13. The Peripheral Nervous System

Choose the true statement.

Which of the following reflexes is particularly important in maintaining balance and often accompanies the flexor reflex in weight-bearing limbs?

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

Which of the following reflexes would test the integrity of L₄ to S₂?

In a reflex arc, the muscle fiber or gland that responds to the efferent impulses is known as the __________.

In a reflex arc, the __________ transmits afferent impulses to the central nervous system.

Stretch reflexes would be hypoactive in all of the following conditions EXCEPT __________.

Reflexes that result from practice or repetition are known as __________.

The following are the steps involved in a neural reflex. 1. activation of a sensory neuron 2. activation of a motor neuron 3. response by an effector 4. arrival of a stimulus and activation of a receptor 5. information processing The proper sequence of these steps is (a) 1, 3, 4, 5, 2. (b) 4, 5, 3, 1, 2. (c) 4, 1, 5, 2, 3. (d) 4, 3, 1, 5, 2. (e) 3, 1, 4, 5, 2.

The reflexes that control the most rapid, stereotyped motor responses to stimuli are (a) monosynaptic reflexes, (b) polysynaptic reflexes, (c) tendon reflexes, (d) extensor reflexes.

The contraction of flexor muscles and the relaxation of extensor muscles illustrate the principle of (a) reverberating circuitry, (b) generalized facilitation, (c) reciprocal inhibition, (d) reinforcement.

List, in sequence, the five steps involved in a neural reflex.

Polysynaptic reflexes can produce far more complicated responses than can monosynaptic reflexes because (a) the response time is quicker, (b) the response is initiated by highly sensitive receptors, (c) motor neurons carry impulses at a faster rate than do sensory neurons, (d) the interneurons involved can control several muscle groups.

What five characteristics are common to all polysynaptic reflexes?

Compare and contrast flexor and crossed-extensor reflexes.

Bowel and urinary bladder control involve spinal reflex arcs that are located in the sacral region of the spinal cord. In both instances, two sphincter muscles—an inner sphincter of smooth muscle and an outer sphincter of skeletal muscle—control the passage of wastes (feces and urine) out of the body. How would a transection of the spinal cord at the L1 segment level affect an individual's bowel and bladder control?

What is the homeostatic value of flexor reflexes?

What clinical information can be gained by conducting somatic reflex tests?

What is the structural and functional relationship between spinal nerves, skeletal muscles, and dermatomes?