If the brain controls practically everything, how does the signal get to your toes? Or your legs? Or arms? By way of the peripheral nervous system, or all the nerves shown here other than the brain and spinal cord. Notice how they go everywhere. Peripheral Nervous SystemThe peripheral nervous system (PNS) consists of all the nervous tissue that lies outside thecentral nervous system. It is shown in yellow in Figure below. It is connected to the central nervous system by nerves. A nerve is a cable-like bundle of axons. Some nerves are very long. The longest human nerve is the sciatic nerve. It runs from the spinal cord in the lower back down the left leg all the way to the toes of the left foot. Like the nervous system as a whole, the peripheral nervous system also has two divisions: the sensory division and the motor division.
The nerves of the peripheral nervous system are shown in blue in this image. Can you identify the sciatic nerve? Somatic Nervous SystemThe somatic nervous system (SNS) controls mainly voluntary activities that are under conscious control. It is made up of nerves that are connected to skeletal muscles. Whenever you perform a conscious movement, from signing your name to riding your bike, your somatic nervous system is responsible. The somatic nervous system also controls some unconscious movements, called reflexes. A reflex is a very rapid motor response that is not directed by the brain. In a reflex, nerve impulses travel to and from the spinal cord in a reflex arc, like the one in Figure below. In this example, the person jerks his hand away from the flame without any conscious thought. It happens unconsciously because the nerve impulses bypass the brain. A reflex arc like this one enables involuntary actions. How might reflex responses be beneficial to the organism? Autonomic Nervous SystemAll other involuntary activities not under conscious control are the responsibility of the autonomic nervous system (ANS). Nerves of the ANS are connected to glands and internal organs. They control basic physical functions such as heart rate, breathing, digestion, and sweat production. The autonomic nervous system also has two subdivisions: the sympathetic division and the parasympathetic division.
What is the role of the brain and hypothalamic regions in the control of eating?The hypothalamus maintains energy homeostasis by regulating homeostatic food intake. The specific hypothalamic neurons sense nutritional and hormonal signals from the blood. It has been reported that the hypothalamus increases appetite by sensing low glucose availability, and decreases it under glucose repletion.
What region of the brain does most of the processing of signals regarding food intake?The amygdala is the primary brain area regulating appetite with response to emotions. Indeed, the amygdala activates to food cues [124, 125], and this response is increased in childhood, adolescent, and adult obesity [126-129].
What is Peripheral food?jerome described the core foods as staple items in a particular meal, secondary core foods as those either added to or substituted for the basic core, and peripheral foods as those used infrequently by most individuals (5).
|