Physiology of Reflexes

Questions and Answers

What is the main function of a simple monosynaptic reflex?

To integrate sensory information from multiple sources

To facilitate rapid motor responses to specific stimuli (correct)

To regulate higher-order cognitive functions

To modulate emotional responses to pain

Which of the following is NOT a component of a reflex arc?

Intemeuron

Sensory receptor

Motor neuron

Cerebral hemisphere (correct)

What is the purpose of reciprocal inhibition in reflexes?

To inhibit the antagonist muscle to facilitate agonist contraction (correct)

To enhance the strength of a reflexive response

To modulate the activity of interneurons

To regulate the rate of sensory transmission

Which type of reflex involves the transmission of signals across multiple segments of the spinal cord?

Intersegmental reflex Signup and view all the answers

What is the primary function of brain stem reflexes?

To modulate respiratory rhythms Signup and view all the answers

What is the term for reflexes that are present during fetal development and early infancy, but disappear as the nervous system matures?

Developmental reflexes Signup and view all the answers

What is the primary characteristic of a reflex?

It is a stereotyped, involuntary response to a stimulus Signup and view all the answers

Which of the following systems mediates autonomic reflexes?

Autonomic nervous system Signup and view all the answers

What is the role of reflexes in the context of movement?

They form the foundation for movement, allowing for fast, automatic behavior Signup and view all the answers

What is the primary difference between autonomic and somatic reflexes?

Autonomic reflexes involve smooth muscle, while somatic reflexes involve skeletal muscle Signup and view all the answers

Which of the following is NOT a characteristic of reflexes?

They require conscious effort Signup and view all the answers

What is the primary function of muscle spindles?

To monitor muscle length and rate of change of length Signup and view all the answers

What is the significance of reflexes in terms of survival?

They provide an evolutionary advantage by allowing for rapid, automatic responses to threats Signup and view all the answers

What is the relationship between simple reflexes and complex neural circuits?

Simple reflexes are the building blocks of complex neural circuits Signup and view all the answers

Which type of fibers are responsible for transmitting information from muscle spindles to the CNS?

Sensory neurons Signup and view all the answers

Which of the following is an example of an autonomic reflex?

Regulation of heart rate in response to changes in blood pressure Signup and view all the answers

What type of fibers are affected by gamma motor neurons?

Intrafusal fibers Signup and view all the answers

What is the role of the sensory neuron in muscle spindles?

To transmit sensory information to the CNS Signup and view all the answers

What is the term for the ability to detect changes in muscle length and tension?

Proprioception Signup and view all the answers

What type of muscle fibers are responsible for generating force during muscle contraction?

Extrafusal fibers Signup and view all the answers

What is the function of Golgi tendon organs?

To detect changes in tendon tension Signup and view all the answers

What is the term for the process by which muscle spindles help to prevent overstretching?

Muscle spindle reflex Signup and view all the answers

Which receptors are important for maintaining posture?

Skin pressure receptors Signup and view all the answers

What is the effect of destroying skin pressure receptors in someone with tabes dorsalis?

They will fall when they close their eyes Signup and view all the answers

What do cerebellar reflexes help to coordinate?

Complex movements Signup and view all the answers

What is the significance of reflexes in clinical diagnosis?

They are used to diagnose disorders before other signs appear Signup and view all the answers

What is hyporeflexia characterized by?

Weak or absent reflex response Signup and view all the answers

Which type of receptors are stimulated when a person is standing?

Pressure receptors in the soles of the feet Signup and view all the answers

What is the role of the reflex centre in cerebellar reflexes?

To integrate sensory information Signup and view all the answers

What is the significance of racing drivers 'driving by the seat of their pants'?

They use their sense of pressure to adjust their position Signup and view all the answers

What happens to motor neurones above and below a closed head injury?

Above - unaffected, below - absent Signup and view all the answers

Which reflex is characterized by an anatomical extensor response in the first two toes?

Babinski reflex Signup and view all the answers

What is the primary function of the dorsal reticulospinal tract in neonates and young infants?

Regulation of flexor reflexes in the lower limbs Signup and view all the answers

What happens to the Babinski sign as an infant develops?

It disappears and then reappears in adulthood Signup and view all the answers

What type of reflexes are characterized by automatic, stereotyped responses to environmental stimuli?

Primitive and developmental reflexes Signup and view all the answers

What is the fate of primitive reflexes as the CNS matures?

They are inhibited to allow mature patterns of response Signup and view all the answers

What is the term for the pattern of response that is present in early life and later inhibited to allow mature patterns of response?

Survival pattern of response Signup and view all the answers

What is the effect of a closed head injury on the oculomotor reflex?

It changes the eye reflex response Signup and view all the answers

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.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Learn about reflexes, including their definition, classification, and control of movement. Understand the role of autonomic and somatic reflexes in the nervous system.