The major foods on which the body lives (with the exception of small quantities of substances such as vitamins and minerals) are carbohydrates, fats, and proteins. They generally cannot be absorbed in their natural forms through the gastrointestinal mucosa, and…
Throughout the gastrointestinal tract, secretory glands subserve two primary functions: (1) digestive enzymes are secreted in most areas of the alimentary tract, from the mouth to the distal end of the ileum; and (2) mucous glands located from the mouth…
The time that food remains in each part of the alimentary tract is critical for optimal processing and absorption of nutrients. In addition, appropriate mixing must be provided. Because the requirements for mixing and propulsion are quite different at each…
The alimentary tract provides the body with a continual supply of water, electrolytes, vitamins, and nutrients, which requires the following: (1) movement of food through the alimentary tract; (2) secretion of digestive juices and digestion of the food; (3) absorption…
Thus far, we have discussed the function of the brain as if it were independent of its blood flow, its metabolism, and its fluids. However, this is far from true because abnormalities of any of these aspects can profoundly affect…
The autonomic nervous system is the portion of the nervous system that controls most visceral functions of the body . This system helps to control arterial pressure, gastrointestinal motility, gastrointestinal secretion, urinary bladder emptying, sweating, body temperature, and many other…
All of us are aware of the many different states of brain activity, including sleep, wakefulness, extreme excitement, and even different levels of mood such as exhilaration, depression, and fear. All these states result from different activating or inhibiting forces…
Control of behavior is a function of the entire nervous system. Even the wakefulness and sleep cycle discussed in Chapter 60 is one of our most important behavioral patterns. In this chapter, we deal first with the mechanisms that control…
It is ironic that of all the parts of the brain, we are the least certain about the functions of the cerebral cortex, even though it is by far the largest and perhaps the most studied portion of the nervous…
In addition to areas in the cerebral cortex that stimulate muscle contraction, two other brain structures are essential for normal motor function—the cerebellum and the basal ganglia . Neither of these structures can control muscle function by itself. Instead, these…