Nervous System Overview and Subdivisions
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Questions and Answers

Which part of the neuron is primarily responsible for protein synthesis?

  • Myelin sheath
  • Cell body (soma) (correct)
  • Dendrites
  • Axon hillock

What characteristic of neurons allows them to respond quickly to stimuli?

  • High lipid content
  • Short lifespan
  • Low metabolic rate
  • Excitability (correct)

What does the term 'dendrite' refer to in relation to its appearance?

  • Branches of a tree (correct)
  • Roots of a plant
  • Leaves of a flower
  • Stems of a shrub

Once mature, what ability do neurons lose?

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

Which part of the neuron initiates the electrical charge that leads to signal transmission?

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

What percentage of neurons in the central nervous system (CNS) are interneurons?

<p>90% (B)</p> Signup and view all the answers

Which type of neuron is characterized by having no axon and all processes being dendrites?

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

Which of the following statements about unipolar neurons is true?

<p>Only one process extends from the cell body. (C)</p> Signup and view all the answers

In which location are multipolar neurons most commonly found?

<p>In the central nervous system (D)</p> Signup and view all the answers

What is the classification for a neuron with two processes extending from the cell body?

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

What is the primary function of the axon in a neuron?

<p>To transmit action potentials (B)</p> Signup and view all the answers

Where does the axon begin in a neuron?

<p>At the axon hillock (D)</p> Signup and view all the answers

What is transported along the axon using molecular motors?

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

What are the chemicals called that are released at the axon terminals?

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

What occurs first in the sequence of information flow in a neuron?

<p>Reception of messages by dendrites (D)</p> Signup and view all the answers

What separates the two cells in a synapse?

<p>Synaptic cleft (D)</p> Signup and view all the answers

What happens at the axon terminals after the action potential is transmitted?

<p>Neurotransmitters are released (B)</p> Signup and view all the answers

Which structure is NOT a part of the axon?

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

What is the primary function of the motor division of the nervous system?

<p>Control the activity of muscles and glands (C)</p> Signup and view all the answers

Which subdivision of the nervous system is responsible for subconscious control?

<p>Autonomic nervous system (B)</p> Signup and view all the answers

What is the role of neuroglia in the nervous system?

<p>Support and protect neurons (A)</p> Signup and view all the answers

Which division of the peripheral nervous system sends information to the CNS?

<p>Sensory (afferent) division (D)</p> Signup and view all the answers

What happens during sympathetic nervous system activation?

<p>Heart rate increases and pupils dilate (A)</p> Signup and view all the answers

Which system is responsible for controlling voluntary movements?

<p>Somatic nervous system (C)</p> Signup and view all the answers

What effect does the parasympathetic nervous system have on the body?

<p>Conserves energy and promotes relaxation (A)</p> Signup and view all the answers

Which of the following accurately describes the sensory division of the nervous system?

<p>Detects and transmits changes in the environment (C)</p> Signup and view all the answers

What role do oligodendrocytes play in the central nervous system?

<p>They form myelin (A)</p> Signup and view all the answers

How does myelin affect the speed of action potentials?

<p>Greatly increases the speed (D)</p> Signup and view all the answers

What primarily composes gray matter?

<p>Unmyelinated axons and cell bodies (C)</p> Signup and view all the answers

What is a key function of astrocytes in the central nervous system?

<p>To absorb excess ions and recapture neurotransmitters (A)</p> Signup and view all the answers

What type of cells line the cavities of the CNS?

<p>Ependymal cells (D)</p> Signup and view all the answers

What characteristic helps ependymal cells circulate cerebrospinal fluid?

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

What is the appearance of areas with high densities of myelinated axons known as?

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

What do astrocytes connect neurons to for nutrient supply?

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

What is the primary function of microglia in the brain?

<p>They monitor the health of nearby neurons. (D)</p> Signup and view all the answers

What happens to microglia when they sense damage to neurons?

<p>They migrate to the injury site and transform into macrophages. (C)</p> Signup and view all the answers

Which type of neuroglia surrounds the cell bodies of neurons in the peripheral nervous system?

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

How do Schwann cells aid in nerve regeneration in the peripheral nervous system?

<p>By guiding the axon sprout back to its original location. (C)</p> Signup and view all the answers

What differentiates myelinated axons from unmyelinated axons?

