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Senses

Senses. Sensory relationships. All of our senses respond to stimuli in the environment Each sense has its own specific organ In each sense organ there are specific sense receptors cells

evelyn-rodriguez
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Senses

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  1. Senses

  2. Sensory relationships • All of our senses respond to stimuli in the environment • Each sense has its own specific organ • In each sense organ there are specific sense receptors cells • The role of sense receptors is to register stimuli in the environment and to provide the other parts of the body with information about these stimuli

  3. Sense organs(Fill out the following table)

  4. Sense organs

  5. 1. The Eye • The eye is the organ of sight • Our eyes enable us to appreciate: • Lines • colours • light properties • movements of the things around us • The eye is made up of a system of 4 membranes and 3 transparent substances

  6. Anatomy of the Eye Membranes: - 1 membrane covers the front part of the eye  the cornea - it is transparent - under the cornea are: 1) The iris : the coloured ring of the eye 2) The pupil: the central portion of this ring (black dot)

  7. Anatomy of the Eye - the other 3 membranes line the posterior (back) of the eye They are all different: • The sclera (outermost membrane) - rigid, gives the eye its shape • The choroid (middle membrane) - provides nourishment for the eye • The retina (innermost membrane) - active nervous membrane = receiver of stimuli

  8. Anatomy of the Eye Transparent Substances: Found inside the eye • The lens • Aqueous humour - located between the cornea and lens - a liquid made up of water and minerals • Vitreous humour - located between the lens and the retina - jelly like substance

  9. What path does light take as it travels through the eye? 1) Light must pass through a number of transparent media before it reaches the nerve cells of the eye. Where are these located?  On the retina. 2) Label these different structures in the order that light passes through: vitreous humour, lens, retina, cornea, aqueous humour 1) cornea  2) aqueous humour  3) lens  4) vitreous humour  5) retina

  10. The Path Light Takes in the Eye • Light passes through and is bent by the cornea and then the lens • Images appear inverted on the retina • When looking at near-by objects = the lens curves and thickens • When looking at far object = the lens flattens • The reflex that causes the lens to change shape is called the accommodation reflex • near-far sightedness

  11. Flattened lens thickened lens

  12. Light rays enter the eye and focus on the retinal nerve cells (neurons) • These retinal nerve cells then change the light waves that strike them into nerve impulses that are carried along the optic nerve to the visual center of the brain • Optic nerve • Nerve tissue formed by the axons of the retinal cells • Transmits nerve impulses form the retina to the optical centre of the brain • Examples of retinal nerve cells: • Rods = detect light and dark • Cones = detect colour

  13. Visual pathway

  14. What is the role of the brain in vision? • It is only when the center for vision in the brain (in the occipital lobe) is stimulated that a person has any visual sensation • Therefore, it is not only the eyes alone that allow us to “see” but also the brain.

  15. Match the following words with the correct term • Eye • Retina • Optic Nerve • Brain • Transformer • Analyzer • Conductor • Receiver

  16. The Chain Reaction Involved in Vision

  17. Recall the blindspot?

  18. Lenses • Convex lenses • Also called converging • Cause light to converge on a focal point • This is like the actual lens inside your eye • Concave lenses • Also called diverging lens • Cause light to diverge from a focal point

  19. Eye Disorders • Hyperopia (far-sighted): • The image is focused behind the retina • Close objects are blurred • Requires CONVEX lenses • Myopia (near-sighted): • The image is focused in front of the retina • Distant objects are blurred • Requires CONCAVE lenses • Presbyopia: • loss of elasticity of the lens (usually in old age) Long eyeball Myopia Short eyeball Hyperopia

  20. Common visual defects

  21. Normal View Myopia Hyperopia Near Sighted Far Sighted

  22. OPTICAL ILLUSIONS

  23. Your brain has learned certain tricks throughout your life. These are “shortcuts” or easier ways to analyze stimuli. • It is possible to use these shortcuts to trick your brain.

  24. Which line is longer?

  25. Are these lines bent, or straight?

  26. Which man is bigger?

  27. What about these doors?

  28. Also, your brain has learned that things can only be one thing… • When something which can be seen as two different things appears out of context, your brain will switch from seeing one, to the other… but not both at the same time.

  29. Your brain fills in certain missing information that is absent because of your blind spot. Sometimes it fills in the wrong information

  30. Read this fast… Aoccdrnig to a rscheearch at an Elingsh uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht frist and lsat ltteer is at the rghit pclae. The rset can be a toatl mses and you can sitll raed it wouthit porbelm. Tihs is bcuseae we do not raed ervey lteter by it slef but the wrod as a wlohe.

  31. http://www.hhmi.org/senses/ http://www.nei.nih.gov/education/visionschool/schintro/VISIONSchoolProgram.pdf

  32. Cataract Surgery Video Online • http://www.cureblindness.org/cataracts/video.html • Lasik eye surgery animation • http://www.mayoclinic.com/health/lasik-eye-surgery/MM00607 • You tube: http://www.youtube.com/watch?v=Y-TUMw1FTmY

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