reflex actions

• reflex actions are automatic and rapid and do not involve the conscious parts of the brain
• reflexes are important to both humans and other animals because they help you avoid danger or harm as they happen so fast
• reflex actions involve three types of neurones:

  -sensory neurons

  -motor neurons

  -relay neurons(these connect the sensory neuron and the motor neuron and are found in the CNS)
• an electrical impulse passes from the receptor along the sensory neurone to the CNS. it then passes along a relay neurone, usually in the spinal cord, and straight back along the motor neurone. from there the impulse arrives at the effector organ. The effector organ will be a muscle or gland. we call this pathway a reflex arc
• Where 2 neurones meet there is a tiny gap called a synapse. signals cross this gap using neurotransmitters(chemicals). one neurone releases the neurotransmitters into the gap. the neurotransmitters diffuse across the gap and makes the next neurone transmit an electrical signal