L19 - L21 Pharmacology and Toxicology

Match the term to the description. [blank_start]Receptor[blank_end]: a protein molecule that receives external chemical signals. [blank_start]Ligand[blank_end]: a molecule or drug that binds to a receptor. [blank_start]Agonist[blank_end]: a chemical capable of activating a receptor to induce or amplify a response. [blank_start]Antagonist[blank_end]: a drug which counteracts the effects of another drug or molecule.

Enzymes vs. Receptors: Enzymes have [blank_start]one active site[blank_end] that binds substrates. The substrate is [blank_start]changed[blank_end] to a product. Enzymes can be membrane bound or free. Receptors have [blank_start]several binding sites[blank_end] that bind ligands. Ligands are released [blank_start]unchanged[blank_end]. Receptors can be membrane bound or free.

Normally, damaged tissues release arachidonic acid, which is a [blank_start]ligand[blank_end] that binds to the COX-2 receptor. This causes prostaglandin to be [blank_start]formed[blank_end] and it produces an inflammatory and pain response. Aspirin in a competitive [blank_start]inhibitor[blank_end] of the COX enzyme, meaning it binds at the same site on COX-2 as arachidonic acid, preventing it from binding. No prostaglandin will be formed, and pain and inflammation will be suppressed. Because aspirin can also bind to COX-1, an enzyme in [blank_start]all cells[blank_end] that regulates release of stomach acid, a side effect of aspirin is [blank_start]stomach ulcers[blank_end].

Choose all correct statements.

The cannabinoid receptor is an ionotropic channel.

Label these steps of G-protein Coupled Receptor action from 1 to 7: [blank_start]1[blank_end]. Receptor at rest. G-protein subunits α, β and γ are bound to the membrane receptor. [blank_start]6[blank_end]. After a period of time the GTP is cleaved to GDP. [blank_start]2[blank_end]. Agonist binds. Low energy GDP is swapped for GTP. [blank_start]7[blank_end]. Sub-units reform the G-protein complex and bind to membrane receptor again. [blank_start]4[blank_end]. The α sub-unit binds with a target protein (eg adenylate cyclase). [blank_start]3[blank_end]. The G-protein complex separates into α and βγ. [blank_start]5[blank_end]. The βγ sub-unit binds with a target protein (eg an ion channel)

Choose the incorrect statement about cannabis/cannabinoid receptors.

In 2012 an estimated 137 million kilograms of nitrogen leached from the soil into waterways, with [blank_start]80[blank_end]% of that being due to animal waste. [blank_start]Urea[blank_end] (CO(NH2)2) from animals gets converted back to nitrogen in the [blank_start]air[blank_end] or to [blank_start]ammonia[blank_end] (NH3+ or NH4) in the [blank_start]soil[blank_end] by enzymes. There, nitrifying bacteria can convert the NO4 to either [blank_start]nitrate[blank_end] (NO3) or [blank_start]nitrite[blank_end] (NO2). Nitrate, the major product, is [blank_start]the least toxic[blank_end] form of soluble nitrogens. Approximately [blank_start]5[blank_end]% of nitrate becomes nitrite in the body. Nitrite is [blank_start]toxic[blank_end], and possibly carcinogenic. It reacts with Fe2+ to oxidise it.

Choose the incorrect statement.

Choose the correct statement.

Nitrate poisoning of cattle and stock is sporadic in NZ, and cattle can consume a toxic amount in under an hour.

Which of these is not an effect nitrogen can have on waterways?

At what value of nitrate would an area be considered in 'poor' condition?

Which of these is not an action being taken to prevent nitrogen drainage into waterways?