Special Senses Flashcards
Lacrimal apparatus
Protects the eye by keeping it moist. Blinking spreads the lacrimal fluid.
Lacrimal sac
Allows lacrimal fluid to drain into the nasolacrimal duct
Extrinsic eye muscles
Control the movement of the each eyeball and hold the eyes in the orbits
Conjunctivae
Secrete mucus to lubricate the eye
Conjunctivitis
Pink eye. Inflammation of conjunctiva
Lateral rectus
Moves eye laterally
Medial rectus
Moves eye medially
Superior rectus
Elevates eye and turns it medially
Inferior rectus
Depresses eye and turns it medially
Inferior oblique
Elevates eye and turns it laterally
Superior oblique
Depresses eye and turns it laterally
Optic disc
Where the optic nerve leaves the eyeball. Also called the blind spot in the fundus (posterior wall)
Sclera
Helps to maintain the shape of the eyeball and provides an attachment point for the extrinsic eye muscles
Cornea
Forms a clear window that is the major light bending (refracting) medium of the eye
Fovea centralis
A tiny pit in the center of the macula lutea, which contains only cones and is the area of greatest visual acuity
Ciliary body
Contains the ciliary muscle and the ciliary process
Suspensory ligaments
Attaches the lens to the ciliary process
Anterior segment/ cavity
Segment anterior to the lens
Anterior chamber
Division of the anterior cavity and is located before the iris
Posterior chamber
Division of the anterior cavity and is
Posterior chamber
Division of the anterior cavity and is located after the iris
Ciliary process
Capillaries here continually form aqueous humor
Aqueous humor
Helps maintain intraocular pressure of the eye and provides nutrients for the avascular lens and corenea
Scleral venous sinus
Drains the aqueous humor
Posterior segment/ cavity
Segment behind the lens and is filled with a gel- like substance called the vitreous humor
Vitreous humor
Gel like substance within the posterior cavity. It provides the major reinforcement for the posterior side of the eyeball and helps to keep the retina pressed firmly against the wall of the eyeball. It is formed only before birth and is not renewed. Functions in light bending as well
Bipolar cells
A cell of the retina in the inner neural layer. Photoreceptors synapse here. Then bipolar cells synapse onto ganglion cells
Ganglion cells
A cell of the retina in the neural layer where bipolar cells synapse.
Optic nerve
Where axons leave the retina in the tight bundle of fibers
Optic chiasma
Where fibers from the medial side of each eye cross over to the opposite side
Optic tract
Fiber tracts leave optic chiasma to form optic tracts. Each optic tract contains fibers from the lateral side of the eye on the same side and from the medial side of the opposite eye
Lateral geniculate body
The optic tract synapses with neurons in the lateral geniculate nucleus of the thalamus
Optic radiation
The axons of the lateral geniculate nucleus form the optic radiation
Primary visual cortex
The optic radiations terminate in the primary visual cortex
Refraction
The bending of light as it passes through a medium and changes speed
Accomodation
The ability of the eye to focus deferentially for objects of close vision
Emmetropic
The normal eye; is able to accommodate
Color Blindness
Color blindness is due to deficiencies in the cones or color photoreceptors
Convergence
Medial eye movements, which is essential for near vision. This is able to occur because of the extrinsic eye muscles
Compare and contrast rods with cones, in as much detail as possible.
The two type of photoreceptors are the rods and cones. Rods are responsible for vision of low light while cones are responsible for bright light. Cones are capable of color vision while rods are not. Visual interpretation of rods are in gray tones. The fovea centralis contains only cones, and the macula lutea contains mostly cones. From the edge of the macular to the retina periphery, cone density declines and rod density increases
a. In farsightedness, the light is focused ____________ the retina, causing _________ vision to be fuzzy.
Behind; near
- Convex lens focuses objects on retina properly
b. In nearsightedness, the light is focused __________ the retina, causing __________ vision to be fuzzy.
Before reaching; far
- Concave lens focuses objects on retina properly
c. The “near point” increases with age because the ____________ of the lens decreases, as we get older, causing ______________.
Elasticity; presobyia
- Presobyia literally means old vision
Explain why there is a retinal blind spot.
The optic disc is where the optic nerve and retinal vessels enter and exit the eyeball. Because of this, there are no photoreceptors here (no cones or rods). Bilateral vision and saccade (involuntary, quick) muscle movements allow our brain to correct for this blind spot/
Glaucoma
When intraocular pressure reaches dangerously high levels, the retina and optic nerve are compressed, resulting in pain and possible blindness
Be able to list the cells of the retina, in the order in which they interact to generate a nerve impulse.
The inner neural layer is composed of three major populations of cells. These are, from outer to inner aspect, the photoreceptors (rods and cones), the bipolar cells, and the ganglion cells. Light enters the eye and passes through the ganglion cells and the bipolar cells in order to excite the photoreceptors. This in turn excites the bipolar cells which then excite the ganglion cells. Their axons then leave the retina through the optic nerve to generate the nerve impulse
Explain the difference between astigmatism and cataracts.
Astigmatism is a blurred vision problem caused from irregularities in the curvatures of the lens and/or the cornea.
Cataracts is a clouding of the lens inside the eye which leads to a decrease in vision.
Explain why reading a computer screen tires your eyes?
During accommodation, the lens becomes:
Flatter to focus the image of a distant object- sympathetic input relaxes the ciliary muscle, tightening the ciliary zonule, and flattening the lens; not tiring
Rounder to focus the image of a nearby object – Parasympathetic input contracts the ciliary muscle, loosening the ciliary zonule, allowing the lens to bulge; potentially tiring for eyes
Be able to explain in detail, the relationship between the frequency of a sound, and our perception of its pitch
Frequency - The number of waves that pass a given point in a given time
Pitch is our perception of different frequencies
Normal sound range is from 20–20,000 Hertz (Hz)
The higher the frequency, the higher the Pitch (the shorter the wavelength)
Wavelength
The distance between two consecutive crests
Wavelength is inversely related to frequency (and PITCH)
Amplitude - The height of the crests (determines VOLUME)
Subjective interpretation of sound intensity (determined by energy content)
Normal range is 0–120 decibels (dB)
Pinna (auricle)
Collects and directs sound waves into the external acoustic meatus
External auditory canal
Transmits sound waves from the auricle to the tympanic membrane. Acts as a funnel to collect sound waves
Tympanic membrane
Vibrates at exactly the same frequency as the sound wave hitting it and transmits vibrations to the auditory ossicles
Malleus, Incus, and Stapes
Malleus (hammer)- transmits and amplifies vibrations from the tympanic membrane to the incus
Incus (anvil)- Transmits and amplifies vibrations from the malleus to the stapes
Stapes (stirrup)- transmits and amplifies vibrations from the incus to the oval window
Oval window
Transmits vibrations from the stapes to the perilymph of the scala vestibuli
Pharyngotympanic tube
Equalizes the pressure in the middle ear cavity with the external air pressure so that the tympanic membrane can vibrate properly
Cochlea
Hearing; receptors in spiral organ
Vestibule
Static equilibrium- linear acceleration of the head; receptors in maculae
Semicircular canals
They monitor the rotational acceleration of the head (Dynamic equilibrium). Planes include horizontal, frontal, and sagittal
Vestibular apparatus
The equilibrium receptors of the internal ear
Ampulla
Enlargement located at the base of each semicircular duct. Within each ampulla is a receptor region called a crista ampullaris
What responds to dynamic equilibrium?
Crista ampullaris
Maculae
Within the membranous utricle and saccule containing other sets of hair cells
Hair cells
Receptors that monitor head position and acceleration in a straight line
