Classification of Nerve Fibres Flashcards
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Classification of Nerve Fibres Flashcards

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Questions and Answers

Based on structure ____________.

myelinated (myelin sheath), non-myelinated

Based on distribution __________.

somatic (skeletal muscle), visceral/autonomic (internal organs)

Based on origin _____________.

Cranial (from brain), Spinal (from spinal cord)

Based on function ___________.

<p>Sensory/afferent (sensory impulses from body to CNS), Motor/efferent (motor impulses from CNS to body)</p> Signup and view all the answers

Which nerve fibers secrete noradrenaline?

<p>Adrenergic nerve fibers</p> Signup and view all the answers

Which nerve fibers secrete acetylcholine?

<p>Cholinergic nerve fibers</p> Signup and view all the answers

Based on secretion of neurotransmitter:

<p>Adrenergic, Cholinergic</p> Signup and view all the answers

What is the ERLANGER-GASSER classification based on?

<p>Diameter and velocity of conduction of impulses</p> Signup and view all the answers

Velocity of impulse through nerve fiber:

<p>Is directly proportional to the diameter</p> Signup and view all the answers

Among these fibers, type _________ nerve fibers are the thickest fibers.

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

Type _________ nerve fibers are the thinnest fibers.

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

Except type __________ all are myelinated.

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

Type A has further how many subtypes?

<p>4</p> Signup and view all the answers

Proprioception and somatic motor function is of which type?

<p>A alpha</p> Signup and view all the answers

Touch and pressure is a function of which fibers?

<p>A beta</p> Signup and view all the answers

Motor to muscle spindles function is of which type?

<p>A gamma</p> Signup and view all the answers

Pain, cold, touch function is of which type?

<p>A delta</p> Signup and view all the answers

Preganglionic autonomic fibers are which type?

<p>Type B</p> Signup and view all the answers

Pain, temperature, mechanoreception is a function of which fibers?

<p>C: Dorsal root</p> Signup and view all the answers

Postganglionic sympathetic fibers are which type?

<p>C: sympathetic</p> Signup and view all the answers

Numerical classification is:

<p>Ia, b, II, III, IV</p> Signup and view all the answers

Relative to ERLANGER GASSER:

<p>I = A alpha, II = A beta, III = A gamma, IV = Dorsal root C</p> Signup and view all the answers

Ia function?

<p>Muscle spindle, annulospiral ending</p> Signup and view all the answers

Ib function?

<p>Golgi tendon organ</p> Signup and view all the answers

Function of type II fibers?

<p>Muscle spindle, flower spray ending, touch, pressure</p> Signup and view all the answers

Function of type III fibers?

<p>Pain, cold, touch</p> Signup and view all the answers

Study Notes

Classification of Nerve Fibres

  • Nerve fibres are classified based on structure: myelinated (with myelin sheath) or non-myelinated.
  • Distribution types include somatic (innervating skeletal muscle) and visceral/autonomic (innervating internal organs).
  • Nerve fibres originate from two main sources: cranial (from the brain) and spinal (from the spinal cord).
  • Functionally, nerve fibres can be sensory/afferent (conducting sensory impulses to the CNS) or motor/efferent (conducting motor impulses from the CNS to the body).

Neurotransmitter Secretion

  • Adrenergic nerve fibres are those that secrete noradrenaline.
  • Cholinergic nerve fibres are responsible for the secretion of acetylcholine.
  • Neurotransmitter secretion classification includes adrenergic and cholinergic types.

Erlanger-Gasser Classification

  • This classification is based on the diameter and conduction velocity of nerve fibres.
  • The three types in this classification are A, B, and C.

Velocity and Diameter

  • Velocity of impulse conduction through nerve fibres is directly proportional to their diameter.

Fiber Thickness

  • Type A nerve fibres are the thickest, while type C nerve fibres are the thinnest.
  • All types are myelinated except type C fibres.

Type A Subtypes

  • Type A fibres consist of four subtypes: alpha, beta, gamma, and delta.
  • Proprioception and somatic motor functions are primarily associated with A alpha fibres.
  • A beta fibres are responsible for touch and pressure sensation.
  • A gamma fibres contribute to motor control of muscle spindles.
  • A delta fibres transmit pain, cold, and touch sensations.

Preganglionic and Postganglionic Fibres

  • Preganglionic autonomic fibres belong to type B.
  • Postganglionic sympathetic fibres are categorized as C fibres (sympathetic).

Numerical Classification

  • Numerical classification of nerve fibres includes Ia, Ib, II, III, and IV.
  • In the context of the Erlanger-Gasser classification:
    • Ia corresponds to A alpha
    • II corresponds to A beta
    • III corresponds to A gamma
    • IV corresponds to Dorsal root C

Functions of Specific Fiber Types

  • Ia fibres respond to muscle spindle information (annulospiral endings).
  • Ib fibres are linked to Golgi tendon organ functions.
  • Type II fibres are involved in muscle spindle (flower spray endings), touch, and pressure sensation.
  • Type III fibres are associated with pain, cold, and touch detection.

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Test your knowledge on the classification of nerve fibres with this quiz. Explore the various criteria such as structure, distribution, origin, and function. Ideal for anyone studying neurobiology or related fields.

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