Ch. 4 (part A)

Question 1

Tonic vs Phasic Adaption

Answer 1

• slow adaption, maintain homeostasis
  ex. baroreceptors, proprioceptors
• rapid adaptation, exhibits “off” response after stimulus stops
  ex. touch, smell

Question 2

Generator vs Receptor Potential

Answer 2

• between depolarized receptor ending and afferent fiber initiates action potential by opening Na channels
• chemical messenger released from separate receptor initiates action potential (chemically gated)

Question 3

Somatosensory Pathways

Answer 3

first order: afferent neuron- directly affected by stimulus
second order: spinal or medulla (RAS)
third order: thalamus to higher cortex

Question 4

Acuity

Answer 4

receptive field: large (from one point) or small (two points)
lateral inhibination: one halts transmission in less intense pathways; focalizes localization
** all sensations use lateral inhabitation eg. eye (oemarcate maragins- contours)

Question 5

Touch Receptors

Answer 5

free nerve endings: eg. pain (noxious stimuli)
Merkel’s discs: eg. texture, pressure
Ruffini’s corpuscles: stretch, bring back to normal (skin or muscle)
Meissner’s corpuscles: stroking eg. fingers, lips
Pacinian corpuscles: large and deep- touch and vibrations

Question 6

Perception/ Modality/ Transduction/ Adaptation

Answer 6

• conscious interpretation, using memory and sensory systems (nerve signalling)
• energy form of a signal (light, sounds, olfaction)
• one modality changed into another (signals)
• fires then decreases over time (reception)