Senses Guided Notes
Name: ________________________
Do Now
Which ‘fact’ is false?
1) Your eye muscles are the most active muscles in your body.
2) Newborns don’t produce tears
3) Corneal scratches heal in about 48 hours.
4) If you sit too close to a TV , computer, or tablet, you will damage your eyes.
External Eye and Accessory Structures
__________________________refers to
tears. Tears __________ and
_________________ the eyes, and also
__________________________.
The lacrimal ducts empty into the nasal
cavity
This is why nose and eye irritation is often
linked.
•
you get the sniffles if cry and
•
you get watery eyes if congested
___________________ are the membranes the line the eyelid and eyeball.
__________________ inflammation of these membranes, caused by irritants, allergies, or infection (e.g. “pink eye”).
Extrinsic Eye Muscles
Control movement of the eyes. Remember: rectus = straight, oblique = slanting
Eye muscle names and actions
Name
Action
Lateral rectus
Medial rectus
Superior rectus
Inferior rectus
Inferior oblique
Superior oblique
Eyeball
The eye has three ______________________, or coats.
•
_______________________ – “whites of the eye” , outermost, thick connective tissue.
•
_______________________ – has blood vessels, middle layer
•
_______________________ – contains the photoreceptors (rods & cones), inner layer
The eye is divided into two fluid-filled chambers:
•
The anterior chamber is filled with ________________________________________
•
The posterior chamber is filled with ______________________________________
•
Both fluids ________________________________, and the aqueous humor
_________________________________________.
•
_______________________________ occurs when the aqueous humor doesn’t drain properly, resulting
in increased eye pressure and blindness
Pathway of Light
1. Light enters the eye at the ________________________ – a clear, hard part of the sclera.
Functions: protects eye and focuses light
Fun fact: the cornea is responsible for ~70% of the eye’s focusing ability
2. Light passes through the ______________________ which is the opening in front of the lens.
•
•
The size of the pupil is controlled by the muscles of the __________ (the
the eye).
colored part of
The pupil dilates or contracts to vary the amount of light hitting the retina.
3. The light passes through the ______________which focuses the light onto the retina.
•
4.
The __________________________ are muscles which change the shape of the lens to focus on
nearby items, a process called __________________________.
The light passes through the _________________________ to land on the retina, which contains the
photoreceptors.
There are no photoreceptors on the _____________________________, which is where the optic nerve exits
the eye – this causes a small blind spot.
Photoreceptors
Rods
Responsible for night and peripheral vision –
•
more abundant
that’s why colors seem to be lost in the dark.
•
sensitive to ______________________________
•
do not discriminate _______________________________________________
Cones - ________________________________________
• 3 types, _______________________________________________________________________
•
triggering of more than one cone is interpreted by brain as different colors
e.g. if both red and green are activated, the brain will interpret the light as yellow or orange
• ________________ than cones
• mostly found in ___________________________________
Responsible for color and fine detail vision – including reading
Color blindness is usually caused by the
absence of one or more cones.
•
Occurs in ~5% of population
•
X-linked trait … much more
common in men
Refraction and Accommodation
Light is bent – or __________________________– by nearly every eye structure that it passes through on the way to the
retina.
However the lens is the only structure that can vary how much the light is bent in order to allow us to focus on different
objects – a process called __________________________.
•
At rest, our eyes naturally focus
on far-away objects.
•
However, by contracting the ________________
____________________, we can make the
lens bulge so that it has greater
refractive ability – allowing us to
focus on close items.
As we get older, our lens loses elasticity – making it harder to focus on nearby items.
This condition is called _____________________________(old eyes)
Refraction flips and reverses the light rays, forming an upside down and reversed image on the retina … but the brain
learns to interpret visual information correctly.
Refractive Errors
Myopia
Common name:
Causes:
Diagram:
Why can myopic individuals see _______________ objects better?
Because light from _____________________________________________________________
________________________________________________________ to properly hit the retina
Correction:
 _________________________corrective lenses / contacts magnify the image (make the light diverge
more), before it enters the eye
 Lasik surgery to flatten cornea makes the light focus less so it can properly reach the
retina.
Hyperopia
Common name:
Causes:
Diagram:
Why can hyperopic individuals see _______________ objects better?
Because light from _____________________________________________________________
________________________________________________________ to properly hit the retina
Correction:
 ________________________ corrective lenses / contacts
 Cornea surgery to make the cornea more ____________________

Both focus the light _______________ so that it properly reaches retina
Astigmatism
 A-stigma = _________________________________ (light focuses unevenly on retina)
 Causes:
 Diagram:
 Signs of astigmatism:
 Fine details are blurry – whether ___________ or __________
 “Halo”effects or glare from lights
 Correction
 Corrective lenses or contacts
 Shape of lens /contact __________________________________ to counteract irregular
shape of the eye
 Contact lenses are often ___________________ so that they align properly with the eye
 Ortho-K / cornea surgery
 _________________ with special contact lenses worn at night or with laser surgery
Ear Structure and Function Guided Notes
Ear Anatomy
Overview
External Ear
Middle Ear
Inner Ear
Structures:
Structures:

Structures:

o
o
o


Function:





Function:


Function:

