This Page provides Nervous System Veterinary Physiology multiple-choice questions (MCQs). These MCQs are designed to help veterinary students master the fundamental principles of nervous system physiology by testing their understanding of how neurons and synapses function. You can use these questions and answers to solidify your knowledge, prepare for exams, and build confidence in applying nervous system physiology concepts to veterinary practice as well as it comes with great explanation below each question.
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Introduction to the Nervous System MCQs
1 What is the major functional unit of the nervous system?
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The neuron is the primary functional unit of the nervous system, responsible for receiving, processing, and transmitting information through electrical and chemical signals. It consists of dendrites (which receive information), a cell body (soma), an axon (which transmits information), and presynaptic terminals (which communicate with other neurons or target cells).
2 The mammalian nervous system is divided into which two main subdivisions?
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The nervous system is divided into the Central Nervous System (CNS), comprising the brain and spinal cord, and the Peripheral Nervous System (PNS), which includes all the nerves outside the CNS. The CNS processes and integrates information, while the PNS connects the CNS to the rest of the body, facilitating sensory and motor functions.
3 Which of the following structures are part of the Central Nervous System (CNS)?
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The Central Nervous System (CNS) consists solely of the brain and spinal cord. These structures are responsible for processing and integrating information, as well as coordinating and influencing the activity of all parts of the body.
4 What are the three protective layers surrounding the Central Nervous System called?
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The CNS is protected by three layers of membranes known as meninges: the pia mater (innermost layer directly covering the brain and spinal cord), the arachnoid mater (middle layer with a spider web-like appearance), and the dura mater (outermost, tough layer). These layers provide structural support and protect the CNS from physical damage.
5 What fluid cushions the brain and spinal cord within the vertebral canal?
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Cerebrospinal fluid (CSF) is a clear, colorless fluid that surrounds the brain and spinal cord, providing cushioning against mechanical shocks. It also plays a role in nutrient transport, waste removal, and maintaining the chemical environment necessary for neuronal function.
6 Which subdivision of the Peripheral Nervous System is responsible for involuntary functions such as heart rate and digestion?
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The Autonomic Nervous System (ANS) controls involuntary bodily functions, including heart rate, digestion, respiratory rate, and glandular activity. It operates automatically without conscious control and is further divided into the sympathetic and parasympathetic systems, which work together to maintain homeostasis.
7 How many major anatomical regions can the Central Nervous System be divided into?
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The Central Nervous System is divided into six major anatomical regions: the spinal cord, medulla, pons, midbrain, diencephalon, and telencephalon (cerebral hemispheres). Each region has distinct structures and functions, contributing to the overall operation of the nervous system.
8 Which part of the brain is primarily involved in regulating physiological and behavioral aspects of homeostasis?
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The hypothalamus plays a crucial role in maintaining homeostasis by regulating the autonomic nervous system and endocrine system. It controls body temperature, hunger, thirst, fatigue, sleep, and circadian rhythms, as well as hormone secretion from the pituitary gland.
9 What is the primary function of the thalamus within the Central Nervous System?
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The thalamus serves as the main relay center for sensory information traveling to the cerebral cortex. It processes and transmits sensory signals (except for olfaction) from the body and the external environment to the appropriate cortical areas for further interpretation and response.
10 Which type of neurons carry action potentials away from the Central Nervous System to muscles and glands?
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Efferent neurons, also known as motor neurons, carry action potentials away from the CNS to muscles and glands, facilitating motor responses and glandular secretions. They are responsible for executing the commands formulated by the CNS.
11 What distinguishes afferent neurons from efferent neurons in the Peripheral Nervous System?
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Afferent neurons (sensory neurons) transmit sensory information from peripheral receptors to the CNS for processing. Efferent neurons (motor neurons) carry motor commands from the CNS to effector organs such as muscles and glands, facilitating appropriate responses.
12 Which of the following best describes the function of glial cells in the nervous system?
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Glial cells provide structural and functional support to neurons. They maintain the extracellular environment, form myelin sheaths around axons to insulate them and speed up signal transmission, assist in nutrient transport, and play roles in immune responses within the CNS. Unlike neurons, glial cells do not transmit electrical impulses.
