A&P 11th Edition "Checkpoint" - Chapter 13

23. After injuring her back, Tina exhibits a Babinski reflex. What does this imply about Tina's injury?

A Babinski reflex is abnormal and adults. It indicates possible damage to descending tracks in the spinal cord.

8. A disease that damages myelin sheaths would affect which part of the spinal cord?

A disease that damages myelin sheaths would affect the columns in the white matter of the spinal cord, because the columns are composed of bundles of myelinated axons.

12. Compression of which nerve produces the sensation that your leg has "fallen asleep"?

Compression of the sciatic nerve produces the sensation that your leg has "fallen asleep."

22. Define reinforcement as it pertains to spinal reflexes.

Reinforcement is an enhancement of spinal reflexes. It occurs when the postsynaptic neuron enters a state of generalized facilitation caused by chronically active excitatory synapses.

17. One of the first somatic reflexes to develop is the suck reflex. Which type of reflex is this?

The suck reflex is an innate reflex.

14. List the five neuronal pool circuit patterns.

The five neuronal pool circuit patterns are divergence, convergence, serial processing, parallel processing, and reverberation.

9. Identify the major networks of nerves known as plexuses.

The major nerve plexuses are the cervical, brachial, lumbar, and sacral.

3. Identify the three spinal meninges.

With her spinal meningitis are the dura mater, arachnoid mater, and pia mater.

13. Define neuronal pool.

A neuronal pool is a functional group of organized interneurons with the CNS.

15. Define reflex

A reflex is a rapid, automatic response to a specific stimulus. It is an important mechanism for maintaining homeostasis.

18. Identify the basic characteristics of the polysynaptic reflexes.

All polysynaptic reflexes involve pools of interneurons; are intersegmental in distribution; and involve reciprocal inhibition, reverberating circuits, and the cooperation of several reflexes.

10. An anesthetic blocks the function of the posterior rami of the cervical spinal nerves. Which areas of the body will be affected?

An anesthetic that blocks the function of the posterior rami of the cervical spinal nerves would affect the skin and muscles of the back of the neck and of the shoulders.

4. Damage to which root of a spinal nerve would interfere with motor function?

Damage to the anterior root of a spinal nerve, which contains both visceral and somatic motor fibers, would interfere with the motor function.

11. Injury to which of the nerve plexuses would interfere with the ability to breathe?

Damage to the cervical plexus - or more specifically to the left and right phrenic nerves, which originate in this plexus and innervate the diaphragm - would greatly interfere with the ability to breathe and might even be fatal.

21. During a withdrawal reflex of the foot, what happens to the limb on the side opposite the stimulus? What is this response called?

During a withdrawal, the limb on the opposite side is extended. This response is called a crossed exterior reflex.

6. Differentiate between sensory nuclei and motor nuclei.

Sensory nuclei receive and relay sensory information from peripheral receptors. Motor nuclei issue motor commands to peripheral effectors.

2. Define spinal reflex.

Spinal reflex is a rapid, automatic response is triggered by specific stimuli that is controlled in the spinal cord.

1. Name the structures of the central nervous system (CNS) and of the peripheral nervous system (PNS).

The central nervous system (CNS) is made up of the brain and spinal cord, while cranial nerves and spinal nerves make up the peripheral nervous system (PNS).

5. Where is the cerebrospinal fluid that surrounds the spinal cord located?

The cerebrospinal fluid that surrounds the spinal cord is located in the subarachnoid space, which lies between the epithelium of the arachnoid mater and the pia mater.

16. What is the minimum number of neurons in a reflex arc?

The minimum number of neurons required for a reflex arc is two. One must be a sensory neuron that brings impulses to the CNS, and the other motor neuron that transmit response to the effector.

7. A man with polio has lost the use of his leg muscles. In which area of his spinal cord would you expect the virus-infected motor neurons to be?

The polio virus-infected neurons would be in the anterior horn of the spinal cord, where the cell bodies of somatic motor neurons are located.

20. A weight lifter is straining to lift a 200-kg barbell above his head. Shortly after he lifts it to chest height, his muscles appear to relax and he drops the barbell. Which reflex has occurred?

The response is the tendon reflex.

19. For the patellar (knee-jerk) reflex, how would the stimulation of the muscle spindle by the gamma motor neurons affect the speed of the reflex?

When intrafusion fibers are stimulated by gamma motor neurons, the muscle spindles become more sensitive. As a result, little of any stretching stimulus would be needed to stimulate the contraction of the quadriceps muscle in the patellar reflex. For this reason, the reflex response would appear more quickly.