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Questions and Answers
The crossed-extensor reflex is initiated by nociceptors and involves antagonistic muscles contracting in the ______ leg to maintain balance.
The crossed-extensor reflex is initiated by nociceptors and involves antagonistic muscles contracting in the ______ leg to maintain balance.
Reciprocal inhibition occurs during which of the following reflexes?
Reciprocal inhibition occurs during which of the following reflexes?
How many neurons are involved in transmitting nerve signals from sensory receptors to the brain in sensory pathways?
How many neurons are involved in transmitting nerve signals from sensory receptors to the brain in sensory pathways?
Where does the secondary neuron synapse in the somatosensory pathway?
Where does the secondary neuron synapse in the somatosensory pathway?
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Which pathway provides information about pain, temperature, touch, and pressure for conscious interpretation?
Which pathway provides information about pain, temperature, touch, and pressure for conscious interpretation?
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Which motor tract innervates appendicular skeletal muscles that control precise, agile, skilled movement in the distal parts of the upper and lower limbs?
Which motor tract innervates appendicular skeletal muscles that control precise, agile, skilled movement in the distal parts of the upper and lower limbs?
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Where is the cell body of an upper motor neuron housed in the direct motor pathways?
Where is the cell body of an upper motor neuron housed in the direct motor pathways?
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Which tract originates in the red nucleus of the midbrain and regulates fine, precise, voluntary movements in the distal parts of the upper limbs mainly?
Which tract originates in the red nucleus of the midbrain and regulates fine, precise, voluntary movements in the distal parts of the upper limbs mainly?
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Which motor pathway involves more than one upper motor neuron?
Which motor pathway involves more than one upper motor neuron?
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Where does decussation occur for the Lateral corticospinal tract?
Where does decussation occur for the Lateral corticospinal tract?
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What is the main function of the sensory receptor in a reflex arc?
What is the main function of the sensory receptor in a reflex arc?
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Which reflex is initiated by nociceptors and involves muscles contracting to withdraw the body part from a painful stimulus?
Which reflex is initiated by nociceptors and involves muscles contracting to withdraw the body part from a painful stimulus?
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In a reflex arc, where is information processed by interneurons?
In a reflex arc, where is information processed by interneurons?
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Which type of reflex involves at least one interneuron in its processing?
Which type of reflex involves at least one interneuron in its processing?
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What is the primary role of an effector in a reflex arc?
What is the primary role of an effector in a reflex arc?
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Which reflex involves reciprocal inhibition preventing the contraction of antagonistic muscles?
Which reflex involves reciprocal inhibition preventing the contraction of antagonistic muscles?
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In a reflex arc, what is the function of a motor neuron?
In a reflex arc, what is the function of a motor neuron?
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What type of reflex involves a muscle spindle proprioceptor and causes a muscle to contract in response to being stretched?
What type of reflex involves a muscle spindle proprioceptor and causes a muscle to contract in response to being stretched?
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What distinguishes a somatic reflex from a visceral (autonomic) reflex?
What distinguishes a somatic reflex from a visceral (autonomic) reflex?
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What is the role of an integrating center in a reflex arc?
What is the role of an integrating center in a reflex arc?
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Study Notes
Reflex Arc Components
- A reflex arc consists of five main components: sensory receptor, sensory neuron, integrating center, motor neuron, and effector.
- The sensory receptor responds to internal or external stimuli, and the effector responds to nerve signals to counteract the stimulus or remove the body part from the stimulus.
Classification of Reflexes
- Reflexes can be classified into five types: spinal reflex or cranial reflex, somatic reflex or visceral reflex, monosynaptic reflex or polysynaptic reflex, ipsilateral reflex or contralateral reflex, and intersegmental reflex or non-intersegmental reflex.
Types of Reflexes
- Stretch reflex: initiated by muscle spindle proprioceptors, contracts muscles in response to being stretched, and is indirectly involved in reciprocal inhibition.
- Withdrawal (flexor) reflex: initiated by nociceptors, contracts muscles to withdraw the body part from a painful stimulus.
- Crossed-extensor reflex: initiated by nociceptors, contracts antagonistic muscles in the opposite leg to maintain balance.
Conduction Pathways
- Conduction pathways are series of neurons and their associated structures that relay nerve signals between the brain and a specific part of the body.
- There are two types of conduction pathways: sensory pathways and motor pathways.
- Sensory pathways are also known as ascending pathways, while motor pathways are also known as descending pathways.
Sensory Pathways
- There are two categories of sensory pathways: somatosensory and viscerosensory pathways.
- Sensory pathways use a series of two or three neurons to transmit nerve signals from sensory receptors to the brain.
- Sensory tracts are found within all funiculi.
- Primary (first-order) neuron extends from the sensory receptor to the brainstem or spinal cord.
- Secondary (second-order) neuron extends from the primary neuron to the thalamus.
- Tertiary (third-order) neuron extends from the secondary neuron to the parietal lobe.
Somatosensory Pathways
- There are three major somatosensory pathways: posterior column medial-lemniscus pathway, anterolateral (spinothalamic) pathway, and spinocerebellar pathway.
- Posterior column medial-lemniscus pathway provides information about touch, pressure, vibration, and proprioception for conscious interpretation.
- Anterolateral (spinothalamic) pathway provides information about pain, temperature, touch, and pressure for conscious interpretation.
- Spinocerebellar pathway provides information about body position and body movements for subconscious interpretation that helps in maintaining balance and posture.
Motor Pathways
- There are two major types of motor pathways: direct (pyramidal) pathways and indirect (extrapyramidal) pathways.
- Motor tracts are found within the anterior and lateral funiculi.
- Upper motor neuron extends from the cerebral cortex, cerebral nuclei, or a specific nucleus in the brainstem to the lower motor neuron.
- Lower motor neuron extends from the anterior horn of the spinal cord to skeletal muscle fibers.
Direct Motor Pathways
- There are two major direct motor pathways: lateral corticospinal tract and anterior corticospinal tract.
- Lateral corticospinal tract innervates appendicular skeletal muscles that control precise, agile, skilled movements in the distal parts of the upper and lower limbs.
- Anterior corticospinal tract innervates axial skeletal muscles like those in the trunk, neck, and shoulders.
Indirect Motor Pathways
- There are two major indirect motor pathways: rubrospinal tract and tectospinal tract.
- Rubrospinal tract regulates and controls fine, precise, voluntary movements in the distal parts of the upper limbs.
- Tectospinal tract regulates reflexive positional changes of the skeletal muscles of the head and trunk due to auditory and visual stimuli.
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Description
Learn about the five main components of a reflex arc, including the sensory receptor, sensory neuron, integrating center, motor neuron, and effector. Understand how these components work together to produce a rapid response to stimuli.
