The Nervous System Flashcards
Describe how the structure of the nervous system is related to its functions. Describe the structure of the reflex arc and explain why reflex actions are important.
What are the five things every automatic control system has?
Receptors detect a stimulus and send electrical impulses down neurones to the central nervous system. The word neurones is another way of saying nerve cells. The central nervous system is the coordination centre. This now sends electrical impulses down other neurones to effectors and the effectors bring about a response
What are the two parts which the nervous system consists of?
The nervous system consists of the central nervous system (CNS) which is the brain and spinal cord and we have the peripheral nervous system which is other nerves running to and from the central nervous system.
What happens when you touch a hot object such as a candle?
First the stimulus is detected by a receptor. In this case the stimulus is heat and the receptor is in the skin. Electrical impulses now pass from the receptor along a sensory neurone to the central nervous system. At the end of the sensory neurone is a junction called a synapse. At the synapse , a chemical is released. This chemical now diffuses across to a relay neurone in the central nervous system where it triggers an electrical impulse. The electrical impulse now passes across the relay neurone and reaches another synapse. Once again a chemical is released, this chemical triggers an electrical impulse in a motor neurone The electrical impulse now passes down the motor neurone to an effector. In this case a muscle is the effector and it now contracts and pulls the hand away from the heat. This is the response.
(remember that sensory neurones are connected to receptors and receptors allow us to sense our environment)
What are special about reflexes?
What’s special about reflexes is that there is no decision making by the conscious part of the brain. This makes them automatic and rapid.
What makes reflexes so quick?
What makes reflexes so quick is there is no decision making involved by the conscious part of the brain. Because they are so rapid they can help protect us from danger.
