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Neuron Structure and Function

Neuron Structure and Function

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Questions and Answers

What is the function of an axon?

To transmit nerve impulses away from the neuron's cell body to other cells.

What are axon terminals?

The branched endings of an axon where a neuron communicates with other cells, typically by releasing neurotransmitters.

What is the main function of the neuron cell body (soma)?

It contains the nucleus and other organelles, integrating signals received from dendrites.

What are the main components of the central nervous system (CNS)?

<p>The brain and the spinal cord.</p>

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What is the primary role of dendrites in a neuron?

<p>To receive nerve impulses (signals) from other neurons.</p>

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True or False: Glial cells transmit nerve impulses just like neurons.

<p>False (B)</p>

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What is the function of an interneuron?

<p>It carries nerve impulses between sensory neurons and motor neurons, primarily within the CNS.</p>

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What is myelin primarily composed of, and what cells produce it in the PNS?

<p>Myelin is a lipid (fatty) substance produced by Schwann cells in the Peripheral Nervous System (PNS).</p>

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What is the main function of the myelin sheath?

<p>It insulates the axon and allows nerve impulses to travel more rapidly.</p>

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What is another term for the electrical signal transmitted by the nervous system?

<p>Action potential (B)</p>

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What constitutes the peripheral nervous system (PNS)?

<p>All the nervous tissue that lies outside the central nervous system (brain and spinal cord).</p>

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Which type of glial cell produces myelin in the peripheral nervous system (PNS)?

<p>Schwann cell (A)</p>

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What is the direction of nerve impulse transmission by a sensory neuron?

<p>From tissues and organs towards the spinal cord and brain (CNS).</p>

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True or False: The endocrine system uses electrical signals to communicate, similar to the nervous system.

<p>False (B)</p>

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What is a nerve?

<p>A cable-like bundle of axons found in the peripheral nervous system.</p>

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What is the primary function of the nervous system?

<p>To send electrical messages throughout the body, controlling and coordinating other body systems and responses to stimuli.</p>

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Provide an example of an organ system besides the nervous system.

<p>Examples include the digestive system, respiratory system, circulatory system, or endocrine system.</p>

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A _____ is a chemical that carries a nerve impulse across the synaptic cleft from one neuron to another.

<p>neurotransmitter</p>

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What is the resting potential of a neuron?

<p>The stable difference in electrical charge (typically around -70mV) across the plasma membrane when the neuron is not transmitting a nerve impulse.</p>

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What is the role of the sodium-potassium pump in a neuron?

<p>It actively transports three sodium ions (Na+) out of the cell for every two potassium ions (K+) it transports into the cell, helping to maintain the resting potential.</p>

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What is a synapse?

<p>The junction between the axon terminal of one neuron and another cell (neuron, muscle cell, or gland cell) where information is transmitted.</p>

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What is the synaptic cleft?

<p>The small gap between the axon terminal of the presynaptic neuron and the membrane of the postsynaptic cell.</p>

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An action potential involves a rapid reversal of electrical charge across the neuron membrane, also known as:

<p>Depolarization (A)</p>

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What is the primary role of the brain in the nervous system?

<p>It serves as the main control center, processing information, coordinating activity, and enabling higher cognitive functions.</p>

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What are some vital functions controlled by the brain stem?

<p>Unconscious functions such as heart rate, breathing, sleep, and swallowing.</p>

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What is the main function of the cerebellum?

<p>Coordination of voluntary body movements, balance, and posture.</p>

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Which part of the brain is responsible for conscious thought, reasoning, and processing sensory information like sight?

<p>The cerebrum.</p>

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What are the two main functions of the spinal cord?

<ol> <li>Connecting the brain with the peripheral nervous system by relaying signals. 2. Mediating reflexes.</li> </ol>

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What structure protects the spinal cord?

<p>The vertebral column, which is made up of repeating bony units called vertebrae.</p>

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Which division of the peripheral nervous system controls involuntary actions like heart rate and digestion?

<p>Autonomic nervous system (C)</p>

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What is the function of the motor division of the PNS?

<p>It carries nerve impulses away from the CNS to effector organs (muscles and glands).</p>

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True or False: Nerves are primarily found within the central nervous system (brain and spinal cord).

<p>False (B)</p>

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What is the general role of the parasympathetic division of the ANS?

<p>It controls "rest-and-digest" activities, conserving energy and managing bodily functions during non-emergency situations.</p>

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What is a reflex arc?

<p>The neural pathway that mediates a reflex action, typically involving a sensory neuron, an interneuron (in some cases), and a motor neuron.</p>

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What is the function of the sensory division of the PNS?

<p>It carries sensory information from receptors in the body towards the central nervous system (CNS).</p>

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Which division of the PNS controls voluntary muscle movements and reflexes?

<p>The somatic nervous system (SNS).</p>

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What is the role of the sympathetic division of the ANS?

<p>It prepares the body for "fight-or-flight" responses during emergencies or stressful situations.</p>

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True or False: Dendrites transmit signals away from the neuron's cell body.

<p>False (B)</p>

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Besides containing the nucleus, what is a key function of the neuron's cell body (soma)?

<p>Integrating signals received from dendrites.</p>

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What type of signal does the axon transmit?

<p>Electrical impulses known as action potentials.</p>

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The _ _ is a fatty layer that insulates the axon and speeds up signal transmission.

<p>myelin sheath</p>

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What are Nodes of Ranvier and what is their role in signal transmission?

