Autonomic Nervous System Flashcards
(100 cards)
- Which of the following neurotransmitters is primarily responsible for muscle contraction at the neuromuscular junction?
* A. Dopamine
* B. Noradrenaline
* C. Acetylcholine
* D. Serotonin
Answer: C. Acetylcholine
Explanation: Acetylcholine is the neurotransmitter responsible for transmitting signals at the neuromuscular junction, causing muscle contraction by binding to nicotinic receptors on the muscle cell.
- Which enzyme is responsible for degrading acetylcholine in the synaptic cleft?
* A. Monoamine oxidase
* B. Acetylcholinesterase
* C. Catechol-O-methyltransferase
* D. Glutaminase
Answer: B. Acetylcholinesterase
Explanation: Acetylcholinesterase breaks down acetylcholine into acetate and choline in the synaptic cleft, terminating the signal transmission.
- What is the primary ion responsible for initiating neurotransmitter release at the synaptic terminal?
* A. Sodium (Na+)
* B. Potassium (K+)
* C. Calcium (Ca2+)
* D. Chloride (Cl-)
Answer: C. Calcium (Ca2+)
Explanation: The influx of Ca2+ into the presynaptic terminal triggers the release of neurotransmitters by causing synaptic vesicles to fuse with the membrane.
- In which part of the neuron is an action potential first generated?
* A. Dendrites
* B. Axon terminal
* C. Soma
* D. Axon hillock
Answer: D. Axon hillock
Explanation: The axon hillock is the site where the action potential is first generated due to the high concentration of voltage-gated sodium channels.
- Which of the following is a characteristic of an inhibitory postsynaptic potential (IPSP)?
* A. Depolarization of the postsynaptic membrane
* B. Hyperpolarization of the postsynaptic membrane
* C. No change in membrane potential
* D. Increased likelihood of an action potential
Answer: B. Hyperpolarization of the postsynaptic membrane
Explanation: An IPSP causes hyperpolarization, making the inside of the postsynaptic neuron more negative and less likely to fire an action potential.
- What is the primary excitatory neurotransmitter in the central nervous system?
* A. Gamma-aminobutyric acid (GABA)
* B. Glutamate
* C. Glycine
* D. Serotonin
Answer: B. Glutamate
Explanation: Glutamate is the main excitatory neurotransmitter in the CNS, playing a key role in synaptic plasticity and cognitive functions
- Which type of glial cell is responsible for forming myelin in the central nervous system?
* A. Schwann cells
* B. Oligodendrocytes
* C. Astrocytes
* D. Microglia
Answer: B. Oligodendrocytes
Explanation: Oligodendrocytes produce myelin in the CNS, which insulates axons and enhances the speed of electrical transmission.
- What is the main function of the blood-brain barrier?
* A. To facilitate nutrient exchange between blood and brain tissue
* B. To protect the brain from harmful substances and pathogens
* C. To allow large molecules to enter the brain
* D. To regulate body temperature
Answer: B. To protect the brain from harmful substances and pathogens
Explanation: The blood-brain barrier selectively allows nutrients to enter the brain while blocking harmful substances and pathogens.
- Temporal summation in neuronal signaling refers to:
* A. Multiple synaptic inputs occurring simultaneously
* B. Successive action potentials in a single presynaptic neuron
* C. The diffusion of neurotransmitters across the synaptic cleft
* D. The activation of multiple postsynaptic receptors
Answer: B. Successive action potentials in a single presynaptic neuron
Explanation: Temporal summation occurs when a single presynaptic neuron fires multiple times in rapid succession, leading to the accumulation of postsynaptic potentials.
- Which receptor type is directly coupled to ion channels and mediates fast synaptic transmission?
* A. G-protein coupled receptors
* B. Tyrosine kinase receptors
* C. Ionotropic receptors
* D. Nuclear receptors
Answer: C. Ionotropic receptors
Explanation: Ionotropic receptors are directly coupled to ion channels and mediate fast synaptic transmission by allowing ions to flow through the channel upon neurotransmitter binding.
- What is the role of astrocytes in the central nervous system?
* A. Producing myelin
* B. Engulfing pathogens and debris
* C. Regulating the extracellular ionic and chemical environment
* D. Transmitting electrical impulses
Answer: C. Regulating the extracellular ionic and chemical environment
Explanation: Astrocytes maintain the extracellular environment by regulating ion concentrations, removing excess neurotransmitters, and providing metabolic support to neurons.
- Which of the following ions primarily contributes to the resting membrane potential of a neuron?
