Download Organs of the Special Senses

Special Senses
• Sight, smell, taste,
touch, and hearing
• Influence:
– learning
– interactions with other
animals
– interactions with the
environment
• Humans rely on vision
(1st) & hearing (2nd)
Special Senses
• Cats have welldeveloped visual
acuity for hunting and
also possess very
sensitive senses of
smell and hearing
• Dogs focus more on
smells and sounds
than on sight
Ocular Anatomy and Physiology
• The eyeballs are located
within a bony socket in
the skull (orbit)
– Adipose tissue provides
cushioning
– Eyelids provide protection
– Dogs and cats have a third
eyelid called the nictitating
membrane
• movement of this
membrane helps spread a
film of tears over the
cornea
Ocular Anatomy and Physiology
• The Eye:
– Cornea (clear part of eye, allows
light in)
– Sclera (white of eye)
– Iris (colored part of eye; controls
pupil/light)
– Pupil (regulates amount of light
entering)
– Anterior chamber (behind
cornea; in front of iris and lens)
– Lens (focuses light onto retina)
– Posterior chamber (behind iris;
in front of lens)
– Retina (receives images formed
by lens; converts to signals for
brain which are transmitted via
optic nerve)
Ocular Anatomy and Physiology
• Two types of pigmented
tissue:
– Tapetum lucidum
– Tapetum nigrum
• Rods
– Transmit black and white
images
– Sensitive to even low levels of
light
• Cones
– Respond to color-generating
wavelengths of light
– Dogs and cats can see yellow,
green, and blue but have very
few cones that respond to the
longer wavelengths of orange
or red light
Anatomy and Physiology of the Ear
• Dogs and cats can detect
sounds inaudible to
humans
– Humans: 20Hz – 20kHz
– Dogs: 60Hz – 45 kHz
– Cats: 45 Hz – 80kHz
• The pinnas of cats and
dogs are mobile
– Allows them to locate
sounds over distances 4
times farther than humans
can detect
Anatomy and Physiology of the Ear
• External ear:
–
–
–
–
Pinna
Vertical canal
Horizontal canal
Tympanic membrane
• Middle ear:
– Eustachian tube (pressure)
– Three small bones
• Incus, malleus, and stapes
– Oval window
• membrane connecting
middle ear to inner ear
Anatomy and Physiology of the Ear
• The inner ear:
– Cochlea
– Vestibule
– Semicircular canals
Anatomy and Physiology of the Ear
•
•
Sound waves traveling through the ear canal vibrate the tympanic
membrane
The malleus is attached to the tympanic membrane. As it moves,
vibrations are transferred to the incus and stapes
The stapes moves through the oval window and strikes the cochlea,
generating fluid waves that stimulate sensory receptors and send nerve
impulses to the brain
The nerve impulses arising from the cochlea are interpreted as sounds
•
https://www.youtube.com/watch?v=qgdqp-oPb1Q (How the Ear Works)
•
•
Purring
• Although still not fully
understood, most scientists
now say that purring begins in
the brain
– A rhythmic, repetitive neural
oscillator sends messages to
the laryngeal muscles,
causing them to twitch at the
rate of 25 to 150 Hz
– Causes a sudden separation
of the vocal cords, during both
inhalation and exhalation
(vibrato)
The Healing Powers of Purring
• Cats purr for many reasons:
when content, in pain, labor, ill,
injured, and even when near
death; kittens purr shortly after
birth
• Cats can manipulate their
purrs to communicate with
their owners
• Is there a significant survival
advantage associated with
purring?
The Healing Powers of Purring
• The 25Hz frequency of
the cat’s purr offers builtin physical therapy
• 25Hz is also used to help
wounds in humans heal
faster
• Low frequency sounds
shown to increase bone
density and decrease
stress
The Healing Powers of Purring
• Purring is an auditory
stimulus that people
attribute to peacefulness
and calmness
• Gives humans positive
reinforcement
• Aids in relaxation when
interacting with cats
Olfaction
• Scent receptors:
– Dogs 220 million
– Cats 200 million
– Humans 5 million
• Dogs and cats use sniffing
to maximize detection of
odors
– Sniffing: rapid inhalations and
exhalations
– Air is forced into a nasal
pocket instead of flowing into
the lungs
– Scent receptors interact with
inhaled molecules generating
nerve impulses that are
interpreted as smells
Olfaction
• Tracking dogs can
detect scents at a
level one million times
greater than a human
– enables dogs to work
in sniffing out drugs,
explosives, and
smuggled fruits and
vegetables
Taste
• The organs of taste are
specialized papillae
located on the front and
sides of the tongue, lips,
and mouth
– Taste buds (470) of cats
respond to foods that are
salty, bitter, or acidic but
not sugars
– Most numerous taste buds
in dogs are sweet
receptors, followed by
those that respond to
acids; no salt though
(1700)
Touch
• Sensory receptors for
touch respond to
pain, pressure,
warmth, cold, and
vibration
Touch
• Dogs and cats use touch
in social interactions
– Dogs and cats frequently
lick their owners, seeking
attention
– Cats rub their heads on
their owner’s legs or body
– Cats and dogs have
whiskers (vibrissae)
– Cats have a large number
of touch receptors in their
paws