<p>They are gaps in the myelin sheath along an axon. Action potentials 'jump' between these nodes, a process called saltatory conduction, which greatly increases transmission speed.</p>

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What substance is typically released from axon terminals to communicate with the next cell?

<p>Neurotransmitters.</p>

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What is the function of motor neurons?

<p>To carry signals from the Central Nervous System (CNS) to effectors (muscles or glands), causing them to respond (e.g., contract or secrete).</p>

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Which cells produce myelin in the Central Nervous System (CNS)?

<p>Oligodendrocytes (B)</p>

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What are the three main functions of the nervous system?

<p>Sensory input (gathering information), integration (processing information), and motor output (causing a response).</p>

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What does 'sensory input' refer to in the context of nervous system function?

<p>The process of detecting stimuli from the internal or external environment using sensory receptors.</p>

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What is 'integration' in the context of nervous system function?

<p>The processing and interpretation of sensory information by the Central Nervous System (CNS).</p>

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What does 'motor output' involve in nervous system function?

<p>The activation of effector organs (muscles and glands) by the nervous system (via the PNS) to produce a response.</p>

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What form do electrical signals take within a single neuron for long-distance transmission?

<p>Action potentials.</p>

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How do neurons typically communicate with each other across a synapse?

<p>Using chemical signals called neurotransmitters.</p>

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List the main organs/structures comprising the nervous system.

<p>Brain, spinal cord (which make up the CNS), and peripheral nerves (which make up the PNS).</p>

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What is the typical voltage of a neuron's resting potential, and what mechanism is key to maintaining it?

<p>Typically around -70 mV; maintained primarily by the Sodium-Potassium (Na+/K+) pump.</p>

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What typically happens to the membrane potential during the peak of an action potential?

<p>It rapidly depolarizes, reaching a positive value (often around +30 mV).</p>

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The Na+/K+ pump actively transports _ Na+ ions out of the neuron for every _ K+ ions it transports in.

<p>3; 2</p>

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What is the significance of the threshold potential (around -55 mV) in a neuron?

<p>If the neuron's membrane potential depolarizes to reach the threshold, it triggers an action potential. If the threshold is not reached, no action potential occurs (all-or-none principle).</p>

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What is the refractory period following an action potential?

<p>A brief period during which the neuron cannot fire another action potential, or requires a stronger stimulus to do so.</p>

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True or False: All synapses involve neurotransmitters crossing a synaptic cleft.

<p>False (B)</p>

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What are the key characteristics of chemical synapses compared to electrical synapses?

<p>They use neurotransmitters, are generally slower, and typically allow only unidirectional signal transmission.</p>

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How do electrical synapses transmit signals, and what are their speed and directionality characteristics?

<p>They allow direct flow of ions between cells through gap junctions; they are faster than chemical synapses and often allow bidirectional transmission.</p>

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Describe the sequence of events at a chemical synapse starting from the arrival of an action potential at the axon terminal.

<ol> <li>Action potential arrives. 2. Voltage-gated Calcium (Ca2+) channels open, Ca2+ enters the terminal. 3. Ca2+ influx triggers fusion of synaptic vesicles with the presynaptic membrane. 4. Neurotransmitters are released into the synaptic cleft. 5. Neurotransmitters bind to receptors on the postsynaptic membrane.</li> </ol>

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Give an example of how nervous system communication can be hindered, and the potential consequence.

<p>Diseases like multiple sclerosis damage the myelin sheath, disrupting nerve signal transmission, leading to impaired movement, sensation, or cognition. Drugs or toxins can also interfere with neurotransmitter function at the synapse.</p>

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True or False: Peripheral nerves are part of the Central Nervous System (CNS).

<p>False (B)</p>

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Which specific lobe of the cerebrum is heavily involved in conscious reasoning and decision-making?

<p>The frontal lobe.</p>

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What part of the brainstem, specifically, controls essential vital functions like breathing and heart rate?

<p>The medulla oblongata (often referred to simply as the medulla).</p>

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What are two functions of the pons, located in the brainstem?

<p>Relaying signals (especially between the cerebrum and cerebellum) and regulating sleep cycles.</p>

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What is a key function of the midbrain related to sensory processing?

<p>It controls reflexes related to vision and hearing (e.g., turning the head towards a sound).</p>

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Why might a spinal cord injury below the neck result in paralysis of the limbs?

<p>Because the injury severs the motor neuron pathways travelling down the spinal cord, blocking signals from the brain from reaching the muscles in the limbs.</p>

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True or False: The sensory division carries commands from the brain to muscles.

<p>False (B)</p>

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The motor division of the PNS carries signals from the CNS to:

<p>Effectors (muscles and glands) (C)</p>

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Which type of muscle is primarily controlled by the somatic nervous system?

<p>Skeletal muscles.</p>

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Name two types of tissues controlled by the autonomic nervous system.

<p>Glands, smooth muscle, and cardiac muscle.</p>

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What common phrase describes the function of the sympathetic nervous system?

<p>"Fight-or-flight".</p>

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What common phrase describes the function of the parasympathetic nervous system?

<p>"Rest-and-digest".</p>

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How does the structure of a neuron relate to its function?

<p>Its elongated axon allows for rapid transmission of electrical signals (action potentials) over distances, while dendrites provide a large surface area for receiving signals. The myelin sheath increases transmission speed.</p>

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Which two body systems are primarily responsible for maintaining homeostasis, and name one part of the nervous system involved?

