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Sense of sight, นางสาวอารียา ตุ่นกระโทก
รหัสนิสิต 63010410118 - Coggle…
Sense of sight
Accessory Structures of the Eye
1. Eyebrows:
- prevent sweat from dripping into the open eyes.
2. Eyelashes:
- Prevent large foreign objects from
contacting the anterior surface of the eye.
3. Eyelids/palpebrae
- protect covering over the surface of the eye
- distributes lacrimal fluid
- Compose of
▪ Tarsal plate (Tp) & glands
▪ Muscles: tarsal, orbicularis oculi (Oo)
▪ Skin (S)
4. Conjunctiva
- A specialized stratified squamous epith.
- contains numerous goblet cell
- numerous blood vessels
- 2 parts
▪ Occular: except cornea (O)
▪ Palpebral (P)
-
Lacrimal Apparatus
Structures produces,collects, and drains lacrimal fluid.
-
Extrinsic Muscles
- Superior rectus
• Rotates eye up and medially
- Inferior rectus
• Rotates eye down and medially
- Medial rectus
• Rotates eye medially
- Lateral rectus
• Rotates eye laterally
- Superior oblique
• Rotates eye down and laterally
- Inferior oblique
• Rotates eye up and laterally
-
Photoreceptor cells
Rods :long, thin
- projections at their
terminal ends
■ Night vision
■ Monochromic vision
Cones: short, blunt
projections
■ Day vision
■ Trichromatic vision
-
Refractive media
- Transparent structures.
- Permits the light pass
through and reach to the
receptors in retina.
- Compose of
○ cornea
○ aqueous humor
○ lens
○ vitreous body
1. Aqueous humor
- Watery fluid
- In anterior and
posterior chamber of the eye
- Produced by epithelium
of ciliary process
- Drain to canal of Schlemm
- Obstruction of this
canal→Glaucoma
2. Lens
- Convex , flexible, no blood vessels & nerve
- Held in position by encircling zonular
fibers from ciliary processes.
- Focus images on the retina to
facilitate clear vision
- Opacity of lens → Cataract
3. Vitreous body
- Fill in vitreous cavity
- A transparent jellylike
- Helps maintain eye shape
- Support the retina
- Transmit light from the lens to the retina
- Degenerative of
vitreous body → Retinal detachment
Pupil Adaptation
Pupillary constriction
⬇️
Contraction of
sphincter pupillae
⬇️
Parasympathetic
Innervation
⬇️
decreases pupil
diameter
⬇️
Reduce the light
entering the eye
Pupillary dilation
⬇️
Contraction of
dilator pupillae
⬇️
Sympathetic
innervation
⬇️
increases pupil
diameter
⬇️
Increase light entry
into the eye
Accommodation
-
(a) Lens shape for distant vision
(b) Lens shape for near vision (accommodation)
-