Chapter 15 review questions

Question 1

what do we call the specialized cells that monitor specific internal or external conditions?

Answer 1

sensory receptors

Question 2

Is it possible for somatic motor commands to occur at the subconscious level?

Answer 2

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

Question 3

define adaptation

Answer 3

adaptation is a decrease in receptor sensitivity or a decrease in perception after constant stimulation

Question 4

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?

Answer 4

receptor A bc it has a smaller receptive field

Question 5

list the 4 types of general sensory receptors, and identify the nature of the stimulus that excites each type

Answer 5

thermoreceptors - temp
mechanoreceptors -physical distortion
nociceptors - pain
chemoreceptors - chemical concentration

Question 6

identify the 3 classes of mechanoreceptors

Answer 6

tactile
proprioceptors
baroceptors

Question 7

what would happen if information from proprioceptors in your legs were blocked from reaching the CNS?

Answer 7

esp the lack of information being sent to the cerebellum would result in your movements being uncoordinated and you could likely not walk

Question 8

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

Answer 8

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

Question 9

which spinal tract carries action potentials generated by nociceptors

Answer 9

lateral spinothalamic

Question 10

which cerebral hemisphere receives impulsues conducted by right fasciculus gracilis

Answer 10

the left cerebral hemisphere (specifically the primary sensory cortex)

Question 11

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?

Answer 11

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

Question 12

an injury involving the superior portion of the motor cortex affects which region of the body?

Answer 12

the ability to control muscles in the upper limb and proximal portion of the lower limb

Question 13

what effect would increased stimulation of the motor neurons of the red nucleus have on muscle tone?

Answer 13

this would increase stimulation of skeletal muscles in the upper limbs, thereby increasing their muscle tone

Question 14

the larger the receptive field……..

Answer 14

the harder it is to locate the exact point of stimulation

Question 15

_____ are receptors that are normally inactive, but become active for a short time whenever there is a change in the condition that they monitor

Answer 15

phasic

Question 16

the CNS interprets information entirely on the basis of……….

Answer 16

the line over which the sensory information arrives

Question 17

the area of sensory cortex devoted to a body region is relative to the….

Answer 17

number of sensory receptors in the area of the body

Question 18

identify 6 types of tactile receptors located in the skin, and describe their sensitivities

Answer 18

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

Question 19

what 3 types of mechanoreceptors respond to stretching, compression, twisiting, or other distortions of the plasma membrane?

Answer 19

tactile receptors
proprioceptors
baroceptors

Question 20

what are the 3 major somatic sensory pathways and what is the function of each pathway?

Answer 20

spinothalamic – crude touch, pressure, temp, and pain
posterior column – fine touch, pressure, vibrations, proprioception
spinocerebellar – positions of joints, muscles, tendons to the cerebellum

Question 21

what are the 2 primary functional roles of the cerebellum

Answer 21

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

Question 22

the corticospinal tract carries information……..

Answer 22

from the cerebral cortex to the spinal cord

Question 23

what 3 steps are necessary for transduction to occur?

Answer 23

1. an arriving stimulus alters the transmembrane potential of the receptor membrane
2. the receptor potential directly or indirectly affects a sensory neuron
3. action potentials travel to the CNS along an afferent fiber

Question 24

differentiate between a tonic receptor and a phasic receptor

Answer 24

tonic – always active
phasic – normally inactive and becomes active only when a change occurs in the condition being monitored

Question 25

describe the relationship among first, second, and third order neurons in a sensory pathway

Answer 25

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

Question 26

what effect does injury to the primary motor cortex have on peripheral muscles?

Answer 26

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

Question 27

what is a motor homunculus? how does it differ from a sensory homunculus?

Answer 27

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

Question 28

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)?

Answer 28

left leg

Question 29

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?

Answer 29

basal nuclei, cerebellum, and red nuclei through commands distributed by the reticulospinal or rubrospinal tracts

Question 30

didnt do critical thinking q’s

Answer 30

review motor pathways. dont really undertsand