<p>The nervous system and the endocrine system. Parts of the nervous system involved include the brain stem and the autonomic nervous system (ANS).</p>

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What are the two main types of signals used by the nervous system for communication?

<p>Electrical signals (action potentials within neurons) and chemical signals (neurotransmitters between neurons).</p>

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How do the Central Nervous System (CNS) and Peripheral Nervous System (PNS) depend on each other?

<p>The PNS relays sensory information from the body to the CNS for processing and carries motor commands from the CNS back to the body's muscles and glands to execute responses.</p>

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What is an axon and what is its function?

<p>An axon is a long extension of the cell body of a neuron that transmits nerve impulses to other cells.</p>

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Describe the axon terminal.

<p>The axon terminal consists of branches at the end of an axon where the neuron communicates with other cells.</p>

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What is the cell body of a neuron?

<p>The cell body is the central part of a neuron that contains the nucleus and other cell organelles.</p>

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Which components make up the central nervous system (CNS)?

<p>Brain and spinal cord (D)</p>

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What is the role of dendrites in a neuron?

<p>Dendrites are extensions of the cell body that receive nerve impulses from other neurons.</p>

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What is a glial cell?

<p>A glial cell is a cell that provides support for a neuron.</p>

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What is the function of an interneuron?

<p>An interneuron carries nerve impulses back and forth between sensory and motor neurons.</p>

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What is myelin?

<p>Myelin is a lipid substance produced by glial cells (Schwann cells in the PNS, oligodendrocytes in the CNS) that forms the myelin sheath around axons.</p>

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What is the purpose of the myelin sheath?

<p>The myelin sheath is a lipid layer around the axon of a neuron that allows nerve impulses to travel more rapidly down the axon.</p>

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What is a nerve impulse?

<p>A nerve impulse is an electrical signal transmitted by the nervous system.</p>

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What does the peripheral nervous system (PNS) consist of?

<p>All nervous tissue outside the central nervous system (A)</p>

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What is a Schwann cell?

<p>A Schwann cell is a type of glial cell found in the peripheral nervous system that is responsible for producing myelin.</p>

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What is the role of a sensory neuron?

<p>A sensory neuron carries nerve impulses from tissues and organs to the spinal cord and brain.</p>

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Define the endocrine system.

<p>The endocrine system is a system of glands that secrete hormones directly into the bloodstream.</p>

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What is a nerve?

<p>A nerve is a bundle of nerve cells (specifically, axons) in the peripheral nervous system.</p>

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Describe the nervous system.

<p>The nervous system is the body system that sends electrical messages throughout the body and controls all other body systems.</p>

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What is an organ system?

<p>An organ system is a group of organs that work together to perform a specific task.</p>

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What is a neurotransmitter?

<p>A neurotransmitter is a chemical that carries a nerve impulse from one nerve cell to another at a synapse.</p>

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What is resting potential in a neuron?

<p>Resting potential is the difference in electrical charge across the plasma membrane of a neuron that is not actively transmitting a nerve impulse, typically around -70mV.</p>

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What does the sodium-potassium pump do?

<p>The sodium-potassium pump is an active transport protein that exchanges sodium ions (3 out) for potassium ions (2 in) across the plasma membrane of animal cells.</p>

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What is a synapse?

<p>A synapse is the junction where an axon terminal of one neuron meets another cell (neuron, muscle cell, or gland cell).</p>

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Define the synaptic cleft.

<p>The synaptic cleft is the physical space between the axon terminal of one cell and the receptors of the next cell at a synapse.</p>

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What is an action potential?

<p>An action potential is a rapid reversal of electrical charge (depolarization) across the membrane of a resting neuron that travels down the axon as a nerve impulse.</p>

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What is the brain?

<p>The brain is the central nervous system organ located inside the skull; it serves as the control center of the nervous system.</p>

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Describe the location and function of the brain stem.

<p>The brain stem is the lowest part of the brain that connects the brain with the spinal cord; it controls unconscious functions such as heart rate and breathing.</p>

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What is the function of the cerebellum?

<p>The cerebellum is the part of the brain located below the cerebrum that coordinates body movements.</p>

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What is the cerebrum?

<p>The cerebrum is the largest part of the brain, responsible for controlling conscious functions such as reasoning and sight.</p>

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Describe the spinal cord.

<p>The spinal cord is a thin, tubular bundle of nervous tissue that extends from the brainstem down the back to the pelvis; it connects the brain with the peripheral nervous system.</p>

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What are vertebrae?

<p>Vertebrae are the repeating bony units that make up the vertebral column (spine) of vertebrates.</p>

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What does the autonomic nervous system (ANS) control?

<p>The autonomic nervous system is a division of the peripheral nervous system that controls involuntary activities not under conscious control, such as heart rate and digestion.</p>

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What is the function of the motor division of the PNS?

<p>The motor division of the peripheral nervous system carries nerve impulses from the central nervous system to muscles and glands (effectors) throughout the body.</p>

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What makes up a nerve in the peripheral nervous system?

<p>In the PNS, a nerve is one of many cable-like bundles of axons.</p>

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What activities does the parasympathetic division of the ANS control?

<p>The parasympathetic division is the subdivision of the autonomic nervous system that controls involuntary activities associated with rest and digestion, not emergencies.</p>

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What is a reflex arc?

<p>A reflex arc is the neural pathway that a nerve impulse follows during a reflex action.</p>

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What is the function of the sensory division of the PNS?

