- ENZYMES, GROWTH FACTORS, PROTEINS, AND RECEPTORS

21β-Hydroxylase (P450c21)

What enzyme's deficiency blocks progesterone conversion to 11-Deoxycorticosterone, resulting in salt wasting due to lack of aldosterone?

11β-Hydroxylase (P450c11)

What enzyme's deficiency reduces 11-Deoxycorticosterone conversion to corticosterone, leading to salt wasting due to lack of aldosterone?

17α-Hydroxylase (P450c17)

What enzyme's deficiency reduces pregnenolone conversion to 17-Hydroxy-pregnenolone, which decreases DHEA but does not cause salt-wasting symptoms?

Desmolase enzyme

What enzyme catalyzes the conversion of cholesterol to pregnenolone, and is inhibited by Aminoglutethimide?

Cytochrome P450 enzymes

What class of enzymes, necessary for the synthesis of all steroids, is inhibited by Ketoconazole?

Glucocorticoid receptors

What receptors, when activated by Hydrocortisone, lead to altered gene transcription, resulting in suppressed inflammation and allergic reactions?

Mineralocorticoid receptors

What receptors are strongly activated by Fludrocortisone, leading to increased Na+ reabsorption and H+ and K+ excretion?

H+/K+ ATPase pump (Potassium-Hydrogen-ATPase pump)

What specific pump does a Proton Pump Inhibitor (PPI) directly inhibit to secrete HCl?

N-acetyltransferase 2 (NAT2) enzymes

What enzymes normally eliminate Isoniazid by converting it to acetylisoniazid and acetylhydrazine derivates?

Phosphokinase

What enzyme involved in pyridoxine and GABA production is inhibited by hepatotoxins formed during Isoniazid poisoning, leading to intractable seizures?

Alcohol dehydrogenase

What enzyme's competitive inhibition by Fomepizole prevents the generation of toxic metabolites from methanol and ethylene glycol poisoning?

Cytochrome oxidase system

What cellular system does cyanide poisoning displace oxygen from, leading to a lack of oxygen and cellular hypoxia?

Acetylcholinesterase (AChE)

What enzyme's inhibition by organophosphates results in an overload of acetylcholine, causing a cholinergic crisis?

μ-receptor (Opioid receptor)

What receptor, when agonized by opioids, causes key clinical features such as miosis, respiratory depression, and CNS depression?

Glucagon

What agent, given for beta-blocker overdose, improves heart rate and blood pressure by acting on receptors to activate adenylate cyclase, increasing cAMP independently of beta-receptors?

Digoxin antibodies

What specific antidote inactivates Digoxin?

Protamine

What antidote binds to Heparin, disabling its anticoagulant effect?

Deferoxamine

What chelating agent is the specific antidote for iron poisoning?

Hydroxocobalamine

What antidote binds to cyanide to form cyanocobalamine?

Sodium nitrate

What agent induces methemoglobinemia, allowing it to bind cyanide (CN-)?

Sodium thiosulfate

What agent binds cyanide (CN-) to form sodium thiocyanate (SCN-)?

NAPQI (N-acetyl-p-benzo-quinone imine)

What toxic metabolite is produced when paracetamol metabolism shunts to the cytochrome P450 pathway in overdose, overwhelming conjugation pathways?

Glutathione

What substance, supplied by N-acetylcysteine, is necessary to break down the toxic metabolite NAPQI into non-toxic cysteine and mercapturic acid conjugates?

G-protein-coupled receptors (GPCRs)

What class of receptors typically mediates the effects of catecholamines?

Haplotypes

What term refers to a set of distinct adrenoceptor polymorphisms that are inherited together?

Choline acetyltransferase (ChAT)

What enzyme combines Acetyl CoA and choline to synthesize Acetylcholine?

Tyrosine hydroxylase

What enzyme catalyzes the conversion of tyrosine to dopa, serving as the rate-limiting step in adrenergic neurotransmitter synthesis?

