Ch. 13 Study Guide

[Ch. 13 CQ #13] Collections of neuron cell bodies in the peripheral nervous system are known as __________. (A) ganglia (B) Schwann cells (C) tracts (D) nerves (E) nuclei

(A) ganglia

[Ch. 13 Specific Question #4] Which nerve plexus roughly covers each of the following areas? (A) anterior thigh (B) leg and posterior thigh (C) neck and shoulders (D) upper limbs

(A) lumbar (B) sacral (C) cervical (D) brachial

[Ch. 13 CQ #4] Which of the following cranial nerves is NOT involved with the eye? (A) trigeminal (B) optic (C) oculomotor (D) trochlear (E) abducens

(A) trigeminal The oculomotor, trochlear, and abducens innervate the extrinsic muscles of the eye. The optic is the sensory nerve of vision and is actually a brain tract.

[Ch. 13 CQ #17] Which of the following cranial nerves controls chewing food? (A) trigeminal nerve (B) vagus nerve (C) vestibulocochlear nerve (D) hypoglossal nerve (E) facial nerve

(A) trigeminal nerve The trigeminal nerve controls the muscles of mastication.

[Ch. 13 CT #14] If the phrenic nerve were severed, what would be the most immediate effect? (A) The upper limbs would be paralyzed. (B) Breathing would stop. (C) The sense of smell would be blocked. (D) The ability to swallow would be blocked.

(B) Breathing would stop. The phrenic nerve serves the diaphragm. If this nerve is irritated, then hiccups result. If this nerve is crushed or damaged, the diaphragm becomes paralyzed and independent breathing ceases.

[Ch. 13 CT #3] Proprioceptors advise the brain of __________. (A) pain localization (B) body movements (C) chemical imbalances (D) temperature of the skin

(B) body movements Proprioceptors advise the brain of our body movements by monitoring how much the organs containing these receptors (skeletal muscles, tendons, joints, and ligaments and in connective tissue coverings of bones and muscles) are stretched.

[Ch. 13 CT #1] Which of the following structures is NOT a part of the peripheral nervous system (PNS)? (A) motor endings (B) brain (C) ganglia (D) sensory receptors

(B) brain The PNS includes all neural structures outside of the brain and spinal cord—that is, the sensory receptors, peripheral nerves and their associated ganglia, and efferent motor endings.

[Ch. 13 CQ #12] Which of the following reflexes would test the integrity of L4 to S2? (A) striking the patellar ligament with a reflex hammer (B) downward curling of the toes as blunt object is drawn downward along the lateral aspect of the foot (C) contraction of the muscles of the anterior compartment of the thigh while the posterior compartment muscle relaxes (D) lifting a cut foot if you step on a piece of glass (E) stroking the skin of the lateral abdomen

(B) downward curling of the toes as blunt object is drawn downward along the lateral aspect of the foot The plantar reflex tests the integrity of the spinal cord from L4 to S2 and determines whether the corticospinal tracts are functioning properly.

[Ch. 13 Clicker Question #6] What is the "modality" of the oculomotor cranial nerve? (A) afferent (B) efferent (C) mixed

(B) efferent

[Ch. 13 Clicker Question #2] The sensory receptors that sense touch, pressure, or tension have ion channels in their dendrites and cell bodies that are (A) ligand-gated (B) mechanically gated (C) voltage-gated (D) ungated (always open)

(B) mechanically gated

[Ch. 13 CT #7] Fast-adapting receptors are called __________. (A) tonic receptors (B) phasic receptors (C) sensory receptors (D) threshold receptors

(B) phasic receptors

[Ch. 13 CQ #23] Concerning sensory perception, the two-point discrimination test assesses the patient's for __________. (A) quality discrimination (B) spatial discrimination (C) pattern recognition (D) magnitude estimation

(B) spatial discrimination

[Ch. 13 CQ #26] Hilton's law states that __________. (A) any nerve serving a muscle that produces a movement at a joint innervates the joint, but it does not innervate the skin over the joint (B) any nerve serving a muscle that produces a movement at a joint does not innervate the joint (C) any nerve serving a muscle that produces a movement at a joint innervates the skin over the joint, but it does not innervate the joint (D) any nerve serving a muscle that produces a movement at a joint also innervates the joint and the skin over the joint

(C) any nerve serving a muscle that produces a movement at a joint innervates the skin over the joint, but it does not innervate the joint

[Ch. 13 RQ #10] A reflex that causes reciprocal activation of the antagonist muscle is the (A) crossed-extensor (B) flexor (C) tendon (D) muscle stretch

(C) tendon

[Ch. 13 CT #10] A nerve that carries autonomic signals away from the central nervous system is classified as a __________. (A) somatic efferent (B) visceral afferent (C) visceral efferent (D) somatic afferent

(C) visceral efferent Visceral refers to autonomic nervous system fibers.

