Final answer:
Cross-tolerance occurs when tolerance to one drug results in resistance to similar drugs. Tolerance involves a need for higher doses of a drug to achieve the same effect, and it is connected to physiological dependence. Psychological dependence is an emotional need for a drug, while immediate hypersensitivity describes allergies like to pollen.
Step-by-step explanation:
When a patient has reduced responsiveness to one drug and becomes resistant to other, similar drugs, the phenomenon is termed cross-tolerance. Cross-tolerance is a situation where tolerance to one drug causes tolerance to related drugs. Tolerance itself occurs when a drug user requires increasingly higher doses of a given drug to experience the same effects of the drug because of the decreased sensitivity to it. This is linked to physiological dependence and can be dangerous, leading to overdose and death.
Psychological dependence refers to a drug craving that stems from emotional needs, unlike physical dependence, which is about the bodily functions and withdrawal symptoms. With regard to the immune system, during the secondary response of the immune reaction, class switching occurs. This allows the immune system to produce different classes of antibodies according to the need. Lastly, allergy to pollen is classified as immediate hypersensitivity, which is an exaggerated immune response to environmental antigens.