PSYC112: Neurons and Neuronal Transmission
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Questions and Answers

What is the primary function of a neuron?

  • To provide structural support to the brain
  • To store memories and experiences
  • To transmit signals in the body (correct)
  • To produce neurotransmitters

Which part of a neuron is responsible for receiving signals from other neurons?

  • Soma
  • Axon
  • Dendrites (correct)
  • Myelin sheath

What process allows neurons to communicate with each other?

  • Cellular replication
  • Synaptic transmission (correct)
  • Neural conduction
  • Action potential

Which of the following best describes neural conduction?

<p>The active movement of ions across a neuron's membrane to generate an electrical signal (C)</p> Signup and view all the answers

What component of a neuron insulates the axon and speeds up signal transmission?

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

What is the primary function of ionotropic receptors?

<p>They are associated with ion channels. (B)</p> Signup and view all the answers

Which of the following methods is NOT involved in neurotransmitter removal from the synaptic cleft?

<p>Neurotransmitter recycling (C)</p> Signup and view all the answers

What role does reuptake play in neurotransmitter management?

<p>It transports neurotransmitters back into the pre-synaptic neuron. (D)</p> Signup and view all the answers

How do metabotropic receptors differ from ionotropic receptors?

<p>Metabotropic receptors are linked to signal proteins. (C)</p> Signup and view all the answers

What can occur if neurotransmitters are not removed from the synaptic cleft?

<p>They disrupt neural processing. (A)</p> Signup and view all the answers

What is the primary function of neurons in the brain?

<p>To conduct and transmit electrochemical signals (C)</p> Signup and view all the answers

Which structure of the neuron is responsible for receiving information from other neurons?

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

What is the role of myelin in neuronal transmission?

<p>To insulate the axon and support efficient signal transmission (A)</p> Signup and view all the answers

Which part of a neuron serves as the metabolic center and contains the nucleus?

<p>Soma (C)</p> Signup and view all the answers

What are the gaps between sections of myelin along the axon called?

<p>Nodes of Ranvier (B)</p> Signup and view all the answers

Which type of neuron has both an axon and a dendrite extending from the soma?

<p>Bipolar neuron (C)</p> Signup and view all the answers

What is the function of the axon terminal?

<p>To release chemicals into the synapses (B)</p> Signup and view all the answers

Which statement about pseudounipolar neurons is accurate?

<p>They do not have any dendrites. (D)</p> Signup and view all the answers

What primarily causes depolarization in a neuron?

<p>The entry of Na+ ions into the neuron (C)</p> Signup and view all the answers

How does the action potential propagate along the axon?

<p>It triggers the opening of adjacent Na+ channels. (A)</p> Signup and view all the answers

What happens during the repolarization phase of action potential?

<p>Na+ channels remain closed and K+ channels open. (B)</p> Signup and view all the answers

What effect does hyperpolarization have on the neuron?

<p>It prevents neuron firing until K+ channels close. (C)</p> Signup and view all the answers

What occurs when a neuron depolarizes?

<p>A decrease in the resting membrane potential making it less negative (A)</p> Signup and view all the answers

What is the role of the Nodes of Ranvier in myelinated axons?

<p>They enhance the propagation of the action potential by facilitating jumps. (B)</p> Signup and view all the answers

What condition is referred to as the 'refractory period'?

<p>The phase when K+ channels are still open and Na+ channels are closed. (D)</p> Signup and view all the answers

What is created when calcium channels open at the postsynaptic membrane?

<p>Inhibitory postsynaptic potential (IPSP) (C)</p> Signup and view all the answers

Which ion's entry into the neuron is crucial for triggering an action potential?

<p>Na+ (A)</p> Signup and view all the answers

How do postsynaptic potentials (PSPs) behave as they travel through the neuron?

<p>They are rapid but decremental (B)</p> Signup and view all the answers

What must occur for a neuron to fire an action potential?

<p>The threshold of excitation (~-65mV) must be reached (B)</p> Signup and view all the answers

Which statement describes the process of depolarization?

