Neuroscience Basics: Nerve Stimulation and Signaling

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Questions and Answers

How is the nerve stimulated?

  • Both A and C
  • An electrode delivers a small electrical impulse that triggers a signal to be sent along the nerve fiber to the brain or muscle causing a response like a sensation or muscle contraction (correct)
  • The nerve cell is directly stimulated by a physical stimulus, such as light, sound, or pressure
  • A chemical messenger is released from the nerve terminal, binding to receptors on the target cell membrane and causing a response

What signals acetylcholine release?

An action potential reaches the axon terminus, causing voltage-gated calcium channels to open. Calcium flows into the cell, triggering the release of acetylcholine.

What is the main neurotransmitter in the nervous system?

glutamate

What is EPSP?

<p>Excitatory Postsynaptic Potential, a temporary depolarization of the neuron's membrane potential.</p> Signup and view all the answers

What is the difference between special and temporal summation?

<p>Special summation occurs when multiple neurons fire at the same time at different places on the postsynaptic neuron, adding their signals together to reach the threshold for an action potential. Temporal summation occurs when one neuron fires rapidly in succession, causing the postsynaptic potential to build up over time to reach the threshold for an action potential.</p> Signup and view all the answers

What are all the anatomical parts of a nerve and what happens at each part?

<p>Axons are cord-like groups of fibers in the center of a nerve, carrying electrical impulses. Dendrites are branches that receive electrical impulses. Endoneurium is a layer of connective tissue that surrounds a group of axons (fascicles)</p> Signup and view all the answers

What is the difference between the central and peripheral nervous system?

<p>The central nervous system (CNS) consists of the brain and spinal cord. The peripheral nervous system (PNS ) is made up of all the nerves that branch out from the spinal cord and extend to the rest of the body.</p> Signup and view all the answers

What are the different types of neurons?

<p>Both A and B (A)</p> Signup and view all the answers

What is the difference between the somatic and autonomic nervous systems?

<p>The somatic nervous system (SNS) controls voluntary movements such as walking and reaching. The autonomic nervous system (ANS) regulates involuntary bodily functions such as heart rate, digestion, and breathing.</p> Signup and view all the answers

What is the difference between the efferent and afferent divisions of the nervous system?

<p>Afferent carries sensory information from the body towards the CNS. Efferent carries motor commands from the CNS to the muscles/glands (A)</p> Signup and view all the answers

What are the different types of neuroglia and what are their functions?

<p>Astrocytes, Oligodendrocytes, Microglia, and Satellite cells (B)</p> Signup and view all the answers

What is the function of the sodium-potassium pump?

<p>The sodium-potassium pump actively transports sodium ions out of the cell and potassium ions into the cell. This is critical for maintaining the resting membrane potential of neurons.</p> Signup and view all the answers

What are the different types of channels and gates in the nerve cell?

<p>Voltage-gated channels, ligand-gated channels, and mechanically-gated channels (A)</p> Signup and view all the answers

What is the difference between repolarization, depolarization, and hyperpolarization?

<p>Repolarization is the return of the membrane potential to its resting state, caused by efflux of potassium ions. Depolarization is when the cell membrane becomes more positive due to influx of positive ions. Hyperpolarization is when the membrane potential becomes even more negative than the resting state due to continued potassium ion outflow.</p> Signup and view all the answers

What is the difference between voltage-gated and chemically gated channels?

<p>Voltage-gated channels open and close in response to changes in the membrane potential of the cell. Chemically gated channels open and close when a specific chemical molecule binds to it.</p> Signup and view all the answers

What is the structural classification for neurons and which one is most abundant in the CNS (central nervous system)?

<p>Multipolar (B)</p> Signup and view all the answers

What happens when the sodium and potassium channels open and how does it affect the cell polarity?

<p>The opening of the sodium channels leads to a positive shift in cell polarity, while the opening of the potassium channels leads to a negative shift.</p> Signup and view all the answers

What are the main steps in the generation of an action potential?

<p>Depolarization (sodium influx), reaching the threshold potential, rapid sodium channel opening, overshoot (positive peak due to influx of sodium ions), repolarization (potassium efflux), hyperpolarization (membrane potential slightly dips) (B)</p> Signup and view all the answers

What is the none-or-all principle?

