This document discusses the senses of smell, taste, and touch. It describes how smell is detected by olfactory receptors in the nasal cavity. Taste is detected by taste receptor cells in taste buds located on papillae on the tongue. The skin contains several types of receptors, including Meissner's corpuscles for touch, Ruffini's corpuscles for pressure, and free nerve endings for pain, cold and heat. Quizzes are also included to test understanding.

1. 12.5 Other sensations

2. 12.5.1 Smell

3. Olfactory receptor嗅觉接受器
• Latin olfacere ‘to smell’
• located at the upper
nasal mucosa
• mainly composed of
hairy olfactory cells.
• A chemoreception that
forms the sense of
smell.
• Detect of hazards,
pheromones, and food

4. Quiz
• What is the purpose of the Olfactory System?
A. Recognise the things we eat
B. Sense of smell perceived by the brain
C. Recognise the things we see
D. Work out what we are hearing

5. Olfactory cells嗅觉细胞
• Ciliated with olfactory cilia嗅毛

6. Quiz
• The sense of smell is dependent on ______ cells.
A. optic
B. auditory
C. olfactory
D. proprioceptor
E. odiferous
There are many different types of olfactory cells
and the smell we perceive depends upon the
combination of olfactory cells that are stimulated.

7. Nasal lining. Coloured scanning electron micrograph (SEM) of the olfactory
epithelium that lines the nasal cavity, showing olfactory cells (green)
surrounded by numerous cilia (hair-like projection, brown).

8. Formation of smell
• Vaporized odor molecules
enter the nostrils and
dissolve in the mucus.
• The olfactory cilia is
stimulated.
• The olfactory cell generate
nerve impulse.
• The olfactory nerve
transmits the nerve
impulses into the brain.
• Smell (olfaction) is created.

9. 12.5.2 Taste

10. Taste receptor
• Tongue is the taste organ.
• Papillae乳头突 (sg. Papilla) are found
on the surface on the tongue.
• Many taste buds味蕾 (taste
receptors) are found on the two
lateral sides of papilla.
• Taste buds are formed by a group of
taste receptor cells.
• Also a chemoreceptor.
Coloured SEM showing papilla.

11. Taste buds
Taste buds of circumvallate
papillae of the mature
cynomolgus (TEM observation)

13. Quiz
• Taste buds are located primarily on the ______.
A. upper palate
B. tongue
C. gums
D. turbinates of the nose
E. uvula

14. Quiz
• Taste buds are pockets of cells that ____________.
A. lie flat on the surface of the tongue epithelium
B. extend through tongue epithelium and open at a taste pore
C. lie along the walls of papillae
D. lack microvilli
E. all of the above

15. Formation of taste
• Saliva dissolves chemical
substances from the
food.
• The microvilli of the taste
receptor cells in the taste
buds are stimulated.
• Nerve impulse is
produced and
transmitted to brain
(gustatory cortex味觉皮层)
via gustatory nerve.

17. Quiz
• The _________ bear receptor proteins for certain molecules; when
molecules bind to these receptor proteins, nerve impulses are
generated in associated sensory nerve fibers that are interpreted in
the brain as tastes.
A. taste buds
B. thermoreceptors
C. taste pores
D. papillae
E. taste receptor cells

18. 味道

19. 12.5.3 Sensation of
skin

20. Receptors in skin
• Skin receptors
include touch,
heat, cold,
pressure, pain
and so on.

21. Quiz
• Skin contains receptors for ____________.
A. touch
B. pressure
C. pain
D. temperature
E. all of the above

22. Functions of skin receptors
Receptors Function(s)
Meissner’s
corpuscle
Touch
Ruffini’s
corpuscle
Pressurized touch
Pacinian
corpuscle
Pressure
Krause
bulbous
corpuscle
Cold
Free nerve
ending
Cold, heat and pain
Krause
bulbous
corpuscle
(cold)

23. Meissner’s Corpuscle
Krause bulbous
corpuscle
Ruffini’s corpuscle

24. Quiz
• The sense of fine touch is due to ___________.
A. Pacinian corpuscles
B. Meissner corpuscles
C. end-bulbs of Krause
D. Ruffini end organs
E. all of the above
The sense of fine touch is due to Meissner
corpuscles and Merkel disks. Pacinian corpuscles,
end-bulbs of Krause, and Ruffini end organs are
general pressure receptors.

25. Quiz
• Pain receptors ______________.
A. are highly specialized nerve endings
B. are free nerve endings
C. have unique neurotransmitters and neuron paths
D. are perceived independently from the brain
E. all of the above are true

26. Quiz
11
2
3

27. Distribution of receptors
• Receptors are distributed unevenly
over the body.
• Finger, tongue, nose and lips all are
very sensitive towards touch.
• Foot pad, thigh and the back portion
of upper arm are least sensitive
towards touch.
• The front portion of upper arm has
numerous temperature receptors
which are sensitive to cold and heat.

28. Quiz
• Receptors for a particular sensation, such as touch, are spread evenly
throughout the skin surface.
A. True
B. False

29. Summary
• Smell is detected by the olfactory receptors in the nasal cavity.
• Taste is detected by the taste receptor cells of the taste buds on the
papillae of the tongue.
• Skin receptors detects touch, pressure, and temperature.
Receptors Function(s)
Meissner’s corpuscle Touch
Ruffini’s corpuscle Pressurized touch
Pacinian corpuscle Pressure
Krause bulbous corpuscle Cold
Free nerve ending Cold, heat and pain