University:
Texas A&M University
Course:
BIOL 319 | Integrated Human Anatomy and Physiology I
Academic year:

2021
Views:

271

Pages:

98
Author:

Lily Callahan

SPECIAL SENSES (EYE & INNER EAR) Objectives • Identify the components Copyright McGraw-Hill Companies of the globe of the eye and the layers of the retina • Correlate the structure and function of the components of the eye • Identify the components of the cochlea • Correlate the structure and function of the components of the cochlea OUTLINE OVERVIEW CELLULAR STRUCTURES THROUGH WHICH LIGHT PASSES A. B. C. CORNEA LENS RETINA STRUCTURES WHICH INFLUENCE THE IMAGE A. B. C. IRIS CILIARY BODIES TRABECULAR MESHWORK EYE Turn the eye so that it is facing you & examine these structures on the front surface of the eye: eyelids - two moveable covers that protect the eye from dust, bright light, and impact sclera - this is the tough, white outer coat of the eye that extends completely around the back & sides of the eye cornea - a clear covering over the front of the eye that allows light to come into the eye (preservative often makes this appear cloudy) iris - round black tissue through the cornea that controls the amount of light that enters the inner part of the eye (may be colored in humans) pupil - the round opening in the center of the eye that allows light to enter and whose size is controlled by the iris Eye – conjuctiva on white of eye THREE LAYERS OF THE WALL OF THE EYE SUPPORTING, VASCULAR, and RETINAL layers Eye - Retina The ora serrata is the serrated junction between the retina and the ciliary body and marks the end of the photosensitive portion of the retina. Slide 8: Eye Posterior chamber Optic nerve Cornea Pupil Connective tissue Anterior chamber Lens Iris Vitreous chamber Chorioid layer Sclera Eye 192 human and 34412 monkey Connective tissue Nerve Posterior chamber 192 Retina Cornea Sclera Pupil Optic nerve Anterior chamber Lens Iris 34412 34412 Vitreous chamber Chorioid layer Ciliary body CELLULAR STRUCTURES THROUGH WHICH LIGHT PASSES A. B. C. CORNEA LENS RETINA cornea CORNEA FUNCTION: • PROTECTION • STRUCTURAL SUPPORT • FILTER OUT UNDESIRABLE LIGHT RAYS • FOCUS IMAGE ON RETINA NUTRITION: • LIMBUS • O2 FROM AIR FOR CORNEAL EPITHELIUM cornea limbus Slide 8: Eye Conjunctiva Endothelium Descement’s membrane Stroma Bowman’s membrane Corneal epithelium Stroma Stroma Eye – corneal epithelium CORNEA lens LENS FUNCTION: FOCUS IMAGE ON PHOTOSENSITIVE PORTION OF PHOTORECEPTOR CELLS NUTRITION: AQUEOUS HUMOR lens 292Eye (toluidine blue) elongation of lens cuboidal cells at bow region Lens (Lens capsule) (Lens epithelium) (Differentiating lens fibers) (Mature lens fibers) Copyright McGraw-Hill Companies • When areas of the lens become opaque or cloudy and vision is impaired, the condition is termed a cataract. In older individuals, denaturation of crystallins commonly begins to occur in lens fibers, making them less transparent and leading to cataracts. 34412 monkey eye CILIARY BODIES lens lens capsule zonules CILIARY BODIES Contraction of muscle reduces tension on zonuales allowing the lens to be more spherical to focus on close objects. Aqueous humor and ciliary zonule fibers Production and removal of aqueous humor Ciliary zonule fibers SEM - Slide 8: Eye Lens Lens Nuclear zone: transitional area from cells to fibers Lens fibers Anterior epithelium Capsule Attached zonula fiber RETINA Retina - RETINA FUNCTION: PHOTORECEPTION OF IMAGE PROCESSING BY NEURONS PREVENT BACKSCATTER OF LIGHT NUTRITION: CHOROID, RETINAL BLOOD VESSELS retina CONES have pigments for the primary colors (red, green, and blue) Slide 8: Eye 1 2a 2b 10 Retina layers 3 4 1. Pigmented epithelium 2a. Layer of rods 2b. Layer of cones 3. External limiting membrane 4. Outer nuclear layer 5. Outer plexiform layer 5 6 7 8 9 10 6. Inner nuclear layer 7. Inner plexiform layer 8. Ganglion layer 9. Nerve fiber layer 10. Inner limiting membrane Photoreceptor cells Cone cell Rod cell phototransduction Rod cell - Functions of Retinal pigment epithelium 1. Vitamin A storage 2. Phagocytosis of rod tips 3. Absorption of light 4. Nutrients to retina 5. Blood retinal barrier 298 Typical retina macula Fovea centralis: a shallow depression with only cone cells at its center; ganglion cells and other conducting neurons are located only at its periphery. It lies directly opposite of the pupil and is where visual acuity or sharpness is maximal. Macula lutea: This surrounds the fovea