Special Senses: Vision
The iris is composed of two smooth muscle layers, one arranged radially and the other circularly. Which of these dilates the pupil?
The radial layer
Inability to focus well on close objects (farsightedness)
Hyperopia
What is conjunctivitis?
Inflammation of the conjunctiva
Explain why vision is lost in the optic disc
No photoreceptors
Ability to focus for close (less than 20 ft) vision
Accommodation
What is a sty?
An infection of the sebaceous gland of the eyelid
Fluid filling the anterior segment of the eye
Aqueous humor
Light-bending media of the eye
Aqueous humor, cornea, lens and vitreous humor
Blurred vision due to unequal curvatures of the lens or cornea
Astigmatism
In farsightedness the light is focused ______ the retina
Behind
Forms the bulk of the heavily pigmented vascular layer
Choroid
Modification of the choroid that controls the shape of the crystalline lens and contains the ciliary muscle
Ciliary body
Smooth muscle structures
Ciliary body and Iris
Form (by filtration) the aqueous humor
Ciliary processes of the ciliary body
The lens required to treat myopia is a _____ lens
Concave
Found in the fovea centralis, operate best in bright light and allow for color vision
Cones
During close vision, the ciliary muscle is ________, the suspensory ligament is ________, lens convexity is __________, and light refraction is ___________
Contracted, relaxed, increased and increased
Medial movement of the eyes during focusing on close objects
Convergence
Anterior continuation of the sclera - your "window on the world"
Cornea
Normal vision in the left eye visual field; absence of vision in the right eye visual field
Damage to the right optic nerve
Normal vision in both eyes for right half of the visual field; absence of vision in both eyes for the left half of the visual field
Damage to the right optic tract
Pupils dilate in what circumstances?
Dim light and when observing distant objects
The "near point" increases with age because the _______ of the lens decreases as we get older
Elasticity
Normal vision
Emmetropia
Area of critical focusing and discriminatory vision
Fovea centralis
Nearsightedness
Myopia
Part of the retina that lacks photoreceptors
Optic disc
Reduced ability to focus on near objects caused by loss of elasticity of the crystalline lens after age 45
Presbyopia
A convex lens, like that of the eye, produces an image that is upside down and reversed from left to right. Such an image is called a _____ image
Real
Light bending
Refraction
During distance vision, the ciliary muscle is _____, the suspensory ligament is _______, the convexity of the lens is _________, and light refraction is ___________
Relaxed, taut, decreased and decreased
Layer containing the rods and cones
Retina
How is the right optic tract anatomically different from the right optic nerve?
Right optic tract contains fibers from the lateral part of the right eye and the medial part of the left eye, right optic nerve only has fibers from the right eye
Dim light receptors, found in the periphery of the retina
Rods
Composed of tough, white, opaque, fibrous connective tissue
Sclera
The "white" of the eye
Sclera
Drains the aqueous humor from the eye
Scleral venous sinus
What is the function of the adipose tissue in the orbit of the eye?
Supports and surrounds the eyeball, protects and cushions
What modification of the choroid that is not present in humans is found in the cow eye? What is its function?
Tapetum Lucidum, reflects light that enters the eye, helps with night vision
Why does one have to blow one's nose after crying?
Tears drain into the nasal cavity through the nasolacrimal duct
The intrinsic eye muscles are controlled by what system?
The autonomic nervous system
Substance occupying the posterior segment of the eyeball
Vitreous humor
What does the retina look like? At what point is it attached to the posterior aspect of the eyeball?
White membrane, the optic disc