* A. Sodium (Na+)
* B. Potassium (K+)
* C. Calcium (Ca2+)
* D. Chloride (Cl-)
Answer: B. Potassium (K+)
Explanation: The resting membrane potential is mainly established by the movement of K+ ions through leak channels, making the inside of the neuron negatively charged relative to the outside.
- During an action potential, the depolarization phase is primarily due to the influx of which ion?
* A. Sodium (Na+)
* B. Potassium (K+)
* C. Calcium (Ca2+)
* D. Chloride (Cl-)
Answer: A. Sodium (Na+)
Explanation: The depolarization phase of an action potential is caused by the rapid influx of Na+ ions through voltage-gated sodium channels.
- Which neurotransmitter is primarily involved in the regulation of mood, appetite, and sleep?
* A. Dopamine
* B. Serotonin
* C. Glutamate
* D. GABA
Answer: B. Serotonin
Explanation: Serotonin plays a crucial role in mood regulation, appetite control, and sleep cycles, with imbalances linked to depression and other mood disorders.
- Long-term potentiation (LTP) is most commonly studied in which part of the brain?
* A. Cerebellum
* B. Hypothalamus
* C. Hippocampus
* D. Thalamus
Answer: C. Hippocampus
Explanation: LTP, a process underlying synaptic plasticity and memory formation, is extensively studied in the hippocampus due to its critical role in learning and memory.
- What is the primary function of the nodes of Ranvier in myelinated axons?
* A. To insulate the axon
* B. To slow down action potential propagation
* C. To regenerate action potentials and enable saltatory conduction
* D. To store neurotransmitters
Answer: C. To regenerate action potentials and enable saltatory conduction
Explanation: Nodes of Ranvier are gaps in the myelin sheath where action potentials are regenerated, allowing for rapid saltatory conduction along the axon.
- Which type of glial cell acts as the main immune defense in the central nervous system?
* A. Oligodendrocytes
* B. Astrocytes
* C. Microglia
* D. Schwann cells
Answer: C. Microglia
Explanation: Microglia serve as the primary immune cells in the CNS, responding to injury and infection by phagocytosing debris and pathogens.
- The blood-brain barrier is formed by which type of cells?
* A. Neurons
* B. Endothelial cells
* C. Astrocytes
* D. Microglia
Answer: B. Endothelial cells
Explanation: The blood-brain barrier consists of endothelial cells with tight junctions, which regulate the passage of substances between the bloodstream and the brain.
- What effect does the parasympathetic nervous system have on heart rate?
* A. Increases heart rate
* B. Decreases heart rate
* C. No effect on heart rate
* D. Irregular effect on heart rate
Answer: B. Decreases heart rate
Explanation: The parasympathetic nervous system, primarily through the action of acetylcholine on muscarinic receptors, reduces heart rate.
- Which part of the neuron is primarily responsible for receiving synaptic inputs from other neurons?
* A. Axon
* B. Axon terminal
* C. Soma
* D. Dendrites
Answer: D. Dendrites
Explanation: Dendrites are branched extensions of the neuron that receive synaptic inputs from other neurons and transmit these signals to the soma.
- Which neurotransmitter is primarily inhibitory in the central nervous system?
* A. Glutamate
* B. GABA
* C. Acetylcholine
* D. Dopamine
Answer: B. GABA
Explanation: GABA (gamma-aminobutyric acid) is the primary inhibitory neurotransmitter in the CNS, reducing neuronal excitability and preventing overstimulation.
- Which ion is primarily responsible for the repolarization phase of an action potential?
* A. Sodium (Na+)
* B. Potassium (K+)
* C. Calcium (Ca2+)
* D. Chloride (Cl-)
Answer: B. Potassium (K+)
Explanation: During repolarization, K+ ions flow out of the neuron through voltage-gated potassium channels, restoring the membrane potential to a negative value.
- The myelin sheath in the peripheral nervous system is formed by which type of cell?
* A. Oligodendrocytes
* B. Astrocytes
* C. Schwann cells
* D. Microglia
Answer: C. Schwann cells
Explanation: Schwann cells form the myelin sheath in the PNS, providing insulation and enhancing the speed of electrical impulses along the axon.
- What is the primary role of synaptic vesicles in neurotransmission?
* A. To store neurotransmitters
* B. To degrade neurotransmitters
* C. To transport ions across the membrane
* D. To generate action potentials
Answer: A. To store neurotransmitters
Explanation: Synaptic vesicles store neurotransmitters and release them into the synaptic cleft during neurotransmission, facilitating communication between neurons.