13 What is the primary difference between oligodendrocytes and Schwann cells?
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Oligodendrocytes are glial cells in the Central Nervous System that form myelin sheaths around multiple axons. Schwann cells, on the other hand, are glial cells in the Peripheral Nervous System that myelinate individual axons. This distinction is crucial for understanding how myelination differs between the CNS and PNS.
14 Which anatomical region of the CNS is responsible for coordinating voluntary movements and maintaining balance?
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The cerebellum is essential for coordinating voluntary movements, maintaining balance, and ensuring smooth and precise motor activities. It receives input from sensory systems and other parts of the brain to fine-tune motor commands, making it critical for activities requiring coordination and timing.
15 What is the role of the spinal cord within the Central Nervous System?
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The spinal cord acts as a conduit for transmitting sensory information from the body to the brain and motor commands from the brain to the muscles and glands. It also coordinates simple reflexes independently of the brain, allowing for rapid responses to certain stimuli without conscious thought.
16 Which layer of the meninges is directly attached to the surface of the brain and spinal cord?
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The pia mater is the innermost layer of the meninges, directly adhering to the surface of the brain and spinal cord. It is a thin, delicate membrane that follows the contours of the CNS, providing a protective barrier and assisting in the circulation of cerebrospinal fluid.
17 How does the Peripheral Nervous System differ from the Central Nervous System in terms of regenerative ability?
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Peripheral Nervous System (PNS) axons have the capacity to regenerate and reconnect with their target tissues after injury, largely due to the supportive environment provided by Schwann cells. In contrast, Central Nervous System (CNS) axons do not regenerate effectively due to inhibitory factors, including glial scarring and molecules released by oligodendrocytes.
18 What are neural circuits or pathways, and how are they organized within the nervous system?
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Neural circuits or pathways consist of groups of interconnected neurons that work together to perform specific functions, such as reflex actions, sensory processing, or motor control. These circuits integrate and process information, enabling coordinated responses and complex behaviors.
19 Which of the following best describes the function of the reticular formation in the brainstem?
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The reticular formation is a network of interconnected nuclei located within the brainstem. It plays a key role in regulating consciousness, arousal, sleep-wake cycles, pain perception, and certain reflexes. This system integrates sensory and motor information, helping maintain alertness and attention.
20 What is the primary role of the blood-brain barrier in maintaining CNS homeostasis?
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The blood-brain barrier is a selective permeability barrier formed by tight junctions between endothelial cells in CNS blood vessels. Its primary role is to protect the brain by preventing most pathogens, toxins, and large or hydrophilic molecules from entering the CNS, while still allowing essential nutrients like glucose and amino acids to pass through.
21 Which of the following statements accurately describes the difference between neural systems and neural circuits?
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Neural circuits are specific pathways of interconnected neurons that carry out particular functions, such as the retinotectal pathway for visual reflexes. Neural systems are broader collections of related neural circuits that work together to perform complex tasks, such as the entire visual system encompassing multiple neural circuits involved in processing visual information.
22 What clinical condition in horses is associated with diffuse neuronal degeneration of the white matter in the medulla and spinal cord?
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Equine degenerative myeloencephalopathy is characterized by diffuse neuronal degeneration in the white matter of the medulla and spinal cord, along with astrocytosis and demyelination. It is associated with factors such as low dietary vitamin E, exposure to insecticides, and other environmental toxins. Clinically, affected horses exhibit abnormal movement, weakness, and incoordination.
23 Which of the following brain regions is involved in processing and relaying visual and auditory information?
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The midbrain, or mesencephalon, contains structures like the superior and inferior colliculi, which are responsible for processing and relaying visual and auditory information, respectively. It also houses cranial nerve nuclei involved in eye movements and pupillary responses.
24 What is the significance of the nodes of Ranvier in myelinated axons?
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Nodes of Ranvier are gaps in the myelin sheath along myelinated axons. These nodes contain a high density of voltage-gated sodium channels, which are crucial for the generation of action potentials. In myelinated axons, action potentials jump from node to node (saltatory conduction), significantly increasing the speed of signal transmission compared to unmyelinated axons.
25 Which clinical sign is NOT typically associated with equine degenerative myeloencephalopathy?
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Equine degenerative myeloencephalopathy primarily affects motor functions, leading to weakness, ataxia (incoordination), and abnormal movements such as stumbling or falling. While seizures can occur, blindness is not a typical clinical sign associated with this condition. Blindness may be associated with other neurological disorders affecting the visual pathways.
