coordination and response

• Communication through our body happens to coordinate our behaviour and respond to our surroundings which is done through the nervous system and the endocrine system.
• Nerve cells (neurones) carry electrical impulses from one point to another.
• Neurones are long, thin and have lots of branch connections to either end which enables them to pass messages onto other nerve cells.
• The synapse is the connection between the cells 
• When an electrical impulse hits the end od a nerve it causes the release of some chemicals which diffuse across the gap to the next nerve cell where they can trigger another electrical impulse
•  Central nervous system is made up of our brain and our spinal cord.
• Body receives information through sensory neurones
• Sensory neurones carry information from receptors all over our body to the CNS
• The information sent through the sensory neurone can be changes in temperature, the level of carbon dioxide in our bloodstream
• When the CNS has decided how to react to the information sent by the sensory neurone it sends out signals via the motor neurones (which are a type of nerve cell) to effectors (muscles and or glands) which contract or release hormones.
• Motor neurons send messages from the central nervous system to muscles and glands
• A reflex arc is a pathway along which a stimulus travels when we have a reflex action
• The nervous system can detect changes both inside and outside of our bodies
• Reflex arcs are the nerve pathway that underlies our unconscious reflexes. These reflexes are rapid and automatic avoiding injuries
• A stimuli is an object outside of our body that our nervous system (receptor cells) detect and react to
• When a stimuli is detected by our receptor cell it sends a signal to the sensory neurone which is sent to the spine (CNS) which is transferred to the relay neurone which passes the impulse along to the motor neurone where it travels back out to the body to an effector.
• Sensory neurones carry information towards the CNS
• Relay neurones connect the spinal cord with other parts of the brain
• Motor neurones carry signals away from the CNS
• Between each of the different neurones there are synapses where the electrical signal is temporarily converted to a chemical signal so that it can be passed between the different nerve cells.
• The synapse is the gap between two neurons, where neurotransmitters pass across to the next neuron
• Neurotransmitter chemicals transmit electrical messages across the synapses
• Effector organs are muscles or glands that respond to messages received from the CNS
• Receptors are specialised cells that receive stimulus and convert them into electrical signals
• The reflex arc is when we have a rapid, automatic reaction to a stimulus without conscious thought or control
• Reflex arcs allow us to respond quickly to danger
• Examples of reflex actions include blinking at bright light, pulling your hand off a hot surface and coughing if something goes down your throat