Card Set Information

2012-10-16 00:40:47
Special Senses Vision Hearing Equilibrium

Special Senses, Vision, Hearing, Equilibrium
Show Answers:

  1. What is the role of the Cornea?
    • Responsible for refraction
    • Anterior Tunic of eye, continual with Sclera
    • Na+ pump removes excess H2O
    • Triggers blink Reflex
  2. What is the role of the Iris?
    • Regulates pupil diameter via constrictors (parasympathetic) and dialators (sympathetic)
    • Occulomotor Nerve initiates Pupillary reflex
  3. What is the role of the Aqueous Humor?
    • Similar to Plasma
    • Drains from Canal of Schlemm
    • Disruption results in glucoma (excess fluid)
  4. What is the role of the Retina?
    Sensory Tunic arranged in Photoreceptors - Bipolar Cells - Innermost Ganglia - Optic Nerve
  5. What are Cones?
    • R G B sensing photoreceptors
    • Opsin
  6. What are Rods?
    Black and White 
  7. What is Dark Adaptation?
    • Rhodopsin that is continually produced is broken down in light (bleaching)
    • When in the dark, Rhodopsin accumulates again ~30 minutes
  8. What is Light Adaptation?
    • Rhodopsin is broken down (bleached) in light
    • Retinal Sensitivity decreases
    • Retinal Neurons switch to cones ~ 60 sec
  9. What is the visual Pathway?
    • Photoreceptors - Bipolar Cells - Ganglia - Optic Nerve - fibres cross giving aspects from the other eye - Thalamus (sorts and sharpens information) - Primary Visual Cortex, Occipital Lobe (Processes basic contrast) 
    • Temporal and Parietal - What and Where?
  10. What are the 3 sections of the ear?
    • Outer Ear - Hearing
    • Middle Ear - Hearing
    • Inner Ear - Hearing and Equilirium
  11. How is sound heard? (Processes/Locations)
    • 1.Tympanic Membrane Vibrates
    • 2. Auditory Ossicles Transmit and Amplify (Malleus, Incus, Staples) to the Oval Window of Cochlea
    • 3. Upper Chamber (Scala Vestibuli) receives pressure waves in fluid medium
    • 4. Cochlear Duct (Scala Media) transmits
    • 5. Lower Chamber (Scala Tympani) transmits waves to Organ of Corti (hair cells)
    • 6. Cilia move toward or away from basal body, opening mechanically gated ion channels
    • 7. CNVIII transmits sound
  12. How is frequency detected?
    • 1.Location - Closer to Oval Window - High Frequencies, Further from Oval Window - Low Frequencies
    • 2. Degree of stiffness/length
  13. How is Pitch detected?
    'Where' the hair cells vibrating are located
  14. How is Loudness detected?
    Different cell thresholds for the same frequency
  15. How is Localisation detected?
    Difference in loudness and timing
  16. What is the difference between Conduction deafness and Sensoneural deafness?
    Conduction impacts on conduction to middle ear while Sensoneural is damage to neural structures 
  17. What is Equilibrium?
    Subconscious sense of movement with input from eyes, stretch receptors and vestibular apparatus
  18. What is the Vestibular System?
    • 2 membranous sacs, Saccule (up and down), Utricle (Side to Side) - House maculae
    • 3 semicircular ducts - House Ampullae
  19. What are the Macullae?
    Hair cells with Kinocilium knob in a gelatinous otolithic membrane which bend according to gravity
  20. What are the Ampullae?
    Mounds of crista in semicircular canals with a tuft of vestibular hair. Movement of endolymph fluid deflects the ampulla
  21. Where does the Vestibular system project to?
    • Vestibular Nuclei in Brain stem
    • Motor centres that control eye, neck, limb and trunk reflexes