26 What role do astrocytes play in the Central Nervous System?
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Astrocytes are a type of glial cell in the CNS that perform several vital functions, including maintaining the extracellular ion balance, regulating neurotransmitter levels, supporting the blood-brain barrier, and providing metabolic support to neurons. They do not conduct electrical impulses or form myelin sheaths; these roles are fulfilled by neurons and oligodendrocytes, respectively.
27 How does the autonomic nervous system influence pharmacology?
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The autonomic nervous system (ANS) regulates involuntary bodily functions such as heart rate, digestion, and respiratory rate. Many pharmacological agents target the ANS to modify these functions, either by stimulating or inhibiting specific receptors within the sympathetic or parasympathetic branches. A thorough understanding of the ANS is crucial for developing effective and safe drugs that influence these involuntary processes.
28 What clinical sign would most likely indicate a problem with the cerebellum?
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The cerebellum is primarily responsible for coordinating voluntary movements, maintaining balance, and ensuring smooth and precise motor activities. Dysfunction in the cerebellum typically manifests as ataxia (lack of coordination), tremors, and difficulty maintaining balance, rather than issues like memory loss or impaired vision, which are associated with other brain regions.
29 What is the function of the retinotectal pathway within the visual system?
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The retinotectal pathway is involved in the reflexive orientation of the eyes toward light sources. It processes basic visual information, allowing for rapid, automatic responses to changes in the visual environment, such as turning the eyes toward a sudden light stimulus.
30 In the context of the nervous system, what is homeostasis?
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Homeostasis refers to the nervous systemโs ability to maintain a stable and balanced internal environment despite external changes. This involves regulating various physiological parameters such as temperature, pH, electrolyte balance, and blood pressure to ensure optimal functioning of cells and organs.
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31 What is the primary source of energy for the Na+, K+ pump in neurons?
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The Na+, K+ pump, which maintains the resting membrane potential by actively transporting sodium out of and potassium into the neuron, primarily relies on energy derived from Adenosine triphosphate (ATP). ATP provides the necessary energy for the pump to function against the concentration gradients of Na+ and K+ ions.
32 What is an action potential and where does it typically begin in a neuron?
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An action potential is a rapid and large change in the neuronโs membrane potential that propagates along the axon. It typically begins at the axon hillock (initial segment) where the integration of excitatory and inhibitory postsynaptic potentials can trigger the threshold needed to initiate the action potential.
33 How do myelinated axons achieve faster conduction of action potentials compared to unmyelinated axons?
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Myelinated axons achieve faster conduction through saltatory conduction, where action potentials jump from one node of Ranvier to the next. The myelin sheath insulates segments of the axon, preventing ion leakage and allowing the electrical signal to travel rapidly between nodes, significantly increasing conduction velocity compared to unmyelinated axons where the action potential must travel continuously along the entire membrane.
34 What mechanism ensures that action potentials travel in one direction along an axon?
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Refractory periods prevent action potentials from traveling backward along the axon, ensuring that they move in one directionโfrom the axon hillock to the axon terminalsโby temporarily inactivating sodium channels right after an action potential occurs.
35 What is the role of the medulla oblongata within the brainstem?
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The medulla oblongata is part of the brainstem and plays a crucial role in regulating vital autonomic functions like heart rate, breathing, and blood pressure. It also contains centers that control reflexes like swallowing and coughing, ensuring basic life support functions continue without conscious control.
36 What is the primary function of the cerebral cortex in the telencephalon?
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The cerebral cortex is the outer layer of the telencephalon and is responsible for the most complex and sophisticated functions of the brain, including sensory perception, voluntary movement, decision-making, problem-solving, and higher cognitive abilities like memory and reasoning.
37 What structure connects the left and right hemispheres of the brain?
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The corpus callosum is a large bundle of nerve fibers that connects the left and right hemispheres of the brain, allowing communication between them.
38 What is the primary role of the hypothalamus in the diencephalon?
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The hypothalamus is a vital regulatory center in the brain that controls autonomic functions such as body temperature, hunger, and thirst. It also regulates the release of hormones from the pituitary gland, influencing processes like growth, metabolism, and reproductive functions.
39 The pons plays an important role in which of the following?
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The pons serves as a bridge between the cerebral cortex and the cerebellum, transmitting motor commands to help coordinate movements. It also contains nuclei that are involved in regulating respiration, sleep, and facial sensations.
