CH8 - Special Senses Flashcards
Lacrimal glands
Makes tears (lubricates)
Nasolacrimal duct
Excess tears drain into nasal cavity
Sebaceous and sudoriferous glands (maintains moisture)
Eyelids
Warn incoming objects
Eyelashes
Membrane secretes mucus; prevents entrance of microbes
Conjunctiva
White connective tissue layer
Sclera
Allows light to enter the eye
Cornea
Coloured part of eye; regulates light allowed to enter
Iris
Hole through the iris where light passes through
Pupil
Changes shape to focus on far/near objects
Lens
Smooth muscle controls lens shape
Ciliary body
Anterior segment
- Anterior to lens
- Contains aqueous humor
Posterior segment
- Posterior to lens
- Contains vitreous humor
Aqueous humor
- Provides nutrients for lens/cornea
- Maintain intraocular pressure
Vitreous humor
- Prevents eye from collapsing
- Maintain intraocular pressure
Blood vessels bring oxygen/nutrients
Choroid (Vascular layer)
Absorbs light; contains photoreceptors
Retina
Focus point for detailed central vision
Fovea centralis
Blind spot; exit point for optic nerve
Optic disc
Photoreceptors - Rods
- Grey tones
- Dim light
- Peripheral vision
Photoreceptors - Cones
- Color
- Densest in center of retina
Cone sensitivity
- 3 types of cones
- Different cones sensitive to different wavelengths
- Color blindness; result of lack of 1 cone type
Pathway of Light Through the Eye
- 20 ft away for distance vision
- Less than 20 ft away for closer objects (accommodation)
Real images
- Formed in retina
- Reversed from left to right
- Upside down
- Smaller than object
Carries signal to occipital lobe
Optic nerve
Internal muscles
Controlled by autonomic nervous system