Lab 11 The Special Senses Flashcards
What is the “white of the eye”?
Sclera
Is the cornea transparent?
Yes.
What fluid is found in the anterior portion of the eye?
Aqueous Humor
What is the function of aqueous humor?
To nourish the eye and maintain internal pressures.
Describe the 2 muscles involved with the iris.
Inner circular portion and outer radial smooth muscles arranged around the central opening (pupil)
What happens to the pupil in bright/dim light?
Bright: the muscles of the iris constrict causing the pupil to constrict allowing less light into the eye
Dim: the muscles of the iris contract dilating the pupil and allowing more light to enter the eye.
What controls the shape of the lens?
Cilliary Muscles
What is the function of the choroid?
To absorb excess light rays to prevent reflection and the scattering of light within the eyeball.
What forms the inner most layer of the eye?
The Retina
What fluid fills the posterior portion of the eye?
Vitreous Humor (body)
What are the photoreceptors involved in the eye?
Rods and Cones
What area contains no photoreceptors?
The optic disc.
What structure of the eye allows for sharpness of vision and why?
The forea centralis contains only cones allowing for high sharpness.
Describe Rods and Cones?
Rods: are stimulated by dimmer light and allow us to see in shades of black, white and grey.
Cones: are stimulated by bright light ad produce color vision (Red Blue Green)
What is glaucoma?
The build up of pressure within the eye which can cause damage to the optic nerve and can result in permanent vision loss.
What is a cataract?
Condition in which the lens of the eye becomes opaque.
What is Accommodation?
At close range the eye must become more rounded or convex in shape in order to view objects at close range.
How do Cilliary muscles and the suspensory ligaments aid in accommodation?
They support and allow for movement of the eye.
What portion of the retina contains a large amount of cones but no rods?
Fovea Centralis
Regarding the Snellen Test, explain what 20/30 vision means?
This means that the person can see at 20 feet what people with normal vision can see at 30 feet.
Describe characteristics of an eye that has Hyperopia?
Eyeball is shorter, lens is flat.
What can happen as a result of having a long shaped eye and long/rounded lens?
Myopia
Where does the light refract during Myopia and Hyperopia?
Myopia (Near Sighted): focal point of light is in front of the retina, causing sight to be blurry far away
Hyperopia (Far Sighted): Focal point of light is behind the eye, causing sight to be blurry at far ranges
What is astigmatism?
The cornea or lens has an irregular shape in surface curvature which can cause objects to appear clear in one axis and blurry in another.
What is the function of the pinna?
Acts as a funnel for sound waves to travel into the ear
What glands are located in the skin of the ear and what do they secrete?
Ceruminous glands; ear wax.
What is the function of ear wax?
To lubricate the ear canal, clean the external auditory canal, keep out bacteria.
Which cranial bone is hollowed out for the middle ear?
Temporal Bone
What are the 3 ossicles?
Malleus, Incus, Stapes
What do the ossicles function as?
Vibrations of the tympanic membrane are transferred and magnified by the ossicles to cause vibrations at the oval window.
What is the functions of the pharyngotympanic tube?
Controls pressure within the middle ear; making the air pressure equal within the ear equal to the air pressure outside the body.
What 2 divisions are found in the internal ear?
- Bony labyrinth
- membranous labyrinth
What fluid is found in the bony labyrinth?
Perilymph fluid
What 3 structures make up the bony labyrinth?
Cochlea, Vestibule, Semicircular canals
Where are the receptors for hearing are located where?
Cochlear Duct
What structure contain the receptors for equilibrium?
Saccule, Utricle, Semicircular ducts
What is the receptor organ for hearing?
organ of Corti
What is the pathway of sound waves from the auricle to the oval window?
Auricle, External Auditory Canal, Tympanic Membrane, Malleus, Incus, Stapes, Oval Window
