Anatomy and Physiology I Lab BSC 2085L Laboratory 10

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Anatomy and Physiology I LabBSC 2085LLaboratory
10

• Visual System
• Eye Anatomy and Physiology
• Ear Anatomy and Physiology

Associate Professor Pamela L. Pannozzo FA
2006 pannozzp_at_pbcc.edu
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Visual System

• Eye
• Accessory structures
• Eyebrows, eyelids, eyelashes, tear glands
• Protect eyes from sunlight and damaging particles
  
• Optic nerve (II)
• Tracts
• Pathways
• Eyes respond to light and initiate action
  potentials

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Accessory Structures of Eye

• Eyelids
• Protect and lubricate
• Conjunctiva
• Mucus membrane lining eyelids and sclera
• Lacrimal apparatus
• Medial and lateral canthus
• Corners of eyelids

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Lacrimal Apparatus

• Lacrimal Gland
• Produces tears to moisten, lubricate, wash
• Lacrimal Ducts
• Collect tears
• Lacrimal Canaliculi
• Collects tears
• Lacrimal Sac
• Empties into nasolacrimal duct
• Nasolacrimal duct
• Opens into nasal cavity

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Anatomy of the Eye

• Three tissue layers
• Fibrous connective tissue Consists of sclera and
  cornea
• Vascular and muscle tissue Consists of choroid,
  lens, ciliary body, iris
• Nervous tissue Consists of retina

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Anatomy of the Eye

• Retina
• Contains neurons sensitive to light
• Macula lutea or fovea centralis Area of greatest
  visual acuity
• Optic disc Blind spot
• Compartments
• Anterior Aqueous humor
• Posterior Vitreous humor
• Lens
• Held by suspensory ligaments attached to ciliary
  muscles
• Transparent

• Sclera
• White outer layer, maintains shape, protects
  internal structures, provides muscle attachment
  point, continuous with cornea
• Cornea Avascular, transparent, allows light to
  enter eye and bends and refracts light
• Choroid
• Iris Controls light entering pupil smooth
  muscle
• Ciliary muscles Control lens shape smooth muscle

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Extrinsic Eye Muscles
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Functions of the Complete Eye

• Eye functions like a camera
• Iris allows light into eye
• Lens, cornea, humors focus light onto retina
• Lens shape adjusted to focus light on fovea
  centralis
• Light striking retina is converted into action
  potentials relayed to brain
• Brain perceives visual spectrum of
  electromagnetic radiation 400-700 nm
• Rods-sensitive to light, night vision
• Cones-color and sharp images red, green, blue

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Focus and Accommodation
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Visual Pathways
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Auditory System Functions

• Hearing
• Convert sound waves into action potentials
• Interpret action potentials as sound (temporal
  lobe)
• Equilibrium
• Detect body position, stabilize body in space
  (temporal lobe and cerebellum)

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Auditory System

• External ear Hearing terminates at eardrum
• Middle ear Hearing contains auditory ossicles
• Inner ear Hearing and balance interconnecting
  fluid-filled tunnels and chambers

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The Ear

• External ear
• Auricle or pinna elastic cartilage
• External auditory meatus

• Middle ear
• Tympanic membrane
• Vibrated by sound waves
• Ossicles
• Malleus, incus, stapes transmit vibrations
• Auditory or eustachian tube
• Opens into pharynx, equalizes pressure

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Inner Ear

• Oval Window
• Transmits fluid waves in cochlea
• Cochlea
• Converts sound waves to action potentials
• Organ of Corti
• Semicircular Canals
• Balance, rotational movement of head
• Vestibule
• Balance, acceleration and deceleration

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Structure of Cochlea
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Hearing

• Vibration of tympanic membrane
• Vibration of malleus, incus, stapes, oval window
• Fluid waves produced in cochlea
• Vibration of basilar membrane of Organ of Corti
  causes action potentials in hair cells
• Action potentials transmitted to temporal lobe

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Balance

• Static Equilibrium
• Vestibule
• Evaluates position of head and movement through
  bending of hair cells

• Rotational Movement
• Evaluates movements of head by pressure of
  gelatinous matrix in canals against hair cells

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CNS Pathways for Balance