Biology Test Neuroscience Fundamentals 3 — Questions and Answers
Question 1: Which neurotransmitter system is most directly implicated in Parkinson's disease due to degeneration of the substantia nigra?
- Serotonin
- Dopamine (Correct answer)
- Glutamate
- GABA
Correct answer: Dopamine
Parkinson's disease results from the loss of dopaminergic neurons in the substantia nigra pars compacta, reducing dopamine signaling in the striatum.
Question 2: What term describes the period after an action potential during which a neuron cannot fire again regardless of stimulus strength?
- Relative refractory period
- Absolute refractory period (Correct answer)
- Hyperpolarization phase
- Summation period
Correct answer: Absolute refractory period
During the absolute refractory period, all voltage-gated sodium channels are inactivated, making re-stimulation impossible no matter how large the stimulus.
Question 3: Which glial cell type is responsible for myelinating axons in the central nervous system?
- Schwann cells
- Astrocytes
- Microglia
- Oligodendrocytes (Correct answer)
Correct answer: Oligodendrocytes
Oligodendrocytes wrap their membrane extensions around multiple CNS axons, forming myelin sheaths that insulate and speed up signal conduction.
Question 4: The hippocampus is critically involved in which type of memory?
- Procedural motor memory
- Declarative episodic memory (Correct answer)
- Emotional fear conditioning only
- Implicit priming
Correct answer: Declarative episodic memory
The hippocampus is essential for forming new declarative (explicit) memories, including episodic memories of personal experiences and semantic facts.
Question 5: Spatial summation in neurons refers to:
- Multiple action potentials from one synapse adding over time
- Simultaneous inputs from multiple synapses combining to reach threshold (Correct answer)
- The spread of depolarization along a myelinated axon
- Inhibitory postsynaptic potentials canceling each other
Correct answer: Simultaneous inputs from multiple synapses combining to reach threshold
Spatial summation occurs when excitatory postsynaptic potentials from several synapses arrive simultaneously and add together to depolarize the neuron to threshold.
Question 6: Which division of the autonomic nervous system uses acetylcholine as its primary postganglionic neurotransmitter?
- Sympathetic
- Parasympathetic (Correct answer)
- Somatic motor
- Enteric only
Correct answer: Parasympathetic
Parasympathetic postganglionic neurons release acetylcholine onto muscarinic receptors, mediating 'rest-and-digest' effects on target organs.
Question 7: Action potentials are described as 'all-or-none' events because:
- They only travel to all neurons or none at all
- Once threshold is reached, the full amplitude is always produced regardless of stimulus size (Correct answer)
- They either fully inhibit or fully excite the postsynaptic cell
- The sodium channels either open completely or not at all individually
Correct answer: Once threshold is reached, the full amplitude is always produced regardless of stimulus size
Once a neuron reaches threshold, it fires a full-amplitude action potential; a stronger stimulus does not produce a larger action potential in that neuron.
Biology Test Neuroscience Fundamentals 3
Which neurotransmitter system is most directly implicated in Parkinson's disease due to degeneration of the substantia nigra?