The Human Nervous System by chocolate.boy 2012/07/14 14:29
The nervous system is essentially a biological information highway, and is responsible for controlling all the biological processes and movement in the body, and can also receive information and interpret it via electrical signals which are used in this nervous system
It consists of the Central Nervous System (CNS), essentially the processing area and the Peripheral Nervous System which detects and sends electrical impulses that are used in the nervous system
The Central Nervous System (CNS)
The Central Nervous System is effectively the centre of the nervous system, the part of it that processes the information received from the peripheral nervous system. The CNS consists of the brain and spinal cord. It is responsible for receiving and interpreting signals from the peripheral nervous system and also sends out signals to it, either consciously or unconsciously. This information highway called the nervous system consists of many nerve cells, also known as neurones, as seen below.
The Nerve Cell
Each neurone consists of a nucleus situated in the cell body, where outgrowths called processes originate from. The main one of these processes is the axon, which is responsible for carrying outgoing messages from the cell. This axon can originate from the CNS and extend all the way to the body's extremities, effectively providing a highway for messages to go to and from the CNS to these body extremities.
Dendrites are smaller secondary processes that grow from the cell body and axon. On the end of these dendrites lie the axon terminals, which 'plug' into a cell where the electrical signal from a nerve cell to the target cell can be made. This 'plug' (the axon terminal) connects into a receptor on the target cell and can transmit information between cells
The nervous system is essentially a biological information highway, and is responsible for controlling all the biological processes and movement in the body, and can also receive information and interpret it via electrical signals which are used in this nervous system
It consists of the Central Nervous System (CNS), essentially the processing area and the Peripheral Nervous System which detects and sends electrical impulses that are used in the nervous system
The Central Nervous System (CNS)
The Central Nervous System is effectively the centre of the nervous system, the part of it that processes the information received from the peripheral nervous system. The CNS consists of the brain and spinal cord. It is responsible for receiving and interpreting signals from the peripheral nervous system and also sends out signals to it, either consciously or unconsciously. This information highway called the nervous system consists of many nerve cells, also known as neurones, as seen below.
The Nerve Cell
Each neurone consists of a nucleus situated in the cell body, where outgrowths called processes originate from. The main one of these processes is the axon, which is responsible for carrying outgoing messages from the cell. This axon can originate from the CNS and extend all the way to the body's extremities, effectively providing a highway for messages to go to and from the CNS to these body extremities.
Dendrites are smaller secondary processes that grow from the cell body and axon. On the end of these dendrites lie the axon terminals, which 'plug' into a cell where the electrical signal from a nerve cell to the target cell can be made. This 'plug' (the axon terminal) connects into a receptor on the target cell and can transmit information between cells
chocolate.boy 2012/07/14 14:30
The Way Nerve Cells Communicate
The "All-Or-None-Law" applies to nerve cell communication as they use an on / off signal (like an digital signal) so that the message can remain clear and effective from its travel from the CNS to the target cell or vice versa. This is a factor because just like electricity signals, the signal fades out and must be boosted along its journey. But if the message is either 1 or 0 (i.e.) on or off the messages are absolute.
Classification of Neurones
Interneurones - Neurones lying entirely within the CNS
Afferent Neurones - Also known as sensory neurones, these are specialised to send impulses towards the CNS away from the peripheral system
Efferent Neurones - These nerve cells carry signals from the CNS to the cells in the peripheral system
The Way Nerve Cells Communicate
The "All-Or-None-Law" applies to nerve cell communication as they use an on / off signal (like an digital signal) so that the message can remain clear and effective from its travel from the CNS to the target cell or vice versa. This is a factor because just like electricity signals, the signal fades out and must be boosted along its journey. But if the message is either 1 or 0 (i.e.) on or off the messages are absolute.
Classification of Neurones
Interneurones - Neurones lying entirely within the CNS
Afferent Neurones - Also known as sensory neurones, these are specialised to send impulses towards the CNS away from the peripheral system
Efferent Neurones - These nerve cells carry signals from the CNS to the cells in the peripheral system
chocolate.boy 2012/07/14 14:31
The Conscious & Unconscious Nervous System
The Central Nervous System is arguably the most important part of the body because of the way it controls the biological processes of our body and all conscious thought. Due to their importance, they are safely encased within bones, namely the cranium protecting the brain and the spine protecting the spinal cord
Brain Divisions
There are three main components of the brain, namely the brainstem, cerebellum and the forebrain. These are elaborated upon below
The Brainstem - The brainstem is the connection between the rest of the brain and the rest of the central nervous system. This part of the brain was the first to be found in the evolutionary chain, though has developed over time and via evolution to develop into the two other components. It is primarily concerned with life support and basic functions such as movement, thus meaning that more advanced processes are left to the more evolved areas of the brain, as explained below.
