...taste, being the lowest or least intellectual of our five senses, is incapable of registering impressions on the mind;consequently, we cannot recall or recover vanished flavours as we can recover, and mentally see and hear, long-past sights and sounds. Smells, too, when we cease smelling, vanish and return not...

W. H. Hudson, Far Away and Long Ago, 1918

Audesirk, Audesirk & Byers Part of Chapter 38, Chapter 28 case study, Figure from Chapter 25, and from Chapter12

Today's musical selection
Foreigner Double vision

In the framework of Stimulus - NS - Response, we covered NS=nervous system, now how stimuli are perceived by senses, after that, how muscles generate responses

Transduction is the way an energy gets turned into a nerve cell potential
Modalities refer to the different senses like seeing vs. hearing

Table 38-2
There are Receptors (cells) for various Stimulus energies

5 (special) senses Taste, smell, touch, hearing & seeing

Taste Gustation

Figure 38-27
Taste [for human, on tongue mostly] - Gustation - chemicals - water -salt, sour, bitter, sweet
Several types of papilla including the circumvallate papillae on the back of the tongue, shown in this picture from our histology course
Within each papilla are numerous clusters of cells called taste buds shown in this histology picture.

Recent paper. Denis Drayna, Founder mutations. Scientific American Oct 2005, 78-85. (There are also several letters to the editor and reply Feb 2006, 12-14)
" different forms of the PTC gene exist in sub-Saharan Africa. But only the major taster and nontaster forms have been found...outside of African populations."
taster detects chemicals with C=N-S
They suggest
(1) taster and nontaster are ancient
(2) tasters and nontasters populated the world as in the "Out of Africa" hypothesis
(3) these people did not interbreed with others (like Neanderthals).
only taster in all other primates

Smell- Olfaction chemicals (air) -

Figure 38-26
Complex (unusual primaries like aromatic and putrid, many primaries, receptors difficult to reach, brain projection complicated), related to motivational affect, especially in other animals (consider how male dogs mark their "territories" with urinary pheromones and check for other dog smells)
Olfaction in humans
Olfactory epithelium with receptors having cilia projecting to olfactory bulb in brain

Figure 25-24a
Pheromones in moths, females release sex attractants, mate at night, male finds female from miles away using large feathery antennae loded with recptors

Figure Chapter 28 opener
Salmon fingerlings get olfactory imprinting (memory) of the stream in which they spawned; then after 5 years of foraging at sea, they go up their home streams to mate, sometimes overcoming hurdles
It's funny how odors bring back memories.

Touch (somesthesis)

Figure 38-17
Receptors - There are different specialized receptor types in the epidermis and dermis.
To some extent, different receptor cell types, with their specialized encapsulations mediate sensation of heat, cold, light touch, touch, and strong pressure, and these are very different sub-modalities within athe modality of somesthesis.
here is a Pacinian corpuscle from our histology course

Figure 38-28
Pane as a chemical sense

Figure 38-14
description of where in the somatosensory cortex different parts of the body project. Note that these areas are adjacent to the corresponding areas in the motor cortex where voluntary muscle movements are initiated. There is a relative "magnification" for areas with high touch sensitivity, hands, lips, tongue, genitals.

Hearing Audition

Figure 38-18
pinna, eardrum,
Eustachian tube to equalize pressures to middle ear
The cochlea is where auditory receptor cells (hair cells) reside.
Hair cells are stimulated as the basilar membrane moves relative to the tectorial membrane creating
pressure in hair cells.

Figure 38-19
Audibility is measured in the sound pressure (relative to a standard) needed to hear, measured in dB (deciBels), and the sense of hearing is very sensitive.
Loud sounds cause damage


Figure 38-21
iris, lens, aqueous, vitreous, retina, fovea, optic nerve

Figure 38-22
Myopia (near-sightedness), Hyperopia (far-sightedness),

Figure 38-21
Rod (sensitive black and white vision) and cones (color vision, acuity)
Outer segment- organelle
Inner segment the whole rest of the cell
Rods are very sensitive - can see 1 photon (quantum) of light
visual pigment
Rhodopsin - vitamin A & protein
Retina wiring
Cones (for yellow, green and blue light) are at the fovea (point of fixation), and mediate color vision at high acuity.

Figure 12-30
Color blindness in people - on X chromosome and hence most noted in males -

Figure 38-15
Visual connections through optic chiasm, to lateral geniculate nucleus (part of the thalamus) to the visual cortex -
development (exposure to form vision) is very important

Figure 38-20
Insect ommatidia of compound eyes

Examples of amazing animal senses:

Figure 38-29
Another amazing animal sense:
Bats are nocturnal predators finnding insect prey by echolocation (sonar) using ultrasound.
Moths avoid bats
Porpoises also use sonar

Magnetism involved in migration in birds and many other animals

Figure 38-30
Electric sense in fish

Questions used in 2007 & 2008 related to this outline

The ability of salmon to locate the stream in which they were spawned is dependent upon which sense?
*(a) olfaction
(b) hearing
(c) vision
(d) magnetic sense
(e) touch

Which of the following is true?
*(a) The sense of touch projects to the cerebral cortex.
(b) Bats find moths by pheromones.
(c) The receptors for salt, sweet, sour and bitter in the human project to the olfactory bulb.
(d) Sympathetic and parasympathetic systems mediate olfaction.
(e) Vitamin A functions in audition.

