Vision Flashcards
What is the conjuctiva?
Transparent mucous membrane over the white of the eye, consisting of the palpebral conjuctiva and bulbar conjunctiva.
What is the lacrimal apparatus?
Consists of the lacrimal gland (tears) and the ducts that drain into the nasal cavity.
What are the muscles of the eye?
The superior, inferior. lateral and medial rectus muscles, and the superior and inferior oblique muscles, mostly served by the oculomotor nerves.
What are the 3 layers of the eye?
fibrous, vvascular and inner layers.
What 2 regions make up the fibrous layer of the eye?
Sclera (white, tough fibrous tissue) and Cornea (clear, fibrous layer which lets light in)
What 3 regions make up the vascular layer?
Choroid (vessel-rich dark brown membrane), Ciliary body (thickened ring of tissue encircling the lens) and the iris (2 smooth muscle layers to move the pupil)
What does the inner layer (retina) consist of?
Photoreceptors, other neurons involved in processing light, and glia.
What are the two types of photoreceptors?
Rods (dim light, less detail) and cones (bright light, high detail and colour)
What does light pass through to get to the photoreceptors?
Cornea, aqueous humor, lens, and vitrous humor, then passes through the neural layer of the retina to exite photoreceptors.
What happens during distant vs close vision?
Distant vision: ciliary muscles are relaxed, tension in the ciliary zonule stretches the lens flat. Close vision: ciliary muscles contract, lens bulges.
How are signals send to the brain from the eye?
Light hyperpolarizes photoreceptors, which stop releasing neurotransmitter (glutamate). This then depolarizes biopolar cells which activates gaglion cells which create an AP. This AP travels through the optic nerve.
Where does the optic tract go?
Most fibres go to the laterial geniculate body of the thalamus, then onto the primary visual cortext. Other tracts go to the superior colliculi, pretectal nuclei and suprachiasmatic nucleus of the hypothalamus.