39 Which type of synapse is characterized by the direct transmission of electrical signals?
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Electrical synapses allow direct transmission of electrical signals between neurons through gap junctions, facilitating rapid communication.
40 What type of neurotransmitter is primarily inhibitory in the central nervous system?
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Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system, playing a key role in reducing neuronal excitability and preventing excessive firing.
41 What is a reflex arc?
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A reflex arc is a simple neural pathway that enables a reflex action. It typically involves sensory neurons that synapse with motor neurons in the spinal cord, allowing for rapid responses without the involvement of higher brain centers.
42 Which structure connects the brain to the spinal cord?
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The medulla oblongata is a part of the brainstem that connects the brain to the spinal cord and is responsible for regulating vital functions such as breathing, heart rate, and blood pressure.
43 What mechanism do inhibitory neurotransmitters typically use to affect the postsynaptic neuron?
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Inhibitory neurotransmitters (like GABA) typically cause hyperpolarization of the postsynaptic membrane by opening channels that allow chloride ions (Cl-) to enter the neuron, making it less likely to generate an action potential.
44 Which of the following best describes the role of microglia in the central nervous system?
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Microglia are the resident immune cells of the central nervous system, responsible for monitoring the environment, responding to injury, and clearing away debris and pathogens.
45 Which of the following structures is NOT part of the brainstem?
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The cerebellum is a separate structure from the brainstem and is primarily involved in coordination and balance. The brainstem consists of the midbrain, pons, and medulla oblongata.
46 What is the primary purpose of the sympathetic division of the autonomic nervous system?
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The sympathetic division of the autonomic nervous system prepares the body for rapid responses to stressful situations, increasing heart rate, blood flow to muscles, and energy availability for immediate action.
47 What process allows the brain to adjust to new experiences and learn over time?
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Neuroplasticity refers to the brainโs ability to adapt and reorganize itself by forming new neural connections in response to learning, experience, or injury.
48 Which type of neuron connects sensory and motor neurons within the central nervous system?
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Interneurons are neurons that connect sensory neurons to motor neurons within the central nervous system. They play a crucial role in processing information and coordinating responses.
49 What is the primary role of the pineal gland?
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The pineal gland produces melatonin, a hormone that helps regulate sleep-wake cycles and circadian rhythms, influencing sleep patterns and overall biological rhythms.
50 What happens during the repolarization phase of an action potential?
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During repolarization, voltage-gated potassium channels open, allowing potassium ions (K+) to flow out of the neuron, which helps return the membrane potential to a negative state after depolarization.
51 Which part of the neuron is responsible for receiving signals from other neurons?
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Dendrites are the parts of the neuron that receive signals from other neurons and transmit that information to the cell body for processing.
52 What occurs during the absolute refractory period of a neuron?
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During the absolute refractory period, the voltage-gated sodium channels are inactivated after an action potential, making it impossible for the neuron to fire another action potential.
53 Which neurotransmitter is primarily associated with mood regulation?
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Serotonin is a neurotransmitter that plays a crucial role in mood regulation, and its imbalance is often associated with mood disorders like depression.
54 Which brain structure is primarily involved in memory formation?
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The hippocampus is a critical brain region involved in the formation of new memories and learning, playing an essential role in spatial navigation and the consolidation of information from short-term to long-term memory.
55 How do action potentials propagate along an unmyelinated axon?
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In unmyelinated axons, action potentials propagate by continuously depolarizing adjacent segments of the membrane, leading to sequential opening of voltage-gated sodium channels along the axon.
56 What is the role of the choroid plexus in the brain?
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The choroid plexus is a structure within the ventricles of the brain that produces cerebrospinal fluid (CSF), which cushions the brain and provides nutrients.
57 What is the main effect of the parasympathetic nervous system?
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The parasympathetic nervous system is responsible for promoting a state of rest and digest, conserving energy, and regulating functions such as slowing the heart rate and stimulating digestion.
58 Which of the following neurotransmitters is commonly implicated in the reward pathway of the brain?
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Dopamine is a key neurotransmitter involved in the brainโs reward pathway, playing a significant role in motivation, pleasure, and reinforcement.
59 Which structure in the brain is primarily responsible for processing visual information?
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The occipital lobe is the region of the brain responsible for processing visual information received from the eyes, allowing for perception and interpretation of visual stimuli.