<p>The sensory division of the peripheral nervous system carries sensory information from the body to the central nervous system.</p>

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What does the somatic nervous system (SNS) control?

<p>The somatic nervous system is the division of the peripheral nervous system that controls voluntary, conscious activities (like skeletal muscle movement) and reflexes.</p>

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What is the role of the sympathetic division of the ANS?

<p>The sympathetic division is the subdivision of the autonomic nervous system that prepares the body for emergencies, often referred to as the 'fight-or-flight' response.</p>

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What is the function of dendrites?

<p>Dendrites receive signals from other neurons.</p>

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What occurs in the cell body (soma) of a neuron?

<p>The cell body contains the nucleus and integrates signals received from dendrites.</p>

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What is the primary role of the axon?

<p>The axon transmits electrical impulses (action potentials) away from the neuron's cell body.</p>

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What is the function of the myelin sheath?

<p>The myelin sheath is a fatty insulation around the axon that speeds up electrical signal transmission.</p>

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What are Nodes of Ranvier?

<p>Nodes of Ranvier are gaps in the myelin sheath where action potentials are regenerated, allowing the impulse to 'jump' (saltatory conduction).</p>

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What happens at the axon terminals?

<p>Axon terminals release neurotransmitters into synapses to communicate with the next cell.</p>

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What is the function of motor neurons?

<p>Motor neurons carry signals from the CNS to muscles or glands (effectors) to trigger movement or secretion.</p>

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Which cells produce myelin in the Peripheral Nervous System (PNS) and Central Nervous System (CNS)?

<p>Schwann cells (PNS) and Oligodendrocytes (CNS) (C)</p>

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List the three fundamental functions of the nervous system.

<p>The three functions are sensory input (detecting stimuli), integration (processing information), and motor output (triggering responses).</p>

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What is sensory input in the context of the nervous system?

<p>Sensory input involves detecting stimuli from the internal or external environment via receptors.</p>

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What does integration involve in the nervous system?

<p>Integration is the process where the central nervous system (CNS) analyzes sensory information and makes decisions.</p>

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What is motor output?

<p>Motor output is the response triggered by the nervous system, carried out by effectors (muscles or glands) via the peripheral nervous system (PNS).</p>

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How are signals transmitted within a neuron versus between neurons?

<p>Electrically within, chemically between (B)</p>

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What are the main organs of the nervous system?

<p>The main organs are the brain and spinal cord (which form the CNS), and peripheral nerves (which form the PNS).</p>

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What is the resting potential of a neuron and how is it maintained?

<p>Resting potential is the stable negative voltage (around -70 mV) across a neuron's membrane when it's not firing. It is maintained primarily by the Na+/K+ pump.</p>

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Describe an action potential.

<p>An action potential is a rapid depolarization (increase in voltage to about +30 mV) of the neuron's membrane that occurs when the threshold potential is reached.</p>

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What is the role of the Na+/K+ pump in neuronal function?

<p>The Na+/K+ pump actively transports 3 Na+ ions out of the neuron and 2 K+ ions into the neuron, using ATP. This maintains the electrochemical gradient necessary for resting potential and repolarization after an action potential.</p>

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What is the threshold potential in a neuron?

<p>The threshold potential (typically around -55 mV) is the minimum membrane potential that must be reached to trigger an action potential.</p>

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What is the refractory period?

<p>The refractory period is a brief time after an action potential during which the neuron cannot fire another action potential or requires a stronger stimulus to do so. It ensures unidirectional propagation of the impulse and limits firing frequency.</p>

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Define synapse and synaptic cleft.

<p>A synapse is the junction between two neurons (or a neuron and an effector cell) where information is transmitted. The synaptic cleft is the small gap between the presynaptic axon terminal and the postsynaptic membrane.</p>

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Compare chemical and electrical synapses.

<p>Chemical use neurotransmitters and are slower; Electrical use gap junctions and are faster (D)</p>

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Briefly describe the process of neurotransmitter release and action at a chemical synapse.

<p>An action potential arriving at the axon terminal causes voltage-gated Ca2+ channels to open. Ca2+ influx triggers synaptic vesicles to fuse with the presynaptic membrane, releasing neurotransmitters into the synaptic cleft. Neurotransmitters then bind to receptors on the postsynaptic neuron, causing a response (excitation or inhibition).</p>

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How can nervous system communication be hindered?

<p>Communication can be hindered by drugs or toxins that interfere with neurotransmitters, or by diseases like multiple sclerosis that damage the myelin sheath, slowing or blocking nerve impulses.</p>

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What are the two main organs of the Central Nervous System (CNS)?

<p>The brain and the spinal cord.</p>

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Which part of the brain is primarily responsible for conscious reasoning and decision-making?

<p>The cerebrum, particularly the frontal lobe.</p>

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What vital functions does the medulla (part of the brainstem) control?

<p>The medulla controls vital autonomic functions such as breathing, heart rate, and blood pressure.</p>

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What are the functions of the pons?

<p>The pons relays signals between the cerebrum and cerebellum and plays a role in regulating sleep, breathing, and other autonomic functions.</p>

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What is the role of the midbrain?

<p>The midbrain is involved in processing visual and auditory information and controls reflex movements related to vision and hearing.</p>

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How does a spinal cord injury below the neck affect motor control?

