The eye can distinguish two qualities of light:
For humans, the wavelengths between ___ and ____ nanometers are called visible light.
400 and 750
3 structures of the Eye
sclera, choroid, and retina
The outer layer of the eye is
The tough white fibrous layer that maintains, protects and supports the shape of the eye.
The front of the sclera is transparent and is called the
The _______ refracts light rays and acts like the outer window of the eye.
The middle thin layer of the eye
it is the vascular layer of the eye lying between the retina and the sclera.
provides oxygen and nourishment to the outer layers of the retina.
contains a nonreflective pigment that acts as a light shield and prevents light from scattering.
The third or the inner layer of the eye
lays over the back two thirds of the choroid coat
what is the bak two thirds located where the retina lyes
posterior compartment is filled with
vitreous humor which is a clear, gelatinous material
there are cells called rod cells and cone cells also known as photoreceptors within what
What cells are very sensitive to light and do not see color
when we are in a darkened room we see only shades of gray bc of what cells
what cells are sensitive to different wavelengths of light,
how are we are able to tell different colors.
sensitivity of the Cone cells
lack of cones sensitive to red, blue, or green light causes
the center of the retina is the
what sometimes is known as "the blind spot" because it lacks photoreceptors.
what is it called where the optic nerve leaves the eye and takes the nerve impulses to the brain.
The cornea and the lens of the eye focuses the light onto a small area of the retina called the
where the cone cells are densely packed
The fovea is a pit that has the _______ visual acuity and is responsible for our _______ central vision
- there are no rods in the
Layer 1 of the retina
Pigment epithelial cell
-absorb stray light and prevent scatter of light.
Layer 2 of the retina
Receptor cells are rods and cones
Layer 3 of the retina
Bipolar cells. The receptor cells (rods and cones) synapse on bipolar cells, which synapse on the ganglion cells.
Layer 4 of the retina
Layer 5 of the retina
Amacrine cells for circuits with the bipolar cells.
Layer 6 of the retina
Ganglion cells are the output cells of the retina. (*Axons of ganglion cells form the optic nerve).
The photosensitive element
rhodopsin is composed of
scotopsin (a protein) and retinal (an aldehyde of vitamin A).
light on the retina converts 11-cis retinal to all-trans retinal
one of the intermediates formed from photoisomerization
is necessary for the regeneration of 11-cis retinal
Deficiency of vitamin A causes
Metarhodopsin II activates G protein (transducin), which in turn activates
- Phosphodiesterase decrease
Decreased levels of cGMP cause closure of
decreased release of either an exitatory neurotransmitter or an inhibitory neurotransmitter.
If the neurotransmitter is exitatory
then the response of the bipolar or horizontal cell to light is hyperpolarization.
. If the neurotransmitter is inhibitory
, then the response of the bipolar or horizontal cell to light is depolarization.
The optic pathways are from the ______ to the ______
retina to the CNS:
what from the retinal ganglion cells form the optic nerves and optic tracts
Axons synapse in the lateral geniculate body of the
Axons ascend to the visual cortex in the
In order from the eye to the visual cortex what are the names to let you see.
(once learned go to slide to depict color for each part)
5.Lateral Geniculate Nucleas
often of genetic nature, but may also occur because of eye, nerve, or brain damage, or due to exposure to certain chemicals causes
from birth, or be caused by injury or malnutrition (for example, a lack of vitamin A) causes
Night blindness (nyctalopia)
retinitis pigmentosa, a disorder in which the rod cells in the retina gradually lose their ability to respond to the light causes what
Night blindness (nyctalopia)
the inability of the brain to make sense of or make use of some part of otherwise normal visual stimulus, and is typified by the inability to recognize familiar objects or faces.
normal. Light focuses on the retina.
farsighted. light focuses behind the retina and is corrected with a convex lens.
nearsighted. Light focuses in front of the retina and is corrected with a biconcave lens.
Curvature of the lens is not uniform and is corrected with a cylindric lens.
The ear has three divisions
1. Outer ear
2. Middle ear
3. Inner ear
the most external portion of the ear
3 parts of outer ear
Auricle, Ear Canal, Surface of Ear Drum
Part of the ear that is air-filled
what contains most of the ear drum (tympanic membrane)
What 3 ear bones does the middle ear contain
-malleus (or hammer)
-incus (or anvil)
-stapes (or stirrup).
The opening of the Eustachian tube is located in the
has a long process (the handle) that is attached to the mobile portion of the ear drum
the bridge between the malleus and stapes
smallest named bone in the human body.
stapes transfers the vibrations of the incus to the oval window
a portion of the inner ear to which it is connected.
it is fluid-filled.
The inner Ear has 4 parts.
-a series of ducts
the duct in the inner ear are called the
The fluid outside the ducts in the inner ear
the fluid inside the ducts in the inner ear
. The scala vestibuli and scala tympani in the cochlea contain
perilymph, which has a high Na+.
The scala media in the cochlea contains
endolymph, which has a high K+.
The scala media is bordered by the
the site of the organ of Corti.
the organ of Corti contains receptor cells for what
what protrudes from the hair cells
what are embedded in the tectorial membrane
cells are arranged in single rows and are few in number.
cells are arranged in parallel rows and are greater in number than inner hair cells.
contains the cell bodies of the auditory nerve CN VIII
synapse on the hair cells
Sound waves cause vibration of the organ of Corti which leads to
bending of the cillia causes depolarization
bending of the cillia causes depolarization which leads to
firing of cochlear nerves.