[Ch. 13 Clicker Question #5] Which cranial nerves concern the tongue? (A) I and IV (B) III and VI (C) VI and IX (D) IX and XII (E) I, II, III, IV, V, VI, VII, VIII, IX, X, XI, and XII

(D) IX (glossopharyngeal) and XII (hypoglossal)

[Ch. 13 CQ #24] Wallerian degeneration is the __________. (A) degeneration of the axon and myelin sheath proximal to the injury site caused by the lack of nutrients (B) degeneration of the axon and myelin sheath caused by repeated stimulation (C) degeneration of the axon and myelin caused by the presence of toxins (D) degeneration of the axon and myelin sheath distal to the injury site caused by the lack of nutrients

(D) degeneration of the axon and myelin sheath distal to the injury site caused by the lack of nutrients

[Ch. 13 CQ #5] Which of the following cranial nerves is purely sensory? (A) trigeminal (B) hypoglossal (C) accessory (D) optic (E) vagus

(D) optic The cranial nerves associated with sensory organs of sight, sound, and smell are considered purely sensory.

[Ch. 13 CQ #6] Which of the following cranial nerves has a name that means "the wanderer"? (A) trochlear (B) glossopharyngeal (C) trigeminal (D) vagus (E) vestibulocochlear

(D) vagus The vagus nerve is the only cranial nerve to extend beyond the head and neck to the thorax and abdomen.

[Ch. 13 Clicker Question #3] Which cells are most helpful in repairing axons of injured neurons? (A) astrocytes (B) ependymal cells (C) microglia (D) oligodendrocytes (E) Schwann cells

(E) Schwann cells

[Ch. 13 Clicker Question #4] In general, the effector of a reflex arc could be (A) a gland (B) cardiac muscle (C) skeletal muscles (D) smooth muscles (E) all of the above

(E) all of the above

[Ch. 13 RQ #5] Dorsal root ganglia contain (A) cell bodies of somatic motor neurons (B) axon terminals of somatic motor neurons (C) cell bodies of autonomic motor neurons (D) axon terminals of sensory neurons (E) cell bodies of sensory neurons.

(E) cell bodies of sensory neurons.

[Ch. 13 Specific Question #2] For the efferent nervous system, "somatic" means voluntary while "visceral" means involuntary. All reflexes are involuntary; they happen automatically. So what does it really mean for a reflex to be "somatic," as opposed to "visceral"?

A somatic reflex is a reflex that activates muscles over which you normally have voluntary control, even if they are sometimes triggered automatically. For example, the patellar tendon reflex activated your quadriceps muscles, which you can control voluntarily, so this is a somatic reflex.

[Ch. 13 CT #19] In a reflex arc, the __________ transmits afferent impulses to the central nervous system. (A) integration center (B) receptor (C) sensory neuron (D) effector

C) sensory neuron The five essential components of a reflex arc are the receptor, the sensory neuron, the integration center, the motor neuron, and the effector. The receptor is the site of stimulation. The sensory neuron transmits afferent impulses to the CNS. Once the afferent signal arrives to the CNS, it will be integrated in the integration center and then transmitted by a motor neuron to the effector.

[Ch. 13 CQ #16] In a reflex arc, the muscle fiber or gland that responds to the efferent impulses is known as the __________. (A) receptor (B) integration center (C) motor neuron (D) sensory neuron (E) effector

E) effector

[Ch. 13 CT #9] Most central nervous system axons are able to regenerate following injury. True or False?

False Unlike axons of peripheral nerves, axons of CNS (brain and spinal cord) neurons do not regenerate following injury. Thus, damage to the brain or spinal cord is typically considered irreversible.

[Ch. 13 CYU #7] Your cortex decodes incoming APs from sensory pathways. How does it tell the difference between hot and cold? Between cool and cold? Between ice on your finger and ice on your foot?

Hot and cold are conveyed by different sensory receptors that are parts of separate "labeled lines." Cool and cold are two different intensities of the same stimulus, detected by frequency coding--the frequency of APs would be higher for a cold stimulus than for a cool one. Action potentials arising in the fingers and foot arrive at different locations in the somatosensory cortex via their own "labeled lines" and in this way the cortex can determine their origin.

[Ch. 13 Specific Question #5] Explain how sensory adaptation affects the axons and output (synaptic transmission) of sensory neurons.

In brief, sensory adaption means that sensory neurons start firing fewer action potentials in response to the same continuing level of a stimulus.

[Ch. 13 RQ #19] Explain why damage to peripheral nerve fibers is often reversible, whereas damage to CNS fibers rarely is.

In the PNS, damaged fibers can be replaced or repaired by physical and chemical processes directed by macrophages and Schwann cells. In the CNS, oligodendrocytes do not aid fiber regeneration because they have growth-inhibiting. (pp. 497-498)

[Ch. 13 Specific Question #1] Your textbook says that a reflex arc has 5 steps. Does that mean it includes 5 neurons?

