Psy 256 Somatosensation, Olfaction and Gustation

Question 1

Where are the dermis & epidermis in the skin? Which is glabrous skin?

Answer 1

• Glabrous skin covers body parts that we use to explore (hand, feet, lips, tongue).
• dermis is the deeper layer that contains majority of sense receptors
  -epidermis is the more superficial layer above the dermis

Question 2

Name the 3 main groups of somatosensory receptors? What are mechanoreceptors? thermoreceptors?

Answer 2

-Three main groups of somatosensory receptors are
nociceptors (pain, temp)
haptic/mechanoreceptors (touch/pressure)
proprioception (position of body parts)

Question 3

Name and give the characteristics of the 2 kind of fibers that transmit pain signals to the brain?

Answer 3

-Fast, myelinated “A delta” fibers- provide a brief burst of activity (such as a sharp pain) when a
stimulus starts & ends
-slower, unmyelinated “C” fibers which respond as long as the stimulus is present (dull pain)

Question 4

Describe the pathway of touch from skin to brain.

Answer 4

-somatosensory signal is transmitted from receptor in the skin to spinal cord, somatosensory axons enter the spinal cord via the spinal nerves and ascend to the brain via the spinothalamic tract, then the spinal cord neurons carry signal to thalamus, the thalamus relays the signal to the body
appropriate portion of the primary somatosensory cortex in the post-central gyrus

Question 5

Where is the primary somatosensory cortex?

Answer 5

-primary somatosensory cortex is located in the post-central gyrus which contains a map of our body

Question 6

Describe the process of smell: What sensory receptors are involved, where are they located, and to
where do they project? What are glomeruli? What kind of cells make up the olfactory tract? Where
are the olfactory bulbs? To what other brain areas do these bulbs project? What are pheromones?

Answer 6

-olfactory receptors located in the nasal cavity allow us to smell they project little balls of dendrites
called glomeruli
-glomeruli receive input from only one receptor type, they connect to mitral cells, the axons of which
form the olfactory tract which project olfactory bulbs
-olfactory bulbs then project to numerous brain targets including amygdala, hypothalamus, entorhinal
cortex.
-pheromones, biochemicals released by one animal that act as chemo signals for other animals

Question 7

• Describe the basic process of taste. What sensory receptors are involved? Where are they located?
  What are the 5 main taste receptors (i.e., what tastes do they mediate)?

Answer 7

-taste receptors are found within taste buds located near papilla (small bumps) on surface of tongue
-taste buds contain 20-50 receptors cells with microvilli at their tips
-5 main taste receptors are Sweet, Sour, Salty, Bitter, & Umami
-Two taste pathways, to the amygdala and hypothalamus (control of eating) or the insula (taste and flavor) and
somatosensory cortex (texture/temp)