(Pics of ear are on slide 15)
The cell bodies of hair cells contact the
The cilia of hair cells are embedded in the
Step 1 of the auditory transduction by the organ of Corti
Sound waves cause vibration of the organ of Corti.
Step 2 of the auditory transduction by the organ of Corti
Bending of the cilia causes changes in K+ conductance of the hair cell membrane .
Step 3 of the auditory transduction by the organ of Corti
The oscillating potential of the hair cells causes intermittent firing of the cochlear nerves.
Step 2 auditory system, The oscillating potential that results is the
Step 2 auditory system, Bending in one direction causes
Step 2 auditory system, bending in the other (opposite) direction causes
Step 1 auditory system, vibration of basilar membrane causes hair cells to bend by force as pushed against
the frequency that activates a particular hair cells depends on the
location of the hair cell along the basilar membrane.
The base of the basilar mambrane (near the oval and round windows) is
narrow and stiff.
what responds best to high frequencies.
base of the basilar membrane
The apex of the basilar membrane (near the helicotrema) is
wide and compliant.
what responds best to low frequencies.
apex of the basilar membrane
Frequency is measured in
Intensity is measured in
symbol for reference pressure measured at the threshold frequency
what is the symbol for decibel?
symbol for sound pressure being measured
Information is transmitted from the hair cells of the organ of Corti to the
afferent cochlear nerves
What nerves synapse on neurons of the dorsal and ventral cochlear nuclei of the medulla
what sends out axons that ascend in the CNS.
Some axons cross to the contralateral side and ascend in the ________ to the __________
the lateral lemniscus (the primary auditory tract) to the inferior colliculus
when other axons do not make it across the the primary auditory tract they remain
The two inferior _______ are connected via the commissure of the inferior colliculus.
Fibers from nuclei of the inferior colliculus ascend to the medial geniculate nucleus of the
Fibers from the thalamus ascend to the
An inflammation of the middle ear segment
It is usually associated with a buildup of fluid and frequently causes an earache.
The fluid may or may not be infected when you have
the tissues surrounding the Eustachian tube swell due to
an infection and/or severe congestion.
how much of the time does the Eustachian tube remains blocked while having Otitis Media
most of the time.
with Otitis Media the air present in the middle ear is slowly absorbed into the
with Otitis Media a strong negative pressure creates a vacuum in the
with Otitis Media the vacuum reaches a point where fluid from the surrounding tissues accumulates in the
What are the most common bacterial causes of otitis media.
-Streptococcus pneumoniae -Haemophilus influenzae
(sometimes common cold)
Study slide 21 anatomy of ear
Study slide 21 anatomy of ear
What detects angular and linear acceleration of the head.
reflex adjustments of the head, eyes, and postural muscles provide a
stable visual image and steady posture
It is a membranous labyrinth consisting of three perpendicular semicircular canals, a utricle, and a saccule.
The semicircular canals detect
angular acceleration or rotation.
The utricle and saccule detect
The semicircular canals are filled with
The semicircular canals are bathed with
The receptors are hair cells located at the end of each
Cilia on the hair cells are embedded in a gelatinous structure called the
A single long cilium
During counterclock wise (left) rotation of the head the horizontal semicircular, the cupula rotates
to the left
the cupula moves more quickly than the
the cupula is dragged through the endolymph; as a result, the cilia on the hair cells
If the stereocilia are bent toward the kinocilium, the hair cell
If the stereocilia are bent away from the kinocilium, the hair cell
cell hyperpolarizes (inhibition).
during the initial counterclockwise (left) rotation, the left horizontal canal is
during the initial counterclockwise (left) rotation, the right horizontal canal is
the endolymph catches up with the movement of the head and the
after the endolymph catches up the cilia return to their upright position and are no longer
depolarized or hyperpolarized
When the head suddenly stops moving, the endolymph continues to move
counterclockwise (left, dragging the cilia in the opposite direction)
when the head suddenly stops, if the hair cell was depolarized with the initial rotation, it now will
when the head suddenly stops, if the hair cell was hyperpolarized with the initial rotation, it now will
when the head stops moving the left horizontal canal will then be
when the head stops moving the right horizontal canal will then be
4 parts in vestibular pathways
what two nuclei receive their input from the semicircular canals
Medial and superior nuclei
what two nuclei project to nerves innervating extraocular muscles via the medial longitudinal fasciculus.
Medial and superior nuclei
what receives input from the utricles
The lateral vestibular nucleus
what projects to spinal cord motoneurons via the lateral vestibulospinal tract
The lateral vestibular nucleus
Projections of the lateral vestibular nucleus play a role in
maintaining postural reflexes.
The inferior vestibular nucleus receives its input from what three things
what projects to the brain stem and the cerebellum via the medial longitudinal fasciculus.
The inferior vestibular nucleus
An initial rotation of the head causes the eyes to move slowly in the opposite direction to maintain
When the limit of eye movements reaches, the eyes rapidly
snap back (nystagmus), then move slowly again.
occurs in the opposite direction of the head rotation.
usually associated with a problem in the inner ear balance mechanisms (vestibular system), in the brain, or with the nerve connections between these two organs.