Chapter 13 concept questions Flashcards
List the general steps of a reflex pathway, including the anatomical structures in the nervous system that correspond to each ste
Sensor (sensory receptor), input signal (sensory afferent neuron), integrating center (central nervous system), output signal (autonomic or somatic motor neuron), targets (muscles, glands, some adipose tissue).
If a cell hyperpolarizes, does its membrane potential become more positive or more negative? Does the potential move closer to threshold or farther from the threshold?If a cell hyperpolarizes, does its membrane potential become more positive or more negative? Does the potential move closer to threshold or farther from threshold?
Upon hyperpolarization, the membrane potential becomes more negative and moves farther from threshold.
Using the standard steps of a reflex pathway (stimulus, receptor, and so forth), draw a reflex map of the stretch reflex.
Your map of a stretch reflex should match the components shown in Fig. 13.3.
Draw a reflex map of the flexion reflex initiated by a painful stimulus to the sole of a foot.
Your flexion reflex map should match the steps shown for the knee jerk in Fig. 13.5, with the added contraction of hip flexor muscles in addition to the quadriceps.
Add the crossed extensor reflex in the supporting leg to the map you created in Concept Check 4.
The initial steps of the crossed extensor reflex are the same as those of the flexion reflex until the CNS. There the crossed extensor reflex follows the diagram shown in Fig. 13.6, step 3c.
As you pick up a heavy weight, which of the following are active in your biceps muscle? alpha motor neurons, gamma motor neurons, muscle spindle afferents, Golgi tendon organ afferent neurons
When you pick up a weight, alpha and gamma neurons, spindle af- ferents, and Golgi tendon organ afferents are all active.
What distinguishes a stretch reflex from a crossed extensor reflex?
A stretch reflex is initiated by stretch and causes a reflex contraction. A crossed extensor reflex is a postural reflex initiated by withdrawal from a painful stimulus; the extensor muscles contract, but the corresponding flexors are inhibited.
