Answer: Cocaine blocks the dopamine transporter (DAT), preventing dopamine reuptake into presynaptic neuron, causing dopamine accumulation in synaptic cleft and prolonged stimulation of reward pathway.
- A Cocaine is understood to act primarily by directly blocking postsynaptic dopamine receptors located within the cortex, preventing any dopamine molecule from ever reaching its target receptor site
- B Cocaine blocks the dopamine transporter (DAT), preventing dopamine reuptake into presynaptic neuron, causing dopamine accumulation in synaptic cleft and prolonged stimulation of reward pathway
- C Cocaine is understood to act by permanently destroying dopamine-producing neurons located within the midbrain, causing irreversible neuronal death rather than any reversible synaptic effect
- D Cocaine is understood to act on the human body in a manner that closely resembles insulin's normal hormonal action, lowering blood glucose levels through receptor binding in peripheral tissue
Correct answer: B. Cocaine blocks the dopamine transporter (DAT), preventing dopamine reuptake into presynaptic neuron, causing dopamine accumulation in synaptic cleft and prolonged stimulation of reward pathway
Explanation: Cocaine blocks DAT (dopamine transporter), NET (norepinephrine), and SERT (serotonin reuptake transporter). Dopamine accumulates in nucleus accumbens (reward center), causing intense euphoria. Norepinephrine accumulation causes tachycardia, hypertension, vasoconstriction. Highly addictive due to strong dopamine reward. Crack cocaine is smoked (faster onset, more addictive).
The Plasmodium parasite needs both hosts: the female Anopheles mosquito injects sporozoites while biting (infecting the human liver and RBCs, causing the malaria fever cycle), then picks up gametocytes from an infected person's blood, completing the parasite's sexual stage inside the mosquito.
Concept context
Pathogens, infectious diseases, non-infectious diseases, drugs, cancer, and public health. High NEET importance.