Questions and Answers
What is the main function of a simple monosynaptic reflex?
Which of the following is NOT a component of a reflex arc?
What is the purpose of reciprocal inhibition in reflexes?
Which type of reflex involves the transmission of signals across multiple segments of the spinal cord?
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What is the primary function of brain stem reflexes?
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What is the term for reflexes that are present during fetal development and early infancy, but disappear as the nervous system matures?
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What is the primary characteristic of a reflex?
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Which of the following systems mediates autonomic reflexes?
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What is the role of reflexes in the context of movement?
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What is the primary difference between autonomic and somatic reflexes?
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Which of the following is NOT a characteristic of reflexes?
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What is the primary function of muscle spindles?
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What is the significance of reflexes in terms of survival?
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What is the relationship between simple reflexes and complex neural circuits?
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Which type of fibers are responsible for transmitting information from muscle spindles to the CNS?
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Which of the following is an example of an autonomic reflex?
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What type of fibers are affected by gamma motor neurons?
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What is the role of the sensory neuron in muscle spindles?
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What is the term for the ability to detect changes in muscle length and tension?
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What type of muscle fibers are responsible for generating force during muscle contraction?
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What is the function of Golgi tendon organs?
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What is the term for the process by which muscle spindles help to prevent overstretching?
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Which receptors are important for maintaining posture?
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What is the effect of destroying skin pressure receptors in someone with tabes dorsalis?
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What do cerebellar reflexes help to coordinate?
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What is the significance of reflexes in clinical diagnosis?
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What is hyporeflexia characterized by?
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Which type of receptors are stimulated when a person is standing?
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What is the role of the reflex centre in cerebellar reflexes?
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What is the significance of racing drivers 'driving by the seat of their pants'?
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What happens to motor neurones above and below a closed head injury?
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Which reflex is characterized by an anatomical extensor response in the first two toes?
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What is the primary function of the dorsal reticulospinal tract in neonates and young infants?
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What happens to the Babinski sign as an infant develops?
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What type of reflexes are characterized by automatic, stereotyped responses to environmental stimuli?
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What is the fate of primitive reflexes as the CNS matures?
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What is the term for the pattern of response that is present in early life and later inhibited to allow mature patterns of response?
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What is the effect of a closed head injury on the oculomotor reflex?
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Study Notes
Reflexes
- Definition: Stereotyped, involuntary response to a stimulus, not subject to conscious control.
- Classification:
- Autonomic reflexes: Mediated by the autonomic nervous system, activate smooth muscle, cardiac muscle, and glands.
- Somatic reflexes: Mediated by the somatic nervous system, activate skeletal muscle.
Monosynaptic Reflex Arc
- Simplest reflex arc, involving one synapse.
Reflex Control of Movement
- Neural circuits are building blocks of CNS, with reflexes being the simplest neural circuit.
- Fast, automatic behavior that is evolutionarily old and ensures survival without conscious effort.
Muscle Spindles
- Monitor muscle length and rate of change of length to prevent overstretching.
- Consist of intrafusal fibers, extrafusal fibers, and a sensory receptor.
Golgi Tendon Organs
- Proprioceptors that monitor muscle tension and length.
- Consist of afferent neurons, sensory receptors, and collagen fibers.
Posture and Reflex Control
- Visual, vestibular, and somatosensory reflexes contribute to posture control.
- Pressure receptors in the skin and soles of the feet monitor weight distribution.
- Clinically, destruction of these receptors (e.g., tabes dorsalis) can lead to loss of posture control.
Higher CNS and Somatosensory Reflexes
- Sitting balance is maintained by pressure receptors in the buttocks.
- Racing drivers use pressure receptors in their buttocks to drive.
Cerebellar Reflexes
- Integrate sensory information to coordinate complex movements and maintain posture.
Clinical Relevance of Reflexes
- Reflexes can be lost before muscle weakness, and their absence can indicate degeneration, demyelination, or other pathology.
- Hyporeflexia (weak or absent response) can occur due to closed head injury or other conditions.
- Babinski sign is a reflex response that can indicate upper motor neuron damage.
Developmental and Clinical Reflexes
- Flexor reflexes are present in neonates and young infants, but disappear as the CNS matures.
- Developmental reflexes are important for survival and are overridden by higher brain areas as the CNS matures.
- Primitive reflexes can reappear in adults as a sign of upper motor neuron damage.
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Description
Learn about reflexes, including their definition, classification, and control of movement. Understand the role of autonomic and somatic reflexes in the nervous system.