Pharm Exam 1- S3 Flashcards
Neurotransmission is ?
Process of cellular communication
2 ways of cellular communication?
Chemical-neurotransmitters
Electrical- passive / active conduction
Which form of cellular communication is faster?
Electrical
Input from nerves can synapse on what?
Dendrites
cell body
axon
nerve terminal
Repolarization occurs naturally from what?
Na-K ATPase
Stored vessicles in nerve terminal are release by what?
Exocytosis after depolarization impulse from Axon.
What gives the impulse for depolarization?
Axon
Passive Conduction?
Brownian motion causes ions to disperse evenly and Diminish. Diffusing out and even. The longer the tube the more fluid= lower concentration at end.
Active Conduction?
Pass the signal down the axon itself, “moving”. Constantly regenerated voltage and marching down. Does not diminish. Voltage-gated Na goes in and K goes out at the same time.
NA goes _____?
K goes ______?
in
out
Active conduction leads to _____ to restore negative polarization?
Na-K pump. 3:2 pump. 3 NA out and puts 2 K back in to make more negative.
Chloride ions influx cause ?
hyperpolarization. -90mv
Normal resting membrane potential?
-70mv or -80mv
Sodium is higher in ?
Extracellular fluid
Potassium is higher in ?
Intracellular fluid
Chemical compounds are stored where?
In vessicles in the nerve terminal or Bouton.
The cell body (Soma) action?
Decides “to fire or not fire” based on signal. Biochemical reaction inside that releases binding substances.
Dendrites action?
Passively transmit information to the cell body.
Axon Hillock action?
Ligand receptor zones associated with Na ion channel. Reacts to intracellular substance.
NOT voltage-gated.
Axon action?
Voltage-gated Na channels that are stimulated by axon hillock.
Nerve terminals (Bouton) action?
Voltage-gated Ca channels that trigger the fusion of Ca and Na ions to pinch vesicles off.
Calcium is higher where?
Extracellular
Dendritic Conduction is a ?
Passive electrical process
Axonal Conduction is a?
Active electrical process, involves voltage gated Na and K channels. Na-K ATPase pump to restore chemical equilibrium.
Signal is initiated where in Axonal conduction?
Axon hillock, by internally ligand-gated Na channels.
Nonmyelinated axons?
Slower, more likely to be disrupted or blocked.
Myelinated axons?
Surrounded by myelin sheaths formed from Schwann cells. FASTER, use less energy. Not as much Na-K ATPase needed.
Ion penetration in myelinated axons is where?
At the Nodes of Ranvier or gaps.
Saltatory Conduction?
Through myelinated axons which allows jumping charge to occur. Rapid conduction.
Cellular changes are due to ?
Differential ionic concentrations
Normal ion concentration of Na?
15mM Intracellular
145mM Extracellular
Normal ion concentration of K?
145mM Intracellular
5mM Extracellular
Normal ion concentration of Cl?
10mM Intracellular
150mM Extracellular
Normal ion concentration of Ca?
0.0001mM Intracellular
2mM Extracellular
What is the second messenger released intracellularly to increase concentration to initiate biochemical reactions?
Calcium
Maintenance of internal voltage is done by?
Potassium
Peripheral nerves are?
Myelinated.
Motor nerves synapse where?
in Muscle
Diffusion vs Electromotive force balance?
Diffusion is driven by High to low
Electromotive force repulsion due to negative charges
Which ions are under electromotive force?
Potassium and Sodium
The primary contributor to resting charge is what?
Potassium channels
The only channel open at rest is ?
Potassium
The ability to balance diffusional flow of potassium and electromotive retention of potassium at equilibrium is what?
Diffusion vs electromotive force balance
allows no net movement.
Action potential is initiated at what?
Axon hillock
Tri-state propagation?
Allows the system to reset itself back to refractory -50mv.
Hysteresis is what?
Structure goes from one form to another and back. 2 state system.