No! A reflex may have as few as 2 neurons (e.g., the patellar tendon reflex, which only has a 1 sensory neuron and 1 motor neuron), or there may be more than that (e.g., at least 1 interneuron and 2 motor neurons for visceral reflexes).

[Ch. 13 Specific Question #3] Classify each of the reflexes that you studied in lab 2 as somatic or visceral and as spinal or cranial.

Patellar tendon: somatic, spinal. Babinski: somatic, spinal. Corneal: somatic, cranial. Salivary: visceral, cranial. Pupillary: visceral, cranial.

[Ch. 13 CYU #6] What is the key difference between tonic and phasic receptors? Why are pain receptors tonic?

Phasic receptors adapt, whereas tonic receptors exhibit little or no adaptation. Pain receptors are tonic so that we are reminded to protect the injured body part.

[Ch. 13 Specific Question #6] Briefly explain what referred pain is and how it reflects the structure/organization of the nervous system.

Referred pain is a phenomenon in which painful stimuli coming from one area of the body are perceived as coming from a different area. For example, in Lab 2 you put your elbow in ice water, but the discomfort of the cold may have felt at times as if it were coming from your palm or fingers. Other examples can be seen in Figure 13.3 in your textbook. The basis for this "confusion" is that your major nerves (e.g., the ulnar nerve, in the case of the ice-water experiment) your collect sensory information from many different areas, so a stimulus from one area may be misinterpreted by the brain as coming from another area.

[Ch. 13 RQ #28] What clinical information can be gained by conduction somatic reflex tests?

Reflex tests assess the condition of the nervous system. Exaggerated, distorted, or absent reflexes indicate degeneration or pathology of specific regions of the nervous system often before other signs are apparent (p. 520)

[Ch. 13 CYU #12] Spinal nerves have both dorsal roots and dorsal rami. How are these different from each other in location and composition?

Roots lie medial to spinal nerves, where as rami lie lateral to spinal nerves. Dorsal roots are purely sensory, whereas dorsal rami carry both motor and sensory fibers.

[Ch. 13 CYU #10] Will's femoral nerve was crushed while clinicians tried to control bleeding from his femoral artery. This resulted in loss of function and sensation in his leg, which gradually returned over the course of a year. Which cells were important in his recovery?

Schawnn cells, macrophages, and the neurons themselves were all important in healing the nerve.

[Ch. 13 General Question #3] If given a symptom relating to a cranial nerve, identify which of the 12 cranial nerves is the likely source of the problem. Example: You are having trouble moving your tongue.

The likely problem is with cranial nerve XII (hypoglossal). Note that cranial nerve IX (glossopharyngeal) also involves the tongue, but is collecting sensory info from the tongue.

[Ch. 13 Specific Question #7] Which reflex is completed faster: patellar or salivary? Why?

The patellar tendon reflex is faster. This can be explained in at least 2 ways. The patellar tendon reflex has only two neurons, so it is faster than the salivary reflex, which involves at least 4 neurons. Also, you could say that the purpose of the patellar tendon reflex is to keep people from falling over, so that reflex needs to happen very fast for it to do its job, whereas the salivary reflex isn't as time-sensitive.

[Ch. 13 General Question #2] If given a symptom relating to a spinal reflex, identify where in the 5 steps of a reflex arc the problem is likely to be. Example: You can feel a pin prick on the sole of your foot, and it feels painful, but it does not lead to withdrawal of your foot.

The sensory information clearly is being transmitted, so the problem must be "downstream" of that, i.e., in the interneuron, motor neuron, or effector (the muscle itself).

[Ch. 13 CYU #19] Juan injured his back in a fall. When his ER physician stroked the bottoms of Juan's foot, she noted that his big toe pointed up and his other toes fanned out. What is this response called and what does it indicate?

This response is called Babinski's sign and it indicates damage to the corticospinal tract or primary motor cortex.

[Ch. 13 CT #13] All spinal nerves are mixed nerves. True or False?

True All 31 pairs of spinal nerves are mixed nerves. They are all able to convey information both to and from the CNS.

[Ch. 13 CT #8] Most nerves are able to transmit impulses both to and from the central nervous system. True or False?

True Nerves that carry impulses only toward the CNS are sensory (afferent) nerves. Nerves that carry impulses only away from the CNS are motor (efferent) nerves. However, most nerves are mixed nerves; they are able to transmit impulses both to and from the CNS.

[Ch. 13 General Question #1] If given a figure like 12.8 in your textbook, say which of two bodily areas has a higher density of somatosensory receptors or a higher degree of motor control (e.g., back vs. hand). Example: In which area can you more easily make subtle adjustments to your muscles: your face, or your feet?

Your face, because it has more cortical space devoted to motor control of this region.