Unit 4: The Brain and Neural Communication
How a single neuron fires, how firing turns into a signal that travels, and how the brain's major structures divide up the mind's work.
5 topics · 17 questions
Each topic is a path, not a menu: work down it in order and every question builds on the one above. Click any of them to watch the answer draw itself.
Neurons and the Resting Potential
- How it worksHow do sodium-potassium pumps and leaky channels hold a neuron's inside at about negative 70 millivolts?
- How it worksHow does a neuron's cell membrane keep charged ions separated to store electrical potential energy?
- Common mistakeWhy isn't a resting neuron actually off just because it isn't firing?
Your turn1 of 2
A neuron sitting quietly, not firing, still holds its inside at about negative 70 millivolts relative to the outside. A student assumes this voltage must just be a passive, default state requiring no ongoing work to maintain. What actually holds a resting neuron at that negative voltage?The Action Potential
- How it worksHow does a wave of sodium channels opening in sequence flip a neuron's voltage from negative to positive and back?
- How it worksHow does the action potential travel down an axon without losing strength the way a signal in a wire would?
- Worked exampleFind how long it takes a signal to cross a 1 meter axon that conducts at 100 meters per second.
- Common mistakeWhy doesn't a stronger stimulus produce a bigger action potential instead of just more of them?
Your turn1 of 2
Find how long it takes a signal to cross a 1.14 meter axon that conducts at 92 meters per second.Synaptic Transmission
- How it worksHow does an arriving action potential trigger neurotransmitter release across the synaptic gap?
- Worked exampleFind what happens to a postsynaptic neuron when the neurotransmitter it receives is excitatory versus inhibitory.
- Common mistakeWhy isn't a neurotransmitter automatically good or bad regardless of which receptor it lands on?
- Going furtherWhat happens to signaling at a synapse when a drug blocks the reuptake of a neurotransmitter like serotonin?
Your turn1 of 2
An action potential arrives at the end of an axon, and moments later a chemical signal has crossed the gap to the next neuron, rather than the electrical signal simply jumping across on its own. A student assumes the electrical signal should be able to leap the tiny synaptic gap directly. How does an arriving action potential actually trigger neurotransmitter release across the gap?The Cerebral Cortex and Its Lobes
- How it worksHow do the frontal, parietal, temporal, and occipital lobes divide up planning, touch, hearing, and vision?
- Common mistakeWhy isn't it true that we only use ten percent of our brain?
- Going furtherWhat happens to behavior when damage to the frontal lobes leaves someone's intelligence intact but their impulse control gone?
Your turn1 of 2
Damage to the very back of the brain, the occipital lobe, causes blindness even though a person's eyes themselves work perfectly well. A student assumes vision must happen entirely in the eyes, with the brain playing only a minor supporting role. How do the brain's lobes actually divide up functions like vision, touch, hearing, and planning?The Split Brain and Hemispheric Specialization
- How it worksHow does cutting the corpus callosum stop the two hemispheres from sharing what each one sees?
- Going furtherWhat happens when an image is flashed only to the left visual field of a split-brain patient?
- Common mistakeWhy isn't it true that some people are simply right-brained or left-brained thinkers?
Your turn1 of 2
A patient whose corpus callosum has been surgically cut can name an object placed in their right hand out loud, but cannot verbally name an object placed in their left hand, even though they can still pick it out by touch. A student assumes this must mean the left hand has simply become numb after the surgery. What is actually happening?