Your brain sends signals every moment to help you think, feel, move, breathe, and respond to the world. These messages travel through special cells called neurons, which form communication pathways between the brain, spinal cord, and body. Fast signaling is important because it lets you pull your hand away from heat, hear a sound, read words, or move a muscle.
Understanding brain signals helps students connect health, biology, and everyday actions.
Key Facts
- Neurons carry electrical signals called nerve impulses along their axons.
- A signal starts when the neuron reaches threshold, usually about -55 mV.
- At rest, many neurons have a membrane potential of about -70 mV.
- At a synapse, neurons use chemicals called neurotransmitters to pass the message to the next cell.
- Myelin insulation helps impulses travel faster along many axons.
- Signal pathway: stimulus -> sensory neuron -> brain or spinal cord -> motor neuron -> response.
Vocabulary
- Neuron
- A neuron is a nerve cell that sends and receives messages in the brain, spinal cord, and body.
- Axon
- An axon is the long part of a neuron that carries an electrical signal away from the cell body.
- Synapse
- A synapse is the tiny gap where one neuron passes a message to another neuron or to a muscle cell.
- Neurotransmitter
- A neurotransmitter is a chemical messenger released at a synapse to help continue or change a signal.
- Myelin
- Myelin is a fatty covering around some axons that helps nerve signals travel faster and more efficiently.
Common Mistakes to Avoid
- Saying nerves are the same as neurons is wrong because a nerve is a bundle of many neuron fibers, while a neuron is one individual cell.
- Thinking signals are only electrical is wrong because neuron messages are electrical along the axon but usually chemical across the synapse.
- Assuming the brain controls movement without the spinal cord is wrong because many body signals travel through the spinal cord on the way to or from the brain.
- Forgetting healthy habits affect brain signaling is wrong because sleep, nutrition, hydration, exercise, and avoiding head injuries all support normal nervous system function.
Practice Questions
- 1 A nerve impulse travels along a myelinated axon at 100 m/s. How long does it take to travel 2.0 m from the spinal cord to a muscle?
- 2 A neuron has a resting membrane potential of -70 mV and reaches threshold at -55 mV. By how many millivolts must the inside of the neuron become less negative to reach threshold?
- 3 Explain why a message from the brain to a hand muscle may involve both electrical signals and chemical signals.