Chapter 17 Part Two Flashcards
Change in direction of photons (rays) of light as they pass from 1 medium to another
Refraction
Four refractive media of the eye
Cornea greatest of refraction
Aqueous humor found in anterior cavity
Lens
Vitreous humor found in posterior
changing the shape of lens to focus on different distances
Accommodation
Viewing a near object
Ciliary muscle contracts
Suspended ligaments go slack
Lens is more rounded
Viewing a distant object
Ciliary muscle relaxes
Suspended ligaments pulled tight
Lens is flattened
Loss of opacity /cloudy lens
Cataract
Abnormal curvature of the cornea or lens
Astigmatism
Is normal vision 20/20
Emmetropia
To be near sighted
Myopia
Is to be far sighted
Hyperopia
Hyperopia is that occurs with age due to a loss of elasticity of the lens
Presbyopia
20 ft by 20 ft
20/20 vision
Eagle eye, you can see at 20 ft what a person has to see at 15 ft
20/15 vision
With corrective lens you are considered legally blind
20/200
Any substance that absorbs the energy of a photon of light
Pigment
Has the greatest of refraction
Cornea
1st order neuron
Bi polar cells
Sends axons out of optic nerve
Ganglion cells
Visual pigment on a ROD is called _______
Visual pigment on a CONE is called ______
Rhodopsin
Iodopsin
Iodopsin 1 can be found in
Iodopsin 2 can be found in ?
Iodopsin 3 can be found in ?
Red
Green
Blue
Layer of cells containing pigments that absorb photons of light that lie outside the visible spectrum; it’s the photons we can’t see.
Pigmented epithelium
Retina has three layers of cells
Photoreceptors
Rods
Cones
Neurons containing pigments that absorb photons within the visible spectrum
Photoreceptors
An area on the retina in the center of our field of view it has the highest concentration of cones only. Sharpest vision
Fovea
Is an area on the retina with no photoreceptors, it is where all the axons of ganglion cells exit via the optic nerve
Optic disk
Color vision active in bright light
Cones
Black white night vision no color
Rods
Active in darkness slopes silhouettes
Rhodopsin
Four different visual pigments
Iodopsin 1 red
Iodopsin 2 green
Iodopsin 3 blue
Rhodopsin reds only
Rods and cones are the photoreceptor cells found in the
Retina
The other segment of a _____ is tapered and contain many membrane folds, within these folds are integral membrane proteins that make up visual pigment called Iodopsin 1, 2, and 3.
Cone
The outer segment of a ___ contains membranous discs with a similar protein that makes the visual pigment rhodopsin.
Rods
Each visual pigment (Iodopsin and rhodopsin) has a molecule of retinal attached. Retinal is a derivative of retinol vitamin A. It is the _______ portion of the pigment that determines the sensitivity to different wavelengths of light.
Protein
Outside the visible spectrum photons will pass
Ganglion
Bipolar
Photoreceptors
Absorb in pigmented epithelium
Photons inside the visible spectrum will pass
Photoreceptors
Bipolar
Ganglion
Optic nerve
The inner ear is made up of a maze of bone called the
Bony labyrinth
Inside of this bony labyrinth is another maze of membrane called the
Membranous labyrinth
Between the bony and membranous labyrinth is a fluid called
Perilymph
The movement of these fluids will distort the auditory receptors (hair cells) and result in sensations of equilibrium and hearing
Perilymph
Endolymph
The sense of equilibrium is detected by the hair cells found in the
Vestibule (vestibular complex)
The semicircular canals detect _________ movements
Rotational
Anterior posterior rotation nodding your head (yes or no)
Anterior semicircular canal
Horizontal rotation (spin like an ice skater or ballerina)
Lateral semicircular canal
Lateral rotation (leaning or cartwheel)
Posterior semicircular canal
The _______ detect angular linear movements and gravitational motion
Utricle and saccule
The vestibular branch of the vestibule cochlear nerve passes impulses from the semicircular canals and the utricle and saccule to the _______ to provide conscious sensations about body position and movements for motor coordination
Brain
The ______ is the portion of the inner ear that processes what we call sound
Cochlea
What we perceive as sound is vibrations of air molecules that bump into the tympanic membrane like waves of water slapping on a dock. These vibrations of air actually act like and are called
Waves or cycles
The distance from the top of one wave to the top of the next can be measured and is often called
Wavelengths or frequency
So the pitch (high or low sounds) we hear is determined by the number of cycles per second, also measured in a unit called a
Hertz
The highest pitch or frequency the human ear can hear is about ________ cycles per second like the sound of broken glass. Very low frequencies like thunder for example, have low frequencies like _____.
20,000
20
The loudness or volume of a sound is determined by the amplitude of a sound wave. The taller the wave, The higher the amplitude, the louder it sounds. This is measured in a unit called
Decibels
Steps involved in hearing
- The PINNA OF EAR channels sound waves into external auditory canal where they strike and vibrate the tympanic membrane
- The vibrations of the tympanic membrane vibrate the auditory ossicles (malleus, incus, and then the stapes, in that order). The function of the ossicles is to amplify the sound vibrations
- The stapes is attached to and vibrates the oval window of the cochlea
- This results in vibrations or pressure waves in the fluid of the vestibular duct, called Perilymph
- The waves of the Perilymph distort the vestibular, tectorial, and basilar membranes causing a movement of the hair cells that distorts the cell membrane. This physical distortion of the stereocilia results in the opening of ion channels and depolarization of the hair cells.
- The receptor potential stimulates neurons of the spiral ganglion which eventually synapses in the auditory cortex of the temporal lobe of the brain.
High pitch sounds stimulate regions within the cochlea that are very near or proximal to the ____
Oval window
Low pitch sounds stimulate distal regions of the _______ of the cochlea
Membranous labyrinth
List the structures in order, through which the aqueous humor would flow after being secreted by the ciliary body
- Secreted at the ciliary muscle
- Flows through POSTERIOR CHAMBER
- Thru the PUPIL
- Flows in to ANTERIOR CHAMBER
- Reabsorbed @the CANAL OF SCHLEMN
Retina damage due to diabetes
Diabetic retinopathy
By the way, carrots and other veggies contain chemicals (_______) that are used to make vitamin A, which is converted to retinal for visual pigments
Beta carotenes
The hair cells of the utricle and saccule are clustered into small structures called_____. The cells are covered with a gelatinous mass on top of which is found a structure called an _____.
Maculae
Otolith
When the head and body suddenly move in a linear or angular direction, the ______ lag behind and distort the gelatinous mass, which then distorts the hair cells and changes the resting membrane potential
Otoliths
At the base of each semicircular canal is an expanded region called the
Ampulla
Damage to the cochlea or the cochlear branch of the vestibulocochular nerve would result in
Hearing loss
Vestibule nerve is for ?
Cochlear nerve is for ?
Equilibrium
Hearing
