The human tissues are interconnected by a reticulum of nerve fibers which is controlled by the Brain and Spinal cord collectively constituting the Nervous System. The nerves form the peripheral nervous system and the brain and spinal cord form the central nervous system. In the worldwide web hierarchy, information is passed to and from the network service provider - the internet service provider and the user. Similarly, in the human body, information is passed to and from the central nervous system – the peripheral nervous system and the tissues. Central nervous system (CNS) is a huge topic to elaborate on; hence, this essay is aimed at providing CNS in a nutshell.
Brain is located in the cranial cavity and spinal cord occupies the upper two-thirds of the vertebral canal. They are covered by three membranous coverings (meninges) from inside outwards – pia mater, arachnoid mater and dura mater with cerebrospinal fluid in the subarachnoid space acting as a water cushion.
Brain has three parts namely prosencephalon (Forebrain) comprising the cerebrum and diencephalon, mesencephalon (midbrain) comprising the crus cerebri, substantia nigra tegmentum and tectum and rhombencephalon (hindbrain) comprising the pons, cerebellum and medulla oblongata. Spinal cord consists of 8 cervical segments, 12 thoracic segments, 5 lumbar segments, 5 sacral segments and one coccygeal segment. Lateral ventricles and third ventricle are the cavities of the forebrain; cerebral aqueduct and fourth ventricle are the cavities of the midbrain and hindbrain respectively. These cavities continue as the central canal of the spinal cord.
CNS is responsible for integrating, coordinating the sensory information and ordering appropriate motor actions. It is the seat of learning, memory, intelligence, speech and emotions. Sensory signals are carried by various afferent tracts in the spinal cord which ultimately projects into the brain. These signals reach appropriate sensory areas of the brain where the information is being processed and the decision of the next action is made by interacting with numerous association areas. To execute the decision that is being made, signals are transmitted to motor areas from which descending tracts carry the signals to the target organs. It seems as simple as a network, but is a more complex and efficient system which carries out the tasks in fraction of seconds.
Any disturbance in the normal physiological equilibrium results in pathology. These disturbances may result in paralysis, convulsions, paraesthesia, rigidity, weakness etc. Higher mental functions may also be affected causing psychiatric and psychological problems like mania, anxiety, depression, schizophrenia etc.
Being a vast field, there are numerous researches going on in CNS; worth mentioning here is the positioning system of the brain which bought the Nobel Prize in Medicine/Physiology for the year 2014. ‘John O’Keefe’ discovered the place cells in the hippocampus. ‘May-Britt Morsel’ and ‘Edward Morsel’ discovered the grid cells. These cells were responsible for the spatial orientation of the brain which is very essential for survival.
In the Central nervous system various cations and anions take part to transmit electrical signals which are carried through cells called neurons. As such, Central nervous system is a unique blender of physics, chemistry and biology well known for its efficiency and accuracy. Awesomeness is what is experienced by aficionados of science while decoding each and every aspect of the central nervous system.