Neuron Structure and Function Quiz
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Questions and Answers

What is acetylcholinesterase?

An enzyme that catalyzes the breakdown of acetylcholine into choline and acetate.

In order name the events that signal transmission at a chemical synapse: The action potential arrives at the ______

synapse

What happens when the action potential arrives at the chemical synapse?

Causes the voltage-gated Ca2+ channels to open.

What do calcium ions bind to in the process of neurotransmitter release?

<p>Synaptotagmin of the vesicle.</p> Signup and view all the answers

What do the vesicles release during neurotransmission?

<p>Neurotransmitters.</p> Signup and view all the answers

How does saltatory conduction work?

<p>Action potentials jump from node to node along the axon, spreading electronically through the internode.</p> Signup and view all the answers

Which of the following statements about events in saltatory conduction is true?

<p>Nodes of Ranvier are packed with voltage-gated ion channels.</p> Signup and view all the answers

The current in a myelinated axon can leak out through the membrane.

<p>False</p> Signup and view all the answers

What is the Axon Hillock?

<p>Where action potential is initiated.</p> Signup and view all the answers

What is the Soma?

<p>Cell body nucleus, Golgi, mitochondria, etc.</p> Signup and view all the answers

What are Dendrites?

<p>Branching extensions that carry signals toward the cell body.</p> Signup and view all the answers

What is the function of the Axon Hillock?

<p>It determines if the action potential will occur.</p> Signup and view all the answers

What are Neurons?

<p>Best known excitable cells.</p> Signup and view all the answers

What is Membrane Potential?

<p>Maintain a voltage difference across cell membranes.</p> Signup and view all the answers

What is the structure and function of the Axon Hillock?

<p>Located at the junction of the cell body and the axon.</p> Signup and view all the answers

What are Schwann Cells?

<p>Responsible for myelin production in the PNS.</p> Signup and view all the answers

What are Axon Terminals?

<p>Specialized areas for signal transmission to target cells.</p> Signup and view all the answers

When does an action potential occur?

<p>When the signal reaches a sufficient threshold.</p> Signup and view all the answers

What is the usual resting membrane potential?

<p>-70 mV.</p> Signup and view all the answers

What is the function of the myelin sheath?

<p>Increase speed of signal conduction.</p> Signup and view all the answers

What is the Nernst equation?

<p>It calculates the equilibrium potential of ions.</p> Signup and view all the answers

Define the difference between a capacitor and an insulator.

<p>A capacitor has two conductive materials separated by an insulator.</p> Signup and view all the answers

When using the Goldman equation, what must be considered?

<p>The charge driven by ions inside and outside the cell.</p> Signup and view all the answers

What are the phases of a typical action potential?

<p>Sodium gates open, potassium gates slowly open, causing depolarization and repolarization.</p> Signup and view all the answers

What happens after the voltage-gated Na+ channels open?

<p>The K+ channels then open.</p> Signup and view all the answers

What is the job of intracellular Ca2+?

<p>Regulates neurotransmitter release.</p> Signup and view all the answers

What is synaptic transmission?

<p>Transferring information across the synapse.</p> Signup and view all the answers

What influences neurotransmitter release?

<p>Action potential frequency.</p> Signup and view all the answers

What are the classifications of neurotransmitters?

<p>Made in the neuron, released from presynaptic membrane following depolarization.</p> Signup and view all the answers

Describe acetylcholine.

<p>It is the major neurotransmitter in vertebrates, especially at the neuromuscular junction.</p> Signup and view all the answers

What are glial cells?

<p>They are the glue associated with neurons.</p> Signup and view all the answers

What is multiple sclerosis?

<p>Breakdown of myelination.</p> Signup and view all the answers

Study Notes

Neuron Structure and Function

  • Axon Hillock: Initiates action potentials; integration point for incoming signals from dendrites and cell body.
  • Soma: Cell body containing nucleus and organelles, processes around 10,000 inputs.
  • Dendrites: Branched extensions that transmit signals toward the soma.
  • Function of Axon Hillock: Determines if an action potential will occur; operates on an all-or-nothing principle.

