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