Monoamine oxidase (MAO)

What enzyme metabolizes catecholamines inside the presynaptic neuron after reuptake?

Catechol-O-methyltransferase (COMT)

What enzyme degrades epinephrine, norepinephrine, and dopamine in the extracellular space after neurotransmitter reuptake has failed?

Muscarinic receptors (M1, M3, M5)

What muscarinic receptors use the Gq protein secondary messenger system, resulting in the formation of IP3 and DAG, and increased intracellular calcium?

Muscarinic receptors (M2, M4)

What muscarinic receptors use the Gi protein mechanism, resulting in the inhibition of adenylyl cyclase and the opening of potassium channels?

Nicotinic receptors (NN or N2)

What ion channel-linked receptors are found in autonomic ganglia, the CNS, and the adrenal medulla, and depolarize the effector organ by opening Na+ and K+ channels?

Nicotinic receptors (NM or N1)

What ion channel-linked receptors are found in skeletal muscles at the neuromuscular endplate and depolarize the muscle cell by opening Na+ and K+ channels?

Alpha 1 receptor (α1)

What adrenergic receptor uses the Gq protein pathway to increase Phospholipase C, resulting in increased cytoplasmic Ca²⁺ and effects like vasoconstriction and pupillary dilation?

Beta 1 receptor (β1)

What adrenergic receptor uses the Gs protein pathway, stimulating adenylyl cyclase, resulting in increased cAMP and effects like increased heart rate and contractility?

Beta 2 receptor (β2)

What adrenergic receptor uses the Gs protein pathway, stimulating adenylyl cyclase, resulting in increased cAMP and effects like bronchodilation and uterine relaxation?

Dopamine D1 (DA1) receptor

What dopaminergic receptor uses the Gs protein pathway to stimulate adenylyl cyclase and increase cAMP?

Dopamine D2 (DA2) receptor

What dopaminergic receptor uses the Gi protein pathway to inhibit adenylyl cyclase and increase potassium conductance?

Sodium-dependent choline transporter (CHT)

What symporter facilitates the entry of choline into the presynaptic terminal along with sodium, a process inhibited by Hemicholinium?

Vesicle-associated transporter (VAT)

What transporter moves Acetylcholine into vesicles for storage, driven by proton efflux, a process inhibited by Vesamicol?

SNARES (VAMPS/SNAPS)

What surface proteins concentrate acetylcholine-containing vesicles on the nerve terminal and facilitate calcium-dependent release?

Vesicular Monoamine Transporter (VMAT)

What high-affinity antiporter moves catecholamines into storage vesicles, a process inhibited by Reserpine and related drugs?

Norepinephrine Transporter (NET)

What presynaptic transporter is highly effective at pumping released norepinephrine back into the neuron from the synaptic cleft?

Serotonin (5-HT)

What neurotransmitter is found in the enteric nervous system (ENS), affects mood and behavior in the CNS, and stimulates vomiting via 5-HT3 receptors?

EDRF/NO (Endothelium Derived Relaxing Factor/Nitric Oxide)

What substances are synthesized and released by vascular endothelium following M3 receptor activation, causing vasodilation?

Dopamine-β-hydroxylase

What enzyme is released along with norepinephrine, ATP, and peptide co-transmitters during the release of catecholamines in adrenergic transmission?

Gq protein

What G-protein is used by Alpha 1, Muscarinic M1, M3, and M5 receptors, leading to increased IP3 and DAG and increased intracellular calcium?

Gi protein

What G-protein is used by Alpha 2, Dopamine D2/D3/D4, and Muscarinic M2/M4 receptors, leading to inhibition of adenylyl cyclase?

Gs protein

What G-protein is used by Beta 1/Beta 2/Beta 3, and Dopamine D1/D5 receptors, leading to stimulation of adenylyl cyclase and increased cAMP?

