Ch.13 PNS

Which of the following is the best explanation of how a stimulus's strength is transmitted to the central nervous system from sensory nerves? An action potential will increase in strength as stimulus strength increases. Action potential frequency is increased as stimulus strength increases. Action potentials as well as graded potentials are sent to the central nervous system when stimulus strength increases. More than one type of receptor will respond to larger stimulus.

Action potential frequency is increased as stimulus strength increases.

Examine the cross section through the lumbar section of the spinal cord and the two patellar reflex pathways shown. Select the true statements (more than one) that identify these synapses. Afferent impulses synapse with motor neurons and interneurons. Both pathways will inhibit muscles. Efferent impulses synapse twice with motor neurons. Pathways will activate one muscle and simultaneously inhibit its antagonist muscle. Both pathways will activate muscles. Afferent impulses synapse twice with motor neurons. Efferent impulses synapse with motor neurons and interneurons.

Afferent impulses synapse with motor neurons and interneurons. Pathways will activate one muscle and simultaneously inhibit its antagonist muscle.

Examine and characterize the two motor pathways in the stretch patellar reflex. Alpha motor neurons activate the quadriceps. Once the quadriceps have contracted, alpha motor neurons inhibit the hamstrings. Alpha motor neurons send efferent messages to excite the quadriceps, and the hamstrings are reduced. Alpha motor neurons send efferent messages to the quadriceps, while parallel efferent messages to the hamstrings are reduced. Interneurons excite alpha motor neurons, which in turn excite the muscle.

Alpha motor neurons send efferent messages to the quadriceps, while parallel efferent messages to the hamstrings are reduced.

You are removing a hot pan of cookies from the oven, using a pot holder. Suddenly, you feel a surge of heat through the pot holder. Why don't you react by dropping the baking pan and spilling cookies all over the floor? Sensory input is temporarily suspended to the spinal reflex center. Cortical integration centers override the spinal reflex. The limbic system inhibits the fear of being burned. Efferent signals by cord ventral cord neurons are interrupted.

Cortical integration centers override the spinal reflex.

What is a benefit of a nerve plexus? A plexus does not allow for redistribution. The dorsal ramus can be distributed to many areas. Damage to one single branch of a plexus does not necessarily disrupt all motor information sent to a region. They provide a straight path from the spinal cord to target muscles

Damage to one single branch of a plexus does not necessarily disrupt all motor information sent to a region. Because individual spinal nerves fuse and mix their flow through branches in the plexus, no one damaged area blocks nervous flow completely.

Lamellar corpuscles can only be exteroceptors or proprioceptors. True False

False

Stretch reflexes can cause reciprocal inhibition because the sensory neuron synapses on the alpha motor neurons of both agonists and antagonists. True False

False The stretch reflex activates agonists directly. However, reciprocal inhibition of the antagonist happens through an interneuron.

Select the statement that is most correct. Ganglia associated with afferent nerve fibers contain cell bodies of sensory neurons. Ganglia are collections of neuron cell bodies in the spinal cord that are associated with efferent fibers. The cell bodies of afferent ganglia are located in the spinal cord. The dorsal root ganglion is a motor-only structure.

Ganglia associated with afferent nerve fibers contain cell bodies of sensory neurons.

Which is the true statement about the synapses in the spinal cord in the stretch reflex? Sensory neurons synapse with motor neuron interneurons to excite the extrafusal fibers of the stretched muscle. Polysynaptic interneurons first synapse with higher brain centers. Interneurons make inhibitory synapses with neurons that prevent contraction of the antagonist muscle. The antagonist muscle is activated by increased frequency stimuli.

Interneurons make inhibitory synapses with neurons that prevent contraction of the antagonist muscle. Inhibitory signals to the muscle antagonistic to the stretched muscle will not counteract the stretching, reciprocal inhibition.

