Topic 11: Senses. Sensory Receptors

Transcription

1 Tpic 11: Senses Sensry Receptrs Part f the nervus system that detects a stimulus A sensry receptr culd be: Types f Sensry Receptrs: Chemreceptrs: detects chemicals ( ) Phtreceptrs: detects light (fund in ) Thermreceptrs: detects changes in Bulb f Krause: sensitive t temperatures Mechanreceptrs: detect mvement ( ) Meissner s crpuscles: sensitive t Pacinian crpuscles: sensitive t Ruffini crpuscles: senses changes in Pain receptrs ( ): detects tissue damage Osmreceptrs: detects changes in the Sense f Tuch: Tactile crpuscles: tuch receptrs fund in the f skin and arund hair fllicles Senses f pressure: lcated in tissues beneath the skin, near jints, muscles and ther deep tissues Sense f Temperature: free nerve endings fund distributed within the skin Separate receptrs fr ht and cld Sense f Psitin Prpiceptrs: receptrs that maintain muscle tne and gd psture in rder t crdinate mvements Sense f Pain

2 Hw Pain is Perceived Hw t Manage Pain Endrphins: naturally released chemicals that impair the flw f pain signals Aspirin: slws the prductin f pain signaling mlecules Mrphine: mimics endrphins Sense f Taste Taste: chemreceptrs that detect chemicals disslved in fluid (tastebuds) Five Main Flavrs: Sense f Smell (Olfactin) Chemreceptrs that bind t specific substances Olfactry nerve carries impulses frm the smell receptrs t the and Vmernasal rgan: sensitive t Sense f Sight Prtected by:

3 Structure f the Eye Outer layer: Sclera: Crnea: Middle layer: Pupil: Iris: Cilary bdy: Chrid: Inner layer: Lens: Aqueus humr: Vitreus humr: Retina Rds: receptrs fr Cnes: receptrs fr Macula lutea: an area that cntains the Fvea centralis: largest cncentratin f cells that has the sharpest visin Optic nerve: leads t, which in turn sends signals t the crtex

4 Hw Phtreceptrs Wrk Rds: disks which cnsist f : a light absrbing pigment made up f (prtein) and Retinal Vitamin A, which helps t manufacture pigments fr the rds Cnes: three types that are sensitive t, and light Visual Prcessing Cnnect t phtreceptrs t receive, prcess and integrate visual signals Different neurns inside the brain respnd t different visual patterns Regin where the ptic nerve exists in the eye is knwn as the. Accmmdatin: the shape f the lens adjusts s that incming light rays fall n the retina Curvature f the lens determines the extent t which light rays will bend Flat: fcuses n bjects Runder: fcuses n bjects Light Pathway Light waves (bend) nce they enter the eye. Muscles f the adjust the pupil Muscle adjusts the lens ( ) Light stimulates receptr cells f the Optic nerve transmits impulses t the brain lbe interprets the impulse Disrders f the Eye 1. Hyperpia: (light fcuses beynd the retina) 2. Mypia: (light fcuses befre the retina) 3. Astigmatism: irregular curvature f the 4. Strabismus: lack f eyeball crdinatin a. Cnvergent: eye deviates tward the b. Divergent: eye deviates 5. Cnjunctivitis: infectin f the cnjunctiva 6. Cataract: cludiness f the lens

5 a. Surgery can remve the lens and implant an artificial ne 7. Glaucma: excess pressure f the a. Can lead t destructin f sme ptic nerve fibers 8. Retinal detachment: retina detaches frm the layer 9. Macular degeneratin: deteriratin f the central area f the Sense f Hearing/Balance Structure f the Ear Outer ear: adapted t gather sund Pinna: prjecting frm the side f the head that cllects sund waves and directs them int the canal Middle ear: amplifies and transmits air waves t the inner ear Ear drum ( ): vibratins transmit sund waves t middle ear bnes Ossicles (bnes) Mallus Incus Stapes Inner ear: cntains the bny labyrinth Vestibule: tw bny chambers that cntain receptrs fr Semicircular canals: 3 prjecting bny tubes cntaining cells which are stimulated by fluid mvements in canals Cchlea: lks like a snail shell and cntains 2 fluid filled cmpartments and receptrs fr Hw d we hear? Organ f Crti: cntains ciliated receptr cells inside the cchlea

6 Sund waves enter the and cause vibratins in the The, and transfer the vibratins t the val windw Vibratins f the val windw are transferred t the canal, which cntains the rgan f Crti The rgan f Crti cntain hairs that transfer impulses t the nerve which then carries the impulse t the brain Hw d we maintain balance? Macula: mechanreceptrs in the vestibule detect mvement in and planes Cristae: mechanreceptrs in the semicircular canal detect and mvement Otliths: calcium carbnate granules fund within special membranes that stimulate the hair cells t detect psitin Disrders f the Ear Otits Media: bacterial r viral infectin f the ear Otitis Externa: swimmer s ear an infectin f the auditry canal caused by a fungus r bacterium Cnductive hearing lss: results frm the inability f sund waves t pass frm the uter t the inner ear May be a result f an bstructin within the ear canal r blckages f the Eustachian tube r damage t the tympanic membrane Otsclersis: hereditary bne disrder which prevents the vibratin f the stapes may als cause cnductive hearing lss Presbycusis: slw prgressive hearing lss assciated with age Vertig: feeling f dizziness due t an inflammatin f the bny labyrinth Tinnitus: ringing, raring, clicking r hissing sund in the ears due t: Sensry Adaptatin Phenmenn in which receptrs adjust themselves t a cntinuus stimulus s that the sensatin becmes less acute Receptrs adapt at different rates: Receptrs fr temperature and pressure adapt rapidly Receptrs fr pain d nt adapt