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Biol 318 Lab 1
eye and ear
| Question | Answer |
|---|---|
| What is the non-vascular covering of the eye? | fibrous tunic |
| What 2 parts make up the fibrous tunic? | cornea and sclera |
| a transparent, nonvascular, fibrous coat found at the anterior part of eye and continues toward the posterior as the sclera | cornea |
| a tough, fibrous connective tissue covering on the outer surface | sclera |
| what does the sclera do? | gives shape to the eyeball and protects it |
| 3 sections that compose the vascular tunic | choroid layer, ciliary body, iris |
| pigmented, vascularized layer of the vascular tunic | choroid layer |
| what is the function of the choroid layer? | nourishes retina and absorbs light (so that it is not reflected back out) |
| the anterior section of the choroid layer of vascular tunic which connects to the iris by means of muscles and suspensory ligaments | ciliary body |
| what is the function of the suspensory ligaments which arise from the ciliary body? | keeps the lens in place |
| what is the ciliary muscle (body) responsible for? | controlling the shape of the lens |
| a circular donut-shaped band of smooth muscle of the vascular tunic | iris |
| what is the function of the iris? | controls the amount of light that enters the eye |
| distinctive portion of the eye composed of several layers of protein fibers that sits just behind the pupil and iris by suspensory ligaments | lens |
| the interior of the eye contains a large cavity divided into what 2 segments and is separated by what? | an anterior segment and posterior segment separated by the lens |
| this is the larger of the 2 cavities of the eye that lies between the lens and the retina | posterior segment |
| what kind of fluid fills the posterior segment of the eye? | 'jellylike' vitreous humor |
| what is the function of the vitreous humor found in the posterior segment of the eye? | helps maintain shape of eyeball and holds the retina in place |
| does the level of vitreous humor remain constant or change? | remains constant |
| this liquid filling the posterior segment of the eye is clear on models and has an indention in the front that holds the lens | vitreous humor |
| this is the smaller of the two cavities that make up they eye and it contains 2 subdivisions | anterior segment (anterior cavity) |
| what are the 2 subdivisions of the anterior segment of the eye? | anterior chamber of the anterior segment and posterior chamber of the anterior segment |
| this subdivision of the anterior segment of eye lies behind the cornea and in front of the iris | anterior chamber of the anterior segment |
| what kind of fluid fills the anterior chamber of the anterior segment of the eye? | aqueous humor |
| this subdivision of the anterior segment of eye lies behind the iris and in front of suspensory ligaments which holds the lens in place | posterior chamber of the anterior segment |
| what kind of fluid fills the posterior chamber of the anterior segment of the eye? | aqueous humor |
| does the aqueous humor found in the posterior chamber of the anterior segment of the eye remain constant or change? | changes - the aqueous humor flows freely and is replaced by a choroid plexus that maintains correct pressure |
| if the pressure in the eye affected by the aqueous humor being replaced by a choroid plexus is not maintained correctly (excessive pressure), what is the result? | glaucoma |
| this is the inner layer of the eyeball and found in the posterior segment only, and it contains 2 layers | retina |
| what is the primary function of the retina? | image formation |
| this layer of the retina lies next to the choroid layer of the eye and extends over the ciliary bodies and iris, and is nonvisual | pigmented layer |
| this layer of the retina lies over the pigmented layer and ends at the ora serrata (the end of the visual portion of the eye) and has 3 zones of neurons | nervous layer |
| what is the function of the 3 zones of neurons found in the nervous layer of the retina? | it is necessary for image formation |
| what series of specialized cells (photoreceptors) make up the nervous layer of the retina? | rods and cones |
| What is the function of rods? | rods are responsible for discriminating b/w different shades of dark and light and permits us to see shapes and movements (dim light) |
| What is the function of cones? | specialized for color vision and sharpness of vision |
| what kind of cones are there? | red, blue, and green cones |
| What happens if someone is deficient in any of the cones? | they have a genetic disorder called color blindness |
| What is the function of the pigmented layer of the retina? | it absorbs light (nonvisual) |
| this is a blind spot (white spot) found on the retina at the back of they eye that has the optic nerve on the other side | optic disc |
| this structure on the retina at the back of the eye is lateral to the blind spot and directly posterior to the lens; it is an area of high cone density and is also called the "yellow spot" | macula lutea |
| this structure on the retina at the back of the eye is a small pit that is inside of the macula lutea; it contains mostly cones and is the area of greatest visual acuity | fovea centralis |
