Unit 3: Biopsychology
The single cell that runs the nervous system, the chemistry between two neurons, and how genes, hormones, and brain structures shape behavior.
13 topics · 49 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.
3.1 Genes, Alleles, and Gene-Environment Interaction
- How it worksHow do dominant and recessive alleles combine to decide which traits actually show up?
- Common mistakeWhy isn't a trait ever purely one hundred percent inherited or one hundred percent learned?
- Going furtherWhat happens to an inherited tendency toward anxiety when it's raised in a calm, low-stress environment?
Your turn1 of 2
Twin studies of a trait find that identical (monozygotic) twins share the trait 69 percent of the time, while fraternal (dizygotic) twins share it 38 percent of the time. Using heritability = 2 times (MZ percent minus DZ percent), what is the estimated heritability of this trait, as a percentage?3.2 Neuron Structure and the Resting Potential
- How it worksHow do dendrites, the cell body, and the axon each move a signal along one neuron?
- How it worksWalk me through how a sodium-potassium pump keeps the inside of a resting neuron negatively charged.
- Common mistakeWhy isn't a neuron's resting potential just the neuron being switched off?
Your turn1 of 2
A student describes a neuron's resting potential as the neuron being 'switched off' between signals, since nothing observable seems to be happening. A neuroscientist disagrees. What is actually happening during the resting potential?3.2 The Action Potential
- How it worksHow does a stimulus crossing the threshold force sodium channels open all along the axon?
- How it worksWalk me through the full voltage trace of an action potential from threshold to depolarization to the return to rest.
- Common mistakeWhy doesn't a stronger stimulus produce a bigger action potential in the same neuron?
- Going furtherWhat happens to a signal's speed when the axon is wrapped in a myelin sheath?
- Worked exampleFind why a neuron's threshold of about -55 millivolts has to be crossed before an action potential fires at all.
Your turn1 of 2
A neuron rests at -70 millivolts and must reach a threshold of -54 millivolts before an action potential fires. How many millivolts of depolarization are needed to reach threshold from rest?3.2 Synaptic Transmission
- How it worksWalk me through a neurotransmitter crossing the synaptic gap from one neuron's terminal to the next neuron's receptors.
- How it worksHow does reuptake clear a neurotransmitter out of the synapse once it's delivered its message?
- Going furtherWhat happens to a signal when a neurotransmitter binds an inhibitory receptor instead of an excitatory one?
- Common mistakeWhy isn't a neurotransmitter itself either excitatory or inhibitory in every synapse it reaches?
Your turn1 of 2
The same neurotransmitter, acetylcholine, excites a neuron in one part of the nervous system but inhibits a different neuron elsewhere. A student is confused, assuming a neurotransmitter must always have one fixed effect. What resolves the confusion?3.2 Neurotransmitters and How Drugs Act on Them
- How it worksHow does an agonist drug mimic a neurotransmitter closely enough to trigger its receptor?
- How it worksWalk me through how an SSRI antidepressant blocks the reuptake of serotonin to keep it active in the synapse longer.
- Worked exampleFind where in the synapse a reuptake-inhibitor drug intervenes compared to a drug that blocks the receptor itself.
- Going furtherWhat happens to a receptor's sensitivity after weeks of a drug flooding the synapse with extra neurotransmitter?
Your turn1 of 2
Drug A has a molecular shape close enough to a neurotransmitter that it directly binds and activates the neurotransmitter's own receptor. Drug B instead blocks the transporter that normally pulls the neurotransmitter back into the sending neuron, so it lingers in the synapse longer. Which statement correctly distinguishes these two drugs?3.2 Glial Cells and Myelin
- How it worksHow do glial cells support, insulate, and clean up after the neurons around them?
- Common mistakeWhy isn't a glial cell just a neuron that doesn't do much?
- Going furtherWhat happens to signal speed and muscle control when myelin breaks down, as it does in multiple sclerosis?
Your turn1 of 2
A student assumes glial cells are simply 'weaker neurons' that don't fire signals as effectively. A neuroscientist points out this badly misunderstands what glial cells do. What is their actual role?3.3 The Central and Peripheral Nervous Systems
- How it worksWalk me through the path a signal takes from a fingertip, up the spinal cord, into the brain.
- How it worksHow do the brain and spinal cord divide the nervous system's central command between them?