What is the stimulus for the pain receptor?
*(a) chemicals
(b) vibration
(c) too much light
(d) morphine
(e) pressure

Seven different forms of the PTC gene exist in
(a) the cone cells of the retina.
(b) the hair cells of the ear.
(c) the nasal epithelium.
*(d) sub-Saharan Africa.
(e) sub-human primates.

Which is the correct order from largest to smallest?
(a) microvillus, papilla, taste bud, receptor cell
*(b) papilla, taste bud, receptor cell, microvillus
(c) receptor cell, taste bud, papilla, microvillus
(d) taste bud, papilla, microvillus, receptor cell
(e) microvillus, papilla, receptor cell, taste bud

Male moths find female moths by
*(a) pheromones.
(b) echolocation.
(c) mechanoreception.
(d) electrical sense.
(e) ultrasound.

A Pacinian corpuscle is used for
(a) taste
(b) smell
*(c) touch
(d) hearing
(e) vision

Why is there a blind spot?
(a) The vitreous humor does not transmit light there.
(b) There is no white matter there.
(c) That's where the limbic system is located.
*(d) There are no rods or cones there.
(e) That's where the fovea is.

Rhodopsin is
*A) a G protein-coupled receptor housed in the rod or cone.
B) used by electric fish to detect objects surrounding them.
C) how male moths find female moths for mating (in the dark).
D) the part of the brain to which olfactory receptors project.
E) the part of the brain that is commonly called the somatosensory cortex.

Myopia is
A) a color vision defect that is on the X chromosome.
*B) nearsightedness.
C) one of the primary qualities in gustation.
D) how pain is transduced at the receptor level.
E) the unit of intensity of sound.

Which of the following is true?
A) The cochlea projects to the primary sensory area.
B) The visual system projects to a brain area immediately posterior to the primary motor area.
C) Receptors for salt, sweet, sour and bitter project to the brain's olfactory structure.
D) An ommatidium is used to detect sex attractant pheromones in the moth.
*E) Pacinian corpuscles are located in the dermis and mediate a sense of rapid movement (touch).

An auditory hair cell is a
A) photoreceptor.
B) chemoreceptor.
C) light receptor.
D) thermoreceptor.
*E) mechanoreceptor.

*A) absorbs light because it is a pigment that contains vitamin A.
B) attracts salmon in their migration to their native stream.
C) is emitted by a female moth to attract a male moth.
D) is used by moths to evade bats who are using sonar.
E) is the word used for the rich, meaty quality of taste mediated by monosodium glutamate.

Each papilla
A) projects to the olfactory bulb of the brain.
B) is part of the outer segment (organelle) of the rod or cone.
C) is a facet of the compound eye of the insect.
*D) houses numerous taste buds each of which has numerous taste cells.
E) reflects light and thus causes the eye glow you may have seen in your dog or cat.

The tectorial membrane
A) is transparent and is at the front of the eye.
*B) is the site where cilia of cells on the basilar membrane are subject to bending.
C) is the cause of nearsightedness.
D) is the location mediating high acuity color vision (the point of fixation).
E) is the location of olfactory receptor cells.

Receptors that belong to (which sense?) project directly into the "first cranial nerve" of the brain.
A) umami
B) monosodium glutamate
*C) olfaction
D) taste
E) vision

Questions used in 2002 relating to this outline (and other outlines)

Which of the following is true?
*(a) The cochlea projects to the temporal lobe.
(b) The visual system projects to a brain area immediately posterior to the primary motor area.
(c) The taste receptors for salt, sweet, sour and bitter in the human project to the olfactory bulb.
(d) Sympathetic and parasympathetic systems are involved in smell.
(e) Semicircular cannals mediate the sense of gustation.

The ability of salmon to locate the stream in which they were spawned is dependent upon which sensory specialization?
(a) electric sense
(b) sensitivity to ultrasound
*(c) olfactory imprinting
(d) magnetic sense
(e) pheromones

.Bats find moths by
*(a) echolocation.
(b) smelling them.
(c) the electric sense.
(d) the magnetic sense.
(e) the Sun azimuth.

Which is a fat soluable vitamin that functions in vision and is related to retinoic acid, an important regulator of development?
*(a) A
(b) B
(c) C
(d) D
(e) E

Odors are important for mating in several species. Which of the following is most famous for its RELEASE of an odor important in mating?
(a) male stickleback
(b) male salmon
*(c) female moth
(d) female bat
(e) male white-crowned sparrow

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