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 well-developed 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 built-in 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