaucoma)
Indirect-Acting Reversible Cholinergic Agonists
Reversibly bind to AChE; prevents it from breaking down ACh
Ex. Edrophonium: Tensilon testing for diagnosis of myastenia gravis; attacks ACh receptors cause less receptors
Edrophonium
Tensilon testing for diagnosis of myastenia gravis
Myasthenia gravis
block acetylcholine receptors at the postsynaptic neuromuscular junction,inhibiting the excitatory effects of the neurotransmitter acetylcholine on nicotinic receptors at neuromuscular junctions.
Tx for Myastenia Gravis
Neostigmine, Pyridostigmine, and Ambenonium (alone with immune suppressants)
Tx for Glaucoma
Physostigmine and Demecarium; opens the drainage angle
Indirect Acting Irreversible Cholinergic Agonists
Echotiophate: topical organophosphate used for tx of glaucoma
What do organophosphates cause?
Excess salivation Lacrimation Urination Vomiting, defacation, GI cramps unable to breathe loss of muscular control death
What can help reduce some of the effects of organophosphates?
Atropine
