Chapter 15 review questions Flashcards
what do we call the specialized cells that monitor specific internal or external conditions?
sensory receptors
Is it possible for somatic motor commands to occur at the subconscious level?
yes. somatic motor commands occur at both the conscious and subconscious level.
regardless, they both travel from motor centers in the brain along SOMATIC MOTOR PATHWAYS
define adaptation
adaptation is a decrease in receptor sensitivity or a decrease in perception after constant stimulation
Receptor A has a circular receptive field with a diameter of 2.5cm
Receptor B has a circular receptive field 7.0cm in diameter.
which receptor provides more precise sensory information?
receptor A bc it has a smaller receptive field
list the 4 types of general sensory receptors, and identify the nature of the stimulus that excites each type
thermoreceptors - temp
mechanoreceptors -physical distortion
nociceptors - pain
chemoreceptors - chemical concentration
identify the 3 classes of mechanoreceptors
tactile
proprioceptors
baroceptors
what would happen if information from proprioceptors in your legs were blocked from reaching the CNS?
esp the lack of information being sent to the cerebellum would result in your movements being uncoordinated and you could likely not walk
as a result of pressure on her spinal cord, jill cannot feel fine touch or pressure on her lower limbs. which spinal tract is being compressed
fasciculus gracilis in the posterior column of the spinal cord which carries information about fine touch and pressure from the lower limbs to the brain
which spinal tract carries action potentials generated by nociceptors
lateral spinothalamic
which cerebral hemisphere receives impulsues conducted by right fasciculus gracilis
the left cerebral hemisphere (specifically the primary sensory cortex)
what is the anatomical basis for the fact that the left side of the brain controls motor function on the right side of the body?
the crossing over (decussation) of axons, so the motor fibers of the corticospinal pathway innervate lower motor neurons on the opposite side of the body
an injury involving the superior portion of the motor cortex affects which region of the body?
the ability to control muscles in the upper limb and proximal portion of the lower limb
what effect would increased stimulation of the motor neurons of the red nucleus have on muscle tone?
this would increase stimulation of skeletal muscles in the upper limbs, thereby increasing their muscle tone
the larger the receptive field……..
the harder it is to locate the exact point of stimulation
_____ are receptors that are normally inactive, but become active for a short time whenever there is a change in the condition that they monitor
phasic
the CNS interprets information entirely on the basis of……….
the line over which the sensory information arrives
the area of sensory cortex devoted to a body region is relative to the….
number of sensory receptors in the area of the body
identify 6 types of tactile receptors located in the skin, and describe their sensitivities
free nerve endings – sens. to touch and pressure
root hair plexus – monitors distortions and
movement across body surface
tactile discs- detect fine touch and pressure
tactile corpuscles - detect fine touch and pressure
lamellated corpuscles - sensitive to pulsing or vibrating stimuli
ruffini corpuscles – sensitive to pressure and distortion of the skin
what 3 types of mechanoreceptors respond to stretching, compression, twisiting, or other distortions of the plasma membrane?
tactile receptors
proprioceptors
baroceptors
what are the 3 major somatic sensory pathways and what is the function of each pathway?
spinothalamic – crude touch, pressure, temp, and pain
posterior column – fine touch, pressure, vibrations, proprioception
spinocerebellar – positions of joints, muscles, tendons to the cerebellum
what are the 2 primary functional roles of the cerebellum
integrate proprioceptive sensations with visual information from the eyes and equilibrium-related sensations from the internal ear
ajust the activities of voluntary and involuntary motor centers on the basis of sensory information and the stored memories of previous experiences
the corticospinal tract carries information……..
from the cerebral cortex to the spinal cord
what 3 steps are necessary for transduction to occur?
- an arriving stimulus alters the transmembrane potential of the receptor membrane
- the receptor potential directly or indirectly affects a sensory neuron
- action potentials travel to the CNS along an afferent fiber
differentiate between a tonic receptor and a phasic receptor
tonic – always active
phasic – normally inactive and becomes active only when a change occurs in the condition being monitored
describe the relationship among first, second, and third order neurons in a sensory pathway
a sensory neuron that delivers sensation to the CNS is a first order neuron. within the CNS, the axon of a first order neuron synapses on a second order neuron, which is an interneuron in the spinal cord or brainstem. The second order neuron synapses with a third order neuron in the thalamus. the axons of 3rd order neurons synapse on neurons of the primary sensory cortex of the cerebral hemispheres
what effect does injury to the primary motor cortex have on peripheral muscles?
affects the ability to exert fine control over motor units. gross movements are still possible because they are controlled by basal nuclei that use the reticulospinal or rubrospinal tracts.
walking, and other voluntary and involuntary movements can be performed but with difficulty, and the movements are imprecise and awkward
what is a motor homunculus? how does it differ from a sensory homunculus?
motor homunculus = a mapped out area of the primary motor cortex, provides an indication of degree of fine motor control available.
a sensory homunculus indicates the degree of sensitivity of peripheral sensory receptors
damage to the posterior spinocerebellar tract on the left side of the spinal cord at the L1 level would interfere with the coordinated movements of which limb(s)?
left leg
by which structures and in which part of the brain id the level of muscle tone in the body’s skeletal muscles controlled? how is this control exerted?
basal nuclei, cerebellum, and red nuclei through commands distributed by the reticulospinal or rubrospinal tracts
didnt do critical thinking q’s
review motor pathways. dont really undertsand