Beta 3 receptor (β3)

What adrenergic receptor is linked to Gs protein and stimulation of adenylyl cyclase, primarily involved in lipolysis in fat cells?

Alpha 2 receptor (α2)

What adrenergic receptor uses the Gi protein pathway, resulting in inhibition of adenylyl cyclase and decreased cAMP, often found presynaptically to inhibit neurotransmitter release?

Dopamine D5 receptor (D5)

What dopaminergic receptor uses the Gs protein pathway to stimulate adenylyl cyclase?

Dopamine D3 receptor (D3)

What dopaminergic receptor uses the Gi protein pathway to inhibit adenylyl cyclase?

Dopamine D4 receptor (D4)

What dopaminergic receptor uses the Gi protein pathway to inhibit adenylyl cyclase?

Serotonin 5-HT3 receptor

What receptor, found on vagal afferents and central receptors, stimulates vomiting and is targeted by anti-emetics like Ondansetron?

Serotonin 5-HT1B receptor

What serotonin receptor, located in the CNS, mediates neuronal inhibition and behavioral changes?

Serotonin 5-HT2A receptor

What serotonin receptor, located in the CNS, smooth muscle, and platelets, mediates cellular excitation, muscle contraction, and vasoconstriction?

Serotonin 5-HT4 receptor

What serotonin receptor, located in the CNS and ENS, primarily affects gut motility?

Tyramine

What indirect-acting sympathomimetic, transported by NET and VMAT to displace norepinephrine from vesicles, promotes its release?

Pralidoxime (2-PAM)

What strong nucleophile compound, known as a cholinesterase regenerator, can break the stable bond formed by organophosphates and acetylcholinesterase if given before aging?

Sugammadex

What novel reversal agent binds specifically to rocuronium and vecuronium in the plasma, creating a concentration gradient that draws the neuromuscular blocker out of the NMJ?

IP3 (Inositol triphosphate) and DAG (Diacylglycerol)

What secondary messengers are formed via the M1, M3, and M5 muscarinic receptor activation pathway, leading to increased intracellular calcium concentrations?

cAMP (cyclic adenosine monophosphate)

What molecule's levels are decreased upon activation of M2 and M4 muscarinic receptors by inhibiting adenylyl cyclase activity?

Muscarinic receptor (M1)

What muscarinic receptor is found in CNS nerves, salivary glands, and parietal cells, and mediates gastric acid secretion and CNS excitation?

Muscarinic receptor (M2)

What muscarinic receptor is often called Cardiac M2 and, when activated, decreases heart rate, force, and AV conduction by opening K+ channels?

Muscarinic receptor (M3)

What muscarinic receptor is found in exocrine glands, smooth muscle, and endothelium, and leads to smooth muscle contraction and glandular secretion?

Dopamine

What catecholamine acts as a neurotransmitter at sympathetic post-ganglionic nerve endings and activates alpha, beta, and dopamine receptors?

Nicotine

What direct-acting alkaloid cholinomimetic is lipid-soluble, rapidly absorbed by the skin, and used for smoking cessation?

Acetylcholine (ACh)

What neurotransmitter is the primary transmitter at ANS ganglia, the somatic neuromuscular junction, and parasympathetic post-ganglionic nerve endings?

Methacholine

What direct-acting choline ester is methylated, reducing its potency at nicotinic receptors, and is used in nonspecific bronchoprovocation tests?

Bethanechol

What direct-acting choline ester has negligible susceptibility to cholinesterase and is the drug of choice for postoperative ileus and urinary retention?

Carbachol

What direct-acting choline ester has negligible susceptibility to cholinesterase and is used exclusively for glaucoma via topical administration?

Pilocarpine

What direct-acting muscarinic alkaloid is used to treat glaucoma and stimulate saliva production (e.g., in Sjögren’s syndrome)?

Edrophonium

What short-acting, simple alcohol cholinesterase inhibitor is used in the Tensilon Test for diagnosing Myasthenia Gravis?