centralis. Here all layers of the retina are present and the two plexiform layers are rich in various carotenoids, which give the area a yellowish color. The carotenoids have antioxidant properties and filter potentially damaging short wavelength light, thus helping to protect the cone cells of the fovea. macula 34412 Eye (toluidine blue) macula blind spot blind spot STRUCTURES WHICH INFLUENCE THE IMAGE A. B. C. IRIS CILIARY BODIES TRABECULAR MESHWORK IRIS FUNCTION: iris REGULATE AMOUNT OF LIGHT THAT REACHES RETINA BLACKENED POSTERIOR SURFACE TO STOP LIGHT RAYS DILATOR (MYOEPITHELIAL) AND CONSTRICTOR (smooth) MUSCLES NUTRITION: LOCAL BLOOD VESSELS Slide 8: Eye Vascular choroid with melanophores Posterior choroid layer Ciliary body Iris Uvea Choroid Sclera Slide 8: Eye Iris Pigmented epithelium Dilator pupillae Ciliary body Pupillae constrictor Ciliary processes Ciliary muscle Canal of Schlemm Monkey eye 34412 Canal of Schlemm Pupillae constrictor Iris Trabecular meshwork Lens Ciliary body Zonula fibers connected to lens Pigmented epithelium Dilator pupillae The dilator pupillae muscle is controlled by the sympathetic innervation. Ciliary processes Ciliary muscle Slide 8: Eye Ciliary processes Zonula fibers Vitreal, nonpigmented ciliary epithelium layer Scleral, pigmented ciliary epithelium layer Lens Zonula fibers connected to lens Eye (toluidine blue) Iris and lens Iris Lens Pupillae constrictor The sphincter pupillae muscle is innervated by the parasympathetic innervation. 192 Eye – pigmented epithelium of iris Pigmented epithelium of iris Lens IRIS DILATOR (MYOEPITHELIAL) AND CONSTRICTOR (smooth) MUSCLE IRIS MYOEPITHELIAL PIGMENTED LAYER CILIARY BODIES CILIARY BODIES FUNCTION: • CONTRACTION OF MUSCLE CHANGES LENS THROUGH ZONULES • CILIARY PROCESSES SECRETE AQUEOUS HUMOR • BLACKENED REGION STOPS LIGHT RAYS NUTRITION: LOCAL BLOOD VESSELS A detached retina occurs when the pigmented epithelium and the photoreceptor layer of the retina separate. 192 Eye – ciliary muscle 295 192 192 Eye – secreatory cells Secreatory epithelium and pigmented epithelium for the CILIARY BODIES Secreatory epithelium Pigmented epithelium Outflow of aqueous humor IRIS 292 Iris of Eye (toluidine blue) Aqueous humor is produced by ciliary processes. It then flows into the posterior chamber of the anterior cavity through the pupil into the anterior chamber, and finally drains through the canal of Schlemm. TRABECULAR MESHWORK FUNCTION: RESISTANCE TO OUTFLOW OF AQUEOUS HUMOR NUTRITION: LOCAL BLOOD VESSELS, PROBABLY AQUEOUS HUMOR TRABECULAR MESHWORK endothelium Trabecular meshwork and Canal of Schlemm: 1. Anterior chamber 2. Canal of Schlemm 3. Endothelial cell 4. Trabecular meshwork Eye – trabecular meshwork and canal of Schlemm The canal of Schlemm functions to drain the aqueous humor from the anterior chamber via the trabuclar meshwork. 34412 192 34412 artifact human head Ear - Cochlea and spiral organ of Corti - Slide 9: Cochlea Copyright McGraw-Hill Companies Bony cochlea Modiolus TAMHSC 280 Slide 9: Cochlea The scala vestibuli and scala tympani contain perilymph. Copyright McGraw-Hill Companies Organ of Corti Slide 9: Cochlea Spiral limbus Scala tympani Organ of Corti Basilar membrane Spiral ligament Stria vascularis Scala media Cochlear nerve Scala vestibuli Spiral ganglion Tectorial membrane Vestibular (Reissner’s) membrane Sound waves - Mechanotransduction in hair cells - Clinical Correlations A patient complains of “foggy” vision. Upon examination, the patient is diagnosed with age-related cataracts. What portion of the eye is affected by this condition? • When areas of the lens become opaque or cloudy and vision is impaired, the condition is termed a cataract. In older individuals, denaturation of crystallins commonly begins to occur in lens fibers, making them less transparent and leading to cataracts. - Between what layers is the separation in a patient with a "detached retina?" • A detached retina occurs when the pigmented epithelium and the photoreceptor layer of the retina separate. Why is this detachment so important? • This is important because when the retina is detached the photoreceptor cells no longer have access to metabolic support from the pigmented layer and choroid and will eventually die, resulting in loss of vision. Prompt repositioning of the retina and reattaching it with laser surgery is an effective treatment. -

Eye and Inner Ear

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