Introduction to Nervous System

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Questions and Answers

What is the primary function of astrocytes in the central nervous system?

  • Generating electrical signals in the body
  • Insulating axons to improve signal speed
  • Providing support and nutrients to neurons (correct)
  • Transmitting signals between neurons

Which part of the neuron is primarily responsible for generating and sending signals?

  • Dendrites
  • Axon terminal
  • Cell body
  • Axon (correct)

Which type of neuron is referenced as having multiple processes and is most commonly involved in motor functions?

  • Bipolar
  • Unipolar
  • Pseudounipolar
  • Multipolar (correct)

What role do interneurons play in the nervous system?

<p>Facilitate communication between neurons (C)</p> Signup and view all the answers

Which structure of a neuron is primarily involved in receiving information?

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

In the context of ion channels, what is their main function?

<p>Allow ions to move across the membrane (D)</p> Signup and view all the answers

What classification applies to sensory neurons that conduct information to the central nervous system?

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

Which direction of signal transmission is associated with efferent neurons?

<p>From CNS to body (D)</p> Signup and view all the answers

What is the primary function of the autonomic nervous system?

<p>Manages smooth muscle and cardiac muscle activities (C)</p> Signup and view all the answers

Which component of the nervous system is responsible for processing sensory input?

<p>Peripheral Nervous System (PNS) (A)</p> Signup and view all the answers

Which division of the nervous system controls cardiac muscle activity?

<p>Autonomic Nervous System (C)</p> Signup and view all the answers

What distinguishes the somatic nervous system from the autonomic nervous system?

<p>The somatic nervous system is primarily responsible for voluntary muscle control. (B)</p> Signup and view all the answers

What role do neurotransmitters play in the nervous system?

<p>They facilitate communication between neurons. (D)</p> Signup and view all the answers

Which statement correctly describes the role of afferent and efferent pathways in the nervous system?

<p>Afferent pathways transmit sensory signals to the CNS, whereas efferent pathways send motor signals away from the CNS. (D)</p> Signup and view all the answers

Which of the following best describes the two branches of the autonomic nervous system?

<p>One branch deals with rest and digest while the other manages emergency responses. (A)</p> Signup and view all the answers

Which part of the nervous system includes cranial and spinal nerves?

<p>Peripheral Nervous System (PNS) (C)</p> Signup and view all the answers

What is the primary role of microglial cells in the central nervous system (CNS)?

<p>Provide immune support and monitor health (C)</p> Signup and view all the answers

Which ion channel is primarily involved in the propagation of action potentials?

<p>Voltage Gated Channels (C)</p> Signup and view all the answers

What is the resting membrane potential typically found in neurons?

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

What type of glial cell in the peripheral nervous system (PNS) supports nerve regeneration?

<p>Schwann Cells (D)</p> Signup and view all the answers

Which neurotransmitter is primarily associated with excitatory effects?

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

Which of the following statements about action potentials is correct?

<p>They involve rapid depolarization followed by repolarization. (B)</p> Signup and view all the answers

What is the role of oligodendrocytes in the central nervous system?

<p>Produce myelin sheath (D)</p> Signup and view all the answers

Which type of neuron is involved in carrying signals from sensory receptors to the central nervous system?

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

Flashcards

Central Nervous System (CNS)

The part of the nervous system comprised of the brain and spinal cord.

Peripheral Nervous System (PNS)

The part of the nervous system outside of the brain and spinal cord; connects the CNS to the body.

Autonomic Nervous System (ANS)

Part of the PNS that controls involuntary actions, including smooth muscle, cardiac muscle, and glands.

Somatic Nervous System

Part of the PNS that controls voluntary movements of skeletal muscles.

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Afferent system

The sensory input system; brings information to the central nervous system.

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Efferent system

The motor output system; carries signals from the central nervous system to muscles or glands.

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Parasympathetic nervous system

Part of the ANS; responsible for normal "rest and digest" functions.

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Sympathetic nervous system

Part of the ANS; responsible for the "fight or flight" response.

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Microglial function

Microglia play a role in the immune system within the central nervous system (CNS), constantly monitoring the health of the CNS.

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Ependymal cell function

Ependymal cells assist in the circulation of cerebrospinal fluid (CSF) throughout the CNS using their cilia.

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Oligodendrocytes function

Oligodendrocytes produce the myelin sheath in the central nervous system (CNS).

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Satellite cell function

Satellite cells in the peripheral nervous system (PNS) perform similar support and nutrient functions to astrocytes in the CNS, but their specific function remains largely unknown.

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Schwann cell function

Schwann cells produce the myelin sheath in the peripheral nervous system (PNS) and also play a vital role in the regeneration of nerves.

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Resting membrane potential

A neuron's electrical charge at rest, typically around -70 mV. It's maintained by the sodium-potassium pump.

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Action potential

An all-or-none signal propagation along a neuron, involving rapid depolarization and repolarization due to the opening and closing of voltage-gated ion channels.

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Saltatory conduction

The rapid propagation of an action potential along a myelinated axon, jumping from one node of Ranvier to another.

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Afferent neurons

Carry sensory information to the central nervous system (CNS).

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Efferent neurons

Carry motor information away from the CNS to the body.

