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Zorluk: OrtaNervous Coordination and Sense Organs

A physiological experiment demonstrates that selective damage to the ventral root of a mammalian spinal nerve results in a complete loss of muscle contraction in a limb, while touch sensation in that limb remains fully intact. Which statement best explains this observation?

  1. The ventral root exclusively transmits motor impulses from the spinal cord to effector muscles.Cevap
  2. B
    The ventral root exclusively transmits sensory impulses from skin receptors to the spinal cord.
  3. C
    The ventral root contains interneurons that integrate sensory input and motor output.
  4. D
    The ventral root carries sensory impulses away from the spinal cord toward peripheral receptors.

Cevap

The ventral root exclusively transmits motor impulses from the spinal cord to effector muscles.
The ventral root of a spinal nerve is composed entirely of efferent (motor) axon fibers that conduct impulses from the central nervous system outwards to effector organs such as skeletal muscles. Consequently, severing or damaging the ventral root prevents motor signal transmission to muscles, leading to loss of movement, while sensory impulses traveling along the intact dorsal root continue to function normally.

Adım Adım Çözüm

1
Identify the anatomical division of functions between spinal nerve roots
Sensory (afferent) nerve fibers enter the spinal cord via the dorsal root, while motor (efferent) nerve fibers exit via the ventral root.
Spinal nerves divide into two distinct roots near their origin at the spinal cord, separating incoming sensory input from outgoing motor commands.
2
Correlate experimental findings with root functions
Targeted damage to the ventral root causes loss of motor activity (paralysis) but leaves sensory perception uncompromised.
Because only muscle contraction was lost while touch sensation remained intact, the ventral root must carry exclusively motor nerve fibers to effector organs.

Anahtar Kavram

Functional organization of spinal nerve roots (dorsal vs. ventral roots)
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Konular

Nervous Coordination and Sense Organs

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