<p>A response to a stimulus will either be a full, complete response or there will be no response at all (the strength of the stimulus doesn't affect the intensity of the response if it reaches the threshold for activation).</p> Signup and view all the answers

What is the difference between continuous propagation and saltatory propagation?

<p>Continuous propagation is a gradual movement of an action potential along an unmyelinated axon, where the electrical signal travels along the entire length of the axon. Saltatory propagation describes the jumping of an action potential from one node of Ranvier to the next along a myelinated axon, which is much faster signal transmission.</p> Signup and view all the answers

What is the threshold?

<p>The minimum level of energy or membrane potential that must be reached to trigger a physiological or psychological response.</p> Signup and view all the answers

What is the difference between absolute refractory and relative refractory?

<p>During the absolute refractory period, the cell is unresponsive to any stimulus, regardless of its strength. During the relative refractory period, the cell is gradually becoming more responsive, but still requires a strong stimulus to trigger a response.</p> Signup and view all the answers

What are myelinated and unmyelinated neurons used for and how/when do they develop?

<p>Myelinated neurons transmit nerve impulses quickly, while unmyelinated neurons transmit nerve impulses more slowly. Myelinated neurons are found in the central and peripheral nervous system, especially in those that require fast signal transmission, while unmyelinated neurons are found in group C nerves that transmit pain or itching signals.</p> Signup and view all the answers

How do neurons stimulate and how do they conduct information?

<p>Neurons stimulate one another by sending electrical impulses (action potentials) along axons, which trigger the release of chemical messengers (neurotransmitters) across the synapse to reach the dendrites of the receiving neuron.</p> Signup and view all the answers

Flashcards

Nerve Stimulation

Triggered by an electrode delivering an impulse causing a response in the brain or muscle.

Acetylcholine Release

Occurs when an action potential causes calcium influx, leading to neurotransmitter release.

Main Neurotransmitter

Glutamate is the primary neurotransmitter in the nervous system, facilitating communication.

EPSP

Excitatory Postsynaptic Potential is a temporary depolarization of the neuron's membrane.

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IPSP

Inhibitory Postsynaptic Potential reduces the chance of neuron firing by hyperpolarizing it.

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Spatial Summation

Multiple neurons firing simultaneously at different locations add signals to reach action potential.

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Temporal Summation

One neuron rapidly fires in succession to build up signals over time for action potential.

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Central Nervous System

Consists of the brain and spinal cord, coordinating all activities in the body.

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Peripheral Nervous System

Includes all nerves that branch out from the spinal cord to the rest of the body.

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Types of Neurons

Motor, sensory, and interneurons serve different functions within the nervous system.

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Somatic Nervous System

Controls voluntary movements like walking and reaching; part of the PNS.

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Autonomic Nervous System

Manages involuntary functions like heart rate and digestion without conscious control.

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Afferent Division

Carries sensory info from the body towards the central nervous system.

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Efferent Division

Carries motor commands from the CNS to muscles and glands to create action.

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Types of Neuroglia

Support cells like astrocytes and oligodendrocytes maintain and protect neurons.

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Sodium-Potassium Pump

Pumps sodium out and potassium into the cell to maintain resting membrane potential.

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Action Potential

Involves depolarization, threshold potential, rapid sodium channel opening, and repolarization.

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Repolarization

Return of the membrane potential to rest, mainly due to potassium outflow.

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Depolarization

Cell membrane becomes less negative due to sodium ions influx.

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Hyperpolarization

Membrane potential becomes more negative, making the neuron less likely to fire.

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Voltage-Gated Channels

Open or close in response to changes in membrane potential; crucial for action potentials.

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Chemically Gated Channels

Open when a specific chemical binds; important for synaptic transmission.

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Continuous Propagation

Gradual movement of action potential along unmyelinated axons, slower transmission.

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Saltatory Propagation

Action potential jumps from node to node in myelinated axons, faster transmission.

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Threshold

Minimum energy level required to trigger an action potential in a neuron.

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Absolute Refractory Period

Period when a neuron cannot fire another action potential, regardless of stimulus strength.

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Relative Refractory Period

Period when neuron can fire again but requires a stronger stimulus than normal.

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Myelinated Neurons

Transmit nerve impulses quickly due to myelin sheath insulating axons.

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Unmyelinated Neurons

Transmit nerve impulses slowly; found in pain and itch signaling.

