Biology Journal 3/25/2014
Hair cells are the receptors inside
of the cochlea that are stimulated
by vibrations in the liquid in the
cochlea. A person may go deaf
by having these cells damaged.
A cochlear implant uses a
speaker on the side of the head
and stimulates the hair cell
receptors electronically, causing
a user to hear sound.
Which parts in the hearing process are
bypassed with a cochlear implant?
E.2 Perception of Stimuli
E.2.1
Outline the diversity of stimuli that can be detected by human sensory receptors, including:

Mechanoreceptors, chemoreceptors, thermoreceptors, photoreceptors
Details of how each receptor functions are not required.
E.2.2
Label a diagram of the structure of the human eye. The diagram should include:

sclera, cornea, conjunctiva, eyelid, lens, choroid, aqueous humour, pupil,

iris, vitreous humour, retina, fovea, optic nerve, blind spot
E.2.3
Annotate a diagram of the retina to show the cell types and the direction in which light moves. Include names of rod
and cone cells, bipolar neurons and ganglion cells.
E.2.4
Compare rod and cone cells. Include:

use in dim light versus bright light

one type sensitive to all visible wavelengths versus three types sensitive to red, blue and green light

passage of impulses from a group of rod cells to a single nerve fibre in the optic nerve versus passage from a single
cone cell to a single nerve fibre
E.2.5
Explain the processing of visual stimuli, including edge enhancement and contralateral processing.

Edge enhancement occurs within the retina and can be demonstrated with the Hermann grid illusion.

Contralateral processing is due to the optic chiasma, where the right brain processes information from the left
visual field and vice versa. This can be illustrated by the abnormal perceptions of patients with brain lesions.
E.2.6
Label a diagram of the ear. Include:

Pinna, eardrum, bones of the middle ear

oval window, round window, semicircular canals

auditory nerve, cochlea
E.2.7
Explain how sound is perceived by the ear, including the roles of the eardrum, bones of the middle ear, oval and round
windows, and the hair cells of the cochlea.
What neurons go in the blanks?
Name of sensory
neuron
What it detects
1
Chemicals
2
Electromagnetic radiation
3
Temperature
4
Pressure, texture, vibration
What neurons go in the blanks?
Name of sensory
neuron
What it detects
1
Chemoreceptors
Chemicals
2
Photoreceptors
Electromagnetic radiation
3
Thermoreceptors
Temperature
4
Mechanoreceptors
Pressure, texture, vibration
Compare rods and cones in a Venn
diagram.
Rods
Both
• Stimulated by • Photoreceptors
light intensity
• Found all
• Connected to bipolar
over retina
cells, ganglia, and
optic nerve
• Work under
• Cooperate to make 1
any amount
image that is
of light
processed in the
visual cortex of brain
• 1 type
• Rod shaped
Cones
• Stimulated by
color
• Found mostly in
fovea
• Only work under
high-light
conditions (not
in the dark)
• 3 types: blue,
green, red
• Cone shaped
Name these parts of the eye. For extra credit, state what they do!
13
12
11
1
9
8
7
2
3
10
4
5
6
13. Conjunctiva
12. Sclera
protective outer layer
of pupil, secretes
mucus
protective
outer layer
11. Eyelid
10. Choroid
protection, cleaning
layer of lightabsorbing pigment
9. Retina
mostly rod cells
8. Fovea
1. Pupil
area of
concentrated
cone cells
opening that
lets light in
7. Blind
Spot
2. Aqueous
Humor
no receptor
cells
transparent jelly
3. Lens
adjusts to focus light
4. Iris
on retina
muscles that control size
of pupil; gives “eye color”
5. Vitreous humor
transparent liquid
6. Optic
Nerve
carries nerve
Name these parts of the retina!
1
2
3
4
Cone cell
Rod cell
Bipolar cell
Ganglion cell
Cone cell
Rod cell
Bipolar cell
Ganglion cell
1. When light hits the retina, list the order in
which it passes through each of these cells.
2. When an action potential happens, list the
order in which it goes through each of these cells.
Cone cell
Rod cell
Bipolar cell
Ganglion cell
1. ganglion cells, bipolar cells, rods/cones
2. rods/cones, bipolar cells, ganglion cells
1. Where is vision processed in the brain?
2. What is contralateral processing?
1. Vision is processed in
the back of the brain,
in an area called the
primary visual cortex.
2. The left sides of both
eyes are processed on
the right side of the
brain. The right sides
of both eyes are
processed on the left
side of the brain.
Name these parts of the ear. For extra credit, state what they do!
1
2
3
4
5
7
8
6
8. Pinna
collects
sound
waves
1. Eardrum
3. Semicircular
Canals
2. Middle Ear
Bones
vibrated by air pressure
changers due to sound
Stimulated by ear drum,
waves
knock against each other
to magnify sound
balance (is not involved
in hearing)
4. Auditory
Nerve
transmits
nerve signals
to brain
5. Cochlea
tiny hairs respond
to individual
wavelengths of
sound, generating
action potential
7. Round Window
dissipates vibrations (lessens
and lessens “old” sounds)
6.Oval Window
transmits vibrations
from middle ear bones
to inner ear
Complete the table comparing the sense
of hearing to the sense of sight!
Hearing
Sight
Sound waves
Light waves
Mechanoreceptors
1
2
Optic nerve
Hair cells
3
Cochlea
4
5
Pupil
Complete the table comparing the sense
of hearing to the sense of sight!
Hearing
Sight
Sound waves
Light waves
Mechanoreceptors
Photoreceptors
Auditory Nerve
Optic nerve
Hair cells
Rods / Cones
Cochlea
Retina
Pinna
Pupil
Many parts of the ear vibrate in order to create the
sense that we call sound. State, in order, which parts
vibrate. Then, what converts the vibrations into
action potentials?
The sequence of vibrating parts is:
Eardrum
Middle ear bones
Liquid inside of cochlea
Hair cells inside of cochlea
When the hair cells vibrate, they turn
the signal into an action potential!
What do the oval and round windows
do?
The last bone of the middle ear bones presses
against the oval window on the cochlea, causing
vibrations. The round window dampens and gets
rid of “old” sounds.
Edge enhancement
makes edges that
you see seem darker.
How does it work?
Photoreceptors (rods and cones)
repress nearby photoreceptors of from
the same wavelength. So, different
wavelengths (edges) are not repressed;
they’re made artificially sharper!