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Anat-Visual System
| Question | Answer |
|---|---|
| accessory structures of the eye | eyebrows, eyelids, eyelashes, lacrimal (tear) glands |
| visual system components | eye, accessory structures of the eye, optic (CNII) |
| transmission path of visual sensory information | sensory information travels along the optic nerve to the thalamus and then to the occipital lobe where the information is processed |
| eyebrows function | prevent perspiration from running into the eyes (channel it away), provides a little bit of shade and some bony protection |
| eyebrows location | bony ridges forming the superior edge of the orbit |
| eyelids | palpebrae (upper and lower) |
| eyelid function | protection and lubrication (blinking moves tear fluid onto the surface of the eye) |
| lacrimal caruncle location | where the eyelids meet on the medial side of the eye |
| lacrimal caruncle function | has sebaceous and sweat glands that produce a water and oil mix that helps to reduce water loss and makes lubrication for the eye |
| extrinsic eye muscles number/function | 6/ move the eye in the orbit |
| lacrimal apparatus function | contains the lacrimal gland; produces, collects, and drains lacrimal fluid (tears) |
| lacrimal gland location | above the eye in the superior region of the orbit |
| lacrimal gland function | produces tears that lubricate and prevent water loss, innervated by the facial nerve (CNVII) |
| pathway of tears | produced in the lacrimal gland and drains into the nasal cavity via the lacrimal groove and a channel down to the nose |
| conjunctiva structure/location | thin epithelial layer of mucous membrane over the inner surface of the eyelids and the anterior surface of the eyeball (except for the cornea), has associated blood vessels (bloodshot eyes and pink eye) |
| three coats/tunics of the eye | fibrous, vascular, neural |
| Parts of the fibrous tunic | sclera, cornea |
| parts of the vascular tunic | choroid, ciliary body, and iris |
| parts of the neural layer | retina |
| sclera structure | made up of dense irregular connective tissue, fairly thick, white outer layer, continuous with the cornea |
| sclera function | maintains shape, protects internal structures, provides muscle attachment point for the 6 eye muscles |
| cornea structure | no blood vessels so they don't scatter light rays, transparent and curved, gets oxygen from dissolved oxygen in the fluid covering it |
| cornea function | first structure of the eye that light passes through (allows light to enter the eye), does most of the refracting (bending) of light rays |
| iris location | between the cornea (immediately behind it) and the lens |
| iris function | controls light entering the pupil by controlling its size (via the oculomotor nerve) |
| iris structure | made of smooth muscle with and opening (pupil) and pigment cells that give us our eye color |
| ciliary muscles function | control the shape of the lens to focus on objects |
| ciliary muscles location | found inside the ciliary body, connected by suspensory ligaments |
| ciliary muscles structure | made of smooth muscle |
| choroid structure | contains capillaries and melanin pigment (produced by melanocytes) |
| choroid function | helps to absorb stray light rays, forms most of the vascular tunic |
| retina structure | very thin; contains photoreceptor cells sensitive to light, macula lutea, fovea centralis, and optic disc; connected to the optic nerve |
| macula lutea structure/function | yellowish region with a concentration of cones |
| fovea centralis structure/function | "dimple" on the macula lutea with the most concentrated amount of cones, area of the greatest visual acuity, eye is adapted to focus here |
| optic disc structure/function | blind spot where blood vessels and the optic nerve enter the eye, no photoreceptors here, brain fills in the missing part of the image |
| cones function/location | provide color vision and give us visual acuity; found within the fovea centralis |
| visual acuity | the ability to see fine details |
| rods function/location | sensitive to low light conditions; scattered throughout the rest of the retina (other than the fovea centralis) |
| anterior cavity location/contents | anterior to the lens; contains aqueous humor |
| posterior cavity location/contents | posterior to the lens, larger of the two cavities; contains vitreous humor |
| lens location/structure | held by suspensory ligaments attached to ciliary muscles; transparent and biconvex |
| structures involved in focusing and accommodation | cornea, lens, suspensory ligaments, ciliary body |
| far vision distance | 20 feet or more from the eye |
| near vision distance | closer than 20 feet from the eye |
| actions that focus far vision | parallel light rays are bent inwards by the cornea, ciliary muscles relax to make the "hole" larger, the suspensory ligaments taut, and the lens flatter so that it only refracts a small bit (cornea already did most of the work) |
| distance of objects we are adapted to looking at | far objects |
| accommodation | focusing on near objects |
| actions that focus near vision | diverging light rays are partially refracted by the cornea, ciliary muscles contract, ciliary body moves towards the lens, suspensory ligaments relax, and tension on the lens is released to make it thicker and more spherical so it can refract more |
| suspensory ligaments function | attach to the lens at its periphery and transmit tension that enables the lens to change shape |
| myopia causes | eyeball is too long and rays from distant objects focus anterior to the retina |
| hyperopia causes | eyeball is too short so light rays from close objects focus posterior to the retina |
| presbyopia causes | lens becomes less resilient and less able to become spherical with old age-stays in the default position |
| astigmatism causes | due to unequal curvatures along the cornea or lens |
| retinal detachment causes | caused when the layers of the retina separate due to head trauma or stretching of the retina |
| retinal detachment symptoms | fluid accumulates between the layers and causes "floaters", flashes of light, and decreased, watery, or wavy vision |
| astigmatism symptoms | causes unequal focusing and blurred images at all distances |
| presbyopia symptoms | difficulties focusing close-up objects |
| hyperopia symptoms | troubles seeing close-up objects, farsightedness |
| myopia symptoms | troubles seeing far-away objects, nearsightedness |
| glaucoma causes | fluid and pressure build-up in the anterior chamber, which causes a posterior dislocation of the lens and a build-up of pressure in the posterior chamber |
| glaucoma symptoms | reduced field of vision, dim vision, and halos around lights; ocular distortion or pain |
| cataract causes | aging, sometimes caused by diabetes, intraocular infections, excessive UV exposure, or glaucoma |
| cataract symptoms | small opacities in the lens that result in difficulty focusing on close objects, reduced visual clarity, clouding of the lens, "milky" vision, and reduced intensity of colors, also causes blindness |
| macular degeneration causes | physical degeneration of the macula lutea, caused by age, diabetes, ocular infection, heredity, or trauma to the eye |
| macular degeneration symptoms | blindness, photoreceptor loss, thinning of the pigmented layer of the retina, bleeding, capillary proliferation, scar tissue formation, loss of visual acuity, straight lines appear wavy, diminished color perception, floaters or dark areas, dry eyes |
Created by:
Jean-O
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