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The Nervous System - Central and Peripheral - Coggle Diagram
The Nervous System - Central and Peripheral
The Peripheral Nervous System (PNS)
The PNS transmits messages throughout the whole body from the brain and relays messages back to the brain
The Somatic System
transmits and receives messages from the senses
An example of this would be visual information from the eyes or touch information from the skin
It then directs the muscles to move appropriately
For example: If your eyes are registering that there is a car coming toward you, the Somatic System would be telling your muscles to move and to get you out of the way
The Autonomic System
The Autonomic System transmits and receives information from the organs
It is divided into two further sections:
The Sympathetic System
The Parasympathetic System
The Sympathetic System increases activity
The Parasympathetic System helps to conserve the body's activity levels and energy by decreasing activity or maintaining it)
The Central Nervous System (CNS)
The CNS is made up of the brain and the spinal cord
The brain is central to maintaining life and has many functions.
Functions include:
Language (production and understanding)
Co-ordinating movement
Coding sensory data from the sensory organs
Problem-solving and planning
Basic functions such as regulating body temperature, heart rate and breathing
The Spinal Cord ensures that signals from the brain are transmitted to the rest of the body via the PNS
It is also involved in reflex actions: Such as how to respond when we are surprised or startled
The Structure & Function of Sensory, Relay & Motor Neurons
Motor Neurons
These carry signals from the Central Nervous System (CNS) toward the organs, muscles and glands in the body
In this respect, they are efferent neurons as they carry information away from the CNS toward the PNS
As they can both transmit and receive messages, they are known as multipolar neurons
Relay Neurons
These are also known as Interneurons as they can take on the role of sensory and motor neurons in the nervous system
They connect the sensory neurons to the motor neurons
They are based in the CNS and carry signals/messages across this part of the nervous system
As they can both transmit and receive messages, they are known as multipolar neurons
Sensory Neurons
These are cells that send information to the brain regarding the senses; these are also known as afferent neurons as they carry information from the Peripheral Nervous System (PNS) towards the Central Nervous System (CNS)
They keep the brain informed about the external and internal environment via processing information coming from the eyes, ears, nose, skin and tongue
They can only transmit messages and so are unipolar
The Synapse
Transmission at a synapse
Electrical impulses cannot ‘jump’ across synapses
When an electrical impulse arrives at the end of the axon on the presynaptic neurone (also called the synaptic knob), chemical messengers called neurotransmitters are released from vesicles at the presynaptic membrane
The neurotransmitters diffuse across the synaptic cleft and temporarily bind with receptor molecules on the postsynaptic membrane
This stimulates the postsynaptic neurone to generate an electrical impulse that then travels down the axon of the postsynaptic neurone
The neurotransmitters are then destroyed or recycled to prevent continued stimulation of the second neurone, which could cause repeated impulses to be sent
The junction where two neurones meet is known as a synapse
A synapse consists of a presynaptic knob, synaptic cleft and postsynaptic membrane
Synapses that use acetylcholine (ACh) as a neurotransmitter are described as cholinergic synapses