Feeling a gentle caress on your arm would likely involve all of the following EXCEPT ________. tactile discs Lamellar (Pacinian) corpuscles hair follicle receptors Tactile (Meissner's) corpuscles

Lamellar (Pacinian) corpuscles

__________ are receptors that can respond to painful stimuli. Photoreceptors Nociceptors Mechanoreceptors Chemoreceptors

Nociceptors Nociceptors respond to potentially damaging stimuli that result in pain.

Select the correct definition. Pattern recognition allows us to see a familiar face. Spatial discrimination allows us to recognize textures. Perceptual detection is the ability to detect how much stimulus is applied to the body. Magnitude estimation is the simplest level of sensation.

Pattern recognition allows us to see a familiar face.

How do proprioceptors help maintain body homeostasis? Proprioceptors help prevent excessive stretching at the joints. Proprioceptors are able to detect temperature so that the body can sweat or shiver if necessary. Proprioceptors detect pain so that the body can be alerted to dangerous stimuli, such as extreme temperatures or harmful chemicals. Proprioceptors help prevent prolonged exposure to harmful chemicals.

Proprioceptors help prevent excessive stretching at the joints. Proprioceptors are located in the muscles, joints, tendons, and ligaments to detect and monitor body position. They send signals to the brain to warn of extensive stretching or hyperextension of a joint.

After axonal injury, regeneration in peripheral nerves is guided by ________. dendrites Wallerian cells Schwann cells Golgi organs

Schwann cells

Which reflex requires gamma motor neurons to set the length of the muscle? tendon reflex stretch reflex crossed-extensor reflex flexor reflex

Stretch reflex The gamma motor neurons signal the intrafusal muscle fibers, which stretch with the skeletal muscle. If the intrafusal fiber is stretched, sensory receptors initiate the stretch reflex.

All processing at the circuit level going up to the perceptual level must synapse in the ________. pons reticular formation medulla thalamus

Thalamus

A patient sustains a ventral horn injury to the lumbar region of the spine. This injury has damaged the cell bodies of several afferent nerves within the region. Predict how the patient's patellar reflex might be affected. The patient's patellar reflex would be absent or weak. The patient's patellar reflex would be hyperactive. The quadriceps would contract, but the hamstring would not relax. Both the quadriceps and the hamstring would contract. The hamstring would relax, but the quadriceps would not contract.

The patient's patellar reflex would be absent or weak.

Which of the following is an incorrect statement regarding the occurrence of a sensation? The stimulus energy must be converted into the energy of a graded potential called a transduction potential. A generator potential in the associated sensory neuron must reach threshold. The stimulus energy must match the specificity of the receptor. The stimulus energy must occur within the receptor's receptive field.

The stimulus energy must be converted into the energy of a graded potential called a transduction potential.

Select the true statements (more than one) about the characteristics of sensory neurons in the stretch reflex. These sensory neurons transmit activating impulses via interneurons. These sensory neurons transmit afferent impulses toward the spinal cord (CNS). These sensory neurons transmit efferent impulses to antagonist muscles. These sensory neurons typically transmit efferent impulses toward antagonist muscles. When a stretch activates the muscle spindle, these sensory neurons transmit impulses at a higher frequency.

These sensory neurons transmit afferent impulses toward the spinal cord (CNS). When a stretch activates the muscle spindle, these sensory neurons transmit impulses at a higher frequency.

What is a difference between tactile (Meissner's) corpuscles and tactile (Merkel) discs? Meissner's corpuscles are classified as mechanoreceptors, while Merkel discs are classified as proprioceptors. Meissner's corpuscles are found in the skin. Merkel discs are found in muscles, ligaments, tendons, and joints. Unlike Merkel discs, Meissner's corpuscles detect light touch. Unlike Merkel discs, Meissner's corpuscles are surrounded (encapsulated) by connective tissue and Schwann cells.

