1. Psychology: Chapter 4, Section 4
Other Senses
Psychology: Chapter 4, Section 4

2. Other Senses Vision and hearing are just two of our senses
Other senses are smell, taste, and the skin and body senses
With vision and hearing, physical energy in the form of light or sound waves stimulates our sensory receptors
Smell and taste are called chemical senses, as we sense molecules of substances
The skin detects touch through pressure, temperature, and pain
Body senses alert us to posture and movement

3. Smell
The olfactory system is the sensory system used for olfaction, or the sense of smell
People do not have as strong a sense of smell as many animals
Dogs use seven times as much of the cerebral cortex for smell as people do
But smell is important for people too
Without smell, we could not taste things as well, and onions and apples would taste the same as each other

4. Smell- Taste Relationship
The smell of food not only goes through our nostrils (nasal odor) but also up the back of the throat (retronasal odor) to the nose.
These smells help us sense flavor

5. Smell
Odors happen when molecules (in the form of a gas) spread from the object causing the odor
Receptor neurons high in the nostrils react to the gas, and send information to the olfactory nerve, which sends the message to the brain
We adapt rapidly to odors
This may be good in a smelly locker room, but not so good if there is a dangerous gas leak in the house

6. Olfactory Epithelium (smell)
Inside your nose is the olfactory epithelium, which is a fancy word for “smell device.”
In the olfactory epithelium are more than 10 million scent receptors.
These receptors can distinguish up to 10,000 different smells.
Olfactory Epithelium (smell)

7. Taste
Never feed a dog chocolate (it could give him or her a heart attack), but dogs do love candy. Cats, on the other hand, don’t particularly like candy. Dogs can taste sweetness, while cats cannot
People have at least four basic taste senses– sweet, sour, salty, and bitter. (Some say another sense is umami, Japanese for “meaty” or “savory.”)

8. Taste Our tongue has taste buds, which are receptor neurons
People have different concentrations of taste buds, leading to some people really enjoying spicy food, while others do not tolerate it
It is possible to damage taste buds from hot foods or scraping your tongue, but fortunately, taste receptor cells reproduce rapidly, unlike other sensory neurons (like hearing or vision)

9. Taste buds are organized and grouped together on the tongue in distinct areas

10. Skin Senses
The sense of touch could more accurately be further categorized into senses of pressure, temperature, itch and pain, so they are collectively called the skin senses

11. The sense of “touch” is actually many different kinds of senses

12. Pressure
Certain areas of our body are more sensitive to the sense of pressure than other areas
For example, your fingertips, lips, and cheeks are more sensitive than your shoulders or calves
We have hair cells that help with our sensitivity to pressure, as sensory receptors near the hair roots fire when skin is touched
There are also other structures under the skin to help with sensitivity to pressure
Touch is very important for a newborn baby to thrive

13. One way to measure touch sensitivity is to see how far apart two points need to be to be felt as two points

14. It’s very important for a baby to be held (they should not be just left alone in a baby seat all the time)

15. Temperature
Sensations of temperature on our skin are relative. If we are feverish, things that might normally feel warm could actually feel cold.
We have receptors just below our skin surface that sense either hot or cold temperatures, and thus fire accordingly
We adapt to hot or cold rather quickly. A cold pool or a hot bath seems relatively comfortable after just a few minutes.

16. When we have a high fever, we can ironically feel very cold

17. Pain How can pain be helpful?
Pain can protect us from further harm, by either having us pull away from a source of injury or immobilizing an injured area
As with pressure receptors, pain receptors are not evenly divided around the body– the sole of your foot is not as sensitive to pain as your neck

18. A swelling can help immobilize a joint that shouldn’t move, and may work as a splint

19. Pain
The pain message travels quickly from the source of the pain to the spinal cord, to the thalamus, to the cerebral cortex, where the location and severity of the pain is interpreted
Chemicals called prostaglandins send pain messages to the brain
Aspirin and ibuprofen curb production of prostaglandins, thus reducing how much pain we feel

20. While all four of these do relieve pain and fever, Tylenol does not reduce swelling

21. Pain Why does rubbing an injured area sometimes help relieve pain?
One possible answer is the gate theory of pain
Gate theory suggests that only a certain amount of information can be processed by the nervous system at a time
Rubbing an area may flood the brain with other sensations, reducing the amount of pain messages able to make it through

22. Large nerve fibers are fast and stimulated by non-painful rubbing
Large nerve fibers are fast and stimulated by non-painful rubbing. They effectively close the gate on pain coming through

23. Pain
Many people who have lost a limb experience pain in the limb that is no longer there
This is known as “phantom limb pain”
There are nerves in the remaining stump of the missing limb that have memories connected with the limb

24. These are the characteristic sensations of phantom limb pain after a leg has been amputated below the knee

25. Body Senses
Body senses help you stay upright and put food in your mouth without looking
There are two main body senses: the vestibular sense and the kinesthetic sense
Your vestibular sense lets you know whether you are upright or falling, or changing speeds in a vehicle
Your kinesthetic sense also lets you know the position and motion of your body, and allows you to touch your nose with your eyes closed or feed yourself with a fork

26. The semicircular canals in your ear help you keep your balance via your vestibular sense

27. Alcohol affects your kinesthetic sense, and so a common roadside test is for suspects to close their eyes, tip back their head, and touch their nose

28. Assessment
Answer all three questions on page 92 and turn that in