<p>Myelinated axons are enveloped multiple times by Schwann cells. (B)</p> Signup and view all the answers

What effect does incomplete myelination have on infants?

<p>Reduces their coordination and physical control. (D)</p> Signup and view all the answers

In multiple sclerosis (MS), which type of neuroglia is primarily damaged?

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

What is a major consequence of myelin loss in conditions like multiple sclerosis?

<p>Loss of muscle control and vision. (A)</p> Signup and view all the answers

Flashcards

Nervous System Functions

The nervous system's role involves detecting changes, interpreting them, and initiating responses.

Sensory Division (Afferent)

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

Motor Division (Efferent)

Carries commands from the CNS to muscles and glands.

Somatic Nervous System

Controls voluntary movements of skeletal muscles.

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Autonomic Nervous System

Controls involuntary actions, like those of glands, smooth, and cardiac muscles.

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Sympathetic Nervous System

Active during stressful situations, often causing increased heart rate and dilating pupils.

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Parasympathetic Nervous System

Generally has effects opposite to the sympathetic system, conserving energy and promoting relaxation.

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Neuroglia and Neurons

Two types of cells that form neural tissue, with neuroglia supporting neurons.

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Neuron structure: Cell body

The cell body, also called the soma, is the central part of a neuron. It contains the nucleus and most organelles and is the site of protein synthesis.

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Neuron structure: Dendrites

Dendrites are branching extensions of the neuron that receive signals from other neurons and transmit them to the cell body.

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Neuron function: Excitability

Neurons quickly respond to stimuli by changing electrical charges across their cell membrane.

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Neuron structure: Axon hillock

The axon hillock is the region where the axon begins on the cell body; it is the decision point for the neuron to transmit a signal.

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Neuron characteristics: Metabolic rate

Neurons have a high metabolic rate because they are very active cells.

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Interneuron function

Interneurons process information between sensory and motor neurons within the central nervous system (CNS).

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Anaxonic neuron

Anaxonic neurons have no distinct axon and all processes resemble dendrites, mainly found in the brain.

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Unipolar neuron

Unipolar neurons have a single process emerging from the cell body, primarily functioning as sensory neurons in the peripheral nervous system (PNS).

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Bipolar neuron

Bipolar neurons have two processes extending from the cell body, commonly found in special sense organs.

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Multipolar neuron

Multipolar neurons have multiple processes extending from the cell body; the most abundant neuron type in the CNS.

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Axon

The extension of a neuron that transmits action potentials.

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Axon terminal (synaptic knob)

The branched end of an axon where neurotransmitters are released.

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Axon hillock

The part of the neuron where the axon originates.

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Neurotransmitters

Chemicals released by axon terminals to communicate with other cells.

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Synapse

The gap between two communicating neurons.

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Synaptic cleft

The very small gap separating two communicating cells at a synapse.

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Sensory neurons

Neurons that carry information from sensory organs to the CNS.

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Motor neurons

Neurons that carry information from the CNS to muscles or glands.

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Oligodendrocytes function

Oligodendrocytes create myelin sheaths in the central nervous system (CNS).

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Myelin's effect on speed

Myelin significantly increases the speed of action potentials.

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Myelin structure

Myelin is formed by extensions of oligodendrocytes wrapping around axons multiple times, insulating the axon.

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White matter composition

White matter contains high densities of myelinated axons.

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Gray matter composition

Gray matter contains many cell bodies and unmyelinated axons.

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Astrocytes' role

Astrocytes are abundant CNS neuroglia that help neurons by anchoring them to capillaries for nutrient access and controlling the chemical environment around them.

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Ependymal cell function

Ependymal cells line CNS cavities, help produce, circulate, and monitor cerebrospinal fluid (CSF).

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Ependymal cells' cilia

Ependymal cells are often ciliated to help circulate CSF.

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Microglia: What do they do?

Microglia are specialized immune cells in the central nervous system (CNS) that monitor the health of neurons. They have long, thorny processes that touch nearby neurons and detect damage. If they sense damage, microglia migrate to the site and transform into macrophages to ingest bacteria or dead neurons.

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Microglia: What happens when they detect damage?

When microglia detect damage to neurons, they migrate to the injury site and transform into macrophages. Macrophages are specialized cells that engulf and destroy bacteria or dead cells.

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Satellite Cells: What do they do?