<p>The influx of Na+ ions reduces the negativity of the membrane. (D)</p> Signup and view all the answers

What defines spatial summation in the context of postsynaptic potentials?

<p>The simultaneous production of PSPs across different locations on the neuron (B)</p> Signup and view all the answers

What is the nature of action potentials in neurons?

<p>They trigger consistently when the threshold is surpassed (D)</p> Signup and view all the answers

What is the effect of an excitatory postsynaptic potential (EPSP)?

<p>It increases the likelihood that the neuron will fire (A)</p> Signup and view all the answers

Which statement about the all-or-none response in action potentials is true?

<p>Action potentials do not occur if the threshold is not exceeded (C)</p> Signup and view all the answers

What is the primary structural component of the neuron cell membrane?

<p>Lipid bilayer (C)</p> Signup and view all the answers

Which type of proteins in the neuron cell membrane allow certain molecules to pass through?

<p>Channel proteins (A)</p> Signup and view all the answers

What change occurs in a neuron when a signal is received by its dendrites?

<p>Electrical potential changes are interpreted by the soma (C)</p> Signup and view all the answers

What is the typical resting potential value of a neuron?

<p>-70 mV (C)</p> Signup and view all the answers

What ion concentration is usually higher inside a resting neuron compared to outside?

<p>Potassium (K+) (C)</p> Signup and view all the answers

What role does the sodium-potassium pump play in a neuron?

<p>Maintains resting potential by moving ions across the membrane (B)</p> Signup and view all the answers

How does myelin affect the transmission of neural signals?

<p>Supports rapid transmission by preventing potentials in myelinated areas (C)</p> Signup and view all the answers

What occurs at the axon terminals of a neuron?

<p>Neurotransmitters are released into the synapse (A)</p> Signup and view all the answers

What happens to sodium channels when a neutron is at rest?

<p>They close to prevent sodium influx (B)</p> Signup and view all the answers

What causes the difference in electrical potential across the cell membrane at resting potential?

<p>Differences in ion concentrations inside and outside the cell (C)</p> Signup and view all the answers

Flashcards

Neuron

A specialized cell that transmits information throughout the nervous system.

Neural Conduction

The process of transmitting electrical signals within a neuron, from the dendrites to the axon terminal.

Synaptic Transmission

The process of transmitting signals between neurons at the synapse.

Dendrites

Branch-like extensions of a neuron that receive signals from other neurons.

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Axon

A long, slender projection of a neuron that transmits electrical signals away from the cell body.

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Soma

The cell body of a neuron, responsible for metabolic processes and containing the nucleus.

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Myelin

A fatty, insulating layer that surrounds the axon, supporting efficient neuronal transmission.

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Nodes Of Ranvier

Gaps between sections of myelin along the axon, supporting efficient signal transmission.

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Axon Terminal

The end of the axon, containing 'buttons' that release chemicals into synapses.

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Synapse

The gap between adjacent neurons, where chemicals are transmitted.

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Cell Membrane

The outer layer of a neuron, composed of a lipid bilayer with embedded proteins. It controls what enters and exits the neuron.

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Channel Proteins

Proteins within the cell membrane that form channels allowing specific molecules to pass through.

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Signal Proteins

Proteins in the cell membrane that receive signals from molecules outside the neuron and transmit them inside.

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Resting Membrane Potential

The electrical difference across the neuron's membrane when it's not actively transmitting a signal.

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Why is the resting potential negative?

The neuron's interior is more negative than the exterior due to a higher concentration of potassium ions inside and sodium ions outside.

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Sodium-Potassium Pump

A protein pump maintaining the resting potential by pumping sodium ions out and potassium ions into the neuron.

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Action Potential

A brief electrical impulse that travels down the neuron's axon, transmitting the signal.

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What triggers an action potential?

A sufficiently strong signal received by the dendrites causes depolarization of the neuron, leading to an action potential.

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Myelin Sheath

A fatty substance covering parts of the axon, speeding up signal transmission.

