part 2

• A gilal cell hold neurons in place
• A reflex arc is a neural pathway that controls a body's automatic response to a stimulus
• All-Or-Nothing principle: a neuron can only fire fully or not at all there is no in between
• Depolarization: The process of the neurons becoming more positive, causing the sodium channels to open and the potassium channels to close
• repolarization: positive ions go out and negative ions come back
• the refractory period is the time between the neuron firing when it cannot fire
• resting potential: the neurons are always ready to fire
• Sensory (afferent)neurons: carry information into the brain and spianl cord
• Motor (efferent) neurons: carry information away from the brain
• interneurons connect the motor and sensory neurons
• neurotransmitters: chemical messengers
• Myasthenia Gravis: the body makes antibodies that block or destroy muscle receptor sites for acetylcholine which causes muscle weakness
• multiple sclerosis: a disease of the central nervous system that causes the myelin sheath to break down
• agonists mimic neurotransmitters
• antagonists block neurotransmitters
• reuptake: the reabsorption of neurotransmitters back into the presynaptic terminal