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Nervous coordination and skeletal muscles Typeit
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The membrane of an unstimulated axon is polarised, with a resting potential of approximately mV inside. When an action potential arrives at a point on the membrane, voltage-gated ion channels open and the membrane becomes depolarised, with a potential difference inside the axon of mV. In order for repolarisation to occur, ions diffuse out through ion channels that open. This results in as the inside of the axon becomes more negative than usual for a short time, which makes it much harder for a new action potential to be generated. This is known as the period.
Gaps between neurones are called . In order for a signal to cross the gap, such as acetylcholine are required. These are also used at junctions between motor neurones and muscle fibres to transmit an impulse to cause contraction.
Contraction in muscle fibres, also called , takes place according to the model. This describes how heads form cross bridges with filaments, pulling them along their length. The energy for this comes from the hydrolysis of , so it is important that cells in endurance muscles have many , which are the site of respiration.