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The Senses Touch and Feeling
• Specialized organs translate a stimulus and • Receptors in skin for heat, cold, pain,
send it to the brain via an electrical nerve pressure
impulse • Specialized pattern on hands and feet (as we
• General: touch- heat, pain, hot/cold in skin studied in the skin unit!)
• Special: smell, taste, sight, hearing • Receptors also in muscles and joints
• What we “feel” is a blend of effects
THE EYE
• Photoreceptors translate light into a nerve
impulse, which is received and “viewed” in
the occipital lobe
EYE Protection
• Eyebrows
• Eyelashes
• Eyelids
• Glands secreting oil, sweat, and tears
– Conjunctiva: membrane secreting mucus
• Pinkeye: conjunctivitis- infected membrane
– Lacrimal glands and ducts for tears- connects to nasal
cavity
• Salty solution contains lysozyme (kills bac)
• Crying: clean out eye? Emotional release?
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The Eyeball STRUCTURES
• A vehicle to capture light and focus it on the • 10- Sclera
cells that can create a nerve impulse (image) • A thick white tissue (white of the eye)
• (Think of this as we label structures and • 6- Cornea “clear window”
discuss functions) • A clear/transparent part of the sclera
• We will label from the outermost structure • 4- Aqueous Humor
to the innermost structure
• Liquid/squishy cushions lens
• 3- Iris • 5- Lens
• Colored portion of eye attached to lens
• Focuses the light (able to change shape and
• Able to regulate the amount of light that enters the
eye through the pupil (add to diagram) position) Also FLIPS the image
– Controls light: bright light? Dim light? Why? • 7- Vitreous Humor
• 1- Cillary body: holds lens and produces pigment • Jelly like substance- makes the eye round
for iris
• 2- Suspensory Ligaments: holds and suspends
lens- helps lens focus the light
The Retina
• 12- Retina • Nerve impulse sent along optic nerve to occipital
• The layer of nerve cells (photoreceptors) lobe (criss cross at optic chiasma in brain)
• 9- Fovea Centralis • Photoreceptors: 2 Types
– RODS: can detect shape and movement
• The spot on the retina where the light • Adapted for vision in dim light
should be focused for a perfect image to be – CONES: detect sharp details and color
transferred • Adapted for vision in bright light
• 8- Optic Disk- the “blind spot” • Red, blue, and green cones: can “blend” to see all colors
– No photoreceptors in this spot
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DISORDERS
• Blindness
• Color blindness
• Night blindness
• Glaucoma
• Cataract
• Retinal Disorders
• Farsighted/Nearsighted/Astigmatism
– Affects ½ of the population
THIS WEEK The EAR
• Today==Finish lab (watch video) • Fxn: hearing and balance
• Three Parts
– 1. Outer ear (transfer sound)
• HW= lab due THURSDAY – 2. Middle ear (transfer and amplify sound)
– 1-2 sentences on purpose of EACH test – 3. Inner ear (sound and balance receptors here)
– 1-2 sentences on your results for EACH test • Sound waves nerve signals to temporal lobes
where we “hear”
• Receptors (inner ear) sense position and
• QUIZ= ear, taste, smell on FRIDAY movement for balance
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OUTER EAR
• 1. Auricle (Pinna)
– Funnel sound waves
• 2. External auditory canal (ear canal)
– Narrow cavity that funnels sound
– Wax produced to fight infection/hairs protect
• 3. Tympanic membrane (eardrum)
– End of canal: vibrates when sounds strike it
MIDDLE EAR INNER EAR
• 3 small bones: ossicles – they magnify gentle • Where it all goes down……
sounds and soften loud ones • 8. Oval window
– 4. Malleus “hammer” – Stapes hits to transfer sound sound vibrations
– 5. Incus “anvil” transferred to the cochlea
– 6. Stapes “stirrup” • 9. Cochlea- tubes filled with fluid
Ear POP: when middle ear pressure is different from – Vibrations cause fluid to move stimulates “hair cells”
environment creates nerve impulse temporal lobes we hear!
10. Eustacian tube: connects middle ear to throat • 7. Semicircular canals- 3 tubes filled with fluid
-when opened (coughing, swallowing) the pressure is – Movement causes hair cells to detect message to
released cerebellum compensates with muscle movement to
-sickness spreads easily…kids more horizontal restore balance (MOTION SICKNESS!!)
DISORDERS
• Infection
• Ruptured eardrum
• Cochlear damage
• Auditory nerve damage
• Vertigo
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TASTE and SMELL: The
SMELL
Chemical Senses
• Nose and Mouth have chemoreceptors: • Olfactory receptors (cells) on roof of nasal cavity
chemicals bind cells transfer to nerve detect chemicals dissolved in air
impulse temporal lobe in brain we • Transferred to impulse olfactory bulb
taste and smell! olfactory nerve thalamus temporal lobe
– *VERY sensitive but quickly adapt
– * closely tied to the EMOTIONAL brain
– DAMAGE? Head injury, cold, allergies, aging,
smoking, cocaine
TASTE
• “to judge”
• Taste buds: receptors- gustatory cells
• 10,000 of them on tongue, palate, cheeks
• Chemicals must be dissolved in saliva 1st
• RECEPTORS:
– Sweet: sugars
– Sour: acidity
– Bitter: alkaloids
– Salty: metal ions Na,K
• Tastes have homeostatic value
– Crave sugar?
– Crave sour?
– Bitter taste?
Affected by…aromas, temperature, texture
EX: coffee?
Hot and Spicy foods?
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