| how is eye movement achieved? | by contraction and relaxation of extrinsic muscles of the eye (red on the models) |
| what are the 3 cranial nerves that control eye movement? | ???? |
| what is the path of light for vision? (flow chart) | light enters thru cornea>> ant chamber of ant segment (aqueous humor) >>pupil >> post chamber of ant segment (aqueous humor) >> lens>> post segment (vitreous humor) >> retina (rods & cones)>> photoreceptors receive the light & convert to a nervous impulse |
| How does visual interpretation take place in the rods and cones (photoreceptors)? pick up stimuli >send impulse to bipolar neurons which synapse w/ganglion neurons> these axons join together in back of eyeball w/o rods & cones(blind spot of optic disc) | >leave as opticnerve>medial optic fibers crossover@ optic chiasma>lateralfibers stay@original side>formed optictracts progress to nucleus in thalamus>they synapse &send impulses to visual areas of cerebral cortex in occipital lobe>here is visual interpret |
| the cartilaginous external portion of the ear | auricle (pinna) |
| what is the function of the auricle (pinna)? | tends to collect and funnel sound waves toward the auditory canal |
| the ear lobe | lobule |
| S-shaped passageway beginning at the auricle and ending at the ear drum | external acoustic meatus |
| what are located along the canal (external acoustic meatus) and what is the function of this? | glands; they secrete ear wax (cerumen) which lubricates and protects the ear from entrance of foreign particles |
| this ear structure vibrates when sound waves hit it | tympanic membrane (eardrum) |
| another name for malleus | hammer |
| another name for incus | anvil |
| shaped like the stirrup on a saddle and the base of it is in contact with the oval window on most models | stirrup or stapes |
| connects the middle ear to the throat | pharyngotympanic (auditory) tube; eustachian tube |
| what are the functions of the eustachian tube? | allows you to equalize the pressure of the middle ear cavity with the external pressure so that the tympanic membrane can vibrate freely; also how microbes can move from the throat to the middle ear & cause infection |
| part of the internal ear anatomy that is filled with perilymph | semicircular canals |
| part of internal ear anatomy; bony structure b/w the semicircular canals and the cochlea | vestibule |
| what are the semicircular canals and vestibule associated with? | equilibrium |
| internal ear anatomy that is below and a little behind the oval window | round window |
| the snail-like bone containing a membranous labyrinth filled with endolymph and the Organ of Corti | cochlea |
| What are the Organ of Corti? | are the hair cells and the receptors for hearing |
| Describe how the hair cells work. | When the hair cells bend, the sound waves are converted to nervous impulses and are carried to the temporal lobe of the cerebral cortex to the hearing functional area |
| part of the internal ear anatomy that branches into the vestibular nerve and cochlear nerve | vestibulocochlear nerve |
| Trace the path of sound through your diagram of the ear. | external acoustic meatus > tympanic membrane > hammer > anvil > stirrup > oval window > vestibule > cochlea > Organ of Corti > cochlear nerve > vestibulocohclear nerve > temporal cortex of brain |
| What can damage of the hair cells lead to? | hearing loss |
| this leaves the eye and contains medial and lateral fibers | optic nerve |
| this has the medial fibers of the optic nerve which cross over | optic chiasma |
| these contain the lateral fiber of same side and medial fibers of opposite side | optic tract |
| How do the fibers in the optic tract synapse? | They synapse with neurons in the lateral geniculate body of the thalamus, whose axons form the optic radiation, terminating in the visual cortex in the occipital lobe of the brain |
| What is accomodation? | The ability of the eye to focus differentially for objects of near vision |
| What is the condition resulting from the decrease in elasticity of the lens due to age? What does it make difficult? | Presbyopia, "old vision." It makes it difficult to focus close vision. |
| What is the average near point vision? | 10cm in young adults - closer in children and farther in old age |
| when vision is normal and no need for vision correction; focal point is the retina | emmetropic eye |
| nearsighted - foal point is in front of the retina (objects far away seemed blurred) | myopic eye |
| farsighted - focal point is behind the retina (objects closer seem blurred) | hyperopic eye |
| what are lenses or glasses used for? | to adjust the focal point so that it lands on the retina |
| Describe the numbers on the Snellan eye chart. | 20 = vision is normal >20 = less than normal <20 = better than normal |
| What is astigmatism and what is it caused by? | A blurred vision problem caused by irregularities in the curvatures of the lens and/or the cornea |
| this provides 3-D vision and an accurate means of locating objects in space b/c the visual fields of each eye overlaps | binocular vision |
| type of vision see in animals that have eyes on the sides of their heads | panoramic vision |
Created by:
carolineprather
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