Drug Receptors & Ligands
A drug that binds a receptor and mimics the endogenous ligand is called a:
What is an agonist?
The primary neurotransmitter released by postganglionic sympathetic neurons is:
What is norepinephrine?
The primary neurotransmitter of the parasympathetic nervous system is:
What is acetylcholine?
The resting membrane potential of most neurons is approximately:
What is –70 mV?
The space between pre- and postsynaptic membranes is called the:
What is the synaptic cleft?
A competitive antagonist does which of the following?
A. Decreases maximal efficacy
B. Shifts the dose-response curve to the right
C. Causes irreversible receptor binding
D. Increases potency
What is B. Shifts the dose-response curve to the right?
Activation of β1-adrenergic receptors primarily causes:
What is increased heart rate and contractility?
Muscarinic receptor activation generally causes which effect?
What is increased GI motility and secretions?
During the upstroke (depolarization) of the action potential, which ion moves and in what direction?
What is Na+ influx?
Calcium influx into the presynaptic terminal triggers:
What is neurotransmitter vesicle release?
The concentration of drug required to produce 50% of the maximal effect is a measure of:
What is potency (EC50)?
Which drug would cause mydriasis (pupil dilation) by stimulating α1 receptors?
What is a sympathomimetic (e.g., phenylephrine)?
Which drug could be used to reverse atropine toxicity?
What is a cholinesterase inhibitor (e.g., physostigmine)?
The Na+/K+ ATPase pump moves ions in which direction?
What is 3 Na+ out, 2 K+ in?
Tetanus toxin blocks neurotransmitter release by targeting which inhibitory neurotransmitters?
What are glycine and GABA?
Which receptor type is most associated with rapid ion flux across membranes?
What are ligand-gated ion channels?
In the sympathetic nervous system, the adrenal medulla releases this catecholamine in the highest proportion.
What is epinephrine (~80%)?
Which muscarinic receptor subtype primarily mediates decreased heart rate?
What is M2?
The refractory period ensures:
What is one-way conduction of action potentials and limits firing frequency?
Which postsynaptic potential brings the neuron closer to threshold?
What is an EPSP (excitatory postsynaptic potential)?
Explain what a partial agonist is:
What is a drug that binds the receptor but produces less than the maximal effect, even at full receptor occupancy?
A β-blocker (e.g., propranolol) would be contraindicated in which patient?
What is a patient with asthma or bronchoconstrictive disease (due to β2 blockade)?
An animal presents with SLUD signs (salivation, lacrimation, urination, defecation) after pesticide exposure. Which receptor type is overstimulated?
What are muscarinic cholinergic receptors?
If extracellular potassium concentration increases significantly (hyperkalemia), what effect does it have on neuronal excitability?
What is depolarization and increased excitability, potentially leading to inactivation?
Contrast electrical vs chemical synapses in one sentence.
Electrical synapses transmit signals via gap junctions (fast, bidirectional), while chemical synapses use neurotransmitters (slower, unidirectional).