Vision Flashcards
What is the central part of vision?
β Fovea
Where is aqueous humour produced?
β Ciliary body
What is the function of aqueous humour?
β keeps the vitreous humour hydrated
β maintains enough pressure to keep the eye rigid
What is glaucoma caused by?
β too much pressure
What do the suspensory ligaments do?
β suspend the lens
What is the function of the ciliary muscles?
β They make the lens more convex or concave
What is the function of the iris?
β Controls the size of the central pupil
β controls how much light enters the eye
What is the function of the lens?
β fine focus
What does the pupil do?
β cut our the light rays that would otherwise go through the edge of the lens
Where is the neural retina generated from?
β The neural tube
What does the neural retina contain?
β Neural circuit which links photoreceptors to retinal ganglion cells
What takes the signal to the brain?
β Retinal ganglions have axons that join with the optic nerve and take the signal to the brain
Describe the pathway to the brain from the eyes
β Axons project back via the optic nerve
β the two nerves meet at the optic chiasm and some axons swap over
β they run into the optic tract which goes up into the brain
β the main branch goes to the lateral geniculate nucleus
β they activate relay cells that carry the signal to the primary visual cortex
βthey run in the subcortical white matter known as the optic radiation
Where is the visual cortex?
β occipital lobe
What are rods used for?
β night vision
What are cones used for?
β high light levels
What does the synaptic terminal release in cones?
β Glutamate
What is the outer segment of cones made from?
β Layers of membranes
What is the ordinary resting potential of cone cells?
β -45mv
What is the resting potential of nerve cells?
β -70mv
What channels do cones have?
β Na+ in the outer segment that leak Na+ inwards