- Common mistakeWhy isn't the spinal cord just a passive cable carrying messages up and down?
- Going furtherWhat happens to sensation and movement below the point where the spinal cord is severed?
- Going furtherWhat happens to reflexes below an injury when the spinal cord is damaged but the brain itself is untouched?
Your turn1 of 2
Touching a hot stove causes a person's hand to jerk back before they consciously feel the pain, because the withdrawal reflex is processed directly in the spinal cord. A student concludes the spinal cord must just be a passive cable relaying messages to and from the brain. What is wrong with that conclusion?3.3 The Somatic and Autonomic Nervous Systems
- How it worksHow does the peripheral nervous system split into the somatic and autonomic divisions?
- How it worksWalk me through how the sympathetic and parasympathetic systems pull the body in opposite directions.
- Worked exampleFind which nervous system division speeds your heart rate during a near-miss car accident and which one slows it back down afterward.
Your turn1 of 2
A driver narrowly avoids a car accident. In the moment, their heart races, pupils dilate, and breathing quickens. A few minutes after reaching safety, their heart rate and breathing gradually return to normal. Which two systems are responsible for the speeding up and the slowing back down, respectively?3.4 The Cerebral Cortex and Its Four Lobes
- How it worksHow do the frontal, parietal, temporal, and occipital lobes each take on a different job?
- How it worksWalk me through what a motor cortex homunculus reveals about which body parts get the most cortical space.
- Going furtherWhat happens to planning and impulse control when the frontal lobe is damaged?
- Worked exampleFind which lobe is most active when someone is recognizing a face versus planning tomorrow's schedule.
Your turn1 of 2
After a severe frontal lobe injury, a previously careful, well-organized person begins acting impulsively, struggles to plan even simple tasks, and shows poor judgment in social situations. What does this pattern of change point to?3.4 The Limbic System and Memory-Emotion Structures
- How it worksHow do the hippocampus, amygdala, and hypothalamus each specialize in a different job below the cortex?
- How it worksWalk me through why damage to the hippocampus destroys the ability to form new memories but not old ones.
- Going furtherWhat happens to fear responses when the amygdala is damaged on both sides of the brain?
- Common mistakeWhy isn't the limbic system a single, cleanly separate structure sitting apart from the rest of the brain?
Your turn1 of 2
A patient with severe hippocampal damage on both sides of the brain can still clearly recall childhood events and can still hold a conversation in the moment, but is completely unable to form any new lasting memories after the injury. What does this pattern reveal about the hippocampus's role?3.4 Hemispheric Specialization and Split-Brain Studies
- How it worksHow does the corpus callosum let the left and right hemispheres share information all day long?
- How it worksWalk me through a split-brain patient naming an object shown only to their right hemisphere and failing.
- Common mistakeWhy isn't it true that some people are simply left-brained and others right-brained?
- Going furtherWhat happens to language ability when a stroke damages the left hemisphere instead of the right?
Your turn1 of 2
In a split-brain experiment, an object is shown only to a patient's right hemisphere, and the patient is asked to name it aloud. The patient cannot name the object, but can point to it correctly with their left hand. What explains this pattern?3.4 Neuroimaging and the Ten Percent Myth
- How it worksHow do an EEG, a PET scan, and an fMRI each measure something different about the working brain?
- Common mistakeWhy isn't it true that people only use ten percent of their brain?
- Going furtherWhat does a brain scan actually look like while a person is solving a math problem versus resting?
Your turn1 of 2
A movie claims a character gains extraordinary abilities after learning to 'use one hundred percent of their brain,' implying most people normally use only about ten percent. What does modern neuroimaging actually show about how much of the brain people use?3.5 The Endocrine System and Hormone Feedback Loops
- How it worksHow does the hypothalamus use the pituitary gland to control almost every other hormone-releasing gland in the body?
- How it worksWalk me through a hormone feedback loop that shuts off its own release once a target level is reached.
- Common mistakeWhy isn't a hormone signal as fast as a nerve signal, even though both carry messages through the body?
- Worked exampleFind how cortisol released during a stressful morning eventually signals the hypothalamus to stop releasing more.
Your turn1 of 2
A student assumes that since both nerves and hormones 'send messages' through the body, a hormone signal must travel just as fast as a nerve signal. A biopsychologist corrects this assumption. What is the actual difference?