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Specail senses ana. physio

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  • 1. SPECIAL SENSES
  • 2. •General senses – all throughout the body. •Special senses – confined in the head, eyes and ears ( hearing and balance, sight, taste, smell) - conveyed by cranial nerves
  • 3. •TYPES OF RECEPTORS based on Location: 1. SUPERFICIAL 2. DEEP 3. CORTICAL (combination of superficial and deep) Info: ↓ ↓ Exteroreceptors Proprioceptors - pain, temp., light touch, pressure -from OUTSIDE the body -position sense, kinesthesia, vibration -- from inside the body (muscle spindle, tendons, ligaments)
  • 4. •Visceral Sensation – relayed by the autonomic efferent fibers - hunger, nausea, visceral pain - visceral pain receptors are only in the viscera and respond differently to stimulation not localized Referred pain – as if coming from other parts of the body Ex: liver and gall bladder problem may be referred to the right shoulder
  • 5. I. MECHANORECEPTORS  Respond to mechanical deformation of receptors A. CUTANEOUS SENSORY RECEPTORS Free nerve ending – pain and temp Merkel’s disk - two-pt discrimination, localization of touch Ruffini – warmth (above 25 deg C) Krause end bulb – cold (100-200 deg C)
  • 6. Meissner’s – discriminative touch (texture recognition) Pacinian – deep touch and vibration B. DEEP/JOINT RECEPTORS Muscle Spindle – velocity of movement GTO- monitors tension Free nerve endings- pain and temp Pacinian II. THERMORECEPTORS – for temperature changes III. NOCICEPTORS – noxious stimuli ( damage to tissues)
  • 7. III. ELECTROMAGNETIC RECEPTORS – respond to light (rods and cones) IV. CHEMORECEPTORS – respond to chemical substance A. Taste- receptors of taste buds B. Smell - receptors of olfactory nerves in olfactory epithelium C. Arterial O2- receptors of Aortic and carotid bodies D. Osmolality - neurons of supraoptic nuclei
  • 8. E. Blood CO2 - receptors in or on surface of medulla and in aortic and carotid bodies F. Blood Glucose, amino acid and fatty acids - receptors in hypothalamus Projection – the brain projects sensation back to the source - person pinpoints region of stimulation
  • 9. Pathways From Sensation to Perception (Example of an Apple)
  • 10. •ACUTE PAIN A-delta fibers Fast Sharp pain Localized •CHRONIC PAIN C fibers Slow associated with dull aching pain diffused (difficult to pinpoint) ACUTE PAIN VS. CHRONIC PAIN
  • 11. •OLFACTION - sense of smell, occurs in response to odors that stimulate sensory receptors - receptors located in the extreme superior region of the nasal cavity, called the olfactory recess PATHWAY: Once olfactory receptors are stimulated, nerve impulses travel through olfactory nerves → olfactory bulbs → olfactory tracts →limbic system (for emotions)  olfactory cortex (for interpretation)
  • 12. •olfactory receptors undergo sensory adaptation rapidly •sense of smell drops by 50% within a second after stimulation •Mechanism of olfactory discrimination - unknown -wide variety of detectable (4000) smells actually combinations of a smaller number of primary odors
  • 13. 7 primary scents •Camphor •Musk •Floral •Peppermint •Ether •Pungent •Putrid GUSTATION/Taste - a chemical sense that requires dissolving substance before it can be tasted.
  • 14. GUSTATORY RECEPTORS Located at the taste buds Can also be found on the soft palate, pharynx and larynx Taste buds declines with age Taste bud Organs of taste Location a. Tongue Papillae b. Mouth(roof) c. Cheeks(lining) d. Pharynx(wall) e. Lips
  • 15. Taste receptors •Chemoreceptors •Taste cells-function as receptors •Taste hairs- microvilli that protude from taste cells;sensitive parts of taste cells 4 major types of Papillae according to shape: 1. Vallate- largest; V-shaped -between anterior and posterior border of tongue 2. Fungiform-mushroom-shaped -contains most sensitive to taste buds -folds on the sides of the tongue
  • 16. -most numerous in CHILDREN -decreases with age 4.Filiform-filament-shaped -most numerous -no taste function
  • 17. Five Primary Sensations •Sweet- stimulated by carbohydrates •Sour- stimulated by acids •Salty- stimulated by salts •Bitter- stimulated by many organic compounds •Umami Spicy foods activate pain receptors Taste Pathway Impulses from taste receptors → cranial nerves97,9,10) →medulla →thalamus ↓ limbi syste,hypothalamus↓ Gustatory cortex
  • 18. Visual System oComponents 1.Eyes- respond to light and initiate afferent action potentials. 2. Accessory structures- help protect the eyes from direct sunlight and damaging particles -includes:eyebrows, eyelids, eyelashes, lacrimal apparatus,conjunctiva, extrinsic eye muscles 3. Optic nerves (II), tracts, and pathways
