The nervous system is made up of a series of specialised and complex network of cells. Its acts as our internal communication system, specialising in two main functions:
The collection, processing and responding to information in the environment.
The coordination of various organs and cells within the body.
The nervous system can be subdivided into two main subsystems:
The Central Nervous System (CNS)
The Peripheral Nervous System (PNS)
The central nervous system is made up of the brain and the spinal cord.
The brain is an organ located within the head of a human being, it is the main source of conscious awareness, and this is where decision-making and reasoning takes place. The brain is split into two almost symmetrical halves known as hemispheres and it is connected through a series of structures, most notably the corpus collosum. The outer layer of the brain is known as the cerebral cortex this layer is about 3mm thick and highly developed in human begins. Parts of the brain can be divided into cortical (belonging to the cortex) or subcortical (below the cortex)
The brain controls the body contralaterally – meaning the opposite side of the body, i.e., the right hemisphere control the left side of the body and the left hemisphere controls the right side of the body.
The Spinal Cord
The spinal cord is a long, thin, tubular structure made up of nervous tissue, which connects to the brain via the brain stem. The spinal cord is responsible for reflex actions and passes information to and from the brain as well as linking it to the peripheral nervous system.
As was mentioned earlier the subcortical structures, are located under the cerebral cortex.
Thalamus – The thalamus receives information from our senses, hearing, sight, and touch but not smell! It then passes it to the relevant areas of the cerebral cortex. The thalamus also carries out some initial processing of its own filtering out information that may not be needed. It has also been linked with playing a role in sleep, wakefulness, and obsessive-compulsive disorder (OCD
Hypothalamus – The hypothalamus is located below the thalamus and is involved in many behavioural processes throughout the human body. The hypothalamus controls motivational behaviours such as hunger, thirst, and sex. It is also involved in the stress response system through its control of the ‘fight’ or ‘flight’ response.
Limbic System – The limbic system consists of several structures – the amygdala, which plays a significant role in emotional responses such as aggression and has a role in memory and learning. The limbic system is interconnected with areas of the cortex hence making it integrated with cortical and subcortical parts.
Cerebellum – The cerebellum is highly convoluted and has two hemispheres just like the brain, hence its meaning ‘little brain’. The primary role of the cerebellum is coordinating posture, balance, and movement. The cerebellum contains 50% of the brains neurons!
Corpus Callosum – The corpus callosum is a dense collection of nerves cells that connect the two hemispheres of the brain to allow communication between them, this is important considering the brains contralateral control.
What is Lateralisation?
As was discussed earlier the brain is split into two hemispheres and have contralateral control over the body. The two hemispheres are structurally identical however their functions are different – the left hemisphere for example is associated with language this is what lateralisation means.
What is Localisation?
Localisation refers to the specific areas within the hemisphere responsible for various functions and behaviours.
The Cerebral Cortex
The cerebral cortex is subdivided into 4 main lobes named by the bones underneath. Each lobe has a different function as localisation states.
Frontal Lobe – The frontal lobe is located at the front of the brain and take up 40% of the cerebral cortex. This lobe is responsible for high level cognitive functioning, problem solving, planning and decision-making.
Parietal Lobe – This lobe is found the top back part of the brain, and it contains the somatosensory cortex which is responsible for the processing of sensory information.
Temporal Lobe -This lobe is found on the lateral side of the brain and contains the auditory cortex which process sound, location, volume, and pitch of sounds.
Occipital Lobe – The occipital lobe can be found at the back of the brain and contains the visual cortex which process out entire field of vision in a contralateral manner.
References/ Further Reading:
The Brain – Wikipedia - https://en.wikipedia.org/wiki/Brain
Nervous System – Wikipedia - https://en.wikipedia.org/wiki/Nervous_system
The Central Nervous System – Wikipedia - https://en.wikipedia.org/wiki/Central_nervous_system
Cerebral Cortex – Wikipedia - https://en.wikipedia.org/wiki/Cerebral_cortex#Connections
Frontal Lobe – Wikipedia - https://en.wikipedia.org/wiki/Frontal_lobe
Parietal Lobe – Wikipedia - https://en.wikipedia.org/wiki/Parietal_lobe
Temporal Lobe – Wikipedia - https://en.wikipedia.org/wiki/Temporal_lobe
Occipital Lobe – Wikipedia - https://en.wikipedia.org/wiki/Occipital_lobe