Final answer:
The rate of salivary secretion is decreased by swabbing the tongue with a solution with a pH of 4, the thought of an unappetizing meal, and a muscarinic receptor activator would increase the rate of salivary secretion.
Step-by-step explanation:
The rate of salivary secretion is decreased by swabbing the tongue with a solution with a pH of 4. The acidic solution disrupts the normal pH balance in the mouth, leading to a decrease in salivary secretion.
In addition, the thought of an unappetizing meal can also decrease the rate of salivary secretion. The brain sends signals to the salivary glands to reduce saliva production when a person anticipates consuming something unpleasant.
A muscarinic receptor activator/agonist, on the other hand, would increase the rate of salivary secretion. Muscarinic receptors are found in the salivary glands and their activation leads to an increase in saliva production.