Responding to the World

The ANS is a component of the peripheral nervous system that uses both afferent (sensory) and efferent (effector) neurons, which control the functioning of the internal organs and involuntary processes via connections with the CNS. The ANS consists of the sympathetic and parasympathetic nervous systems. The efferent nerve fibers that terminate in the endocrine, vascular, and visceral structures coordinate the inner workings of the body in response to several afferent inputs. The sympathetic and parasympathetic neural circuits coordinate stress responses and relaxation responses, respectively. The enteric nervous system regulates visceral organ function. A balance between these systems results in homeostasis, whereas an imbalance leads to pathological conditions.

Sleep is a reversible phase of diminished responsiveness, motor activity, and metabolism. This process is a complex and dynamic phenomenon, occurring in 4–5 cycles a night, and generally divided into non–rapid eye movement (NREM) sleep and REM sleep stages. NREM sleep, consisting of 3 stages, represents the period of transition from wakefulness, somnolence, and then deep sleep. REM sleep is characterized by rapid irregular eye movement, but with voluntary muscle atonia. The sleep stages and associated disorders are studied through the use of polysomnography, a multimodal test evaluating the brain waves, along with ocular and motor activities. Sleep disorders can be primary (which do not stem from any health problem) or can be attributable to underlying conditions or medications.

Are you able to name the six basic human emotions? Happiness, sadness, anger, fear, surprise, and disgust. How do emotions arise and how can they be measured? What anatomic correlations should you know? What are the most important theories about emotions? The following article answers all of these and even more questions. Moreover, you will learn important clinical connections: anxiety disorders and depression are common diseases that you will encounter in your clinical routine. Make yourself familiar with the basics so that you are perfectly prepared for preclinical exams and your "Physikum".