Statistics for forensic toxicology - plant toxins - alkaloids

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Answer Stats

Hint	Answer	% Correct
what is the LD50 of nicotine?	0.5 to 1.0mg/kg for adults	0%
what is the LD50 of strychnine?	1-2mg/kg in humans	0%
what is the LD50 of ricin?	22ug/kg from injection or inhalation (approx 1.8mg/adult - 20 castor seeds could kill an adult)	0%
what are alkaloids?	a basic organic compound containing nitrogen	0%
what is the primary ligand for the cholinergic receptor?	acetylcholine	0%
	action potentials are triggered by very low levels of neurotransmitter, causing constant muscle contractions/twitching	0%
	after excessive stimulation, receptor levels are depressed	0%
what is ricin?	a lectin (carbohydrate-binding protein) from the seeds of the castor oil plant	0%
what is muscarine?	an alkaloid found in many species of mushroom	0%
what is strychnine?	an alkaloid found in the seeds of the Strychnos tree (one of the most bitter chemicals known)	0%
	an essential precursor in the synthesis of porphyrins (most important porphyrin in haem)	0%
what is its function in the CNS?	an inhibitory neurotransmitter	0%
what is nicotine?	a parasympathomimetic alkaloid found in the Solanaceae (nightshade) family of plants	0%
	autonomic nervous system (regulates homeostasis)	0%
	bronchoconstriction and severe gastrointestinal symptoms	0%
what are the physiological consequences of muscarine toxicity?	cardiac arrest via M2 receptors (through bradycardia & low blood pressure)	0%
muscarinic	central nervous system	0%
where are cholinergic receptors found?	central nervous system	0%
	convulsion and hypothermia via M1, M4, and M5 receptors in the brain	0%
	death usually occurs as a result of respiratory arrest and asphyxia	0%
	death usually occurs from circulatory shock due to a shutdown of metabolism	0%
does it have a faster or slower response?	faster	0%
does it have a faster or slower response?	faster (direct channel opening)	0%
how are alkaloids synthesised?	from the amino acids phenylalanine, tryptophan, and tyrosine	0%
muscarinic	gastric secretions, CNS	0%
muscarinic	glands (e.g. salivary, pancreas)	0%
	G protein-coupled receptors	0%
muscarinic	heart muscle (contraction)	0%
what are the two main classes?	heterocyclic	0%
what are the physiological consequences of strychnine toxicity?	initial symptoms include restlessness, muscle twitching, and stiffness of the neck	0%
what are the physiological consequences of nicotine toxicity?	initial symptoms: nausea, vomiting, hypertension, tachycardia, dizziness, and seizure	0%
where are glycine receptors (GlyRs) found?	in the CNS (especially in the brain cord, brain stem, and retina)	0%
what kind of receptors are they?	ion channel-linked receptors	0%
what kind of receptor is the GlyR?	ionotropic receptor	0%
what are the two main types of cholinergic receptors?	ionotropic receptors (direct neurotransmitter action)	0%
what is the mechanism of action of strychnine?	it acts as an antagonist, and prevents glycine from binding to GlyR	0%
	it also interacts with nicotinic receptors in the adrenal gland, stimulating the release of adrenaline	0%
what is the mechanism of action of muscarine?	it binds to the muscarinic receptors and activates them (same as ACh)	0%
what is the mechanism of action of nicotine?	it binds to the nicotinic receptors in the CNS & acts as a 'volume control'	0%
	it increases release of neurotransmitters, providing a stimulant effect	0%
how can this lead to a toxic effect?	it irreversibly hydrolyses a glycosidic bond in the rRNA of the 60s ribosomal subunit	0%
what is the mechanism of action of ricin?	it is a type 2 ribosome-inactivating protein (RIP) or holotoxin (a single ricin molecule can inactivate 1500 ribosomes per minute)	0%
how does it function as a neurotransmitter?	it opens ligand-gated ion channels	0%
	later symptoms include convulsions and dilation of the pupils	0%
muscarinic	M1	0%
muscarinic	M2	0%
muscarinic	M3	0%
muscarinic	M4 & M5	0%
	metabotropic receptors (indirect neurotransmitter action)	0%
	muscarinic acetylcholine receptors	0%
	musculoskeletal system	0%
what are the main types of these receptors?	N1	0%
nicotinic	N2	0%
nicotinic	neuronal receptors (nerve synapses)	0%
what are the two classes of cholinergic receptors?	nicotinic acetylcholine receptors	0%
	non-heterocyclic	0%
what does it do?	regulates chloride movement	0%
what are the physiological consequences of ricin toxicity?	severe diarrhea	0%
where are they found?	skeletal muscle (neuromuscular)	0%
	slower	0%
	slower (act via secondary messengers)	0%
	subsequent symptoms: hypotension, bradycardia, CNS depression, coma, and paralysis	0%
what is glycine?	the smallest of the 20 common amino acids (MW: 75 Da)	0%
	this creates an inhibitory post-synaptic potential, making the neuron less likely to generate an action potential	0%
	this rapidly and completely inactivates the ribosome	0%
	this shuts down protein synthesis within the cells	0%
how can this lead to a toxic effect?	through excessive activation of the muscarinic acetylcholine receptors	0%
how can this lead to a toxic effect?	through excessive stimulations of the nicotinic acetylcholine receptors	0%
what is the LD50 of muscarine?	unknown in humans (0.23mg/kg in mice)	0%
	when the receptor is activated, chloride enters the neuron	0%
how can this lead to a toxic effect?	without the glycine inhibiting GlyR, the nervous system becomes hypersensitive	0%