Pyridostigmine

What intermediate-acting carbamate cholinesterase inhibitor is used for the long-term therapy of Myasthenia Gravis?

Physostigmine

What carbamate cholinesterase inhibitor is lipid soluble, crosses the BBB, and is the drug of choice for treating Atropine overdose with CNS effects?

Echothiophate

What organophosphate, unlike most others, is highly polar and stable in aqueous solution, allowing its clinical use because it does not cross the CNS?

Botulinum Toxin

What substance, produced by Clostridium botulinum, inhibits the release of Acetylcholine by acting on SNARE proteins, causing paralysis?

Atropine

What prototype non-selective antimuscarinic agent is an inverse agonist that blocks cholinomimetic actions at muscarinic receptors and is the treatment for cholinergic poisoning?

Scopolamine

What tertiary amine antimuscarinic is rapidly distributed in the CNS and is used for motion sickness and abdominal cramps/GI spasms?

Benztropine

What antimuscarinic drug acts as an antagonist at M receptors in the basal ganglia, reducing the tremor and rigidity associated with Parkinson’s disease?

Ipratropium bromide

What inhalational antimuscarinic drug is used for COPD and acute exacerbations of asthma?

Tiotropium

What long-acting antimuscarinic agent is used for the maintenance treatment of COPD exacerbations?

Oxybutynin

What antimuscarinic drug, somewhat selective for M₃ receptors, is the drug of choice for overactive bladder and relief of bladder spasms after urologic surgery?

Pancuronium

What non-depolarizing neuromuscular blocker is known for causing a moderate increase in heart rate and smaller increase in cardiac output?

Rocuronium

What non-depolarizing neuromuscular blocker has the most rapid onset (60-120 seconds) and is reversed by Sugammadex?

Tubocurarine

What non-depolarizing neuromuscular blocker can cause histamine release, leading to hypotension and bronchospasm?

Succinylcholine

What short-acting depolarizing neuromuscular blocker is used for short procedures like endotracheal tube placement, rapidly hydrolyzed by cholinesterase in the plasma?

Dantrolene

What drug is the treatment for malignant hyperthermia, acting by targeting the abnormal release of calcium from stores in skeletal muscle?

Neostigmine

What intermediate-acting carbamate is used to indirectly reverse neuromuscular blockade by inhibiting acetylcholinesterase?

Glycopyrrolate

What quaternary amine antimuscarinic is used as a maintenance drug for COPD?

Pirenzepine

What M1 selective antimuscarinic agent selectively blocks excitatory M1 receptors on vagal ganglion cells to reduce gastric acid secretion?

Carbamylated acetylcholinesterase

What complex is formed when carbamate esters bind to acetylcholinesterase, leading to a covalent bond that is resistant to hydration and prolongs the inhibitory effect?

Fesoterodine and Tolterodine

What M₃-selective antimuscarinics are prescribed for adults with urinary incontinence?

Epinephrine (Adrenaline)

What mixed alpha and beta agonist has equal affinity for all adrenergic receptors (α1=α2, β1=β2) and is the most important treatment for anaphylactic shock?

Norepinephrine (Noradrenaline/Levarterenol)

What mixed alpha and beta agonist has greater affinity for beta 1 over beta 2 (α1=α2; β1>>β2) and is used for septic shock?

Dobutamine

What beta agonist has greater affinity for β1 (β1>β2) and is used to stimulate heart contractility in cardiogenic shock?

Isoproterenol

What non-specific beta agonist has equal affinity for β1 and β2 (β1=β2>>>>α) and produces a positive inotropic and chronotropic effect?

Albuterol (Salbutamol)

What beta agonist has high selectivity for $\beta$2 ($\beta$2>>$\beta$1>>>>$\alpha$) and is a common bronchodilator used for asthma and COPD?

Terbutaline and Ritodrine

What beta agonists have high selectivity for $\beta$2 and are used for uterine relaxation to halt premature labor?