What are the functions of Nerve Cells, Receptors & Effectors?

1) Nerve Cells - bundle of neurons, adapted to carry electrical impulses from place to place. 3 main neurons: sensory, motor & relay. Features: long fibre (axon), carry messages up and down body; tiny branches (dendrons) branch of as dendrites & receive incoming impulses from other neurons 2) Receptors - Detect stimuli and stimulate electrical impulses in response. Sense organs contain a group of receptors that respond to specific stimuli: skin - touch, temperature, pain; tongue - chemicals; nose - chemicals; eye - light; ear - sound & position of head 3) Effectors - (muscles/glands) produce specific response to a detected stimulus (e.g. muscle contracting to move an arm; a gland releasing hormone into blood)