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Postsynaptic Potential (PSP)

A change in the electrical potential of a neuron's membrane, caused by a signal from an adjacent neuron at the dendrites. It can be excitatory (EPSP) or inhibitory (IPSP).

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Excitatory Postsynaptic Potential (EPSP)

A depolarizing PSP that increases the likelihood of a neuron firing. This happens when sodium channels open, making the neuron less negative.

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Inhibitory Postsynaptic Potential (IPSP)

A hyperpolarizing PSP that decreases the likelihood of a neuron firing. This happens when chloride channels open, making the neuron more negative.

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Graded Potentials

PSPs are graded potentials, meaning their amplitude is proportional to the intensity of the stimulating signal.

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Decremental

PSPs decrease in amplitude as they travel along the neuron.

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Summation

The combined effect of multiple PSPs at a neuron, which determines whether the neuron will fire. It can be spatial or temporal.

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Spatial Summation

PSPs occurring simultaneously on different parts of the receptive membrane summate at the soma.

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Temporal Summation

PSPs occurring in rapid succession at the same synapse summate.

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Ionotropic Receptors

Receptors that directly open ion channels when a neurotransmitter binds, allowing ions to flow into or out of the cell, changing the neuron's electrical potential.

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Metabotropic Receptors

Receptors that indirectly influence ion channels by activating a series of intracellular signaling molecules, leading to a more complex and longer-lasting change in the neuron's activity.

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Neurotransmitter Removal

The process of removing neurotransmitters from the synaptic cleft, ensuring efficient signaling and preventing continuous activation.

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Diffusion

A method of neurotransmitter removal where the neurotransmitter simply moves away from the synapse, gradually reducing its concentration.

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Enzymatic Degradation

Breakdown of neurotransmitters by enzymes, effectively 'deactivating' them so they can be taken back into the presynaptic neuron.

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Depolarization

The neuron becomes less negative (closer to 0mV) due to the influx of Na+ ions through Na+ channels.

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Action Potential Propagation

Depolarization at one point in the axon triggers the opening of adjacent Na+ channels, causing the action potential to travel down the axon.

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Myelinated Axon

The action potential 'jumps' between the gaps in the myelin (Nodes of Ranvier) which speeds up neural transmission.

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Repolarization

Na+ channels close and K+ channels open, causing the rapid movement of K+ ions out of the cell, making the membrane potential negative again.

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Hyperpolarization

K+ channels remain open, making the membrane potential even more negative than the resting potential.

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Refractory Period

The brief period after an action potential during which the neuron cannot be stimulated again, while the membrane potential returns to its resting state.

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Study Notes

PSYC112/132: Introduction to Neuroscience

  • Week 6: Friday 15th November 2024.
  • Lecturer: Dr Abigail Fiske ([email protected])
  • Discussion prompt: Can psychology exist without neuroscience? Why/why not?

Lecture 3: Neurons and Neuronal Transmission

  • Learning Objectives:
    • Identify and describe the parts of a neuron and their function.
    • Understand the process of neural conduction.
    • Understand the process of synaptic transmission.
    • Students will achieve a basic understanding of neuronal anatomy and signal transmission.

The "Why"

  • Neurons are the building blocks of the brain.
  • Understanding information flow in the nervous system shows how biological processes relate to thoughts, emotions, and behaviour.

Part I: Cells of the Nervous System

  • Neurons (approximately 86 billion in the human brain) are specialized nerve cells that receive, transmit, and conduct electrochemical signals.

Anatomy of Neurons

  • Neurons have a cell membrane.
  • The soma (cell body) is the metabolic center, containing the nucleus.
  • Dendrites extend from the cell body to receive information from other neurons.
  • The axon is a long, narrow part carrying signals away from the cell body.
  • The axon hillock is at the junction between axon and cell body.
  • Myelin surrounds the axon, supporting efficient neuronal transmission.
  • Nodes of Ranvier are gaps between myelin sections supporting efficient transmission.
  • Axon terminals release chemicals into synapses

Types of Neurons

  • Bipolar neurons have both an axon and a dendrite.
  • Pseudounipolar neurons have no dendrites.
  • Sensory neurons respond to environmental input.
  • Multipolar neurons have multiple dendrites.
  • Motor neurons transmit signals from the spinal cord to muscles.
  • Interneurons connect motor and sensory neurons.