60 What is the function of the temporal lobe?
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The temporal lobe is involved in processing auditory information and is also important for memory formation, including aspects of language and visual memory.
The Neuron MCQs
61 What are the four distinct anatomical regions of a typical neuron?
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A typical neuron consists of four main anatomical regions: dendrites (which receive signals), the cell body (soma, which processes information), the axon (which transmits signals), and presynaptic terminals (which communicate with other neurons or target cells). Each part plays a crucial role in the neuronโs function.
62 What is the resting membrane potential of most mammalian neurons?
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The resting membrane potential of most mammalian neurons is approximately -70 mV, indicating that the inside of the neuron is negatively charged relative to the outside. This potential is primarily maintained by the differential distribution of ions, particularly sodium (Na+) and potassium (K+), across the neuronal membrane.
63 What is the primary function of the myelin sheath?
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The myelin sheath, formed by glial cells (Schwann cells in the PNS and oligodendrocytes in the CNS), insulates axons, which significantly increases the speed of action potentials through a process called saltatory conduction. This allows electrical impulses to jump from node to node (nodes of Ranvier), speeding up signal transmission along the axon.
64 How is an action potential initiated in a neuron?
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An action potential is initiated when the membrane potential of a neuron depolarizes to a threshold level, typically around -55 mV. This depolarization occurs primarily due to the influx of sodium ions (Na+) through voltage-gated sodium channels, resulting in a rapid change in membrane potential.
65 Which type of signal decreases the likelihood of an action potential in a postsynaptic neuron?
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An inhibitory postsynaptic potential (IPSP) occurs when the membrane potential of the postsynaptic neuron becomes more negative (hyperpolarized) due to the influx of chloride ions (Cl-) or the efflux of potassium ions (K+). This hyperpolarization decreases the likelihood of reaching the threshold for action potential initiation.
66 What is the role of neurotransmitters in synaptic transmission?
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Neurotransmitters are chemical messengers released from presynaptic terminals into the synaptic cleft. They bind to specific receptors on the postsynaptic cell, leading to changes in membrane potential and initiating either excitatory or inhibitory responses in the postsynaptic neuron.
67 What occurs during the depolarization phase of an action potential?
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During the depolarization phase of an action potential, voltage-gated sodium channels open, allowing sodium ions (Na+) to flow into the neuron. This influx of positive ions makes the inside of the neuron more positive, leading to a rapid rise in membrane potential.
68 What is the significance of the nodes of Ranvier in myelinated axons?
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The nodes of Ranvier are gaps in the myelin sheath where voltage-gated sodium channels are concentrated. These nodes allow action potentials to jump from one node to the next, significantly increasing the speed of signal transmission in myelinated axons through a process known as saltatory conduction.
69 Which of the following accurately describes the action potential?
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An action potential is an all-or-nothing response that occurs when a neuronโs membrane potential reaches a threshold level. Once initiated, it propagates along the axon without decrement, meaning the amplitude remains consistent as it travels down the length of the axon.
70 What is the function of the synaptic cleft?
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The synaptic cleft is the small gap between the presynaptic and postsynaptic neurons where neurotransmitters diffuse after being released from the presynaptic terminal. This diffusion is crucial for synaptic transmission, enabling communication between neurons.
71 What is the primary mechanism for repolarization during an action potential?
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Repolarization during an action potential occurs primarily due to the efflux of potassium ions (K+) from the neuron. After the peak of the action potential, voltage-gated potassium channels open, allowing K+ to exit the cell, which helps return the membrane potential to its resting state.
72 What type of neurotransmitter is primarily involved in excitatory postsynaptic potentials (EPSPs)?
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Acetylcholine (ACh) is a common neurotransmitter involved in creating excitatory postsynaptic potentials (EPSPs) by binding to receptors on the postsynaptic neuron, leading to depolarization and increased likelihood of generating an action potential.
73 What is the role of the axon hillock in a neuron?
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The axon hillock is the region of the neuron where the axon originates from the cell body. It is crucial for integrating signals received from the dendrites and cell body and determining whether the membrane potential reaches the threshold to initiate an action potential.
74 What physiological process allows for the rapid conduction of action potentials along myelinated axons?
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Saltatory conduction is the process by which action potentials jump from one node of Ranvier to the next along myelinated axons. This method allows for much faster transmission of electrical signals compared to continuous conduction along unmyelinated axons.
