Humans can recognize approximately 10,000 different smells. Explain how this is possible, including a general description of the olfactory process
What will be an ideal response?
Answer: A good answer will include the following key points.
? Olfaction begins with nasal airflow bringing in molecules that bind with receptors at the top of the nasal cavity.
? Within the nasal cavity is the olfactory epithelium, a thin layer of cells that are lined by sensory receptors called cilia, which are tiny hair-like projections that contain specialized proteins that bind with the airborne molecules that enter the nasal cavity.
? Despite the fact that we have only about 1,000 different types of receptors, we can detect many more distinct odors. This is because odor molecules can simultaneously stimulate several receptors at once. It is the pattern of the stimulation, involving more than one receptor, which gives rise to the experience of a particular smell.
? The information is transmitted to the olfactory bulb, which is the brain's central region for processing smell. The olfactory bulb connects with several regions of the brain through the olfactory tract, including the limbic system (emotion) as well as regions of the cortex where subjective experience of pleasure (or disgust) occurs.
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The sensation of arousal and alertness after encountering a dangerous stimuli is triggered by which structure?
a. the cerebral cortex b. the amygdala c. the somatic nervous system d. the autonomic nervous system
According to the textbook, in 2002, the Women's Health Initiative study provided results that changed the recommendations about hormone replacement therapy. These results showed that
a. the dosage of hormones that women had been taking was too low. b. women with an intact uterus should take only estrogen, and not progestin. c. the benefits of both estrogen and progestin were so clear-cut that women should begin hormone replacement therapy within one year after menopause. d. the combination of estrogen and progestin slightly increased the risk of heart disease, contrary to earlier research showing a decreased risk with those hormones.