<p>A spinal cord injury below the neck can sever motor neurons, blocking signals from the brain to the limbs, potentially resulting in paralysis.</p>

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Differentiate between the sensory and motor divisions of the PNS.

<p>The sensory division carries signals <em>to</em> the CNS from sensory receptors, while the motor division carries signals <em>from</em> the CNS to effectors (muscles and glands).</p>

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Contrast the somatic and autonomic nervous systems.

<p>The somatic nervous system controls voluntary movements (skeletal muscles) and reflexes. The autonomic nervous system controls involuntary functions (smooth muscle, cardiac muscle, glands).</p>

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What is the 'fight-or-flight' response associated with?

<p>The 'fight-or-flight' response is associated with the sympathetic division of the autonomic nervous system.</p>

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What is the 'rest-and-digest' state associated with?

<p>The 'rest-and-digest' state is associated with the parasympathetic division of the autonomic nervous system.</p>

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How does the structure of a neuron relate to its function?

<p>A neuron's structure (dendrites for input, cell body for integration, axon for output, myelin for speed) is specialized for rapid, long-distance electrical and chemical signaling.</p>

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How does the nervous system contribute to homeostasis?

<p>The nervous system, particularly the brain stem and autonomic NS, helps maintain homeostasis by regulating vital functions (like heart rate, breathing, temperature) and coordinating responses to internal and external changes.</p>

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How does the nervous system use communication?

<p>The nervous system uses both electrical signals (action potentials within neurons) and chemical signals (neurotransmitters between neurons) to rapidly communicate information and coordinate responses throughout the body.</p>

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Describe the interdependence between the CNS and PNS.

<p>The PNS relays sensory information to the CNS for processing and carries motor commands from the CNS to the rest of the body. They are functionally interdependent; one cannot operate effectively without the other.</p>

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What is the function of the axon in a neuron?

<p>The axon is a long extension of the cell body that transmits nerve impulses to other cells.</p>

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What are axon terminals?

<p>Axon terminals are the branches at the end of an axon where the neuron communicates with other cells, typically by releasing neurotransmitters.</p>

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What does the cell body (soma) of a neuron contain and what is its main function?

<p>The cell body is the central part of a neuron containing the nucleus and other organelles; it integrates signals received from dendrites.</p>

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Which of the following are the main components of the Central Nervous System (CNS)?

<p>Brain and spinal cord (C)</p>

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What is the primary role of dendrites in a neuron?

<p>Dendrites are extensions of the cell body that receive nerve impulses (signals) from other neurons.</p>

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What is the role of glial cells in the nervous system?

<p>Glial cells provide support, nutrition, insulation (myelin), and protection for neurons.</p>

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What type of neuron carries nerve impulses back and forth between sensory and motor neurons?

<p>Interneuron</p>

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_____ is a lipid produced by Schwann cells (in the PNS) or oligodendrocytes (in the CNS) that forms the myelin sheath around axons.

<p>Myelin</p>

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True or False: The myelin sheath slows down the speed of nerve impulses.

<p>False (B)</p>

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What is a nerve impulse?

<p>A nerve impulse is an electrical signal (specifically, an action potential) transmitted by the nervous system.</p>

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Which division of the nervous system consists of all the nervous tissue outside the brain and spinal cord?

<p>Peripheral Nervous System (PNS) (C)</p>

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Which type of glial cell produces myelin in the Peripheral Nervous System (PNS)?

<p>Schwann cell</p>

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What is the function of a sensory neuron?

<p>A sensory neuron carries nerve impulses from sensory receptors in tissues and organs towards the central nervous system (spinal cord and brain).</p>

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What is the endocrine system?

<p>The endocrine system is a system of glands that secrete hormones directly into the bloodstream to regulate various bodily functions.</p>

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A cable-like bundle of axons that make up the peripheral nervous system is called a _____.

<p>nerve</p>

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What is the overall function of the nervous system?

<p>The nervous system sends electrical and chemical messages throughout the body, controlling and coordinating all other body systems and responses to stimuli.</p>

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What is an organ system?

<p>An organ system is a group of organs that work together to perform a specific function or set of functions.</p>

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What is a neurotransmitter?

<p>A neurotransmitter is a chemical messenger that carries a nerve impulse across a synapse from one neuron to another cell (neuron, muscle cell, or gland cell).</p>

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What is the resting potential of a neuron?

<p>The difference in electrical charge across the plasma membrane of a neuron that is not actively transmitting a nerve impulse (typically around -70 mV). (A)</p>

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What is the role of the sodium-potassium ($Na^+/K^+$) pump in a neuron?

<p>The $Na^+/K^+$ pump is an active transport protein that maintains the resting potential by pumping three sodium ions ($Na^+$) out of the cell for every two potassium ions ($K^+$) pumped into the cell.</p>

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What is a synapse?

<p>A synapse is the junction where an axon terminal of one neuron meets another cell (neuron, muscle, or gland), across which nerve impulses are transmitted.</p>

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What is the synaptic cleft?

<p>The synaptic cleft is the small physical space between the axon terminal of the presynaptic neuron and the membrane of the postsynaptic cell.</p>

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An _ _ is a rapid reversal of electrical charge (depolarization) across the membrane of a resting neuron (reaching about +30 mV) that travels down the axon as a nerve impulse.

<p>action potential</p>

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What is the main control center of the nervous system, located inside the skull?

<p>Brain</p>

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Which part of the brain connects to the spinal cord and controls vital unconscious functions like heart rate and breathing?

