Answer to Question 1
D
The major sleep center in the body is the hypothalamus. The suprachiasmatic nucleus (SCN) nerve cells in the hypothalamus control the rhythm of the sleep-wake cycle and coordinate this cycle with other circadian rhythms. Researchers believe that the ascending reticular activating system located in the upper brainstem contains special cells that maintain alertness and wakefulness. Circadian rhythms influence the 24-hour pattern of major biological and behavioral functions such as the predictable changing of body temperature, heart rate, blood pressure, hormone secretion, sensory acuity, and mood. Sleep causes the basal metabolic rate to fall; falling of the metabolic rate does not cause sleep. Normal sleep involves two phases: nonrapid eye movement (NREM) sleep and rapid eye movement (REM) sleep.
Answer to Question 2
A
Because the patient is postoperative, the primary reason for sleep it to help the body to heal by restoring biological processes. Sleep allows the body to restore biological processes. During deep slow-wave (NREM stage 4) sleep, the body releases human growth hormone for the repair and renewal of epithelial and specialized cells such as brain cells. Protein synthesis and cell division for the renewal of tissues also occur during rest and sleep. The basal metabolic rate is lowered during sleep, which conserves the body's energy supply. REM sleep is important for cognitive restoration. During REM sleep patients experience rapid eye movement, fluctuation in heart and respiratory rate, increased/fluctuating blood pressure, loss of skeletal muscle tone, and increase in gastric secretions. (This is not a mental and physical calm.) During REM sleep there is increased oxygen consumption and epinephrine is released, not decreased. Sleep does not cause an increase in appetite as the metabolic rate slows down.