Flashcards in Workbook - Eye and ear Deck (92)
Where is the optic nerve and optic disc located?
In the posterior aspect of the eye.
What is the area anterior to the lens called?
The anterior chamber.
What occupies the anterior chamber?
Aqueous humor (fluid).
-enters from the posterior chamber through the pupil
Where is aqueous humor absorbed from the anterior chamber?
Into the scleral venous sinus.
What structures does light pass through before reaching retinal photoreceptors? (6)
>> anterior chamber (aqueous humor)
>> posterior chamber (aqueous humor)
What is the conjunctiva?
Epithelium over exposed sclera and inner eyelids.
What is the function of the conjunctiva?
-produces mucous and tears
What is the function of the sclera (white of the eye)?
-Protective covering (contains collagen and elastin)
-Muscular attachments (extraocular muscles)
What is the function of the iris?
-Controls the size of the pupil (autonomic control)
-Divides ant/post compartments
Which muscles control the size of the pupil? (2)
-Sphincter pupillae (contraction constricts pupil)
-Dilator pupillae (contraction dilates pupil)
What is the circular muscle of the iris?
What is the radial muscle of the iris?
What is the nerve supply to the sphincter pupillae?
Occulomotor (III) nerve.
What is the nerve supply to dilator pupillae?
Superior cervical ganglion (T1).
What is the nerve supply to the ciliary muscle in the ciliary body?
Occulomotor (III) nerve .
What effect does contraction of the ciliary body have upon the lens?
Contraction causes the lens to become more convex.
-improves focus of closer objects
What are cataracts?
Clouding of the lens.
-clumps of protein/pigment
What are the main functions of the ciliary body? (2)
-Muscles control the shape of the lens
-Produces aqueous humor (>> ant compartment)
What is the function of the aqueous humor?
Helps to maintain the shape of the cornea.
>> refractive properties of the eye
What is the route of aqueous humor before being reabsorbed into the blood stream?
>> post chamber
>> ant chamber
>> trabecular meshwork
>> scleral venous canal
>> episcleral veins
What is glaucoma?
Build up of pressure in eyes leading to decreased vision.
-can damage optic nerve
What causes glaucoma?
Problems with drainage of aqueous humor.
What are the main functions of the choroid layer of the eyeball? (4)
-Nourishes outer laters of retina (v. vascular)
-Regulates retinal heat
-Controls intraocular pressure
-Contains dark pigment >> absorbs light
What lines most of the posterior compartment of the eye?
What structures does the retina contain?
-1st and 2nd order neurons
What are the layers of the retina? (2)
-Outer pigment cell layer
-Multi layered neural retina
What is the outer pigment layer of the retina composed of?
Single layer of cuboidal epithelial cells with melanin filled microvilli.
List 4 functional differences between rod and cone cells.
-responds to dim light, insensitive to colour
-20x more numerous
-predominantly in peripheral parts
-multiple served by 1 bipolar neuron
-colour vision (high visual acuity)
-more abundant centrally (fovea)
-each has its own bipolar neuron
What type of visual cell has high visual acuity and is responsible for colour vision; rod cell or cone cell?