<p>Brain stem (A)</p>

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What is the function of the cerebellum?

<p>The cerebellum, located below the cerebrum, primarily coordinates voluntary body movements, posture, and balance.</p>

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True or False: The cerebrum is the largest part of the brain and controls unconscious functions like reflexes.

<p>False (B)</p>

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Describe the spinal cord and its function.

<p>The spinal cord is a thin, tubular bundle of nervous tissue extending from the brainstem down the back. It connects the brain with the peripheral nervous system and mediates reflexes.</p>

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What are vertebrae?

<p>Vertebrae are the repeating bony units that make up the vertebral column (spine), which protects the spinal cord.</p>

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The _____ nervous system is the division of the PNS that controls involuntary activities such as heart rate, digestion, and breathing.

<p>autonomic</p>

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What is the function of the motor division of the PNS?

<p>The motor division carries nerve impulses from the central nervous system (CNS) to muscles and glands (effectors) throughout the body, initiating action.</p>

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Which division of the autonomic nervous system controls involuntary activities during non-emergency, 'rest-and-digest' situations?

<p>Parasympathetic division (C)</p>

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What is a reflex arc?

<p>A reflex arc is the neural pathway that mediates a reflex action. It typically involves a sensory neuron, sometimes an interneuron, and a motor neuron.</p>

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What is the function of the sensory division of the PNS?

<p>The sensory division carries sensory information from receptors in the body (e.g., skin, eyes, ears) to the central nervous system (CNS).</p>

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The _____ nervous system is the division of the PNS that controls voluntary, conscious activities (like skeletal muscle movement) and reflexes.

<p>somatic</p>

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True or False: The sympathetic division of the autonomic nervous system is responsible for the 'rest-and-digest' response.

<p>False (B)</p>

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What structures in a neuron are primarily responsible for receiving signals from other neurons?

<p>Dendrites</p>

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What are the gaps in the myelin sheath called, and what is their function?

<p>The gaps are called Nodes of Ranvier. They allow the action potential to 'jump' from node to node (saltatory conduction), greatly increasing the speed of nerve impulse transmission.</p>

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What type of neurons carry signals from the CNS to muscles and glands to cause a response?

<p>Motor neurons</p>

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List the three main functions of the nervous system.

<ol> <li>Sensory input (detecting stimuli), 2. Integration (processing information in the CNS), 3. Motor output (triggering responses via the PNS).</li> </ol>

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Action potentials within a neuron are an example of what type of signaling?

<p>Electrical signaling (A)</p>

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What approximate voltage is considered the resting potential of a typical neuron?

<p>Approximately -70 mV (millivolts)</p>

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What is the threshold potential required to trigger an action potential in a typical neuron?

<p>Approximately -55 mV (millivolts)</p>

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What happens during the refractory period after an action potential?

<p>During the refractory period, the neuron cannot fire another action potential immediately. This ensures the action potential travels in one direction and limits firing frequency. It involves resetting ion gradients and channel inactivation.</p>

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Which type of synapse uses neurotransmitters and is typically slower but allows for more modulation?

<p>Chemical synapse (D)</p>

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Briefly describe the sequence of events for neurotransmitter release at a chemical synapse.

<ol> <li>Action potential arrives at the axon terminal. 2. Voltage-gated calcium ($Ca^{2+}$) channels open, and $Ca^{2+}$ enters the terminal. 3. $Ca^{2+}$ influx triggers synaptic vesicles (containing neurotransmitters) to fuse with the presynaptic membrane. 4. Neurotransmitters are released into the synaptic cleft. 5. Neurotransmitters diffuse across the cleft and bind to receptors on the postsynaptic membrane.</li> </ol>

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Which lobe of the cerebrum is primarily associated with conscious reasoning and decision-making?

<p>Frontal lobe</p>

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What structure within the brainstem relays signals between the cerebrum and cerebellum and helps regulate sleep?

<p>Pons</p>

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How does the nervous system contribute to maintaining homeostasis?

<p>The nervous system helps maintain homeostasis by monitoring internal conditions (e.g., temperature, blood pressure via sensory input), integrating this information (CNS), and initiating appropriate responses (e.g., via the autonomic nervous system adjusting heart rate or triggering shivering).</p>

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True or False: The Peripheral Nervous System (PNS) can function completely independently of the Central Nervous System (CNS).

<p>False (B)</p>

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Flashcards

Axon

Long extension of the cell body of a neuron; transmits nerve impulses to other cells.

Axon Terminal

Branches at the end of an axon of a neuron; points where the neuron communicates with other cells.

Cell Body

Central part of a neuron; contains the nucleus and other cell organelles.

Central Nervous System (CNS)

One of two main divisions of the nervous system that includes the brain and spinal cord.

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Dendrite

Extension of the cell body of a neuron; receives nerve impulses from other neurons.

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Glial Cell

A cell that provides support for a neuron.

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Interneuron

Neuron that carries nerve impulses back and forth between sensory and motor neurons.

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Myelin

A lipid produced by a Schwann cell; forms the myelin sheath.

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Myelin Sheath

Lipid layer around the axon of a neuron; allows nerve impulses to travel more rapidly down the axon.

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Nerve Impulse

Electrical signal transmitted by the nervous system.

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Peripheral Nervous System (PNS)

One of two major divisions of the nervous system; consists of all the nervous tissue that lies outside the central nervous system.

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Schwann Cell

A type of glial cell responsible for producing myelin.