Neuron Characteristics

  • Neurons: Primary excitable cells responsible for processing and transmitting information.
  • Membrane Potential: Voltage difference across cell membranes, essential for neuron function.

Axon Structure and Function

  • Axon: Slender extension for signal conduction, specialized for rapid transmission; arises from the axon hillock.
  • Myelin Sheath: Insulating layer formed by Schwann cells in the PNS, increases conduction speed.
  • Axon Terminal: End of the axon where synapses with target cells occur.

Action Potential Mechanism

  • Action Potential: Initiated when a substantial signal reaches the threshold at the axon hillock.
  • Voltage-Gated Ion Channels: Essential for rapid depolarization and repolarization during an action potential.
  • Phases of Action Potential: Involves sodium channels opening to let Na+ in (depolarization), followed by potassium channels opening to allow K+ out (repolarization).

Membrane and Resting Potentials

  • Resting Membrane Potential: Typically around -70 mV; maintained by Na+/K+ ATPase pumping ions against concentration gradients.
  • Equilibrium Potential: Established when an ion concentration gradient is balanced by the electrical gradient; influenced by ionic concentration and permeability.

Synaptic Transmission

  • Neurotransmitter Release: Triggered by action potentials arriving at synapses, causing Ca2+ influx and vesicle fusion with the membrane.
  • Acetylcholine: Major neurotransmitter at neuromuscular junctions, regulated by acetylcholinesterase for signal termination.
  • Signal Transmission: Neurotransmitters diffuse across synaptic cleft to bind to receptors, instigating intracellular responses.

Graded vs Action Potentials

  • Graded Potentials: Localized changes that vary in strength; important for initiating action potentials at the axon hillock.
  • Action Potentials: Long-distance signals that propagate along axons without degradation, driven by voltage-gated channels.

Types of Neurons

  • Multipolar Neurons: Multiple dendrites and one axon; commonly found in the CNS.
  • Bipolar Neurons: Two main processes; typically seen in sensory systems.
  • Unipolar Neurons: One extension; primarily sensory neurons.

Neurotransmitter Classifications

  • Types: Include acetylcholine, amino acids, biogenic amines, peptides, and other categories.
  • Function: Facilitate communication between neurons and influence various physiological responses.

Supporting Cells and Repair

  • Glial Cells: Provide support, nourishment, and protection to neurons; include oligodendrocytes and astrocytes.
  • Schwann Cells: Create myelin sheaths in the PNS; crucial for rapid signal transmission.

Disorders and Conditions

  • Multiple Sclerosis: Characterized by the breakdown of myelin sheaths in the CNS, impairing signal transmission.
  • Myasthenia Gravis: Condition aided by acetylcholinesterase inhibitors to enhance neuromuscular transmission.

Important Terminology

  • Saltatory Conduction: Rapid transmission of action potentials along myelinated axons, jumping from one node of Ranvier to the next.
  • SNARE Proteins: Involved in neurotransmitter release by facilitating vesicle fusion with the presynaptic membrane.### Events in Saltatory Conduction
  • Myelination prevents the loss of electrical charge through the axon membrane, enhancing signal transmission efficiency.
  • The action potential initiates when the current at the node of Ranvier exceeds the threshold, leading to the generation of new action potentials.
  • Nodes of Ranvier are densely populated with sodium (Na+) and potassium (K+) channels, facilitating rapid ion exchange.
  • The action potential propagates by jumping from one node to another, a process termed saltatory conduction, which significantly accelerates signal transmission compared to unmyelinated axons.
  • Increased resistance in the internode regions helps maintain the strength of the signal as it travels along the axon, minimizing degradation.
  • Saltatory conduction results in faster neural communication, vital for quick reflexes and coordinated movements.

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Description

Test your knowledge on the structure and function of neurons, including the roles of the axon hillock, soma, dendrites, and myelin sheath. This quiz will cover essential concepts in neurobiology and how these components work together to transmit signals. Dive deep into the fascinating world of neuronal functions!

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