Somatic and Special Senses

1. Somatic and Special Senses Chapter 10

2. Introduction • Sensory Receptors- detect environmental changes and trigger nerve impulses that travel on sensory pathways into the CNS for processing and interpretation http://michaeldmann.net/pix_4b/gust_receptors.gif

3. 2 large types of sensory receptors • 1. Somatic senses: touch, pressure, temperature, and pain • 2. Special senses: smell, taste, hearing, equilibrium, and vision http://www.medicalook.com/systems_images/Somatic_senses.gif

4. Receptors and Sensations • Receptors are distinct to a type of environmental change • This selective response distinguishes the senses • 5 kinds

5. 1. Chemoreceptors • Stimulated by changes in the chemical concentration of substances

6. 2. Pain Receptors • Stimulated by tissue damage https://courses.cit.cornell.edu/psych396/student2006/the_biology_of_pain/receptor2.jpg

7. 3. Thermoreceptors • Stimulated by changes in temperature http://resource.rockyview.ab.ca/t4t/bio30/images/m1/b30_m1_022_l.jpg

8. 4. Mechanoreceptors • Stimulated by changes in pressure or movement http://bdml.stanford.edu/twiki/pub/Haptics/ProjectOverview/mechanoreceptors.jpg

9. 5. Photoreceptors • Stimulated by light energy http://thebrain.mcgill.ca/flash/d/d_02/d_02_m/d_02_m_vis/d_02_m_vis_1a.jpg

10. Sensation • Sensation-a feeling that occurs when the brain interprets sensory impulses • Impulse is read depending on what area of the brain receives it • One area may be sound and one area may be touch

11. http://www.drugabuse.gov/sites/default/files/slide4.gif

12. Projection • Projection-process where the cerebral cortex causes a feeling to stem from a source • It allows a person to pinpoint the region of stimulation (eyes & ears)

13. Sensory Adaptation • Sensory adaptation-sensory receptors stop sending signals when they are repeatedly stimulated • Can only be triggered if stimulus strength changes again • Think smell (phasic)

14. http://www.cyndan.com.au/Portals/0/Media/F/Farm%20Mate%20cow.jpghttp://www.cyndan.com.au/Portals/0/Media/F/Farm%20Mate%20cow.jpg

15. Somatic Senses • 1. Sensory Nerve Fibers • Common in epithelial tissues • Are associated with touch and pressure http://www.exploringnature.org/graphics/anatomy/sensory%20organs.jpg

16. 2. Meissner’s Corpuscles • Small masses of connective tissue • Located in hairless portions of the skin (lips, fingertips, palms, soles, nipples, external genitalia) • Interpret light touch http://www.exploringnature.org/graphics/anatomy/sensory%20organs.jpg

17. 3. Parcinian Corpuslces • Large structures of connective tissue • Located in deep tissue layers like ligaments and tendons • Respond to heavy pressure

18. Temperature Senses • 1. Warm Receptors - nerve endings that respond to warmer temperatures (sensitive above 77°, unresponsive above 113°F) • 2. Cold Receptors - nerve endings that respond to colder temperatures (sensitive between 50°F and 68°F)

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20. Sense of Pain • These protect the body because tissue damage stimulates them • Usually unpleasant and signals the person to remove the stimulation • Pain is persistent and doesn’t go away • Four types

21. 1. Visceral Pain • Occurs in visceral tissues such as heart, lungs, intestine http://wehelpwhathurts.homestead.com/visceral-somatic_referral_patterns_resize_smaller.jpg

22. 2. Referred Pain • Feels as though it is coming from a different part (heart pain may be felt as pain in arm or shoulder) • Caused from Nerves passing through the same area http://www.merckmanuals.com/media/home/figures/NEU_referred_pain.gif

23. 3. Acute Pain • Originates from skin, usually stops when stimulus stops (needle prick) https://courses.cit.cornell.edu/psych396/student2006/the_biology_of_pain/receptor2.jpg

24. 4. Chronic Pain • Dull aching sensations http://criticalscience.com/wp-content/uploads/2011/08/pain-map_alphachimp_com.jpg

25. Regulation of pain • Pain is interpreted by the Cerebral Cortex in the brain. • Three types of neuropeptides that inhibit pain: serotonin, enkephalins, endorphins. • Natural brain chemicals can be mimicked by drugs such as morphine.

26. Morphine http://recoverylife.com/resources/gallery_photo/morphine60.jpg

27. Special Senses • Smell: olfactory organs • Taste: taste buds • Hearing equilibrium: Ears • Sight: Eyes

28. http://www.exploringnature.org/graphics/anatomy/poster_special_senses_small.jpghttp://www.exploringnature.org/graphics/anatomy/poster_special_senses_small.jpg

29. Sense of Smell • The sense of smell is associated with complex sensory structures in the upper region of the nasal cavity http://www.umm.edu/graphics/images/en/8689.jpg

30. Olfactory Receptors • Chemoreceptors that are stimulated by chemicals that are dissolved in liquid • Aid in food selection because smell and taste are closely related http://www.yalescientific.org/wp-content/uploads/2011/05/fulllengths-olfaction-2.jpg

31. Olfactory Organs • Contain the olfactory receptors which are masses that cover the upper parts of the nasal cavity http://www.medicalook.com/systems_images/Olfactory_sense.gif

32. Olfactory Receptor Cells • Bipolar neurons surrounded by epithelial cells • Covered in cilia which have receptor proteins that the odor chemicals bind to http://openwetware.org/images/b/ba/Olfactory_System_2.jpg

33. Olfactory Bulbs • Receive the nerve impulses from the receptor cells (located in the brain) http://lynlaukimdak.wikispaces.com/file/view/42.jpg/219698964/42.jpg

34. Olfactory Tracts • Located inside the olfactory bulbs and interpret the nerve impulses Smell Video http://www.medicalook.com/systems_images/Olfactory_sense.gif