The Cerebellum - Consisting of two hemispheres, the cerebellum is primarily concerned with movement and works in partnership with the brainstem area of the brain and focuses on the well being and functionality of muscles. The structure can be found below the occipital lobe and adjacent to the brainstem
The Forebrain - The forebrain lies above the brainstem and cerebellum and is the most advanced in evolutionary terms. Due to its complexity, more info is divulged about this part of the brain below
The Conscious & Unconscious Nervous System
The Central Nervous System is arguably the most important part of the body because of the way it controls the biological processes of our body and all conscious thought. Due to their importance, they are safely encased within bones, namely the cranium protecting the brain and the spine protecting the spinal cord
Brain Divisions
There are three main components of the brain, namely the brainstem, cerebellum and the forebrain. These are elaborated upon below
The Brainstem - The brainstem is the connection between the rest of the brain and the rest of the central nervous system. This part of the brain was the first to be found in the evolutionary chain, though has developed over time and via evolution to develop into the two other components. It is primarily concerned with life support and basic functions such as movement, thus meaning that more advanced processes are left to the more evolved areas of the brain, as explained below.
The Cerebellum - Consisting of two hemispheres, the cerebellum is primarily concerned with movement and works in partnership with the brainstem area of the brain and focuses on the well being and functionality of muscles. The structure can be found below the occipital lobe and adjacent to the brainstem
The Forebrain - The forebrain lies above the brainstem and cerebellum and is the most advanced in evolutionary terms. Due to its complexity, more info is divulged about this part of the brain below
chocolate.boy 2012/07/14 14:32
The Forebrain
The forebrain has many activities that it is responsible for and is divided into many component parts. The below list elaborates on the localised areas of the forebrain and their functions.
The Hypothalamus - A section of the brain found next to the thalamus that is involved in many regulatory functions such as osmoregulation and thermoregulation. The hypothalamus has a degree of control over the pituitary gland, another part of the brain situated next to it, and also controls sleeping patterns, eating and drinking and speech. The hypothalamus is also responsible for the secretion of ADH (Anti-Diuretic Hormone) via its neurosecretory cells
The Cerebrum - The cerebrum is the largest part of the human brain, and the part responsible for intelligence and creativity, and also involved in memory. The 'grey matter' of the cerebrum is the cerebral cortex, the centre that receives information from the thalamus and all the other lower centres in the brain.
The Cerebral Cortex - Part of the cerebrum, this part of the brain deals with almost all of the higher functions of an intelligent being. It is this part of brain that deals with the masses of information incoming from the periphery nervous system, furiously instructing the brain of what is going on inside its body and the external environment. It is this part that translates our nervous impulses into understandable quantifiable feelings and thoughts. So important is the cerebral cortex that it is sub-divided into 4 parts, explained below
Frontal Lobe - Found at the front of the head, near the temples and forehead, the frontal lobe is essential to many of the advanced functions of an evolved brain. It deals with voluntary muscle movements and deals with more intricate matters such as thought and speech
Parietal Lobe - Situated behind the frontal lobe, this section deals with spatial awareness in the external environment and acts as a receptor area to deal with signals associated with tough.
Temporal Lobe - The temporal lobes are situated in parallel with the ears, they serve the ears by interpreting audio signals received from the auditory canal
Occipital Lobe - This is the smallest of the four lobe components of the cerebrum, and is responsible in interpreting nerve signals from the eye at the back of the brain
The Forebrain
The forebrain has many activities that it is responsible for and is divided into many component parts. The below list elaborates on the localised areas of the forebrain and their functions.
The Hypothalamus - A section of the brain found next to the thalamus that is involved in many regulatory functions such as osmoregulation and thermoregulation. The hypothalamus has a degree of control over the pituitary gland, another part of the brain situated next to it, and also controls sleeping patterns, eating and drinking and speech. The hypothalamus is also responsible for the secretion of ADH (Anti-Diuretic Hormone) via its neurosecretory cells
The Cerebrum - The cerebrum is the largest part of the human brain, and the part responsible for intelligence and creativity, and also involved in memory. The 'grey matter' of the cerebrum is the cerebral cortex, the centre that receives information from the thalamus and all the other lower centres in the brain.
The Cerebral Cortex - Part of the cerebrum, this part of the brain deals with almost all of the higher functions of an intelligent being. It is this part of brain that deals with the masses of information incoming from the periphery nervous system, furiously instructing the brain of what is going on inside its body and the external environment. It is this part that translates our nervous impulses into understandable quantifiable feelings and thoughts. So important is the cerebral cortex that it is sub-divided into 4 parts, explained below
Frontal Lobe - Found at the front of the head, near the temples and forehead, the frontal lobe is essential to many of the advanced functions of an evolved brain. It deals with voluntary muscle movements and deals with more intricate matters such as thought and speech
Parietal Lobe - Situated behind the frontal lobe, this section deals with spatial awareness in the external environment and acts as a receptor area to deal with signals associated with tough.
Temporal Lobe - The temporal lobes are situated in parallel with the ears, they serve the ears by interpreting audio signals received from the auditory canal
Occipital Lobe - This is the smallest of the four lobe components of the cerebrum, and is responsible in interpreting nerve signals from the eye at the back of the brain
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