Satellite cells surround the cell bodies of neurons in the peripheral nervous system (PNS). They control the chemical environment around neurons, ensuring a stable and healthy environment.

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Schwann Cells: What do they do?

Schwann cells are specialized neuroglia in the PNS that shield all axons from the extracellular fluid. They also play a crucial role in repairing damaged axons by guiding the axon sprout back to its original location.

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Myelinated vs. Unmyelinated Axons: What's the difference?

Myelinated axons are wrapped tightly by Schwann cells, providing excellent insulation and increasing the speed of action potentials.Unmyelinated axons are only loosely enveloped by Schwann cells, offering little insulation and slower action potential speeds.

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Why are infants not as coordinated?

Infants are not as coordinated because their myelination process is not complete. Myelination is essential for fast and efficient nerve impulse transmission, and it takes time for this process to fully develop.

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Multiple Sclerosis (MS): What's damaged?

Multiple sclerosis (MS) is an autoimmune disease that results in the gradual loss of myelin in the central nervous system (CNS). This damage primarily targets oligodendrocytes, the neuroglia responsible for myelination in the CNS.

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Why do MS patients lose muscle control and vision?

Loss of myelin in MS disrupts the efficient transmission of nerve impulses, affecting communication between the brain and muscles, leading to impaired muscle control. Similarly, damage to the myelin sheath in the optic nerve can cause vision problems.

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Study Notes

Nervous System Overview

  • The nervous system has three main functions: sensory input (detecting changes), integration (interpreting sensory input), and motor output (controlling muscles and glands).
  • The nervous system is divided into two major subdivisions: the central nervous system (CNS) and the peripheral nervous system (PNS).
  • The CNS (brain and spinal cord) is the main integration and command center.
  • The PNS consists of nerves that carry information to and from the CNS.

Nervous System Subdivisions

  • The PNS is further divided into the sensory (afferent) division and the motor (efferent) division.
  • The sensory division carries sensory information to the CNS.
  • The motor division transmits motor commands from the CNS to effectors (muscles and glands).
  • The motor division is further divided into the voluntary (somatic) nervous system, controlling skeletal muscles, and the involuntary (autonomic) nervous system, controlling smooth and cardiac muscles and glands.
  • The autonomic nervous system is further divided into the sympathetic nervous system (active during stressful situations) and the parasympathetic nervous system (conserves energy).

Neuronal Structure and Function

  • Nervous tissue consists of two main cell types: neurons and neuroglia.
  • Neurons are responsible for transmitting electrical signals. They are excitable, have a high metabolic rate, are extremely long-lived, and cannot divide after maturity.
  • Important characteristics of neurons include excitability (respond rapidly to stimuli), conductivity (propagate electrical signals), secretion (release neurotransmitters), and longevity (last a lifetime).

Parts of a Neuron

  • The cell body (soma) is the central region of the neuron, containing the nucleus and organelles.
  • Dendrites are extensions of the soma that receive signals from other neurons.
  • The axon is a long projection that transmits signals from the soma to other cells. It begins at the axon hillock.
  • Axon terminals are the branches at the end of the axon, releasing neurotransmitters into the synapse.

Synapses and Integration

  • Synapses are the junctions between neurons where neurotransmitters transmit signals.
  • Information flows in a specific order: dendrites receive signals, the cell body integrates them, the axon transmits the signal as an action potential, and the axon terminals release neurotransmitters.
  • Neuroglia (glial cells) provide support and protection to neurons in both the CNS and PNS (e.g., astrocytes, oligodendrocytes, microglia, ependymal cells, satellite cells).
  • Schwann cells in the PNS form myelin sheaths around axons, increasing the speed of nerve impulses.

Neuron Classification

  • Neurons can be classified functionally (sensory, motor, interneurons) or structurally (anaxonic, unipolar, bipolar, multipolar).
  • Interneurons are entirely within the CNS, connecting other neurons and integrating information.
  • Sensory neurons transmit signals from sensory receptors to the CNS.
  • Motor neurons transmit signals from the CNS to effectors (muscles and glands).
  • Structural classifications depend on the number of processes extending from the soma.

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Intro to Nervous System PDF

Description

Explore the essential functions and subdivisions of the nervous system. This quiz covers the distinctions between the central and peripheral nervous systems, as well as the sensory and motor divisions. Enhance your understanding of how the nervous system acts as the body’s control center.

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