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Directed study: to complement your understanding of the sensory pathways, now study the
body’s receptors and the ‘special’ senses.
Choose from the following texts to support your learning: Chapter 15 in Tortora, Chapter 11 in Seikel
et al (2005), Chapter 5 in Love & Webb (2001), and/or Chapter 9 in Atkinson & McHanwell (2002).
Now attempt the following questions:
1. What is meant by sensation?
2. Sensation can be divided into the somatic (bodily) and the special senses. What do we mean by
the special senses?
3. Four events typically occur in order for a sensation to arise. What are these events/components of
sensation?
4. Sensory receptors can be classified according to their location in the body
exteroreceptors (near the surface),
interoreceptors (internally in the blood vessels or organs) and
proprioceptors (some of which we have already briefly discussed when looking at muscle function)
or the nature of the stimulus….
a) define the terms exteroreceptor, interoreceptor and proprioceptor
b) What are the different functions of receptors?
5. Which area of the body has the highest concentration of mechanoreceptors? Why might this be?
6. How does stimulation of a receptor transduce into a generator potential?
7. How is information about intensity and duration of a stimulus conveyed to the CNS?
8. With reference to sensation, what is meant by adaptation?
9. Revise the sensory pathways (see ‘Pathways’ lecture).
Draw yourself a basic diagram showing the whole pathway, including receptor, first, second and
third order neurons, the spinal cord and the thalamus.
Which pathway decussates in the spinal cord? Which pathway decussates in the brainstem?
10. Some of the spinal cord pathways, as well as the somatosensory cortex , are organised
somatotopically. What does this mean?
11. What aspects of sensation are integrated at the level of the spinal cord?
12. Sensory pathways from the head:
Which cranial nerve carries the sensory information from the face to the CNS?
Where is the nucleus of this nerve located?
What cranial nerves carry somatic sensation from the buccal cavity/posterior third
tongue/anterior two-thirds of the tongue?
Good sections to read to get an overview of gustation (taste) and olfaction (smell) can be
found in the recommended texts eg Tortora et al, Seikel et al.