Unlike Merkel discs, Meissner's corpuscles are surrounded (encapsulated) by connective tissue and Schwann cells. Merkel discs are classified as unencapsulated. They lack a connective tissue capsule around the nerve ending.

Nerves that carry impulses toward the CNS only are ________. mixed nerves efferent nerves afferent nerves motor nerves

afferent nerves

Classify the neuron at A. afferent sensory neuron afferent motor neuron interneuron efferent motor neuron

afferent sensory neuron A is an afferent sensory neuron carrying information from the muscle to the CNS.

Three main levels of neural integration operate in the somatosensory system. Which level involves the spinal cord? integrative level perceptual level receptor level

circuit level Processing at the circuit level includes the transmission of action potentials along ascending spinal pathways. These pathways deliver impulses to the appropriate regions of the cerebral cortex for localization and perception of the stimulus.

Which reflex has a contralateral component? crossed-extensor tendon flexor stretch

crossed-extensor The crossed-extensor reflex activates opposing actions in the opposite limb.

Which reflex is triggered when a stranger suddenly grasps your arm? tendon reflex plantar reflex stretch reflex crossed-extensor reflex

crossed-extensor reflex The grasped arm is withdrawn (via the flexor reflex) as the opposite arm pushes you away from the attacker (via crossed-extensor reflex). As in this scenario, the crossed-extensor reflex often accompanies the flexor reflex.

What is the specific function of the structure labeled F? increase tension of the surrounding muscle determine amount of muscle stretching determine muscle tension increase tension of the antagonistic muscle

determine amount of muscle stretching The muscle spindle indicated by F functions as a proprioceptor that is responsive to stretching of the surrounding muscle.

Which type of stimulus would activate nociceptors of the skin? moderate sunlight exposure a vibrating cell phone extreme cold warm bathtub water

extreme cold Nociceptors respond to stimuli that might damage the body, experienced as pain. These stimuli might include extreme heat or cold, excessive pressure, or inflammatory chemicals.

Which of the following is NOT required for a reflex arc? sensory neurons receptors interneurons motor neurons

interneurons In many cases, the interneurons are the integration point for reflexes, but they are not necessary.

Which receptors respond to stimuli within the body? photoreceptors exteroceptors interoceptors proprioceptors

interoceptors

Inborn or intrinsic reflexes are ________. autonomic only always mediated by the brain involuntary, yet may be modified by learned behavior rapid, predictable, and can be learned responses

involuntary, yet may be modified by learned behavior

Regeneration within the CNS ________. typically allows axonal sprouting of 20 mm is more successful than with the PNS is promoted by growth inhibitors and glial scars is prevented due to growth-inhibiting proteins of oligodendrocytes

is prevented due to growth-inhibiting proteins of oligodendrocytes

A person has gone for an appointment to receive a deep-tissue therapeutic massage. Which of the following receptors would be stimulated by the massage? tendon organ lamellae corpuscle bulbous corpuscle free nerve ending

lamellae corpuscle

Which type of sensory receptor allows us to feel an insect landing on our skin? mechanoreceptor nociceptor thermoreceptor chemoreceptor

mechanoreceptor Mechanoreceptors respond to mechanical force such as pressure, vibration, stretch, and touch, allowing us to feel an insect landing on our skin.

Tactile sensation is a combination of touch, pressure, stretch, and vibration. Which of the following is most likely the receptor type that senses tactile stimulation? mechanoreceptors proprioceptors thermoreceptors nociceptors

mechanoreceptors

Hiccups could occur if there was irritation or damage to the ______. cutaneous branches of rami associated with the C3-C5 region of the spinal cord motor branches of ventral rami associated with the C3-C5 region of the spinal cord afferent neurons of spinal nerves associated with the C3-C5 region of the spinal cord dorsal rami of spinal nerves associated with the C3-C5 region of the spinal cord

motor branches of ventral rami associated with the C3-C5 region of the spinal cord The ventral rami of spinal nerves contain motor fibers that originate from neuron soma found in the spinal cord. These efferent pathways activate the contraction of skeletal muscle. The phrenic nerve branches from this region and innervates the skeletal muscle of the diaphragm.