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Sensory Neuron

Neuron that carries nerve impulses from tissue and organs to the spinal cord and brain.

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Endocrine System

System of glands that secrete hormones into the bloodstream.

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Nerve

Bundle of nerve cells.

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Nervous System

Body system that sends electrical messages throughout the body; controls all other body systems.

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Organ System

Groups of organs that work together to perform a specific task.

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Neurotransmitter

Chemical that carries a nerve impulse from one nerve to another at a synapse.

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Resting Potential

Difference in electrical charge across the plasma membrane of a neuron that is not actively transmitting a nerve impulse.

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Sodium-Potassium Pump

Active transport protein; exchanges sodium ions for potassium ions across the plasma membrane of animal cells.

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Synapse

Junction where an axon terminal meets another cell.

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Synaptic Cleft

Space between the axon terminals of one cell and the receptors of the next cell.

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Action Potential

Reversal of electrical charge across the membrane of a resting neuron that travels down the axon of the neuron as a nerve impulse.

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Brain

Central nervous system organ inside the skull; the control center of the nervous system.

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Brain Stem

Lowest part of the brain that connects the brain with the spinal cord; controls unconscious functions such as heart rate and breathing.

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Cerebellum

Part of the brain below the cerebrum; coordinates body movements.

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Cerebrum

Largest part of the brain; controls conscious functions such as reasoning and sight.

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Spinal Cord

Thin, tubular bundle of nervous tissue that extends from the brainstem down the back to the pelvis; connects the brain with the peripheral nervous system.

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Vertebrae

(singular, vertebra): Repeating bony units that make up the vertebral column of vertebrates.

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Autonomic Nervous System (ANS)

Division of the peripheral nervous system; controls involuntary activities not under conscious control, such as heart rate and digestion.

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Motor Division

Division of the peripheral nervous system; carries nerve impulses from the central nervous system to muscles and glands throughout the body.

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Nerve (PNS)

One of many cable-like bundles of axons that make up the peripheral nervous system.

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Parasympathetic Division

The subdivision of the autonomic nervous system; controls involuntary activities that are not emergencies.

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Reflex Arc

The path taken by a reflex.

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Sensory Division

Division of the peripheral nervous system; carries sensory information from the body to the central nervous system.

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Somatic Nervous System (SNS)

Division of the peripheral nervous system; controls voluntary, conscious activities and reflexes.

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Sympathetic Division

The subdivision of the autonomic nervous system that deals with emergencies.

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Dendrites

Receive signals from other neurons.

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Cell Body (Soma)

Contains nucleus; integrates signals.

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Axon

Transmits electrical impulses (action potentials).

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Myelin Sheath

Fatty insulation around axon (speeds up signals).

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Nodes of Ranvier

Gaps in myelin where action potentials 'jump' (saltatory conduction).

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Axon Terminals

Release neurotransmitters into synapses.

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Motor Neurons

Carry signals from CNS to muscles/glands (effectors) to trigger movement or secretion.

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Myelin

A fatty layer produced by Schwann cells (PNS) and oligodendrocytes (CNS). It insulates axons, speeding up nerve impulses.

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Sensory Input

Detect stimuli via receptors.

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Integration

CNS processes information.

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Motor Output

PNS triggers responses.

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Electrical Signals

Action potentials within neurons.

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Chemical Signals

Neurotransmitters between neurons at synapses.

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Main nervous features

Brain, spinal cord (CNS), and peripheral nerves (PNS).

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Resting Potential

Neuron's stable voltage (-70 mV); maintained by Na+/K+ pumps.

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Action Potential

Rapid depolarization (+30 mV) when threshold is reached.

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Na+/K+ Pumps

Actively transport 3 Na+ out and 2 K+ in, creating a negative interior.

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Threshold

Reached at -55 mV.

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Refractory Period

Resets neuron after action potential.

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Synapse

Junction between neurons where neurotransmitters cross the synaptic cleft.

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Chemical Synapses

Use neurotransmitters (e.g., dopamine); slower, unidirectional.

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Electrical Synapses

Gap junctions allow direct ion flow; faster, bidirectional (e.g., heart).

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Neurotransmitter process

Action potential reaches axon terminal, Ca2+ influx triggers vesicle fusion, neurotransmitters released into cleft, bind receptors on postsynaptic neuron.

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Hindered communication

Drugs, toxins, or diseases (e.g., multiple sclerosis) disrupt signaling → impaired movement/cognition.

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Central Nervous System (CNS)

Organs: Brain and spinal cord.

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Conscious Reasoning

Cerebrum (frontal lobe for decision-making).

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Medulla

Controls vital functions (breathing, heart rate).

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Pons

Relays signals; regulates sleep.

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Midbrain

Vision/hearing reflexes.

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Spinal cord injury

Severed motor neurons below the neck, blocking signals to limbs.

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Sensory division

Carries signals to CNS.

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Motor division

Carries signals from CNS to effectors.

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Somatic nervous system

Voluntary control (skeletal muscles).

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Autonomic nervous system

Involuntary (glands, smooth/cardiac muscle).

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Sympathetic division

"Fight-or-flight" (e.g., increases heart rate).

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Parasympathetic division

"Rest-and-digest" (e.g., slows heart rate).

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Structure-Function

Neuron anatomy enables rapid signaling; brain regions specialize.

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Homeostasis

Nervous/endocrine systems regulate balance (e.g., brain stem, autonomic NS).

