Chapter 4 - Somatosensory Senses and Chemical Senses

Question 1

What sensations can be felt on the skin surface?

Answer 1

• texture
• pressure
• low-frequency vibration
• high-frequency vibration
• pain

Question 2

Thermoreceptors

Answer 2

Nerve fibers that sense cold and warmth when skin temperature changes

Question 3

What do touch receptors look like?

Answer 3

Donut shaped receptive field

Question 4

Haptic perception/exploration

Answer 4

Active exploration of size, contour, texture and weight of objects. Requires integration of motoric and somatosensory senses

Question 5

Pain (Gateway theory)

Answer 5

Pain arises as a result of the activation of particular nerve fibers (A-delta fibers [initial sharp pain] and C fibers [dull pain that lasts longer]).

These fibers travel through the (dorsal horn of the) spinal cord, where the signal can be forwarded to the brain (the ‘gate’ is open – pain is perceived) or blocked (the ‘gate’ is closed – no pain is perceived).

So-called A-beta fibers that are activated by light touch and pressure, also run through the spinal cord, and their activation can prevent the pain signal from being forwarded to the brain.

Question 6

How can the brain relieve pain by itself?

Answer 6

Under high levels of stress, endorphins can modulate activity in the periaqueductal grey (PAG), a midbrain structure that is thought to be involved in pain inhibition

Question 7

Sense of body

Answer 7

Limb position, muscle length and tension (proprioception), the head’s and body’s angle relative to gravity, changes in speed and rotation

Question 8

Vestibular system

Answer 8

Sense organ in the inner ear

Question 9

What do semicurcular canals detect?

Answer 9

Head rotation

Keep the head straight and are connected to the eyes to allow them to fixate and produce a stable image. Also maintain balance and update our position relative to gravity

Question 10

What do otoliths detect?

Answer 10

Linear acceleration

Question 11

How is motion sickness caused?

Answer 11

Discrepancy between visual and vestibular information

Question 12

How do scencts and odors control social and emotional behavior and memories?

Answer 12

Odorant molecules present in air molecules bind to receptors in the olfactory epithelium that send information directly (i.e. without crossing hemispheres) to the bulbus olfactorius which connects to areas controlling social and emotional behavior and memories

Question 13

Adaptation of olfactory receptors

Answer 13

New odors that may require action are detected, but after our initial evaluation, it makes sense to reduce our sensitivity in order to detect new odors

Sensitivity to substances differs between smells and individuals

Question 14

Pheromones

Answer 14

Some animal species possess glands that secrete pheromones. These may attract potential partners and accommodate partner choice. The evidence for a role of pheromones in humans is mixed

Question 15

What is flavor?

Answer 15

The combination of smell and taste

Question 16

What 5 qualities of taste can we detect?

Answer 16

Sweet, salty, sour, bitter, and umami (savoury, although existence is debated)

Question 17

What are papilae?

Answer 17

Visible bumps on the tongue that contain taste buds which contain taste receptors connecting to the cranial nerve

Question 18

Where are different sensors localized?

Answer 18

On the tongue, roof of the mouth, and in the throat

Taste is supplemented by sensations regarding texture, temperature, and pain

Taste declines with age