NOT NEUROTRANSMISSION
Sodium channels open(depolarize) at what mv?
-40mv
Refractory mv?
-50mv
Resting state mv?
-70 to -80mv
Hyperpolarization mv?
-90mv to -100mv
Factors that lead to increased conduction rates?
Myelination
High resting membrane potential(-40)
Increasing Na channel density
Increasing axonal diameter
Decreased capacitance?
Movement of ions across membrane increases the conduction rate.
Saltatory conduction?
Jumping of currents between nodes of Ranvier which increases speed of conduction.
Higher resting potential is what?
Less negative -60 or -50mv
Bigger axonal diameter =
Less resistance, increased conduction rate.
Synaptic transmission occurs at the end of a nerve terminal where?
Ca released from storage in sarcoplasm and leads to biochemical change allowing fusion of vesicles with inner cell membrane.
With synaptic transmission vessicles are?
Filled and pinched off.
Primary excitatory Neurotransmitters are?
Acetycholine
Norepinephrine/ Epinephrine
Dopamine
Serotonin (Ionophore 5-Ht3)
Glutamic acid
Aspartic acid
What are the two most common excitatory neurotransmitters?
Aspartic acid and Glutamic acid
Excitatory Serotonin neurotransmitters is where?
Ionophore 5-Ht3
Primary Inhibitory transmitters are?
GABA
Glycine
Serotonin (G-protein type receptor)
Functions as a diode that transmits the energy of an action potential from presynaptic to post synaptic.
Synapse
Principle inhibitory neurotransmitter in the spinal cord?
Glycine
Causes hyperpolarization of cell.
Principle inhibitory neurotransmitter in the brain?
GABA
Causes hyperpolarization of the cell.
What is the major excitatory neurotransmitter in the CNS?
Glutamate
Ligand-gated ion channels?
Transmit signal across the synapse
Voltage-gated ion channels?
Propagate action potentials
Francis Rynd in 1845
First hollow needles, injection of morphine to treat neuralgia.
Which IV anesthetic drug first administered?
Thiopental in 1934
Agent cause mild suppression of arousal and behavior, slight decrease in alertness and response to stimuli?
Sedative
Agent cause pronounced sedative effects and induction of sleep.
Hypnotic
Which drug is used to induce sleep?
Sedative or hypnotic
Hypnotic
Sedatives become hypnotics at higher doses
Alcohols?
Cause CNS depression, increased side effects and death with too much.
Ethanol and Chloral hydrate
Which drug builds up with its own metabolism. One persons dose may kill another person?
Phenobarbital
Barbituates are ?
Sedative, hypnotics, and not used much anymore due to low TI.
Benzodiazepines are?
Anxiolytics, cause CNS depressant, used for short term procedures, and require less anesthetic dose.
Cause anterograde amnesia!
Sedative/hypnotic MOA?
Complex, but most act on polysynaptic pathways. Increase presynaptic inhibition to shut off release. Seperate binding sites to GABA to increase Cl conduction.
Benzos/Barbs most believed effect?
Enhance the effects of GABA by decreasing depolarization.
Hyperpolarizing
GABA ionophore is a ?
Pentameric ligand-gated structure
Sedative/hypnotics need 2 binding sites on GABA in order to?
Open chloride channel allowing Cl flow in by diffusion to hyperpolarize the cell.
GABA binding site is ?
Alpha-1
Beta-2
What site blocks GABA and closes Cl channel?
Picrotoxin
Picrotoxin does what?
Blocks GABA, closes Cl channel to cause CNS stimulation leading to seizure.
Too much excitatory in brain leads to?
Seizure, epilepsy.
Steroid Site effect on GABA receptor complex?
Can enhance GABA binding.
ie: Anesthetics
How does Ethanol affect GABA receptor complex?
Decreases ratio of Inhibitory/Excitatory
Blocks more inhibitory than excitatory.