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Communication

Electrical/chemical signals coordinate responses.

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Interdependence

PNS relays signals between CNS and body.

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Study Notes

Neuron Structure and Function

Axon: A long extension from the neuron's cell body transmits nerve impulses to other cells.
Axon Terminal: Branches at the end of a neuron's axon facilitate communication with other cells.
Cell Body: It is the central part of a neuron, containing the nucleus and other organelles, integrating signals received by the neuron.
Dendrite: An extension from the neuron's cell body receives nerve impulses from other neurons.
Myelin Sheath: A lipid layer around the axon of a neuron enables faster nerve impulse transmission.
Nodes of Ranvier: Gaps in the myelin sheath allow action potentials to "jump," speeding up signal conduction (saltatory conduction).
Myelin: A fatty layer produced by Schwann cells (in PNS) and oligodendrocytes (in CNS) insulates axons to speed up nerve impulses.

Cells of the Nervous System

Glial Cell: Provides support for neurons.
Interneuron: Carries nerve impulses between sensory and motor neurons.
Schwann Cell: A glial cell responsible for producing myelin.
Sensory Neuron: Carries nerve impulses from tissues and organs to the spinal cord and brain.
Motor Neurons: Motor neurons carry signals from the CNS to muscles or glands (effectors), triggering movement or secretion.

The Nerve Impulse

Nerve Impulse: An electrical signal transmitted by the nervous system.
Resting Potential: The difference in electrical charge across a neuron's plasma membrane when it is not actively transmitting a nerve impulse, typically around -70 mV.
Sodium-Potassium Pump: An active transport protein exchanges sodium ions for potassium ions across the plasma membrane, maintaining the resting potential.
Action Potential A reversal of electrical charge across the membrane of a resting neuron that travels down the axon as a nerve impulse, reaching approximately +30 mV during depolarization.
Threshold Action potential happens when it is reached at -55 mV.
Refractory Period The period that resets the neuron after action potential.

Synaptic Transmission

Synapse: A junction where an axon terminal meets another cell.
Synaptic Cleft: The space between the axon terminal of one cell and the receptors of the next cell.
Neurotransmitter: A chemical that carries a nerve impulse from one nerve to another at a synapse.
Neurotransmitter Process: When an action potential reaches the axon terminal, Ca2+ influx triggers vesicle fusion, and neurotransmitters are released into the synaptic cleft to bind receptors on the postsynaptic neuron.
Chemical Synapses Neurotransmitters are used , which are slower and unidirectional.
Electrical Synapses Gap junctions facilitate in direct ion flow, are faster and bidirectional.

Organization of the Nervous System

Nervous System: A body system that sends electrical messages throughout the body and controls all other body systems.
Central Nervous System (CNS): One of the two main divisions of the nervous system that includes the brain and spinal cord.
Peripheral Nervous System (PNS): Consists of all nervous tissue outside the CNS.
Brain: The control center of the nervous system, located inside the skull.
Spinal Cord: A thin, tubular bundle of nervous tissue extending from the brainstem to the pelvis that connects the brain with the PNS.
Vertebrae: Repeating bony units that make up the vertebral column.
Autonomic Nervous System (ANS): A division of the PNS that controls involuntary activities like heart rate and digestion.
Somatic Nervous System (SNS): A division of the PNS that controls voluntary, conscious activities and reflexes.
Sensory Division: Carries sensory information from the body to the CNS.
Motor Division: Carries nerve impulses from the CNS to muscles and glands throughout the body.
Nerve: A bundle of nerve cells.

Brain Structures and Functions

Brain Stem: The lowest part of the brain connects the brain with the spinal cord and controls unconscious functions such as heart rate and breathing.
Cerebellum: Part of the brain below the cerebrum coordinates body movements.
Cerebrum: The largest part of the brain controls conscious functions such as reasoning and sight.
Medulla: Controls vital functions like breathing and heart rate.
Pons: Relays signals and regulates sleep.
Midbrain: Vision and hearing reflexes.

Divisions of the Autonomic Nervous System

Sympathetic Division: Subdivision of the autonomic nervous system that deals with emergencies ("fight-or-flight" response, e.g., increases heart rate).
Parasympathetic Division: Controls involuntary activities that are not emergencies ("rest-and-digest," e.g., slows heart rate).

Additional Terms

Endocrine System: A system of glands that secrete hormones into the bloodstream.
Organ System: Groups of organs that work together to perform a specific task.
Reflex Arc: The path taken by a reflex.

Nervous System Processes

Sensory Input: Detecting stimuli via receptors.
Integration: CNS processes information.
Motor Output: PNS triggers responses.

Concepts

Electrical Signals: Action potentials within neurons.
Chemical Signals: Neurotransmitters between neurons at synapses.
Main Organs: Brain, spinal cord (CNS), and peripheral nerves (PNS).
Conscious Reasoning Cerebrum (frontal lobe for decision-making)
Structure-Function Neuron anatomy enables rapid signaling; brain regions specialize.
**Homeostasis:**The nervous and endocrine systems regulate balance (e.g., brain stem, autonomic NS).
Communication: Electrical and chemical signals coordinate responses.
Interdependence: The PNS relays signals between the CNS and the body.

Nervous System Disruption

Hindered Communication: Drugs, toxins, or diseases disrupt signaling, leading to impaired movement/cognition.
Spinal Cord Injury: Severed motor neurons block signals to limbs.

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