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NEURON FUNCTION STUDY GUIDE TESTED
QUESTIONS 2026 100% CORRECT.
⫸ What is the central nervous system (CNS) composed of? Answer: The brain and spinal cord. ⫸ What does the peripheral nervous system (PNS) consist of? Answer: Nerves that extend from the brain and spinal cord. ⫸ What are the two functional divisions of the peripheral nervous system? Answer: Sensory (afferent) division and motor (efferent) division. ⫸ What is the role of the somatic nervous system? Answer: It controls voluntary movements by conducting impulses from the CNS to skeletal muscles. ⫸ What does the autonomic nervous system (ANS) regulate? Answer: Smooth muscle, cardiac muscle, and glands. ⫸ What are the two subdivisions of the autonomic nervous system? Answer: Sympathetic division and parasympathetic division. ⫸ What are neuroglia? Answer: Supportive cells that surround and wrap delicate neurons.
⫸ Name the four main types of neuroglia in the CNS. Answer: Astrocytes, microglial cells, ependymal cells, and oligodendrocytes. ⫸ What is the primary function of astrocytes? Answer: Support and brace neurons, control the chemical environment, and help form the blood-brain barrier. ⫸ What do microglial cells do? Answer: Monitor neurons and can transform to phagocytize microorganisms and debris. ⫸ What is the function of ependymal cells? Answer: Line the central cavities of the brain and spinal column and circulate cerebrospinal fluid (CSF). ⫸ What do oligodendrocytes form? Answer: An insulating myelin sheath around CNS nerve fibers. ⫸ What are satellite cells in the PNS? Answer: Cells that surround neuron cell bodies and function similarly to astrocytes in the CNS. ⫸ What is the role of Schwann cells? Answer: Surround peripheral nerve fibers and form myelin sheaths around thicker nerve fibers. ⫸ What are the structural units of the nervous system? Answer: Neurons, or nerve cells.
⫸ What is the blood-brain barrier? Answer: A selective barrier formed by astrocytes that protects the brain from harmful substances in the blood. ⫸ What is the enteric nervous system? Answer: A part of the PNS that contains neurons in the walls of the gastrointestinal tract. ⫸ What is the primary role of the sensory (afferent) division? Answer: To convey impulses from sensory receptors to the CNS. ⫸ What is the primary role of the motor (efferent) division? Answer: To transmit impulses from the CNS to effectors such as muscles and glands. ⫸ What are dendrites and their function in neurons? Answer: Dendrites are short, tapering, diffusely branched processes that convey incoming messages toward the cell body as graded potentials. ⫸ What is the structure of an axon? Answer: Each neuron has one axon that starts at the axon hillock, has a uniform diameter, and can vary in length, with some being very long. ⫸ What are axon terminals? Answer: Knob-like distal ends of axons that release neurotransmitters into the extracellular space. ⫸ What is the myelin sheath and its function? Answer: The myelin sheath is a white, fatty substance that coats many axons, protecting
and electrically insulating them while increasing the speed of nerve impulse transmission. ⫸ How is the myelin sheath formed in the peripheral nervous system (PNS)? Answer: In the PNS, the myelin sheath is formed by Schwann cells that wrap around the axon in a jelly roll fashion. ⫸ What are nodes of Ranvier? Answer: Gaps between adjacent Schwann cells in the myelin sheath that allow for the emergence of axon collaterals. ⫸ What is the difference between myelinated and nonmyelinated axons? Answer: Myelinated axons have a segmented sheath that increases impulse speed, while nonmyelinated axons do not have this sheath and conduct impulses more slowly. ⫸ What are the three structural classifications of neurons? Answer: The three types are multipolar neurons (many processes), bipolar neurons (two processes), and unipolar neurons (one process). ⫸ What type of neuron is most common in the central nervous system (CNS)? Answer: Multipolar neurons, which make up 99% of neurons in the CNS. ⫸ What is the role of sensory (afferent) neurons? Answer: Sensory neurons transmit impulses from sensory receptors toward the CNS and are mostly unipolar.
⫸ What is the axon hillock? Answer: The axon hillock is the cone- shaped area where the axon begins, crucial for initiating action potentials. ⫸ What are axon collaterals? Answer: Occasional branches of the axon that allow for multiple signals to be transmitted simultaneously. ⫸ How does myelination differ in the central nervous system (CNS)? Answer: In the CNS, myelin sheaths are formed by oligodendrocytes, which can wrap around multiple axons at once. ⫸ What is the role of neurotransmitters? Answer: Neurotransmitters are signaling chemicals released from axon terminals that can excite or inhibit other neurons, muscles, or glands. ⫸ What is the function of the axolemma? Answer: The axolemma is the plasma membrane of the axon that conducts nerve impulses away from the cell body. ⫸ What is the relationship between neuron structure and function? Answer: The structure of neurons, including the number of processes and the presence of myelin, directly influences their functional roles in transmitting signals. ⫸ What is an action potential (AP)? Answer: A brief reversal of membrane potential with a change in voltage, allowing neurons to send signals over long distances.
⫸ In which types of cells do action potentials occur? Answer: In excitable membranes, specifically neurons and muscle cells. ⫸ How do action potentials differ from graded potentials? Answer: Action potentials do not decay over distance, while graded potentials do. ⫸ Where are action potentials typically generated in neurons? Answer: In the axons of neurons. ⫸ What role do voltage-gated channels play in action potentials? Answer: They open to allow the generation and propagation of action potentials. ⫸ What factors affect the conduction velocity of action potentials? Answer: Axon diameter and degree of myelination. ⫸ How does axon diameter influence action potential conduction? Answer: Larger-diameter fibers have less resistance to local current flow, resulting in faster impulse conduction. ⫸ What is the difference between continuous conduction and saltatory conduction? Answer: Continuous conduction occurs in nonmyelinated axons and is slower, while saltatory conduction occurs in myelinated axons and is about 30 times faster.
⫸ What is the role of neurotransmitters in chemical synapses? Answer: They diffuse across the synaptic cleft and bind to specific receptors on the postsynaptic membrane, leading to graded potentials. ⫸ What can the binding of neurotransmitters to receptors cause? Answer: It can create either excitatory or inhibitory graded potentials in the postsynaptic cell. ⫸ How are neurotransmitter effects terminated? Answer: Through reuptake by astrocytes or axon terminal, degradation by enzymes, or diffusion away from the synaptic cleft. ⫸ What is the presynaptic neuron? Answer: The neuron conducting impulses toward the synapse, sending information. ⫸ What is the postsynaptic neuron? Answer: The neuron transmitting the electrical signal away from the synapse, receiving information. ⫸ What are axodendritic synapses? Answer: The most common type of synapse, occurring between axon terminals of one neuron and dendrites of another. ⫸ What is the function of synaptic vesicles? Answer: They store neurotransmitters in the axon terminal of the presynaptic neuron.
⫸ What is synaptotagmin? Answer: A protein that reacts with SNARE proteins to control the fusion of synaptic vesicles with the axon membrane during neurotransmitter release. ⫸ What is the synaptic cleft? Answer: The fluid-filled space that separates the axon terminal of the presynaptic neuron from the receptor region of the postsynaptic neuron. ⫸ What happens during the graded potential in the postsynaptic cell? Answer: Ion channels open due to neurotransmitter binding, leading to changes in membrane potential. ⫸ What are the three overlapping functions of the nervous system? Answer: Sensory input, integration, and motor output.
