| A | B |
|---|
| regulation | Is the control and coordination of all life activities |
| Nervous System | 3 basic structures:. Receptors, Neurons &Effectors |
| Receptors | sensitive to changes in the external and internal environment |
| Neurons | Are nerve cells |
| Effectors | Are muscles or glands in which neurons are attached to |
| Impulse | electrochemical message |
| Stimulus | is a change in the external or internal environment |
| Dendrites | Fibers that detect stimuli and generate an impulse toward the cyton |
| Cyton | Contains the nucleus of the neuron |
| Axon | transmits the impulse away from the cyton |
| Terminal Branches | The ends of axons that secrete neurotransmitters |
| Synapse | The gap between the terminal branches |
| Neurotransmitters | aid in the transmission of an impulse across the synapse |
| Sensory neuron | carry impulses from the receptors toward the spinal cord and brain |
| Interneuron | relay impulses from one neuron to another |
| Motor neuron | carry impulses from brain and spinal cord toward the effectors |
| Hydra | Contains no brain or control center |
