The study and understanding of the body’s various nervoussystems is integral to the discipline of Biological Psychology. The CentralNervous System, Peripheral Nervous System and both branches of the AutonomicSystem are all vital to the correct functioning of the human body both mentallyand physically. The CNS is the overall controller for the Nervous System.
Bodily sensations and changes in our external environment are relayed fromreceptors and sense organs to the CNS to be interpreted. The way in which thePNS differs is that it is divided into many smaller components that are allresponsible for differing tasks. The two major divisions in the PNS are the Motor System andSensory System. The Sensory System is comprised of Sensory Neurons thatcommunicate information from receptors around the periphery of the body to thebrain and spinal cord. For example, the sensation of touch is sent through theSensory System, the brain interprets this and a sensation is returned to thehand such as pain or pleasure. Additionally, the Motor System is comprised ofMotor Neurons that communicate information from the brain and spinal cord toglands and muscles.
This is the where the PNS varies heavily to the CNS throughfurther subdivision of the Motor System with two more branches. The SomaticNervous System is responsible for conducting impulses from the brain and spinalcord to skeletal muscle. This is the process that results in humans responding orchanging to an external environment. The other branch at this stage of the Motor System is the AutonomicSystem (ANS). Interestingly, although the ANS is considered a major component ofthe overall Nervous System, it does not stem directly from the main body of theNS and is instead an element of the PNS.
The ANS is responsible for involuntaryactions, another way in which it differs from other elements of the Nervous System.It can further be divided into two components: The Sympathetic and ParasympatheticSystem. The Sympathetic System Is designed for instinctual situationswhere thinking about actions could potentially be detrimental to human survival,at least to an evolutionary extent. The SS is responsible for the ‘fight or flight’response. This is an involuntary physiological reaction that occurs in times ofdanger.
Blood is diverted away from the non-essential organs such as the liver andstomach to the systems considered vital for immediate survival such as the heartand muscles. Conversely, the Parasympathetic System is responsible for timeswhen the body needs more productivity when no threat is present. For example, speedingup the process of digestion after a large meal. These can be referred to as ‘vegetativeactivities’. Another of its key responsibilities is that it slows down processesafter the Sympathetic System is not needed.
For example, slowing heart beat andreducing blood flow when the danger has passed.