Toxicology (1305) Flashcards
What kind of neurotransmitters do cholinergic neurons use?
AcH
What kind of neurotransmitters do adrenergic neurons use?
Epinephrine/norepinephrine
Where do SYMPATHETIC NEURONS originate from?
Thoracic and lumbar regions of spinal cord
What are preganglionic (myelinated) fibers classified as? Cholinergic or Adrenergic?
Cholinergic fibers. Preganglionic fibers for BOTH PNS AND SNS is ALWAYS AcH
Are preganglionic nerves in the SNS short or long?
Short
Are postganglionic nerves in the SNS short or long?
Long
What are postganglionic (non-myelinated) fibers classified as? Cholinergic or Adrenergic?
Postganglionic fibers for PNS ALSO release AcH; therefore cholinergic
Postganglionic fibers for SNS release norepi; therefore adrenergic
* WITH THE EXCEPTION OF SWEAT GLANDS AND ADRENAL CORTEX - they don’t have a postganglionic fiber attached to the preganglionic fiber
What does the SNS do to our bodies/organs?
- Dilation of pupils
- Inhibition of salivation
- Relaxation of airways
- Acceleration of heartbeat
- Inhibition of digestion
- Stimulates glucose release from liver
- Inhibition of gallblader/intestine activity
Where do PARASYMPATHETIC NEURONS originate from?
Cranial nerves 3, 7, 9, 10 and sacral region S2 and S4
Are preganglionic nerves in the PNS short or long?
Long
Are postganglionic nerves in the PNS short or long?
Short
What does the PNS do to our bodies/organs?
- Constriction of pupils
- Stimulation of salivation
- Constriction of airways
- Slowing of heartbeat
- Stimulation of digestion
- Stimulation of glucose uptake
- Stimulation of gallblader/intestine activity
What kind of receptors are on POSTGANGLIONIC NERVES in BOTH SNS and PNS?
Nicotinic receptors (receptors in skeletal muscle are also nicotinic)
What are nicotinic receptors also known as?
Ionotropic receptors (meaning they work as an ion channel)
i.e: if AcH binds to a nicotinic receptors, it opens up which allows passage of ions such as Na - eventually leads to an action potential
What are adrenergic receptors?
Receptors on EFFECTOR ORGANS receiving signals from SYMPATHETIC NEURONS
i.e: this will cause DILATION in the eyes (remember that postganglionic nerves in the SNS are ADRENERGIC since they release epi/norepi)
What are muscarinic receptors?
Receptors on EFFECTOR ORGANS receiving signals from PARASYMPATHETIC NEURONS
i.e: this will cause CONSTRICTION in the eyes (remember that postganglionic nerves in the PNS are CHOLINERGIC since they release AcH)
Importance of QT interval and QTc?
QT interval correlates with HR since it measures ventricular depolarization and complete repolarization.
IF assessing QT, use the QTc (which is the corrected QT interval)
What do organophosphates do?
Inhibit acetylcholinesterase (enzymes that break down AcH) causing a MASSIVE cholinergic response (too much AcH in your receptors, over-stimulated)
Tl;dr if you don’t have Alzheimer’s you’re getting fucked
S&S of someone with organophosphate poisoning? (SLUDGE-M)
Salivation
Lacrimation
Urination
Diaphoresis
GI Upset
Emesis
Miosis
What are anticholinergics?
Drugs that inhibit AcH by blocking nicotinic and muscarinic receptors
Examples of anticholinergics?
TCAs
Antihistamines (Benadryl)
Gravol
Atropine
Jimson Weed
TCA’s have a large therapeutic window. T or F?
False. Super narrow (10-20mg/kg is overdosed already)
Patho behind TCA overdose?
Causes loss of vascular tone via blockage of alpha AND muscarinic receptors. Results in:
Tachycardia
Red (flushed), hot, dry skin
Blockage of Na channels (huge for cardiac cycle)
Mydriasis (blindness)
Why is the blockage of Na channels important when to comes to TCA overdose?
Slows down action potential within cardiac muscles, causing QT prolongation
Patho behind sympathomimetics?
Releases norepi from presynaptic terminal OR inhibiting reuptake of norepi
Examples of sympathomimetics and their functions?
Cocaine - blocks reuptake of norepi, serotonin, and dopamine causing euphoria. Chronic intake depletes dopamine causing depression
Methamphetamine - Similar to cocaine, but also releases catecholamines into synaptic space
Sympathomimetic Patient vs Anticholinergic Patient?
Sympathomimetic patients will have diaphoresis AND bowel sounds; this is because muscarinic receptors are NOT blocked when it comes to sympathomimetics
What is Serotonin?
Neurotransmitter in CNS responsible for mood/behaviour and sleep
What is Serotonin Syndrome?
Occurs when excess serotonin is available for the body to use (ex: taking too much of antidepressants)
S&S of Serotonin Syndrome?
Hyperactivity, hyperventilation, agitation, combative, arrhythmias
What is Delirium Tremens?
Happens if alcohol withdrawal is left untreated. Patients present with hallucinations, tachycardia, confusion, hypertension, hyperthermia, and diaphoresis
Mortality rate of DT due to cardiovascular collapse?
5-15%
How do you treat benzodiazepine overdose?
Maintain ABC’s as much as you can; aggressive interventions are rarely needed.
*Competitive agonist called flumazenil but has a high risk of seizures so not widely used
What happens in acetaminophen overdose?
-Occurs intentionally or unintentionally
- Toxicity occurs at 7g within a day; rapidly absorbed in <2 hours and as quickly as 30 minutes
- Asymptomatic in first 18-24 hours, followed by RUQ pain and hypotension, followed by liver failure, renal failure, metabolic acidosis by 3rd day, death normally occurs on 3rd or 4th day
- Rapid transport to hospital; not much you can do pre-hospital
*Antidote for acetaminophen OD is Acetylcysteine
What do beta blockers do?
Block epinephrine’s effect on beta receptors (if selective to B1) which decreases rate and strength of contraction; decreases CO
What do calcium channel blockers do?
Relaxes smooth muscle causing vasodilation of coronary arteries and sodium channels
What happens if you overdose on beta blockers and calcium channel blockers?
Will cause profound hypotension, bradyarrhythmias + cardiac arrest.
