A&P II Ch. 15 Sensory Pathways and the Somatic Nervous System
Descending (motor) pathways always involve at least ________ motor neuron(s).
2.
How many major motor pathways are there?
3
Sensory information requires __________ neuron(s) to reach the thalamus.
3
Stimulation of a neuron that terminates in the superior region of the left postcentral gyrus would produce...
A sensation in the right leg.
A reduction in sensitivity in the presence of a constant stimulus is referred to as...
Adaptation.
The pyramidal system includes which of the following?
All of the listed responses are correct.
Which of the following serve as receptors to measure body position and balance?
All of the listed responses are correct.
The spinal tract that relays information concerning crude touch and pressure to the CNS is the...
Anterior spinothalamic.
Mechanoreceptors that respond to changes in blood pressure are called...
Baroreceptors.
A brain injury to a patient results in facial paralysis. Which descending tract is most likely affected?
Corticobulbar tract.
The pyramids on the ventral surface of the medulla oblongata are formed by fibers of the ________ tracts.
Corticospinal.
Which neuron delivers sensations to the CNS?
First-order.
Which of these is NOT a property of the somatic nervous system?
Has control of cardiac muscle.
Which of the following statements about the sensory homunculus is FALSE?
Hearing from the left ear is processed in the right sensory homunculus.
The cerebellum:
If damaged leads to uncoordinated and jerky movements, compares intended movement to actual movement, receives input from the motor cortex and basal ganglia, functions to maintain proper posture and equilibrium.
Some neurons within the basal nuclei are known to...
Inhibit neurons with GABA and stimulate neurons with acetylcholine.
Which role does the medulla play in somatic motor control?
It balances reflexes and respiratory reflexes.
Which of the following statements about adaptation is FALSE?
It is a feature of tonic receptors but not of phasic receptors.
Which of these is NOT a property of fast pain?
It is fast-adapting.
If a nerve impulse was transmitted to the central nervous system (CNS) on a C fiber, __________.
It would lead to a slow sensation of pain.
The link between peripheral receptor and cortical neuron is called a(n)...
Labeled line.
A very large, fast-adapting tactile receptor that is composed of a single dendrite enclosed by concentric layers of collagen is a...
Lamellated (Pacinian) corpuscle.
Axons that decussate between the pyramids of the medulla oblongata belong to the ________ tracts.
Lateral corticospinal.
The descending spinal tract that crosses to the opposite side of the body within the medulla oblongata is the ________ tract.
Lateral corticospinal.
The spinal tract that relays information concerning pain and temperature to the CNS is the...
Lateral spinothalamic.
The upper motor neurons of the medial pathway are located within any of the following except the...
Mamillary bodies.
Descending tracts in the spinal cord relay ________ information.
Motor.
Proprioceptors signal all BUT __________.
Muscle temperature.
Endorphins can reduce perception of sensations initiated by...
Nociceptors.
Sensory neurons that adapt quickly are called ________ receptors.
Phasic.
Which of the following is not one of the special senses?
Pressure.
Receptors that monitor the position of joints belong to the category called...
Proprioceptors.
The basal nuclei:
Provides the background patterns of movement involved in voluntary motor activities.
The corticospinal system is often referred to as the...
Pyramidal system.
The ________ is the area monitored by a single receptor cell.
Receptive field.
Feeling pain in the left arm during a heart attack is an example of ________ pain.
Referred.
Complex motor activities such as riding a bicycle...
Require the coordinated activity of several regions of the brain.
The spinal tract that normally plays a role in the subconscious regulation of the muscles of the arms is the ________ tract.
Rubrospinal.
We can localize sensations that originate in different areas of the body because...
Sensory neurons from specific body regions project to specific cortical regions.
The ________ nervous system carries impulses to skeletal muscles.
Somatic.
Which of these sensory pathways carries afferent impulses that DON'T produce perceptions?
Spinocerebellar pathway.
The spinal tract that carries sensations from proprioceptors to the CNS is the...
Spinocerebellar.
A tactile receptor composed of highly coiled dendrites that are surrounded by modified Schwann cells and a fibrous capsule is a...