If someone spills very hot coffee (200°F) on their skin, they will likely perceive much pain. Which of the following receptor types is causing this sensation? chemoreceptors mechanoreceptors thermoreceptors nociceptors

nociceptors

We can touch our finger to our nose while our eyes are closed in part because we can sense the position and movement of our joints as well as the length of stretch in our muscles. These sensations create awareness of our body's positioning. Which of the following receptors is most likely responsible for this ability? proprioceptors interoceptor sexteroceptors nociceptors

proprioceptors

Which of the following is the correct simple spinal reflex arc? receptor, efferent neuron, integration center, afferent neuron, effector effector, efferent neuron, integration center, afferent neuron, receptor receptor, afferent neuron, integration center, efferent neuron, effector effector, afferent neuron, integration center, efferent neuron, receptor

receptor, afferent neuron, integration center, efferent neuron, effector

Which of the following lists the hierarchy of motor control from lowest to highest level of control? projection level, precommand level, segmental level segmental level, precommand level, projection level precommand level, projection level, segmental level segmental level, projection level, precommand level

segmental level, projection level, precommand level The hierarchy of motor control from lowest to highest level of control is segmental level, projection level, and precommand level.

Which body locations typically lack proprioceptors? skeletal muscles skin surface connective tissues covering bones and muscles tendons and ligaments

skin surface The skin surface does not contain proprioceptors. Proprioceptors receive stimuli from deeper within the body than the skin surface.

Transduction refers to conversion of ________. afferent impulses to efferent impulses stimulus energy into energy of a graded potential presynaptic nerve impulses to postsynaptic nerve impulses receptor energy to stimulus energy

stimulus energy into energy of a graded potential

The knee-jerk reflex is an example of a __________. superficial reflex tendon reflex flexor reflex stretch reflex

stretch reflex The most familiar clinical example of a stretch reflex is the knee-jerk reflex. The overall goal of a stretch reflex is to maintain a muscle's length and in turn maintain body position. For example, the knee-jerk reflex, during which the knee extensors contract in response to being stretched, helps keep your knees from buckling when you are standing upright.

A reflex that causes muscle relaxation and lengthening in response to muscle tension is called a ________. tendon reflex plantar reflex flexor reflex crossed-extensor reflex

tendon reflex

What reaction would occur if the muscle labeled E were suddenly pulled longer? the relaxation of the both muscles E and G the contraction of muscle E the relaxation of muscle E the contraction of the both muscles E and G

the contraction of muscle E A sudden stretch in a muscle leads to the contraction of the stretched muscle (E) and the relaxation of the antagonistic muscle (G).

A patient has lost the ability to taste food. Which nerve may have been damaged? trigeminal nerves the facial nerves the abducens nerves the optic nerves

the facial nerves

Receptors that respond to changes in room temperature are found in the skin. Which of the following pairs of classifications below best fit the receptor type that is being described above? thermoreceptors that are also interoceptors thermoreceptors that are also exteroceptors mechanoreceptors that are also interoceptors mechanoreceptors that are also exteroceptors

thermoreceptors that are also exteroceptors

Which of the following characteristics is representative of receptor-level processing, NOT perceptual-level processing? spatial discrimination magnitude transduction detection

transduction Transduction is converting a stimulus into a nervous signal; this happens at the receptor level.

A knee-jerk reflex that is unusually strong may be caused by ______. inhibition of reciprocal inhibition transmission of excitatory signals from the brain to the neurons that form the femoral nerve suppression of muscle spindle activity in the lower limb enhancement of activity in the antagonistic muscles

transmission of excitatory signals from the brain to the neurons that form the femoral nerve The femoral nerve innervates all of the muscles that act to extend the knee (quadriceps).