75 How do inhibitory postsynaptic potentials (IPSPs) affect a neuron?
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Inhibitory postsynaptic potentials (IPSPs) result in hyperpolarization of the postsynaptic membrane, making it more negative and reducing the likelihood that the neuron will reach the threshold necessary to generate an action potential.
76 Which type of channel opens in response to depolarization during an action potential?
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During the depolarization phase of an action potential, voltage-gated sodium channels open in response to a change in membrane potential, allowing sodium ions to flow into the neuron and causing further depolarization.
77 What is the primary mechanism by which neurotransmitters are removed from the synaptic cleft?
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Neurotransmitters are removed from the synaptic cleft primarily by reuptake into the presynaptic neuron or by enzymatic degradation. Reuptake is a common mechanism where neurotransmitters are transported back into the presynaptic neuron, while enzymatic degradation involves specific enzymes breaking down neurotransmitters, such as acetylcholinesterase for acetylcholine.
78 Which of the following statements about the resting membrane potential is TRUE?
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The resting membrane potential is established by the differential distribution of ions, primarily sodium (Na+) and potassium (K+), across the neuronal membrane. The sodium-potassium pump plays a key role in maintaining this gradient, which results in a negative charge inside the neuron at rest.
79 In the context of neuron signaling, what is meant by โgraded potentialsโ?
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Graded potentials are local changes in membrane potential that vary in magnitude depending on the strength of the stimulus. They can be excitatory (depolarizing) or inhibitory (hyperpolarizing) and are crucial for determining whether an action potential will be generated at the axon hillock.
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80 What happens during the hyperpolarization phase of an action potential?
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During the hyperpolarization phase, voltage-gated potassium channels remain open, allowing potassium ions (K+) to exit the neuron. This outflow makes the inside of the neuron more negative than the resting potential, temporarily increasing the difference in charge across the membrane.
81 Which of the following processes occurs at the presynaptic terminal during neurotransmitter release?
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When an action potential reaches the presynaptic terminal, it causes voltage-gated calcium channels to open, allowing calcium ions (Ca2+) to flow into the terminal. This influx of calcium triggers the release of neurotransmitters from synaptic vesicles into the synaptic cleft.
82 What determines whether a postsynaptic neuron will fire an action potential?
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Whether a postsynaptic neuron fires an action potential depends on the summation of excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs) that it receives. If the net effect brings the membrane potential to threshold, an action potential will be generated.
83 What type of synapse is characterized by the release of neurotransmitters?
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A chemical synapse is characterized by the release of neurotransmitters from the presynaptic neuron into the synaptic cleft, where they bind to receptors on the postsynaptic neuron. This process allows for complex signaling between neurons.
84 What is the effect of an excitatory neurotransmitter on the postsynaptic neuron?
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Excitatory neurotransmitters bind to receptors on the postsynaptic neuron, causing depolarization of the membrane. This depolarization increases the likelihood that the neuron will reach the threshold required to generate an action potential.
85 Which of the following is a feature of action potentials?
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Action potentials are all-or-nothing responses; once the membrane potential reaches a certain threshold, an action potential is generated. The strength of the action potential is consistent and does not vary, unlike graded potentials.
86 What causes the refractory period in a neuron?
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The refractory period occurs after an action potential when the voltage-gated sodium channels are inactivated and potassium channels are open, preventing the neuron from firing another action potential for a brief period. This period ensures that action potentials travel in one direction and that the neuron has time to recover.
87 Which of the following statements about neurotransmitter receptors is true?
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Neurotransmitter receptors are located on the postsynaptic neuron and can initiate various responses (excitatory or inhibitory) when a neurotransmitter binds to them. Each receptor type is specific to particular neurotransmitters, leading to a specific physiological effect.
88 How do local anesthetics work on neurons?
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Local anesthetics work by blocking voltage-gated sodium channels in neurons, preventing the influx of sodium ions. This inhibition stops the generation and propagation of action potentials, effectively blocking sensation in the area where the anesthetic is applied.
89 How does the nervous system maintain homeostasis?
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Homeostasis is maintained through feedback mechanisms involving the nervous system, which helps regulate body temperature, blood pressure, and other critical physiological processes.
90 Which part of the brain is responsible for voluntary motor control?
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The motor cortex, located in the frontal lobe, is responsible for controlling voluntary movements, sending signals to muscles throughout the body.
