20 MCQs on The Functioning Brain – Neurons, Neural Conduction & Synaptic Transmission
Test your knowledge with 20 multiple-choice questions on the functioning brain, neuron structure, neural conduction, and synaptic transmission. Includes answers and explanations for easy learning.
1. What is the basic functional unit of the nervous system?
A) Glial cell
B) Neuron
C) Synapse
D) Axon
Answer: B) Neuron
Explanation: Neurons are the fundamental units of the nervous system responsible for transmitting information.
2. What is the primary function of dendrites in a neuron?
A) Conduct nerve impulses away from the cell body
B) Receive signals from other neurons
C) Release neurotransmitters
D) Insulate the axon
Answer: B) Receive signals from other neurons
Explanation: Dendrites are tree-like structures that receive and transmit electrical signals to the neuron’s cell body.
3. The axon is responsible for which function in a neuron?
A) Producing neurotransmitters
B) Conducting electrical impulses away from the cell body
C) Receiving sensory information
D) Regulating cell metabolism
Answer: B) Conducting electrical impulses away from the cell body
Explanation: The axon carries action potentials from the neuron's cell body to the synaptic terminals.
4. Which of the following is the gap between two neurons where communication occurs?
A) Axon hillock
B) Synapse
C) Node of Ranvier
D) Soma
Answer: B) Synapse
Explanation: The synapse is the junction where neurotransmitters are released to transmit signals between neurons.
5. What is the function of the myelin sheath?
A) Transmit nerve impulses
B) Speed up electrical conduction along the axon
C) Generate neurotransmitters
D) Maintain neuron shape
Answer: B) Speed up electrical conduction along the axon
Explanation: Myelin sheath insulates the axon and enhances the speed of neural impulses.
6. Which type of neuron transmits signals from sensory receptors to the central nervous system?
A) Motor neuron
B) Sensory neuron
C) Interneuron
D) Glial cell
Answer: B) Sensory neuron
Explanation: Sensory neurons carry information from sensory organs to the brain and spinal cord.
7. What is the resting membrane potential of a neuron?
A) +70 mV
B) -70 mV
C) 0 mV
D) -30 mV
Answer: B) -70 mV
Explanation: The resting potential of a neuron is approximately -70 mV due to the difference in ion concentration inside and outside the cell.
8. What triggers an action potential in a neuron?
A) A decrease in neurotransmitter release
B) Depolarization beyond the threshold level
C) Hyperpolarization of the cell membrane
D) Increased calcium ion concentration
Answer: B) Depolarization beyond the threshold level
Explanation: When a neuron is depolarized to its threshold (about -55 mV), an action potential is generated.
9. During an action potential, which ion rushes into the neuron?
A) Potassium (K⁺)
B) Sodium (Na⁺)
C) Calcium (Ca²⁺)
D) Chloride (Cl⁻)
Answer: B) Sodium (Na⁺)
Explanation: Sodium ions rush into the neuron during depolarization, leading to an action potential.
10. The process of returning the neuron to its resting state is called?
A) Depolarization
B) Hyperpolarization
C) Repolarization
D) Excitation
Answer: C) Repolarization
Explanation: Repolarization restores the negative resting membrane potential after depolarization.
11. What is the role of the sodium-potassium pump?
A) Generate action potentials
B) Maintain resting potential by pumping Na⁺ out and K⁺ in
C) Block neurotransmitter release
D) Strengthen synaptic connections
Answer: B) Maintain resting potential by pumping Na⁺ out and K⁺ in
Explanation: The sodium-potassium pump actively transports sodium ions out and potassium ions into the neuron to maintain resting potential.
12. Which ion is necessary for neurotransmitter release at the synapse?
A) Sodium (Na⁺)
B) Potassium (K⁺)
C) Calcium (Ca²⁺)
D) Magnesium (Mg²⁺)
Answer: C) Calcium (Ca²⁺)
Explanation: Calcium ions trigger neurotransmitter release at the synapse by promoting vesicle fusion with the presynaptic membrane.
13. Which neurotransmitter is involved in muscle movement?
A) Serotonin
B) Dopamine
C) Acetylcholine
D) GABA
Answer: C) Acetylcholine
Explanation: Acetylcholine is crucial for muscle contractions and communication at neuromuscular junctions.
14. Which type of synapse directly transmits electrical signals between neurons?
A) Chemical synapse
B) Electrical synapse
C) Neuromuscular junction
D) Inhibitory synapse
Answer: B) Electrical synapse
Explanation: Electrical synapses allow direct transmission of ions between neurons through gap junctions.
15. What happens when an excitatory neurotransmitter binds to a postsynaptic receptor?
A) Hyperpolarization occurs
B) An action potential is inhibited
C) The postsynaptic neuron becomes depolarized
D) Sodium-potassium pump is deactivated
Answer: C) The postsynaptic neuron becomes depolarized
Explanation: Excitatory neurotransmitters increase the likelihood of an action potential by depolarizing the neuron.
16. Which neurotransmitter is associated with mood regulation?
A) GABA
B) Serotonin
C) Glutamate
D) Dopamine
Answer: B) Serotonin
Explanation: Serotonin plays a significant role in mood, appetite, and sleep regulation.
17. The refractory period ensures that:
A) Action potentials travel in one direction
B) Neurons constantly fire
C) Ions do not move across membranes
D) Synaptic vesicles do not release neurotransmitters
Answer: A) Action potentials travel in one direction
Explanation: The refractory period prevents backward conduction of action potentials.
18. Which neurotransmitter is the primary inhibitory neurotransmitter in the brain?
A) Acetylcholine
B) Dopamine
C) Glutamate
D) GABA
Answer: D) GABA
Explanation: GABA inhibits excessive neuronal activity and helps regulate brain excitability.
19. What is saltatory conduction?
A) Slow transmission in unmyelinated axons
B) Jumping of action potentials between nodes of Ranvier
C) Continuous conduction along the entire axon
D) Blockage of neurotransmitter release
Answer: B) Jumping of action potentials between nodes of Ranvier
Explanation: Saltatory conduction increases the speed of nerve impulses by allowing them to "jump" between myelinated sections.
20. Which glial cell type forms the myelin sheath in the central nervous system?
A) Schwann cells
B) Astrocytes
C) Oligodendrocytes
D) Microglia
Answer: C) Oligodendrocytes
Explanation: Oligodendrocytes produce the myelin sheath that insulates axons in the CNS.
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