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Ion channels

Proteins in excitable cells' membranes that convert chemical/mechanical signals into electrical signals.

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G-proteins

Proteins that maintain open ion channels for extended periods, amplifying the signal.

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Neuron cell body

Part of the neuron responsible for its metabolism, and contains the nucleus.

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Dendrites

Receives signals from other cells - input site of the neuron.

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Astrocytes

Glial cells in the CNS that support neurons, maintain chemical balance, and act in info processing.

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Neuron axon

Transmits the electrical signal away from the cell body to other cells - output site.

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Study Notes

Introduction to Nervous System

  • The nervous system monitors conditions and corrects them when needed to keep the body functioning properly.
  • The nervous and endocrine systems, along with the special senses, control bodily functions.

Objectives

  • Structurally and functionally organize the nervous system.
  • Define afferent and efferent.
  • Explain how action potentials occur (general overview).
  • Describe different neurotransmitters and their effects.

Organization

  • Central Nervous System (CNS): Includes the brain and spinal cord.
  • Peripheral Nervous System (PNS): Everything outside the CNS, including:
    • Autonomic Nervous System (ANS): Controls involuntary functions like cardiac muscle, smooth muscles, and glands.
    • Somatic Nervous System: Controls voluntary movements.

Parts and Basic Operations

  • The brain and spinal cord form the CNS, which controls the entire nervous system.
  • Everything outside the brain and spinal cord is the PNS.
  • The sensory system receives input, while the motor system provides output.
  • The somatic nervous system controls voluntary skeletal muscles.
  • The autonomic nervous system controls involuntary smooth and cardiac muscles, and various glands.

Terms and Directions

  • Afferent: Carries sensory information to the CNS.
  • Efferent: Carries motor information from the CNS to the body.

Terms

  • Ion Channels: Proteins in cell membranes that convert chemical/mechanical signals into electrical signals.
  • Ligand-gated channels: Open in response to a neurotransmitter.
  • Voltage-gated channels: Important for action potential propagation.
  • Mechanically-gated channels: Open based on pressure or physical force.
  • G-Proteins: "Memory" proteins that allow doors to stay open longer.

Tissue Types

  • Main Actor: The cell body (nuclei in the CNS, ganglia in the PNS).
  • Supporting Actor: Glial cells.

Neurons (1 of 3)

  • The nervous system's control functions rely on neurons.
  • Neurons have branches and a tail-like structure.
  • Each part of a neuron has a specific function.

Neurons (2 of 3)

  • Soma: Protein synthesis for neurotransmitters.
  • Dendrites: Input site to the neuron.
  • Axon: Output portion of the neuron.
  • Presynaptic terminals: Transmitting portion, transmitting info via neurotransmitters.

Neurons (3 of 3)

  • Axon terminal: Where the signal leaves the cell.
  • Synapse: Where the axon terminal and receiving cell meet.

Neuron Types

  • Multipolar: Most common type, including motor neurons and neurons in the autonomic nervous system.
  • Pseudounipolar: Used for senses, and sensory neurons in the PNS.
  • Bipolar: Has one axon and one dendrite.

Classification of Neurons (1 of 2)

  • Structural Classification:
    • Bipolar: Two processes (axon and dendrite).
    • Unipolar: One process (splits into central and peripheral).
    • Multipolar: Multiple processes (usually one axon and many dendrites).

Classification of Neurons (2 of 2)

  • Functional Classification:
    • Sensory: Input neurons.
    • Motor: Output neurons.
    • Interneurons: Communication between neurons (association neurons).

Central Nervous System Glial Cells

  • Astrocytes: Abundant, support and nourish neurons, regulate chemical environment.
  • Microglial: Immune system role in CNS.
  • Ependymal: Aids in CSF circulation.
  • Oligodendrocytes: Produce myelin sheath in CNS.

Peripheral Nervous System Glial Cells

  • Satellite cells: Support and nourish neurons in the PNS.
  • Schwann cells: Produce myelin sheath in the PNS.

How Neurons Work (1 of 2)

  • Neurons are excitable cells.
  • They conduct electrical charges.
  • They send and receive signals using electrical currents.

How Neurons Work (2 of 2)

  • All muscle types and many gland cells are excitable.
  • Cells create currents by altering membrane permeability.

Propagation of Information

  • Electrical potential arises from differences in ion distribution.
  • Four types of ion channels:
    • Leak channels
    • Mechanically gated channels
    • Ligand-gated channels
    • Voltage-gated channels

Electric Potentials

  • Resting Membrane Potential (RMP): Typically -70 mV, maintained by the Na+/K+ pump.
  • Local Potentials: Graded potentials, not all-or-none, important for sensory systems.
  • Action Potentials: All-or-none, rapid depolarization and repolarization due to opening/closing of voltage-gated Na+ and K+ channels.

Propagation of Action Potential

  • Speed of conduction depends on axon diameter and myelination.
  • Saltatory conduction occurs in myelinated axons.

Synapses

  • Neurons connect at synapses.
  • Neurotransmitters are released to transmit signals across synapses.

Neurotransmitters

  • Neurotransmitters are chemical messengers.
  • Table shows examples and their effects.

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