91 What is the function of the vagus nerve in the autonomic nervous system?
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The vagus nerve is a key component of the parasympathetic nervous system, helping to regulate heart rate, digestion, and respiratory functions.
92 What distinguishes sympathetic from parasympathetic responses?
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Sympathetic responses prepare the body for emergencies (e.g., increasing heart rate), while parasympathetic responses help restore the body to a restful state, promoting digestion and energy conservation.
93 Which of the following describes the absolute refractory period?
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The absolute refractory period is the time during which a neuron is unable to fire another action potential, regardless of the strength of the incoming stimulus. This occurs because the voltage-gated sodium channels are inactivated after an action potential, preventing further depolarization.
94 Which of the following best describes a neurotransmitter?
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Neurotransmitters are chemicals released from the presynaptic neuron into the synaptic cleft that bind to receptors on the postsynaptic neuron. They play a crucial role in transmitting signals between neurons, influencing various physiological processes.
95 What is the purpose of the synaptic vesicles in the presynaptic neuron?
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Synaptic vesicles are membrane-bound structures within the presynaptic neuron that store neurotransmitters. When an action potential reaches the presynaptic terminal, these vesicles fuse with the membrane and release their contents into the synaptic cleft, allowing for signal transmission.
96 Which neurotransmitter is primarily involved in the โfight or flightโ response?
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Norepinephrine is a neurotransmitter that plays a key role in the sympathetic nervous systemโs response to stress, known as the โfight or flightโ response. It increases heart rate, blood flow to muscles, and energy availability, preparing the body for immediate action.
97 What is the role of ligand-gated ion channels in postsynaptic signaling?
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Ligand-gated ion channels are activated when neurotransmitters bind to their specific receptors on the postsynaptic membrane. This binding causes the channels to open, allowing the flow of ions (such as Na+ or Cl-) across the membrane, which can lead to depolarization or hyperpolarization of the postsynaptic neuron.
98 What is the primary role of dendrites in a neuron?
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Dendrites are the branching structures of a neuron that receive signals from other neurons and transmit this information to the cell body for processing. They play a crucial role in integrating synaptic input and determining the overall response of the neuron.
99 What is the significance of the sodium-potassium pump in maintaining resting membrane potential?
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The sodium-potassium pump is an active transport mechanism that moves three sodium ions (Na+) out of the neuron and two potassium ions (K+) into the neuron, maintaining the concentration gradients essential for the resting membrane potential. This activity helps keep the inside of the neuron negatively charged compared to the outside.
100 What is the primary role of neuroplasticity?
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Neuroplasticity refers to the ability of the brain and nervous system to adapt and reorganize by forming new neural connections throughout life. This process allows the nervous system to adjust to new experiences, learning, and recovery from injuries.
101 Which type of glial cell is responsible for forming the myelin sheath in the central nervous system?
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Oligodendrocytes are the glial cells that produce the myelin sheath around axons in the central nervous system (CNS). Schwann cells perform a similar function in the peripheral nervous system (PNS).
102 What is the function of excitatory neurotransmitters in the nervous system?
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Excitatory neurotransmitters, such as glutamate, bind to receptors on the postsynaptic neuron and cause depolarization, increasing the likelihood that the neuron will reach the threshold to generate an action potential.
103 Which phase of an action potential is characterized by the opening of voltage-gated potassium channels?
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During repolarization, voltage-gated potassium channels open, allowing potassium ions (K+) to flow out of the neuron, which helps to restore the negative charge inside the neuron after the rapid depolarization phase.
104 Which neurotransmitter is involved in motor control and is deficient in Parkinsonโs disease?
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Dopamine is a neurotransmitter crucial for regulating movement and coordination. In Parkinsonโs disease, there is a deficiency of dopamine due to the degeneration of dopaminergic neurons in the substantia nigra, leading to motor control difficulties.
105 How does the presence of myelin affect the conduction velocity of action potentials?
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Myelin acts as an insulator around axons, allowing for faster transmission of action potentials via saltatory conduction, where action potentials jump from one node of Ranvier to the next. This significantly increases conduction velocity compared to unmyelinated axons.