  • 19. Eyebrows- Protects eyes 1. Perspiration 2. Shade from the sun  Eyelid(PALPEBRA)-for blinking (protects the eye from foreign objects) -Average blinking: 25x/min  Muscles a. Orbicularis Oculi- closes b. Levator Palperbrae Superiosis- opens • Canthi: angels where the eyelids join at the medial and lateral margins of the eye • Caruncle: small reddish, on the medial canthi; contains modified sabaceous and sweat galnds
  • 20. CONJUNCTIVE-mucous membrane; lines eyelid and covers portion of eyeball Conjunctivitis-”pink eye” -Inflammation caused by infection or irritation
  • 21. Extrinsic Eye Muscles Lateral rectus- outward; paralysis of both lateral will cause eyes to deviate inward (internal strabismus) Medial rectus- inward; paralysis of both medial will cause eyes to deviate outward (external strabismus) Superior rectus- up and in Inferior rectus- down and in Superior oblique- down and out Inferior oblique- up and out EYELASHES-double or triple row of hairs to the free edges of the eyelids -lubricates lids and restrains tears from flowing over the margin of the eyelids; openings behind the lashes
  • 22. •Lacrimal Apparatus Lacrimal •Lateral to eye •Secretes tears Canaliculi •Collect tears Lacrimal Sac •Collects from canaliculi Punctum •Opening of each lacrimal canaliculis Nasolacrimal Duct •Collects from lacrimal sac •Empties tears into nasal cavity
  • 23. Optical Components:
  • 24. •LAYERS/TUNICS: 1. Outer Fibrous Tunis Sclera Cornea 2. Middle/Vascular Tunic Choroid Ciliary Body Iris 3.Inner Retina Cornea Anterior portion AVASCULAR Transparent Light permission
  • 25. Light refraction One of the first organs transplanted Central part of the cornea receives oxygen from the outside air. soft plastic contact lenses worn for periods must be permeable to air to reach the cornea. Sclera Posterior portion; firm, opaque, white functions: Protection Muscle attachment Shape of the eye Iris Anterior portion pigmented
  • 26. Smooth muscle Controls light intensity Pupil is the hole in iris Dim light stimulates radial muscles and pupil dilates Bright light stimulates circular muscles and pupil constricts -blue eyes: decreased melanin -black/brown: increased melanin
  • 27. •Ciliary Body Anterior portion Pigmented Holds lens Moves lens for focusing Forms internal ring around front of eye Ciliary processes-radiating folds Ciliary muscles-contract and relax to move lens •Choroid Coat Provides blood supply Pigments absorb extra light
  • 28. •Retina Contains visual receptors Continuous with optic nerve Macula lutea- yellowish spot in retina Fovea centralis-center of macula lutea;produces sharpest vision Optic disc-blind spot; contains no visual receptors Vitreous humor- thick gel that holds retina flat against choroid coat fluid in anterior cavity of eye •Aqueous Humor Fluid in the anterior cavity; provides nutrients Maintains shape of anterior portion of eye
  • 29. •Lens Transparent Biconvex Lies behind iris Held in place by suspensory ligaments of ciliary body
  • 30. Accomodation Changing of lens shape to view objects
  • 31. •Refraction Bending of light Occurs when light waves pass at an oblique angle into mediums of different densities Convex lenses cause light waves to converge Concave lenses cause light waves to diverge
  • 32. •Focusing on retina  As light enters eye, it is refracted by  Convex surface of cornea  Convex surface of lens  Image focused on retina is upside down and reversed from left to right
  • 33. Visual Receptors •Rods oContain light sensitive pigment called rhodopsin oMore sensitive to light than cones oProvide vision in dim light oProduce colorless vision oProduce outlines of objects •Cones oShort, blunt projections oProvide vision in bright light oProduce sharp images oProduce color vision
  • 34. Clinical Correlation •Myopia-nearsightedness, too ↑ refraction •Hyperopia- farsightedness, ↓ refraction •Astigmatism- curvature of either lens or cornes is greater in 1 axis or meridian •Scotomas- abnormal blind spot in visual fields
  • 35. Visual Pathway and Visual field cuts Lesions: a.Blindness in one eye b.Bitemporal Hemianopia c.Homonymous Hemianopia d.Quadrantanopsia e.Homonymous Hemianopsia
  • 36. HEARING AND BALANCE EAR
  • 37. External ear •Consists of: auricle and external auditory meatus •Function: hearing only Middle Ear/Tympanic Cavity •Consist of: air-filled CAVITY within the temporal bone, and auditory ossicles •Function in both hearing balance Auricle/Pinna: •Fleshy part of the external ear on the outside of the head •Shape helps to collect sound waves and direct them toward the external auditory meatus •Elastic cartilage covered with skin, extrinsic and intrinsic mm
  • 38. External auditory meatus •Sinus tube that leads to tympanic cavity •Isthmus: narrowest potion of meatus Functions: 1. Conduct sounds waves from auricle to tympanic membrane 2. Prevents foreign objects from reaching the delicate eardrum thru the lined hairs and ceremonous glands, which produce cerumen(earwax) o Tympanic Membrane/Eardrum  Thin, semitransparent, nearly oval  Separates the external ear from the middle ear.