90I : 10E. now
45I: 5E
Where does propofol/etomidate/ barbituates bind on GABA receptor complex?
Alpha-1
Beta-2
NMDA glutamate receptor complex is a ?
Voltage-dependent ionophoric system.
Allowing Ca and Na ions to enter
NMDA glutamate receptor complex shape?
4 protein structure, Quadrameric
Ketamine acts on what receptor?
PCP binding site on the NMDA glutamate receptor complex. Inhibits the conductance of Ca (Excitation) in the thalamus.
What is also needed to bind for the Glutamate Receptor antagonist site?
Glycine
Glycine is in ?
the Spinal Cord, a similar action to GABA as an inhibitory neurotransmitter
Benzos cause mild muscle relaxant effects where?
Nicotinic ACh receptor inhibition.
2 phases of sleep?
Slow wave sleep (SWS)
Rapid eye movement sleep (REM)
Slow wave sleep (SWS) EEG shows?
High voltage synchronous activity.
Rapid Eye movement (REM) shows?
Skeletal muscle relaxation, 25% of overall sleep, 1-2hrs. eye movement
Changes to sleep pattern from hypnotic agents?
- SWS patterns shortened
- REM sleep depressed
- Total sleep is prolonged
Barbituates MOA?
Augment GABA Cl- ionophore causing hyperpolarization. Decreasing dissociation of GABA.
Different location than benzos
Barbituates negative affect?
Heavily abused and altered sleep patterns.
Highly toxic with narrow TI
Which drug class inhibit oxidative phosphorylation?
Barbituates
Slowing of cellular function
Which drugs exist in keto and enol tautomers forms?
Barbituates
Replacement of C-2 oxygen with sulfur results in what?
(Barb)
Thiopental
Greater lipid solubility
Addition of a phenyl group at C-5 enhancing anticonvulsant activity?
(Barb)
Phenobarbital
Addition of a methyl group to the ring N shortens duration of action?
(Barb)
Methohexital
Long-acting barbituate?
Phenobarbital
Intermediate duration barbituate?
Pentobarbital
Secobarbital
Short-acting barbituate?
Methohexital
Thiopental
Base structure of a barbiturate?
Barbituric acid
The more lipid soluble the IV agent is the ____ its onset is?
Shorter onset due to rapid increase in brain concentration
Barbituates are_____ and packaged as ____?
Weak acids
Packaged as sodium salt in basic form
Barbituate primary metabolic pathway is?
Hydroxylation via PHASE 1
Potent inducers of the hepatic microsomal enzyme system.
OWN METABOLISM which can metabolism other drugs faster requiring higher doses.
Which drug class is used for Wada speech test prior to neurosurgery?
Barbituates
Slow brain function and slow metabolite buildup
Barbituates safe for pregnancy?
NO, placental transfer
Which has greater CNS specificity
BARBS or BENZOS?
Benzos
Ultra short-acting (10-15s)
High lipid solubility
Induction or short procedures
Metabolized by P-450 system
Half life- 6hrs
Lowers pain threshold- increase sensitive
POTENT RESP DEPRESSANT
DEPRESSES MYOCARDIUM
Neuroprotective
Unavailable in the US
Thiopental
2-3 more potent than thiopental
Metabolized faster by P-450 oxidation
Faster recovery
Used in ECT to Trigger seizures
Decreased seizure threshold
Methohexital
At high doses Benzos produce?
Hypnosis and unconsiousness
Half life of Midazolam?
1 hour
Half life of Diazepam?
Half life of effect of diazepam?
24-36 hrs
4 days (96hrs)
Midazolam is metabolized via ?
Microsomal hydroxylation
Diazepam is metabolized via ?
Microsomal N-demethylation
Oxazepam is eliminated rapidly by?
Glucoronide conjugation, PHASE II
Which benzo is converted into several active metabolites that increase clinical effect?
Diazepam