106 What is the primary role of calcium ions in synaptic transmission?
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Calcium ions (Ca2+) play a crucial role in synaptic transmission. When an action potential arrives at the presynaptic terminal, the influx of Ca2+ through voltage-gated calcium channels triggers the fusion of synaptic vesicles with the presynaptic membrane, leading to the release of neurotransmitters into the synaptic cleft.
107 What role does acetylcholine play at the neuromuscular junction?
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At the neuromuscular junction, acetylcholine (ACh) is released from motor neurons and binds to receptors on muscle fibers, leading to depolarization of the muscle membrane and triggering muscle contraction. It is essential for voluntary muscle movement.
108 What physiological change occurs when a neuron is depolarized?
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Depolarization occurs when the membrane potential of a neuron becomes less negative (more positive) due to the influx of sodium ions (Na+) when voltage-gated sodium channels open. This shift in membrane potential can lead to the generation of an action potential.
109 What effect do neurotransmitter reuptake inhibitors have on synaptic transmission?
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Neurotransmitter reuptake inhibitors block the reabsorption of neurotransmitters by the presynaptic neuron, leading to an increased concentration of neurotransmitters in the synaptic cleft. This prolongs their action on the postsynaptic receptors, enhancing synaptic transmission.
110 Which part of the neuron is responsible for transmitting signals to other neurons?
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The axon is the part of the neuron that conducts electrical impulses away from the cell body to other neurons, muscles, or glands. It is essential for transmitting signals over long distances.
111 What characterizes the all-or-nothing principle of action potentials?
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The all-or-nothing principle states that once a neuronโs membrane potential reaches a certain threshold, an action potential will be generated at full amplitude. If the threshold is not reached, no action potential occurs.
112 Which of the following describes the function of Schwann cells?
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Schwann cells are glial cells in the peripheral nervous system that wrap around axons to form myelin sheaths. This myelination increases the speed of action potential conduction and provides insulation for the axons.
The Synapse MCQs
113 What is the main function of the neuromuscular junction?
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The neuromuscular junction is a specialized synapse where motor neurons release acetylcholine, which binds to receptors on the muscle fiber membrane, causing muscle contraction.
114 Which ion is necessary to release neurotransmitters from the presynaptic terminal?
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The influx of calcium ions into the presynaptic terminal triggers the fusion of synaptic vesicles with the presynaptic membrane, releasing neurotransmitters into the synaptic cleft.
115 What type of neurotransmitter receptor is found at the neuromuscular junction?
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The neuromuscular junction contains nicotinic acetylcholine receptors, which are ligand-gated ion channels that open when acetylcholine binds, allowing sodium ions to enter the muscle fiber and trigger contraction.
116 What happens to acetylcholine after it is released into the synaptic cleft?
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Acetylcholinesterase rapidly breaks down acetylcholine in the synaptic cleft into acetate and choline, terminating the signal. The choline is then recycled by the presynaptic neuron.
117 Which process ensures that neurotransmitter release is tightly regulated at the neuromuscular junction?
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Calcium ions entering the presynaptic terminal trigger the fusion of synaptic vesicles with the membrane, ensuring that neurotransmitter release occurs only in response to an action potential.
118 How does acetylcholinesterase affect synaptic transmission at the neuromuscular junction?
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Acetylcholinesterase is responsible for breaking down acetylcholine in the synaptic cleft, terminating the signal, and allowing the muscle fiber to relax.
119 What causes the depolarization of the postsynaptic muscle fiber at the neuromuscular junction?
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When acetylcholine binds to nicotinic receptors on the muscle fiber, sodium ions enter the muscle, causing depolarization and triggering an action potential that leads to muscle contraction.
120 How does the SNARE complex contribute to neurotransmitter release?
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The SNARE complex is involved in the priming and docking of synaptic vesicles, facilitating their fusion with the presynaptic membrane when calcium ions enter, leading to neurotransmitter release.
121 What is the role of acetylcholinesterase inhibitors in conditions like myasthenia gravis?
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Acetylcholinesterase inhibitors block the enzyme acetylcholinesterase, preventing it from breaking down acetylcholine, thus increasing its availability at the synapse and improving muscle contraction in conditions like myasthenia gravis.
122 Which toxin interferes with neurotransmitter release by cleaving SNARE proteins, preventing vesicle fusion?
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Botulinum toxin cleaves SNARE proteins, preventing synaptic vesicles from fusing with the presynaptic membrane, thereby blocking neurotransmitter release and causing paralysis.
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