NOTE: Diagrams are misleading.
The entire inner is bony, except for the labyrinth which is a series of cavities (spaces) within the bone.
Outer Ear
Function: __________________________________________________________
 Pinna collect sound waves and direct to the tympanic membranes … but in humans, not very
effectively.
 Cerumen (ear wax) lines the external auditory canal.
◦ Antibacterial
◦ Also discourages bugs, mold, etc.
◦ Lubricates ears
◦ Helps trap / remove foreign particles
 The tympanic membrane (ear drum) vibrates when sound waves hit it,
transmitting the sound to the middle ear
Disorders of the outer ear
Ear Wax Blockage
 Ear wax can become impacted, usually from hear aid use or inappropriate methods of cleaning the ears
 Can cause temporary loss of hearing
Otitis Externa (Swimmer’s Ear)
 Infection of external auditory ear canal, usually due to excess moisture in the ear canal (such as from
swimming), though cuts and scrapes to the ear canal can also become infected.
Middle Ear
Function: _____________________________________________________________________________
How? The tympanic membrane transmits sound to the three ossicles. The ossicles act like levers, amplifying
the sound and transmitting it to the oval window, a membrane-covered opening to the inner ear.
Eustachian tubes
Structure
 Tube that connects the middle ear to the nose and throat
 Mostly closed, but opens when we move our jaw
Why do we have it?
 Equalize pressure in the middle ear
 Drain fluids to the throat
Disorders of the middle ear
Otitis media (middle ear inflammation / infection) –
 Inflammation (often with the buildup of infected fluids) within the middle ear




Visible with an otoscope as a bulging eardrum
Usually caused from a respiratory infection
Babies who are allowed to drink bottles while lying down are also very likely to get ear infections
Much more common in young children, because their Eustachian tubes are narrower and more
horizontal
 Ear tubes are often recommended for children who experience chronic middle ear infections or fluid
build-up
 The tube is placed in the ear drum, but performs the functions of a eustachian tube – ventilating and
draining the middle ear.
Hearing and the inner ear
Hearing takes place within the cochlea of
the inner ear.

Cochlea is a long, curled cavity with
three layers
◦
2 layers of _______________ – a
plasma-like fluid
◦
In-between: a system of
membranes that contain the
______________________ and
the ______________________
_______________________
that create the nerve impulse
The top diagram is a cross-section of the
cochlear cavity.
Take a moment to figure out …
◦
What fills the scala vestibuli?
◦
The scala tympani?
◦
The cochlear duct?
 When the stapes beats against the oval window, it causes pressure waves within the perilymph
 The movement of the perilymph disturbs the cilia (receptors) of the Organ of Corti, generating a nerve
impulse
 Different frequencies (pitch) vibrate the membrane in different locations. High pitches are heard that
the front, low at the back.
 The round window is a membrane-covered opening just below the oval window. It bulges to keep the
pressure waves from bouncing back.
Balance and Aging Guided Notes
How do we maintain balance?
Cerebellum monitors and controls balance.
It receives input from four main sources:
 __________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________
__________________________________________________________________________
Static vs Dynamic Equilibrium
Static equilibrium has to do with our ____________________________________________________________

e.g. upside down, tilted to the left, slowing down, etc.

Sensed by the _________________________ of the _____________________
Dynamic equilibrium has do to with ________________________________________________________

E.g. spinning, roller coasters, boat rides

Sensed by the _____________________________ of the ______________________________
Static Equilibrium

The ___________________contains hair cells surrounded by an _______________________________ (a jellylike material) that contains ________________________________ (tiny calcium stones)

The otolithic membrane slides due to gravity or linear acceleration, bending the hairs

When the hairs are bent, the hair cell generates a nerve impulse
Dynamic Equilibrium

3 canals, oriented in the three planes of space

At the base of each is a receptor region called the _____________________________, which consists of hair
cells covered with a gelatinous cap called the __________________.

During angular / rotational movements, the _____________________________ in one or more canals will
move, pushing against the hair cells

When the hair cells are bent, they generate a nerve impulse.
Types of Receptors
Sense
Type of Sensor
Name
Location
Vision
______________ &
___________
Retina of eye
Hearing
____________ ( on organ of
Corti)
Cochlea of ear
Balance
____________________ (on
crista ampullaris)
Vestibule of ear
Semicircular canals of ear
Tendons, muscles, joints
_____________________
Smell
Olfactory receptor
Top of nasal cavity
Taste
Taste buds
Papillae of tongue
Pain
nocioreceptors
Skin, muscles, bladder, digestive
system, mucus membranes, cornea
Temp
Thermoreceptors
Skin
Pressure
Pacinian corpuscle
Skin & internal organs
Touch
Meissner’s corpuscle
Skin
Senses and Aging
Vision
 Develops slowly in babies
 Kids are far-sighted until around 6 because the eye needs to grow
 In old age
 _________________________________, causing _________________ – an inability to accommodate
and focus on near items
 Other factors which reduce visual acuity include ___________________, inability to fully dilate pupil,
loss of photoreceptors
 Many diseases more common with age: cataracts, glaucoma, macular degeneration, etc.
Hearing
 ___________________ –
 a loss of hearing, especially speech sounds and high pitches – due to damage to the organ of Corti
 A type of __________________________l hearing loss
 Associated with age and noise exposure
 ____________________ hearing loss  Anything that prevents sound from getting to the inner ear, including fusion of ossicles
Smell & Taste
 Very sharp at birth
 Declines starting around age 40
 Most people over 80 have poor taste sensation and almost no ability to smell
Balance, Touch, Pain
 Begin to decline around age 50
 Leads to increased risk of falls
 Inability to recognize injury