How does the circadian input system work? Photic information is transmitted from the retina directly to the oscillator network in the SCN via the RHT. However, the photic information is not communicated by retinal rod and cone cells. Within the retinal there are non-rod, non-cone cells, the so-called retina ganglion cells (RGCs). These cells contain a photopigment, melanopsin, …
How is the circadian system organized? Using engineering parlance, the organization of the circadian system consists of three parts: (1) input system, (2) oscillator network, and (3) output system. The input system is represented by the retinal hypothalamic tract (RHT). The oscillatory network , itself with three parts, is represented by SCN, entrainment and tissue oscillators. The output system is represented …
Basic mechanisms of Process C Research has uncovered core molecular clock machinery responsive to process-C in most tissues! The bilateral or paired SCN of the hypothalamus are regarded as the sole master 24-hour pacemaker. Research has shown the circadian process to be a hierarchy of oscillations starting with oscillations from the SCN centrally emanating to the periphery—that is, downstream oscillations within …
What are the two basic processes controlling sleep timing and sleep quality and, therefore, contributing to anterior pituitary hormone cycling in a 24-hour period? The following should serve as a framework for understating these two time-honored processes. For more in-depth rendering, please see selected references. The first process is called process-C , for circadian process ( circadian from Latin …
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What are the systems and neurotransmitters responsible for wakefulness and for the sleep state? Our contemporary understanding of the endocrine system includes much more neuroendocrinology. The discussion in this chapter highlights the interactions among the cortex, brain stem, hypothalamus, and pituitary. Central nervous system (CNS) accomplishment of sleep–wake changes can be best modeled as flip …
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What are the fundamental changes in the nervous system in NREM versus REM sleep, and what other differences are noted between the phases of NREM and REM? Cortical deactivation and autonomic nervous system (ANS) changes typify sleep. While awake, we interact with our environment, but when asleep we are largely unresponsive to sensory input and …
How do the sleep stages change during ones life span? As we age, total sleep time decreases and sleep begins to fragment. The time in sleep declines with age from 16 to 18 hours a day in a newborn to 9 to 10 hours in a 10-year-old, to 7.5 to 8 hours in the average …
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