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Study Notes

Nerve Stimulation

  • An electrode delivers a small electrical impulse, triggering a signal along the nerve fiber to the brain or muscle, causing a response.

Acetylcholine Release

  • Action potentials reach the axon terminus, opening voltage-gated calcium channels.
  • Calcium influx triggers acetylcholine release.

Main Neurotransmitter

  • Glutamate is the main neurotransmitter in the nervous system.

EPSP (Excitatory Postsynaptic Potential)

  • A temporary depolarization of the neuron's membrane potential.

IPSP (Inhibitory Postsynaptic Potential)

  • An electrical signal that makes a postsynaptic neuron less likely to fire an action potential by hyperpolarizing the membrane.

Summation

  • Spatial Summation (SS): Multiple neurons firing simultaneously at different locations on the postsynaptic neuron, combining signals to reach the threshold for an action potential.
  • Temporal Summation (TS): A single neuron firing rapidly, the postsynaptic potential builds up over time to reach the threshold for an action potential.

Nerve Anatomy

  • Axons: Cord-like fiber bundles within nerves.
  • Dendrites: Branches that carry electrical impulses.
  • Endoneurium: Connective tissue surrounding groups of axons.

CNS vs. PNS

  • CNS (Central Nervous System): Consists of the brain and spinal cord.
  • PNS (Peripheral Nervous System): All nerves branching from the spinal cord to the rest of the body.

Neuron Types

  • Motor Neurons: Control muscle movements.
  • Sensory Neurons: Carry sensory information to the brain and spinal cord.
  • Interneurons: Located between sensory and motor neurons.
  • Unipolar Neurons: One axon that splits into dendrites.
  • Bipolar Neurons: One axon and one dendrite extending from the body.
  • Multipolar Neurons: One axon and multiple dendrites extending from the body.

Somatic vs. Autonomic Nervous Systems

  • SNS (Somatic Nervous System): Controls voluntary movements like walking and reaching.
  • ANS (Autonomic Nervous System): Regulates involuntary bodily functions like heart rate and digestion.

Neuroglia

  • Astrocytes: Maintain extracellular environment, provide nutrients to neurons, guide neural development.
  • Oligodendrocytes (CNS): Produce myelin sheaths around axons in the CNS.
  • Microglia (CNS): Immune cells that engulf debris and pathogens through phagocytosis.
  • Schwann Cells (PNS): Produce myelin sheaths around peripheral neurons.
  • Satellite Cells (PNS): Surround neuron cell bodies, providing structural support.

Sodium-Potassium Pump

  • Actively transports sodium ions out of the cell and potassium ions into the cell.

Nerve Cell Channels

  • Voltage-Gated Channels: Open and close in response to changes in membrane potential.
  • Chemically (Ligand) Gated Channels: Open and close when a specific chemical molecule binds.
  • Mechanically Gated Channels

Membrane Potential Changes

  • Depolarization: Cell membrane becomes less negative due to influx of positive ions.
  • Repolarization: Return of the membrane potential to its resting state due to potassium ion outflow.
  • Hyperpolarization: Membrane potential becomes even more negative than the resting state.

Types of Channels

  • Voltage-gated channels: Open or close depending on the membrane voltage
  • Chemically-gated channels (receptor channels): Open or close depending on a binding of a specific chemical (e.g., neurotransmitters).

Action Potential Stages

  • Depolarization (Sodium influx): The membrane potential shifts from negative to positive.
  • Repolarization (Potassium efflux): Repolarization follows, returning the membrane to a negative potential.
  • Hyperpolarization: The potential briefly drops below resting potential.

Refractory Periods

  • Absolute Refractory Period: The cell is unresponsive to further stimulation.
  • Relative Refractory Period: The cell requires a stronger stimulus to trigger a response.

Myelinated vs. Unmyelinated Neurons

  • Myelinated Neurons: Faster signal transmission due to the myelin sheath, enabling electrical impulses to "jump" between nodes of Ranvier.
  • Unmyelinated Neurons: Slower signal transmission as the electrical signal travels along the entire axon.

Neuron Stimulation and Information Transmission

  • Neurons stimulate one another by sending electrical impulses (action potentials).
  • These impulses trigger the release of neurotransmitters across synapses, reaching the dendrites of the receiving neuron.

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