1 / 49

Somatic Senses Special Senses

Special Senses special location. Smell (olfaction)taste (gustation)Vision (optic)Balance (equilibrium)Hearing (auditory). General Senses Somatic

orlando
Télécharger la présentation

Somatic Senses 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. Somatic Senses & Special Senses Chapter 12

    2. Special Senses special location Smell (olfaction) taste (gustation) Vision (optic) Balance (equilibrium) Hearing (auditory)

    3. General Senses Somatic & Visceral Somatic senses: Temperature Touch Pressure Vibration Proprioception Pain Visceral senses: Internal organ conditions

    4. Definition of Sensation Conscious or subconscious awareness of change in external or internal environment Requires: Stimulus Sensory receptor Neural pathway Brain region for integration

    5. Characteristics Perception- conscious awareness Cerebral cortex function Adaptation- decreased receptor response with prolonged stimulation decreased perception Adaptation speed varies with receptor

    6. Structural Types Free nerve endings- pain, thermal, tickle, itch & some touch receptors Encapsulated nerve endings Touch pressure & vibration Specialized cells: e.g. hair cells in inner ear

    7. Receptor Mechanisms Mechanoreceptors- cell deformation, stretching or bending Thermoreceptors- temperature Nociceptors – pain Photoreceptors- light Chemoreceptors- chemicals Taste, smell, body fluid content

    8. Somatic Senses Receptors- distributed unevenly In skin, mucous membranes, muscles, tendons,& joints Dense receptors concentration in fingertips, lips & tip of tongue

    9. Tactile sensations Touch, pressure, vibration, itch & tickle Itch & tickle – free nerve endings encapsulated mechanoreceptors

    10. Touch ? Rapidly adapting receptors: Meisner corpuscles Hair root plexuses Slowly adapting receptors: Type I mechanoreceptors= Merkel discs- surface receptors- stratum basale Type II mechanoreceptors= Ruffini corpuscles- deep in dermis & tendons

    11. Pressure & Vibration Sensation over large area Lamellated or Pacinian corpuscles Rapid adapting & widely distributed Vibration = rapidly repetitive stimuli Corpuscles of touch- low frequency Lamellated corpuscles- higher frequency

    12. Figure 12.1

    13. Itch & tickle Itch- chemical stimulation of free nerve endings Bradykinin from inflammation response Tickle- from free nerve endings & lamellated corpuscles Requires someone else- blocked by signals from cerebellum

    14. Thermal Sensations Two kinds of thermoreceptors- Between 10o & 40o C - cold Located in epidermis Between 32o & 48o C – warm located in dermis Outside these ranges – nociceptors Both adapt rapidly but continue slow signals during prolonged stimulus

    15. Pain Sensations Nociceptors- free nerve endings Found in every tissue but brain Very little adaptation Fast pain= acute, sharp pain (0.1 sec) not felt in deep tissues and well localized Slow pain- slow starting & increases Chronic, burning, aching or throbbing sensation Visceral pain location displaced to surface = referred pain

    16. Figure 12.2

    17. Proprioception Head and limb position & motion Located in muscles (muscle spindles), tendons (tendon organs), in & around synovial joints (joint kinesthetic receptors) Kinesthesia= perception of movements Inner ear (hair ceils)- head position Tracts to primary sensory area of cerebral cortex & cerebellum Slow & slight adaptation

    18. Figure 10.13

    19. Smell- Olfaction In upper surface of superior concha, below cribiform plate Olfactory receptors- first order neurons of olfactory pathway Connect to olfactory bulb Have olfactory hairs containing chemoreceptors Supporting cells- epithelial cells – support & electrical insulation Basal cells- stem cells for receptors

    20. Figure 12.3a

    21. Stimulation of Receptors Genetic evidence- 100’s of primary odors Binding of chemical stimulates nerve Recognition of 10,000 odors from combination of primary receptor input Rapid adaptation by ~50% in 1 sec.

    22. Figure 12.3 b

    23. Taste- Gustatory Sensation 5 primary tastes: salt, sweet, sour, bitter & umami Perception of what we call taste includes olfactory input Receptors in taste buds (~10,000) Located on tongue & pharynx & epiglottis In structures called papillae Vallate (back), fungiform (all over) filiform- touch receptors only

    24. Figure 12.4a

    25. Figure 12.4b

    26. Structure of Taste Bud Epithelial cells: Supporting cells surrounding Gustatory receptor cells Gustatory hair projects from receptor through taste pore Basal cells= stem cells Produce supporting cells that develop into receptor cells (10 day life span)

    27. Figure 12.4c

    28. Vision- Eyes Accessory structures- eye brows, eyelashes- protection eye lids- protection & lubrication (blinking) extrinsic muscles- moving eyeball Superior Rectus, inferior rectus, lateral rectus, medial rectus, superior oblique, inferior oblique Lacrimal apparatus- Gland? lacrimal duct? surface of upper eyelid ? lacrimal canal & nasolacrimal duct ? nasal cavity

    29. Figure 12.5

    30. Layers of Eyeball Fibrous tunic – Anterior clear cornea Sclera- white of eye Vascular tunic- contains: Choroid- Lines most of internal surface carries blood vessels Ciliary body- focuses the lens and secretes aqueous humor Iris- opens & closes pupil- contains pigment of eye color. Pupil = hole for light passage Adjusted by iris to control amount of light through the lens

    31. Figure 12.6

    32. Figure 12.7

    33. Photoreceptors Rods very sensitive, black & white Cones- color sensitive, 3 types-blue, green & red Color vision results from combined input Cones mostly in central fovea 6 million cones 120 million rods

    34. Figure 12.8

    35. Interior of Eyeball Two cavities- divided by lens Anterior cavity: filled with aqueous humor Vitreous chamber: filled with vitreous body Gel-like - holds retina against choroid

    36. What you see Lens- focuses light on the retina Image is inverted but brain adjusts & interprets distance and size

    37. Figure 12.12

    38. Structures of ear Outer ear- Auricle, external auditory canal & tympanic membrane (ear drum) Canal contains hairs & ceruminous glands Middle ear- auditory tube (eustachian tube) & ossicles Ossicles = Malleus, incus, & stapes-attached to oval window Inner ear- Bony labyrinth & membranous labyrinth filled with endolymph Cochlea- sense organ of hearing , vestibule & semicircular canals- organs of balance

    39. Spiral Organ Contains supporting cells & hair cells Hair cells =receptors for auditory sensations

    40. Figure 12.13a

    41. Figure 12.13b

    42. Figure 12.14

    43. Physiology of Equilibrium Static equilibrium- position relative to gravity Dynamic equilibrium- position in response to head movement

    44. Static equilibrium gravity pulls on otoliths in otolithic membrane bends hair cells

    45. Figure 12.15a

    46. Figure 12.15b

    47. Dynamic Equilibrium Semicircular canals- at right angles to each other Cristae in each ampulla have hair cells and supporting cells When head turns hair cells move Endolymph lags and bends hair cells Bend triggers nerve impulse in vestibular branch

    48. Figure 12.16a

    49. Figure 12.16b

More Related