3.03 Remember and understand the structures and functions of the sensory system

1. 3.03 Remember and understand the structures and functions of the sensory system

2. Essential questions What are the structures of the sensory system? 3.03 Remember the structures of the sensory system

3. The Senses • Eyes • Sight • Ears • Hearing • Nose • Smell • Tongue • Taste • Skin • Touch 3.03 Remember the structures of the sensory system

4. Eyes 3.03 Remember the structures of the sensory system

5. Structures of the eyes • External structures • Orbital socket • Eyelids • Eyelashes • Conjunctiva • Lacrimal gland and duct • Extrinsic muscles

6. Structures of the Eyes • Internal structures • Sclera • Choroid • Retina • Cornea • Iris • Pupil • Lens • Ciliary body 3.03 Remember the structures of the sensory system

7. Structures of the Eyes • Internal structures • Sclera – outer layer/white part of eye. Tough capsule.

8. Structures of the Eyes • Internal structures • Choroid – vascular middle layer 3.03 Remember the structures of the sensory system

9. Structures of the Eyes Internal structures • Retina – • Innermost layer at back of eyeball. • Has light-sensitive cells. • Where light from objects form images. • Images are transmitted as nerve impulses via optic nerve to occipital lobe. • Located on retina are: • Rods • Cones • Optic disk

10. Structures of the eyes RETINA - • Rods ! • Active in dim light • Do not perceive color • Cones ! • Active in bright light • Perceive color • Optic disk ! • “blind spot” • Point of entry for optic nerve • No rods or cones blind spot. • Macula - • Area on retina responsible for sharp central vision 3.03 Remember the structures of the sensory system

11. Structures of the Eyes Internal structures • Cornea – “window of the eye” • Clear circular area at front of sclera 3.03 Remember the structures of the sensory system

12. Structures of the Eyes Internal structures • Iris– colored muscular layer around the pupil. Responsible for pupil constriction/dilation.

13. Structures of the Eyes Internal structures • Pupil –circular opening in choroid where light enters the eye.

14. Structures of the Eyes Internal structures • Lens –biconvex disc that changes shape to help focus at different distances • Divides front chamber from back chamber 3.03 Remember the structures of the sensory system

15. Structures of the Eyes Internal structures • Ciliary Body – Suspensory ligaments that hold the lens in place cornea

16. Structures of the Eyes Internal structures • Aqueous humor – watery fluid in front chamber • Vitreous humor – jelly fluid in back chamber

17. Pathway of Vision • Images in light  • cornea  • pupil  • lens  where light is bent  • retina  • rods and cones pick up the stimulus  • optic nerve  • Optic chiasma  • occipital lobe

18. Name the structures… Eyes Choroid Cho

19. Ears 3.03 Remember the structures of the sensory system

20. Structures and functions of the ears Structures: • Outer ear • Middle ear • Inner ear Functions: • Hearing • Balance 3.03 Remember the structures of the sensory system

21. Structures of the ears • Outer ear • Pinna or auricle • Collects sound waves • Auditory canal • Ceruminous glands • Glands in auditory canal that make cerumen (earwax) • Tympanic membrane • “eardrum” • Vibrates to transfer sound 3.03 Remember the structures of the sensory system

22. Structures of the ears • Middle ear • Ossicles – tiny bones that transmit sound waves from tympanic membrane to inner ear • Malleus – “hammer” • Incus – “anvil” • Stapes – “stirrup” • Eustachian tube – connects to pharynx. Equalizes air pressure. Eustachian tube 3.03 Remember the structures of the sensory system

23. Structures of the ears Inner ear • Cochlea • Filled with fluid that vibrates when the stirrup hits it. Cells pick up that vibration and transmit them as a sensory impulse to brain. • Semicircular canals • Filled with fluid and cells that sense when that fluid is set in motion by movement. These impulses are sent to cerebellum. 3.03 Remember the structures of the sensory system

24. Name the structures… Ears 3.03 Remember the structures of the sensory system

25. Trace the pathway of sound… Ears 3.03 Remember the structures of the sensory system

26. Nose 3.03 Remember the structures of the sensory system

27. Structures of the nose • Nares • Nasal cilia • Nasal septum • Olfactory epithelium – patch of tissue in nasal cavity (size of postage stamp) has cells that pick up smells and transmit them as nerve impulses to the brain via the olfactory nerve 3.03 Remember the structures of the sensory system

28. Structures of the nose 3.03 Remember the structures of the sensory system

29. Structures of the nose • Olfactory area 3.03 Remember the structures of the sensory system

30. Tongue 3.03 Remember the structures of the sensory system

31. Structures of the tongue • Mass of muscle • Papillae - Tiny bumps that give the tongue its rough texture. Thousands of taste buds cover the surfaces of the papillae. • Receptor cells in taste buds send stimuli to brain 3.03 Remember the structures of the sensory system

32. Trivia Tongue • Did you know… • Taste is the weakest of the five senses • We have almost 10,000 taste buds inside our mouths; even on the roofs of our mouths • Everyone’s tongue print is different similar to fingerprints 3.03 Remember the structures of the sensory system

33. Skin 3.03 Remember the structures of the sensory system

34. Structures of the skin • Epidermis layer – outermost covering. Avascular. • Dermis layer – “true skin”. Vascular with nerve ending, sweat glands, hair follicles. • Subcutaneous layer • Touch receptors - Tactile corpuscles located in the skin • Temperature sensors • Pain receptors • Referred pain - perceived at a location other than the site of the painful stimulus. Ex: MI • Phantom pain – feelings in a limb or organ that is no longer there.

35. Structures of the sensory system Myth: The eye is full size at birth. Fact: The eye is NOT full size at birth but continues to grow with your child. This growth partially accounts for refractive (glasses) changes that occur during childhood. Did you know….. • Our eyes are always the same size from birth, but our nose and ears never stop growing! 3.03 Remember the structures of the sensory system

36. Essential questions What are the structures and functions of the sensory system? The End 3.03 Remember the structures of the sensory system