1 / 22

Special Senses

Special Senses. Week 12 Dr. Walid Daoud A. Professor. Physiological Anatomy of the Eye. I- Layers of the eye: . Outer fibrous layer (protective): Cornea, sclera and conjunctiva. . Middle vascular layer (nutritive): Iris, ciliary body and choroid. . Inner nervous layer ( light perception)

abdalla
Download Presentation

Special Senses

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Special Senses Week 12 Dr. Walid Daoud A. Professor

  2. Physiological Anatomy of the Eye I- Layers of the eye: . Outer fibrous layer (protective): Cornea, sclera and conjunctiva. . Middle vascular layer (nutritive): Iris, ciliary body and choroid. . Inner nervous layer ( light perception) Retina, optic disc and nerve.

  3. Physiological Anatomy of the Eye II- Ocular chambers: 1- Aqueous chamber: Anterior to the lens. 2- Vitreous chamber: Behind the lens.

  4. The Cornea Transparent anterior 1/6 of outer layer of eye wall. Sensitive to pain, touch, temperature. Protection of the cornea: 1- Lids and lid reflex (blinking). 2- Corneal reflex. 3- Tears contain lysozymes (antibacterial). Nutrition and metabolism: Cornea is avascular and obtain O2 & glucose by diffusion from capillaries.

  5. Functions of the cornea 1- Refractive power of the eye. 2- Transparency allows passage of light. 3- Regular curvature forms sharp and clear retinal image. 4- Eye protection: . Hardness. . Corneal reflex.

  6. Causes of corneal transparency I-Anatomical: - Regular arrangement of epithelial cells. - Regular arrangement of collagen lamellae. - Absence of bl. vessels & myelinated n. fibers II-Physical: -Relative corneal dehydration: Osmotic and metabolic pumps -Refractive index of collagen fibers is nearly the same

  7. Factors maintaining corneal transparency 1- Vitamin A. 2- Vitamin B12 (riboflavin). 3- Moistening of corneal surface by tear flow.

  8. Intraocular fluid I- Aqueous humour: Function: - Refractive medium of the eye. - Nutrition and O2 supply of avascular cornea and lens. - Maintain intraocular pressure to keep shape of eye ball.

  9. Intraocular fluid II- Vitreous humour: Functions: - Refractive medium of the eye. - Supports retina and maintain globular shape of eye ball. - Prevents backward displacement of the retina.

  10. Uveal Tract 1- Functions of iris: - Regulate amount of light entering eyes. - Increasing depth of focus by constriction. - Limits passage of light to central parts of lens forming clear image on the retina. - Diagnosis of disease affecting reflexes of pupil.

  11. Uveal Tract 2- Functions of Ciliary body: - Ciliary muscle: Diopteric power of lens. Accomodation on near vision. - Ciliary processes: Secrete aqueous humour.

  12. Uveal Tract 3- Functions of Choroid: - Gives nutrition to retina, ciliary body & iris. - Supports the retina. - Gives attachment to ciliary muscle. - Plays role in accommodation. - Choroid pigments prvent reflection of light from inside the eye.

  13. 1- Coditions associated with pupillary dilatation (Mydriasis) 2- Coditions associated with pupillary constriction (Miosis)

  14. Crystalline lens Functions: 1- Enables eye to see near objects. 2- Refractive media of the eye. 3- Protects retina from harmful effects of UV rays which is absorbed by lens & cornea.

  15. Errors of Refraction 1- Myopia (short-sight). 2- Hypermetropia (far-sight). 3- Presbyopia (old-sight). 4- Astigmatism.

  16. Retina Photoreceptors: 1- Cones: for bright (day) vision. 2- Rods: for dim (night) vision. Functions: 1- Vision. 2- Light and accomodation reflexes. 3- Maintain tone, posture and equilibrium. Image formed in the retina is inverted but cerebral cortex interpret it in upright position.

  17. Protective mechanisms of the eye 1-Lacrimal apparatus: Functions of tears: -Keep cornea & conjunctiva moist & clear. -Bacteriolytic action by lysozyme. 2- Eye lids: Function: -Regulation of light entering the eye. -Protection from excessive illumination or FB -Distribution and conduction of tears. 3-Corneal reflex.

  18. Hearing Physiological anatomy: 1- External ear. 2- Middle ear: bony ossicles & muscles 3- Inner ear: cochlea and vestibular appartus. Mechanism of hearing.

  19. Taste Chemoreceptors stimulated by chemical substances: Taste buds: 3 types of cells: 1- Taste (gastratory) cell. 2- Supporting cell. 3- Transitional cell.

  20. Types of taste sensation 1- Sweet taste. 2- Salty taste. 3- Bitter taste. 4- Sour taste.

  21. Factors affecting taste sensation 1- Concentration of tasted substance. 2- Contrast. 3- Surface area stimulated. 4- Temperature. 5- Olfaction. 6- Adaptation. 7- Individual variation.

  22. Smell Olfactory reception cell. Olfactory epithelium: 1- Basal cell. 2- Supporting cell. 3- Bowman,s gland. 4- Receptors. Abnormalities of olfactory sensation: 1- Anosmia. 2- Hyperosmia.

More Related