Lecture on the Peripheral Nervous System and Reflex Activity

These flashcards cover key concepts related to the peripheral nervous system and reflex activities as outlined in the lecture notes.

What is an inborn reflex?

A rapid, involuntary, predictable motor response to a stimulus.

What are examples of inborn reflexes?

Maintaining posture and controlling visceral activities.

What is a learned reflex?

A reflex that results from practice or repetition, such as driving skills.

What are the five components of a reflex arc?

Receptor, sensory neuron, integration center, motor neuron, effector.

How are reflexes classified functionally?

As somatic reflexes (activate skeletal muscle) and autonomic reflexes (activate visceral effectors).

What is the role of the sensory neuron in a reflex arc?

To transmit afferent impulses to the central nervous system.

What happens during a stretch reflex?

It causes the muscle to contract in response to being stretched.

What kind of reflex is the knee-jerk reflex?

A stretch reflex that keeps the knees from buckling.

What is reciprocal inhibition in reflexes?

Inhibition of antagonist muscles when a reflex is activated.

What type of reflexes are the flexor reflexes?

Ipsilateral and polysynaptic reflexes initiated by a painful stimulus.

What is the plantar reflex?

A superficial reflex that tests the integrity of the spinal cord involving the downward flexion of toes.

What indicates an abnormal plantar reflex?

The presence of Babinski's sign, where the hallux dorsiflexes and smaller toes fan laterally.

What is an important clinical application of testing somatic spinal reflexes?

It helps assess the condition of the nervous system.

How does the tendon reflex function?

It prevents damage by producing muscle relaxation in response to excessive stretch.

What maintains muscle spindle sensitivity during muscle contraction?

Activation of gamma efferent fibers.

What does the crossed-extensor reflex accomplish?

It helps maintain balance by extending the opposite limb while withdrawing the stimulated limb.