Tactile (Meissner) corpuscle.
The medial pathway that controls involuntary movements of head, neck, and arm position in response to sudden visual and auditory stimuli is the ________ tract.
Tectospinal.
Which of the following kinds of information do fine-touch and light-pressure mechanoreceptors provide?
Texture of the stimulus, shape of the stimulus, location of the stimulus, movement of the stimulus
Why is it that one cannot identify the location of internal organs, although joints and bone location can be identified?
The internal organs have no proprioceptors like joints, bones, and muscles.
Which of the following statements about levels of processing and motor control is correct?
The number of neurons in the cerebral cortex continues to increase until at least age four.
Sensory information from all parts of the body is routed to...
The somatosensory cortex.
Sensory encoding of the perceived location of a stimulus depends on...
The specific location of the cortical neuron that is stimulated.
Which of the following is NOT a component of the spinocerebellar pathway?
The thalamus.
Which descending pathway is found in the anterior white column and carries impulses relating to equilibrium and balance?
The vestibulospinal tract.
Which of these is NOT a property of phasic receptors?
They are always active.
What is the minimum number of synapses that must be crossed before an afferent nerve impulse becomes a perception?
Three.
The cerebellum adjusts motor activity in response to all of the following except...
Touch sensations.
The conversion of a sensory input to a change in membrane potential in the receptor is known as...
Transduction.
Which of these are NOT part of the afferent division of the nervous system?
Ventral roots.
The heart muscle is a ________ effector.
Visceral.
The pyramidal system provides...
Voluntary control over skeletal muscles.
The sensory homunculus is __________.
a functional map of the somatosensory cortex
Which of the following is a progressive degenerative disorder that affects motor neurons in the spinal cord, brain stem, and cerebral hemispheres?
amyotrophic lateral sclerosis
Which of the following tracts are NOT involved in proprioception?
anterior and lateral spinothalamic tracts
Which type of receptor detects pressure changes?
baroreceptor
Chemoreceptors are located in __________.
both the carotid arteries and the aorta
In somatic motor control, the cerebellum's role involves __________.
coordinating complex motor patterns
The extrapyramidal tracts do NOT include which of the following?
corticobulbar
The anterior spinothalamic pathway carries the sensations of __________.
crude touch and pressure
The relative proportions to the sensory and motor homunculus are __________.
different because some sensitive areas have few muscles
Which of these types of sensory receptors is INCORRECTLY linked with its function?
exteroceptor—monitors pressure in the lungs
The posterior column pathway carries the sensations of __________.
fine touch and pressure
Which of the following best describes the sensory information provided by the fasciculus gracilis?
fine touch, pressure, and vibration from the inferior half of the body
A receptor potential large enough to generate an action potential is called __________.
generator potential
Which of the following INCORRECTLY pairs centers of somatic motor control with their activities?
inferior medulla oblongata—coordinates complex motor patterns
Which of the following INCORRECTLY pairs types of tactile receptors with their functions?
lamellated corpuscles—Also called Meissner corpuscles, these measure fine touch and pressure and low-frequency vibrations in eyelids, fingertips, and lips.
Which of the following correctly links components of the pyramidal motor pathways?
lateral corticospinal tracts—descend without crossing to level of spinal nerves
Which receptors are common in superficial portions of the skin, in joint capsules, within the periostea of bones, and around the walls of blood vessels?
nociceptors
Which of the following is NOT classified as a general sense?
olfaction
Which of the following correctly defines referred pain?
pain felt in an uninjured body area rather than in the area where the injury actually occurred
Somatic sensory information does NOT travel to which of the following locations?
primary motor cortex
The spinocerebellar pathway carries the sensations of __________.
proprioception
Which of the following is NOT considered a special sense?
proprioception
Which one of the following is NOT a correct linkage of a receptor type with the stimulus that excites it?
proprioceptor—touch on skin surface
The simplest reflexes are mediated at the level of the __________.
spinal cord
Your ability to localize sensations depends on __________.
the projection of sensation to the primary sensory cortex
The area monitored by a single receptor is called __________.
the receptive field
There are __________ major sensory pathways.
three