Structure and functions of neurons

• There are three main types of neurons, including: sensory,relay and motor.
• Each neurons has a different function, depending on its location in the body and its role within the nervous system.
• Sensory neurons are found in receptors such as the eyes, ears, tongue and skin, and carry nerve impulses to the spinal cord and brain.
• Not all sensory neurons reach the brain, as some neurons stop at the spinal cord, allowing for quick reflex actions.
• Relay neurons are found between sensory input and motor output/ response.
• Relay neurons are found in the brain and spinal cord and allow sensory and motor neurons to communicate.
• Motor neurons are found in the central nervous system (CNS) and control muscle movements.
• When motor neurons are stimulated, they release neurotransmitters that bind to the receptors on muscles to trigger a response, which leads to movement.
• The dendrites receive signals from other neurons or from sensory receptor cells. The dendrites are typically connected to the cell body.
• The axon is a long slender fibre that carries nerve impulses, in the form of an electrical signal known as action potential, away from the cell body towards the axon terminals, where the neuron ends.
• Most axons are surrounded by a myelin sheath (except for relay neurons) which insulates the axon so that the electrical impulses travel faster along the axon.
• The axon terminal connects the neuron to other neurons (or directly to organs), using a process called synaptic transmission.
• Sensory neurons are the nerve cells that are activated by sensory input from the environment, e.g. when you touch a hot surface with your fingertips.
• A sensory neuron is a nerve cell that detects and responds to external signals.
• Sensory neurons receive information via their receptors, which are part of the peripheral nervous system, and convert this information into electrical impulses.
• Motor neurons control movement.
• Sensory neurons allow us to feel sensations.
• Relay neurons allow motor neurons and sensory neurons to communicate with one another.
• Different types of sensory neurons respond to different stimuli, for example, some neurons detect temperature while others detect pain.
• A typical neuron is comprised of dendrites, an axon and a cell body.
• In motor neurons, the new nerve impulse is generated in the neuron of the motor cortex of the brain, whereas in sensory neurons, the new signal is generated in the peripheral nervous system.
• Motor neurons are efferent (meaning they carry information out towards the periphery from the central nervous system).
• A sensory neuron usually has the cell body on the axon, sticking out like a sore thumb.
• Motor neurons are connected to effectors/ muscles for movement.
• Relay neurons look long and thin (like some athletes).
• The sequence of neurons goes from sensory to relay to motor.
• Structure of 3 main neurones

  A) myelin sheath

  B) cell body

  C) dendrite

  D) pre synaptic terminal

  E) axon

  F) Nodes of ranvier

  G) Cell body

  H) dendrite