Nerve Transmission

A nerve is made up of a number of single cells called neurons. These neurons a cell body, and an axon. The axon is a bit like a tail! Each neuron can be very long and it is the length of the axon that is important. The diagram to the right shows a motor neuron. Motor neurons have the cell body at one end of the cell and are used to send signals to the effector (i.e. muscles). The cell body does contain a nucleus which contains DNA in the same way as all the cells in your body.

At each end of the cell are a number of Dendrites. These are the hair like things located at the ends of the axon and cell body. These are able to release and/or detect chemical signals called neurotransmitters. You don't need to know the names really but the two most common types of neurotransmitter are acetylcholine and noradrenaline.

When a neurotransmitter is released by the Central Nervous System (for example: the brain) it is detected by the detection end of the nerve (often the cell body in motor neurons). A electrical charge is then transmitted down the axon to the other end of the nerve. When the signal reaches the end a neurotransmitter is released which the effector (i.e. muscle) detects and the effector carries out the action. The Myelin Sheath speeds up the transmission of the nervous impulse.

The electrical charge that is transmitted is created by the movement of ions (electrically charged atoms) in and out of the axon. The myelin sheath cells have small gaps between them know as nodes of Ranvier, The transmission occurs between these nodes in myelinated neurons and this is why transmission is quicker. Axons normally have a relatively high concentration of potassium (K+) ions which are positively charged. The tissue surrounding contains a relatively high concentration of sodium (Na+) ions which have a stronger positive charge than potassium ions. Therefore the outside of the axon is positively charged compared to the inside. When a signal is transmitted the ions are swapped (relatively speaking) and so the charge is reversed. It then returns to the resting potential. See the diagram below.


	Nerve Transmission A nerve is made up of a number of single cells called neurons. These neurons a cell body, and an axon. The axon is a bit like a tail! Each neuron can be very long and it is the length of the axon that is important. The diagram to the right shows a motor neuron. Motor neurons have the cell body at one end of the cell and are used to send signals to the effector (i.e. muscles). The cell body does contain a nucleus which contains DNA in the same way as all the cells in your body. At each end of the cell are a number of Dendrites. These are the hair like things located at the ends of the axon and cell body. These are able to release and/or detect chemical signals called neurotransmitters. You don't need to know the names really but the two most common types of neurotransmitter are acetylcholine and noradrenaline. When a neurotransmitter is released by the Central Nervous System (for example: the brain) it is detected by the detection end of the nerve (often the cell body in motor neurons). A electrical charge is then transmitted down the axon to the other end of the nerve. When the signal reaches the end a neurotransmitter is released which the effector (i.e. muscle) detects and the effector carries out the action. The Myelin Sheath speeds up the transmission of the nervous impulse. The electrical charge that is transmitted is created by the movement of ions (electrically charged atoms) in and out of the axon. The myelin sheath cells have small gaps between them know as nodes of Ranvier, The transmission occurs between these nodes in myelinated neurons and this is why transmission is quicker. Axons normally have a relatively high concentration of potassium (K+) ions which are positively charged. The tissue surrounding contains a relatively high concentration of sodium (Na+) ions which have a stronger positive charge than potassium ions. Therefore the outside of the axon is positively charged compared to the inside. When a signal is transmitted the ions are swapped (relatively speaking) and so the charge is reversed. It then returns to the resting potential. See the diagram below.