Neurological Pharmacology Flashcards
Two basic steps by which neurons influence the behaviour of postsynaptic cells
Axonal conduction - Action potenital
Synaptic transmission – information is carried across the gap b/w the neuron and the postsynaptic cell
Drugs that alter axonal conduction are not selective T/F
True, axons are all alike. Ex. local Anesthetics (decrease speed of action potential).They suppress transmission in any nerve they reach, thus the use of local anesthetics are very limited
Feedback loops - Example / Where are they located?
Carotid Artery
A patient is required to have a procedure that requires Axon conduction blockade, what medication will be used?
A local anesthetic will alter axonal conduction
How do drugs alter receptor activity at the synapses? (5 steps involved)
Transmitter Synthesis, Transmitter storage, transmitter release, receptor binding, termination of transmission.
What are the three primary neurotransmitters in the PNS
Acetylcholine, Norepinephrine and Epinephrine
How is acetylcholine released?
All pre-ganglionic neurons of the PNS All pre-ganglionic neurons of the SNS All post-ganglionic neurons of the PNS All motor neurons of the SNS Most post-ganglionic neurons of the SNS innervates sweats glands.
How is Norepinephrine released?
All post-ganglionic neurons of the SNS - except those that innervates sweat glands
How is Epinephrine released?
The Adrenal Medulla
What are the two receptor types in the PNS
Cholinergic Receptors - mediate responses of acetylcholine
Adrenergic receptors - mediate responses to Epinephrine
and Norepinephrine
What are three cholinergic subtypes
Nicotinic N
Nicotinic M
Muscarinic
**All respond to Acetylcholine but have different effects from one another **
Nicotinic N
Activation of this receptor causes ganglionic transmission at all ganglia of the SNS and PNS. It also promotes release of epinephrine from the adrenal medulla
Muscarinic
Ex.
Activation of these receptors cause;
Increased glandular secretions
Contraction of smooth muscle in the bronchi and GI tract.
Organophosphate
What are Adrenergic subtypes? (four types)
A1, A2, B1, B2
A1 - location, causes, effects.
Located in the eyes, blood vessels, male sex organs, prostate capsule and bladder
Causes: Pupil dilation, vasoconstriction, ejaculation
A2 - location, causes, effects.
Located on nerve terminals and not organs innervated by the autonomic nervous system.
Norepinephrine binds to A2 receptors and this causes a further suppression of norepinephrine release.
This can help reduce Norepinephrine release when too much transmitter has accumulated in the synaptic gap.
B1 - location, causes, effects.
Located in the heart and kidneys
Causes the release of Renin into the blood, this promotes synthesis of angiotensin (vasoconstriction)
Increase dromotropic, chronotropic and inotropic effects in the heart
B2 - location, causes, effects.
Located in the lungs, uterus, skeletal muscle and liver
Causes; bronchial dilation, uterine smooth muscle relaxation, vasodilation in arterioles
What are two basic categories of receptors?
Cholinergic receptors - Mediated by acetylcholine
Adrenergic receptors - Mediated by Epi / Norepi
Nuerotransmitter Life Cycles - Many drugs produce their effects by interfering with what three life cycles?
Acetylcholine, Epinephrine and Norepinephrine
Life Cycle - Epinephrine
Synthesized within chromatin cells of the adrenal medulla
Life Cycle - Norepinephrine
Made from a series of precursors Stored in vesicles for release Released into the synapse Interacts with A1, A2, B1 receptors Undergoes re-uptake back into the nerve terminals
Once it is back in the nerve terminal it is reused or degraded by enzyme Monoamine Oxidase (MAO)
Neuropharmacology
The study of drugs that alter the processes controlled by the nervous system.
Neuropharmacology - two categories
Drugs that alter the Central Nervous System and the Peripheral Nervous System
Neuropharmacological drugs alter what process
CO, Skeletal muscle contraction, vascular tone, respiration, GI function, Uterine motility, Glandular secretion, Ideation, mood, and perception of pain
Where are neurotransmitter molecules released from and where do they bind
Axon Terminals, and they bind on the postsynaptic cells
What happens if the postsynaptic cell is another neuron?
It increases its firing rate
What happens if the postsyncaptic cell is a muscle? or A granular
It will either contract or relax.
Granular with increase or decrease secretions
Do most neuro drugs alter synaptic transmissions or axonal conduction and which ones are more selective?
Most drugs alter synaptic transmission, only a few drugs alter axonal conduction.
Drugs that alter synaptic transmission can produce effects that are much more selective than those altering axonal conduction.
Step 1: Transmitter synthesis
Transmitters must be present in the nerve terminals for synaptic transmission to take place.
Step 2: Transmitter storage
Once the transmitter is synthesized it is stored until the time of its release Transmitter storage takes place within vesicles (tiny packets in the axon terminal)
Each nerve terminal contains many of the vesicles
Step 3 Transmitter release
Release of the transmitter is triggered by arrival of an action potential (through the axon) at the terminal. The vesicles undergo fusion with the terminal membrane, and the contents are released into the synaptic gap. Each action potential causes only a small fraction of vesicles to discharge their contents
Step 4 Receptor Binding
Following release, transmitter molecules diffuse across the synaptic gap and undergo reversible binding to receptors on the post synaptic cell. Binding to receptors causes a cascade of events that result in altered behavior of the post synaptic cell
Step 5 Termination of Transmission
Transmission is terminated by dissociation of the transmitter from its receptors. Transmitter molecules can then either undergo:
Reuptake (pumped) into axon terminals from where they were released.
Enzymatic degradation in the synapse. Diffusion away from the synaptic gap
PNS physiology what two systems are included?
Includes:
Autonomic nervous system (ANS):
Parasympathetic – rest and digest
Sympathetic – fight or flight
Somatic Motor System – voluntary nervous
system (skeletal muscle)
What are Three principal functions of the ANS
- Regulate the heart
- Regulate the secretory glands (salivary, gastric, sweat, and bronchial)
- Regulate the smooth muscles (bronchi, blood vessels, urogenital system, and gastrointestinal tract).
What are the 7 regulatory functions of PNS?
- Slowing the heart rate
- Increasing the gastric secretions
- Emptying the bladder
- Emptying the bowel
- Focusing the eye for near vision
- Constricting the pupil
- Contracting the bronchial smooth muscle
