Interoceptors
respond to stimuli arising within the body
Exteroceptors
react to stimuli in the external environment, closest to the body surface
Backing into a sun-heated iron railing
Exteroceptor, pain receptor
Someone steps on your foot
Exteroceptor, pain receptor
Reading a book
Exteroceptor, photoreceptor
Leaning on your elbows
Exteroceptor and Interoceptor, pacinian corpuscle and proprioceptor
Doing sit-ups
Interoceptor, proprioceptor
The "too full" sensation
Interoceptor, visceral receptor
Seasickness
Exteroceptor, equilibrium of the inner ear
Explain how sensory receptors act as transducers.
Changing the environmental stimuli into nerve impulses that are relayed to the CNS
Stimulus
anything that can trigger a response (action potential)
What was determined by the two-point discrimination test?
testing touch receptors and how they are distributed in different areas of the body
What is the relationship between the accuracy of the subject's tactile localization and the results of the two-point discrimination test?
the distance of both were not closely similar
Punctate distribution
the type of distribution of sensory receptors in which they are not distributed uniformly, but instead have discrete locations and are characterized by clustering at certain points
Which cutaneous receptors are the most numerous?
pain receptors
Which two body areas tested were the most sensitive to touch?
lips, fingers
What two body areas tested were least sensitive to touch?
ventral forearm, back of the neck
Where would referred pain appear if (1) gallbladder, (2) kidneys, (3) appendix were receiving painful stimuli?
1. right inferior thorax
2. lumbar
3. right lower quadrant
Where was the referred pain felt when the elbow was immersed in ice water?
medial hand
What region of the cerebrum interprets the stimuli (type and intensity) that causes cutaneous sensation?
somatosensory cortex
Adaptation of sensory receptors
when the receptors discharge slows and conscious awareness of the stimulus declines or is lost until some type of stimulus change occurs
Why is it advantageous to have pain receptors that are sensitive to all vigorous stimuli, whether heat, cold, or pressure?
protection, prevention of injury, to warn you quickly of harm or dangers that are happening to your body
Why is the non-adaptability of pain receptors important?
provides an on going alertness; prevention of on going injury or damage
Imagine yourself without any cutaneous sense organs. Why might this be very dangerous?
lack of a warning means increased potential for damage or injury
Referred pain
a sensory experience in which pain is perceived as arising in one area of the body when in fact another, often quite remote area is receiving the painful stimulus
What is the probable explanation for referred pain?
referred pain may occur because the nerves innervating both viscera (organs) and somatic structures travel along the same pathways