Nervous System (IB QUESTIONS) Flashcards
NOT ACTUAL IB QUESTIONS, ONLY PREDICTIONS (6 cards)
Describe how cocaine disrupts dopamine signalling in the brain. [4]
Cocaine binds to dopamine transporters on the presynaptic membrane ✔
Prevents reuptake of dopamine from the synaptic cleft ✔
Dopamine continues to bind to postsynaptic receptors ✔
Prolonged stimulation of reward pathways leads to euphoria/addiction ✔
Explain why saltatory conduction is faster than conduction in non-myelinated axons. [4]
Myelin sheath insulates axon and prevents ion leakage ✔
Action potentials only occur at nodes of Ranvier (where ion channels are present) ✔
Impulse “jumps” from node to node (saltatory conduction) ✔
Fewer depolarizations needed; increases conduction speed and efficiency ✔
Distinguish between excitatory and inhibitory neurotransmitters, with reference to their effect on membrane potential. [4]
Excitatory neurotransmitters cause depolarization; inhibitory cause hyperpolarization ✔
Excitatory neurotransmitters open Na⁺ channels; inhibitory open Cl⁻ or K⁺ channels ✔
Excitatory increase likelihood of reaching threshold and firing an action potential ✔
Inhibitory decrease likelihood of firing by making membrane more negative than resting ✔
Describe the events that occur at a chemical synapse following the arrival of an action potential. [4]
Action potential arrives at axon terminal and depolarizes the presynaptic membrane ✔
Voltage-gated Ca²⁺ channels open and Ca²⁺ diffuses into the terminal ✔
Vesicles fuse with the membrane and release neurotransmitter via exocytosis ✔
Neurotransmitter diffuses across synaptic cleft and binds to postsynaptic receptors ✔
Outline how the sodium-potassium pump maintains the resting potential of a neuron. [4]
Uses ATP to actively transport ions against concentration gradients ✔
Pumps 3 Na⁺ out of the neuron and 2 K⁺ into the neuron per cycle ✔
Creates a net negative charge inside the neuron ✔
Contributes to membrane polarization (resting potential ~ -70 mV) ✔
