Physical Characteristics of the Peripheral Nervous System
The nervous system is divided into the Central Nervous System and the Peripheral Nervous System.
The Central Nervous System consists of the brain and the spinal cord.
The Peripheral Nervous System consists of spinal nerves, cranial nerves and the Autonomic Nervous System.
There are 31 pairs of spinal nerves these are disposed at regular intervals along with the spinal cord. The spinal nerves are classified into five groups.
- Cervical.
- Thoracic
- Lumbar
- Sacral
- Coccygeal
There are 12 pairs of cranial nerves. They serve the sensory and motor functions of the head and the neck region...
The Autonomic Nervous System (ANS) is concerned with the regulation of smooth muscles, cardiac muscles and the glands.
The (ANS) is of two types.
- Sympathetic Nervous System
- Para Sympathetic Nervous System.
The Sympathetic Nervous System plays an important role in emotional processes. It is most important when catabolic processes are at work.
The sympathetic and Para sympathetic divisions are largely, although not completely antagonistic in their effects.
In general, the sympathetic system mobilizes the resources of the body for use in work and special emergencies. Whereas, the parasympathetic system conserves and stores bodily resources.
The Brain and its essential features.
The human brain lies protected in the hard bony skull. The meninges are the protective sheaths around the brain and the spinal cord. The meninges consist of three layers.
- Dura mater: The outer layer is thick, tough and untreatable.
- Arachnoids: This middle layer is soft and spongy.
- Pia mater: This inner layer is closely attached to the brain and spinal cord, following every surface convolution.
In between the Arachnoids and the Pia mater is a gap called the sub arachnoids space, this space is filled with Cerebrospinal Fluid (CSF)
The Cerebrospinal Fluid (CSF) is manufactured by a special vascular structure called the Choroids Plexus, from blood plasma. The CSF is continuously produced, the total volume being approximately 125 ml. The brain floats in the bath of CSF.
The brain receives approximately 20 percent of the blood flow from the heart, it receives this blood flow continuously, and it always receives its share.
The brain cannot store its fuel (primarily glucose and ketone bodies), nor can it temporarily extract energy without oxygen as the muscles can; therefore, a consistent blood supply is essential. A one second interruption of the blood flow to the brain uses up much of the dissolved oxygen. A six second interruption produces nconsciousness, permanent damage occurs within a few minutes.
Divided Attention
Divided attention is associated with attention and perception. It refers to paying attention to two sources of information the best example is the phenomenon of Dichotic listening, paying attention to two stimuli of the same sensory channel or different sensory channel is difficult unless one of the activities has become automatic.
The area of divided attention asks the question of whether and to what extent two activities or two sources of information can be attended to. In modern information processing terminology, the question can be phrased as whether the human is a serial processor (can attend to only one thing or channel at a time) or a parallel processor (can attend to multiple sources of information at a time). The answer is that with sufficient practice under appropriate conditions, processing can become parallel or automatic i.e.: two or more information sources can be attended to with the same efficiency as a single source.
An important concept in the area of divided attention is that of resource allocation. As long as multiple tasks can be carried out in parallel with no decrease in performance in either one.