Nervous System

Question 1

somesthetic receptor / somatosensory

Answer 1

a sensory end organ concerned with reception of stimuli producing one of the generalized sensations (such as temperature, pressure, position, or movement)

Question 2

sensory information goes to _____ horn

Answer 2

posterior / dorsal

Question 3

motor signal leaves from _____ horn

Answer 3

anterior / ventral

Question 4

the journey of sensory information to brain

Answer 4

sensory information travels from receptors → sensory neurons (1st order neuron - from receptor to dorsal horn) → spinal cord or brainstem (2nd order neuron - to contralateral thalamus) → thalamus (3rd order neuron - from thalamus to sensory cortex) → sensory cortex

Question 5

sensation

Answer 5

signals transmitted by receptors to brain in form of light, sound, tactile, thermal, pain, etc

Question 6

perception

Answer 6

how sensory information is organized, interpreted and consciously experienced

Question 7

unconscious processing (sensation) occurs at ____ level

Answer 7

subcortical

Question 8

perception (conscious) occurs at the _____ level

Answer 8

cortical

Question 9

meissner’s corpuscles

Answer 9

mechanoreceptors present in highly sensitive areas like fingertips, palms, soles, tongues, lips, and genital skin

• small receptive fields to allow two-point discrimination
• respond to low frequency stimuli (flutter)

Question 10

pacinian corpuscles

Answer 10

• rapidly adapting mechanoreceptors for pressure and vibration
• get used to the sense and stop sending signals to perceive (ex - clothes on skin)

Question 11

hair follicle receptors

Answer 11

rapidly adapting mechanoreceptors that respond to movement across surface of skin

Question 12

merkel’s disks

Answer 12

slow adapting mechanoreceptors that respond to pressure and touch

Question 13

ruffini’s corpuscles

Answer 13

slow adapting mechanoreceptors that respond to stretch found in dermis and joints

Question 14

thermal receptors

Answer 14

free nerve endings that respond to temperature changes; divided in cold and warm slow adapting receptors (specific ones for each temp category)

Question 15

nociceptors

Answer 15

• free nerve endings found in skin, muscle, joints, periosteum and visceral organs capsules
• respond to noxious chemicals, mechanical stimuli (stretch) and temperature

Question 16

Muscle Spindles (in muscles) & Golgi Tendon (in tendons)

Answer 16

proprioception (awareness of your body and its position in space) and coordination of motor activity

Question 17

Sensory Receptive Fields

Answer 17

region of skin that elicits a response in a somatic sensory neuron; vary in diameter (1-2 mm on fingertips [high precision], 5-10 mm on palms, larger in abd and back [lower precision] and may overlap)

Question 18

Transduction of Sensory Signals

Answer 18

• stimuli will generate a graded potential in receptors that if strong enough (summation to threshold) will elicit an AP in a sensory neuron axon
• APs travel to thalamus that will send each sensation modality to specific area of sensory cortex
• cortex has the task of assembling all the information - modality (what), magnitude (how strong), duration (when), location (where) and deciding if it is important (nociceptors get priority!)

Question 19

ascending (afferent) tracts - anterior column

Answer 19

ventral spinothalamic tract (pressure and crude touch)

Question 20

ascending (afferent) tracts - lateral column

Answer 20

lateral spinothalamic tract (pain and temperature); ventral and dorsal spinocerebellar tracts

Question 21

ascending (afferent) tracts - posterior column

Answer 21

fasciculus cuneatus and gracillis (vibration, proprioception, two-point discrimination/fine touch)

Question 22

descending (efferent) tracts - anterior column

Answer 22

ventral corticospinal (pyramidal) tract (voluntary movements, reflexes)

Question 23

descending (efferent) tracts - lateral column

Answer 23

lateral corticospinal (pyramidal) tract (voluntary movements, reflexes)

Question 24

thalamus

Answer 24

• integration and relay of motor and sensory functions except olfactory
• awareness of nociceptive stimuli (non-discriminative form)
• controls subjective response to sensation
• activation and arousal with reticular formation
• modification of affective component of behavior with limbic system
• — limbic system: includes hippocampus, amygdala -> emotion, behavior and long term memory

Question 25

reticular formation

Answer 25

functions: - conscious awareness and behavioral responses to stimuli - maintains wakefulness - muscle tone and posture - respiratory centers (rhythm, depth, pattern) - blood pressure and cardiac output - blood distribution to organs

Question 26

wernicke's area

Answer 26

comprehension of written and spoken language

Question 27

broca's area

Answer 27

production of language

Question 28

Somatic Sensory Cortex / Postcentral Gyrus

Answer 28

receives information from thalamus (skin sensation, proprioception, stereognosis [perception of depth or 3D]); integrates information with visual and auditory signals

Question 29

Sensory Association Area

Answer 29

complex sensory information processing (spatial relationships, body image, two-point discrimination, graphesthesia [ability to recognize symbols when they’re traced on skin])

Question 30

pain fibers

Answer 30

- group A fibers = transmit sharp, shooting intense pain | - group C fibers = transmit steady, slow, constant pain

Question 31

pain

Answer 31

- free nerve endings detect damage to tissues (ischemia - low blood flow, mechanical - pressure or stretch, thermal damage, muscle spasm) - visceral pain is produced by distension, spasm, contraction, torsion, ischemia, chemical irritation or inflammation of viscera - has associated autonomic manifestations and is often referred to parts of body that share a spinal segment with injured viscus (internal organ)

Question 32

ascending pain pathways

Answer 32

- spino-thalamic-somatosensory cortex = mediates sensation of pain - spino-thalamic-frontal cortex/anterior cingulate gyrus = subjective psychological and physiological effects of pain

Question 33

descending pain pathways

Answer 33

- modulation by fibers from periaqueductal grey matter, nucleus raphe and reticular formation to doral horn (descend in dorsolateral funiculus) - neurotransmitters = adrenaline, GABA, serotonin, endorphins (opoids)