  • 39. Auditory Ossicles: 1. Malleus: largest; handle is attached to the center of the eardrum 2. Incus: attached to the other side of malleus :Whenever malleus moves, incus moves with it. 3. Stapes: attatched to opposite end of incus - Lies against the membranous labyrinth in the opening of oval window where sound waves are conducted into inner ear.
  • 40. Middle ear Chorda tympani -branch if the facial nerve carrying taste impulses from the anterior two-thirds of the tongue -no function in hearing Inner ear Bony Labyrinth: 1. Vestibule: for balance 2. Semicircular canals: for balance 3. Cochlea: for hearing  Membranous labyrinth 1. Utricle 2. Saccule 3.Semilunar ducts 4. Cochlear ducts
  • 41. STEPS IN HEARING 1. The auricle collects sound waves that are then conducted through the external auditory meatus to the tympanic membrane, causing it to vibrate. 2. The vibrating tympanic membrane causes the malleus, incus, and stapes to vibrate. 3. Vibration of the stapes produces vibration in the perilymph of the scala vestibuli. 4. The vibration of the perilymph produces simultaneous vibration of the vestibular membrane and the endolymph causes in the cochlear duct. 5. Vibration of the endolymph causes the basilar membrane to vibrate.
  • 42. 6. As the basilar membrane vibrates, the hair cells attached to the membrane move relative to the tectorial membrane, which remains stationary. 7. The hair cell microvilli, embedded in the tectorial membrane, become bent. 8. Bending of the microvilli causes depolarization of the hair cells. 9. The hair cells induce action potentials in the cochlear neurons. 10. The action potentials generated in the cochlear neurons are conducted to the CNS. 11. The action potentials ate translated in the cerebral cortex and are perceived as sound.
  • 43. Auditory Pathway: Sensory axons from the cochlear ↓ Ganglion terminate in the cochlear nucleus in the brainstem ↓ Superior olivary nucleus or to the inferior colliculus ↓ Medial geniculate nucleus of the thalamus ↓ Auditory cortex ↓ Neurons in the superior olivary
  • 44. Neurons in the superior olivary nucleus send axons to the inferior colliculus, back to the inner ear, or to motor nuclei in the brainstem that send efferent fibers to the middle ear muscles. Clinical correlation: 1. Tinnitus- ringing, buzzing, roaring or “paper crushing” noises in the ear, frequently an early sign of peripheral cochlear disease 2. Deafness a. conduction- impaired conduction through the external canal and ossicles to endolymph and tectorial membrane -cause:external/middle ear diseases
  • 45. b. sensorineural/nerve- interruption of cochlear nerve fibers from hair cells to BS -cause: cochlear nerve/ inner nerve VESTIBULAR SYSTEM For maintenance of stance and body posture; coordination of the body, head and eye movements; and visual fixation STATIC LABYRITH -Stuctures involved: 1. Saccule 2. Utricle -involved in evaluating the position of the head relative to gravity
  • 46. -responds to linear acceleration deceleration, such as when a person is in a car that is increasing or decreasing speed •Macula of the Utricllie: determines person’s head position w/ respect to gravitational force when person is in upright position •Macula of the saccule: equilibrium in lying down OTOLITHS/OTOCONIA: small Ca Carbohydrates crystals in saccule and utricle -displaces the hair cells and excites the saccule and utricle in response to Vertical and Horizontal acceleration
  • 47. •KINETIC LABYRITH -Detects head rotation: Angular Rotation -When head begins to rotate-endolymph in S.D. remain stationary while S.D moves w/ the head direction-cause flow to flow into ampula, bending cupula to side -From hair cells- vestibular nerve to apprise the N.S of change in the rate of direction -Pathway For Balance 1. Sensory axons from the vestibular ganglion pass through the vestibular nerves to the vestibular nucleus, which also receives input from several other sources, such as proprioception from the legs.
  • 48. 2. Vestibular neurons send axons to the cerebellum, which influences postural muscles, and to the motor nuclei (oculomotor, trochlear, andabducents), which control extrinsic eye muscles. 3. Vestibular neurons also send axons to the posterior ventral nucleus of the thalamus. 4. Thalamic neurons project to the vestibular area of the cortex.  OTOSCLEROSIS -Is an ear disorder in which spongy bone grows over the oval window and immobilizes the stapes, leading to progressive loss of hearing
  • 49.  TINNITUS Consists of noises such as ringing, clicking, whistling, or booming in the ears MOTION SICKNESS Consists of nausea, weakness and other dysfuntions caused by stimulation of the semicircular canals during motion, such as is boat, automobile, airplane, swing or amusement park ride OTITIS MEDIA Infections of the middle ear VERTIGO