Glial Cells

  • Glial cells are non-neuronal cells in the nervous system that support neurons.
  • They surround neurons, holding them in place.
  • They supply nutrients and oxygen to neurons.
  • Protect and insulate neurons.
  • Destroy and remove dead neurons. Examples include astrocytes, oligodendrocytes, microglia, and Schwann cells and ependymal cells

Cell Membrane

  • Surrounds every neuron.
  • Composed of a lipid bilayer (two layers of fat molecules).
  • Contains proteins that allow molecules to pass through.
  • Certain proteins transfer signals across the membrane

Part II: Neural Conduction

  • Signal received by receptors on dendrites.
  • Electrical potential changes in the neuron are interpreted by soma.

Neurons at rest

  • Electrical potential difference across the cell membrane when the cell isn't stimulated.
  • Sodium channels are closed at rest.
  • Resting potential is usually between -50 and -100 mV.

Resting Membrane Potential

  • Differences in electrical charge across membrane when the cell isn't stimulated.
  • Ions (sodium and potassium) have differing concentrations inside and outside the cell.
  • Membrane's permeability to potassium is greater than sodium
  • Active transport pumps maintain concentration gradients.

Neurons in action!

  • Disturbances in resting membrane potential based on incoming signals.
  • Depolarization (reduction in negative membrane potential) or hyperpolarization (increase in negative membrane potential).
  • Excitatory postsynaptic potentials (EPSPs) increase the likelihood of a neuron firing.
  • Inhibitory postsynaptic potentials (IPSPs) decrease the likelihood of a neuron firing

Synaptic Transmission

  • Junction between neurons to transfer information.
  • Use electrical signals and chemical signals like neurotransmitters.
  • Specific kinds of synapses exist.

Different types of synapses

  • Axodendritic synapse: between axon terminal and dendrite
  • Axosomatic synapse: between axon terminal and soma
  • Axomyelenic synapse: between axon terminal and myelin sheath.

Pre-synaptic Neuron

  • Action potential travels down the axon.
  • Depolarization of presynaptic terminal triggers calcium ion entry
  • Calcium triggers release of neurotransmitters from vesicles.
  • Neurotransmitters bind to receptors on the postsynaptic membrane. This causes the change in membrane potential.

Neurotransmitter Release

  • Action potential reaches axon terminal.
  • Calcium-gated channels open; calcium enters the cell
  • Calcium triggers synaptic vesicle fusion with membrane, releasing neurotransmitters
  • Recycling of synaptic vesicles for reuse.

Post-synaptic Neuron

  • Neurotransmitters bind to postsynaptic receptors
  • These receptors can trigger actions in the postsynaptic neuron
  • Neurotransmitters are removed from the synaptic cleft.

Post-synaptic Receptors

  • Different types of receptors based on their function.
  • Ionotropic receptors are associated with ion channels.
  • Metabotropic receptors are linked to signal proteins

Neurotransmitter Removal

  • Neurotransmitters are removed from the synaptic cleft
  • Diffusion, enzymatic degradation, and reuptake

Synaptic Transmission - Summary

  • Summarizes the entire process.

Homework

  1. Read Chapter 4 of the textbook.
  2. Watch the YouTube videos for this topic (details in the readings table).
  3. Review Lecture 3 prep for Lecture 4 next week.

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Lecture 3 - Neurons and Neuronal Transmission PDF

Description

This quiz focuses on the anatomy and functions of neurons, as discussed in PSYC112/132 Introduction to Neuroscience. You will explore the processes of neural conduction and synaptic transmission, gaining insights into how these biological functions relate to psychology. Test your understanding of the critical building blocks of the brain.

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