Lecture 15 Questions UNFINISHED Flashcards
describe the functional anatomy of the eye
Spherical, fluid-filled structure enclosed by 3 tissue layers:
- Sclera/cornea
- Choroid/ciliary body/iris
- Retina
Interior consists of 2 fluid-filled cavities separated by the lens
- Posterior cavity
- Anterior cavity
- Iris
- Pupil
- Lens
what does the lens of the eye accomplish? What properties allow it to do this?
focuses light
- can change shape & can allow you to focus on objects that are near or objects that are distant depending how that lens changes shape
• Process of focusing called Accommodation
– Change in strength of lens
– Fast: takes only 350 ms to change focus from far to
near.
– Accomplished by action of autonomic nervous system on
ciliary muscle. (parasympathetic; ACh)
• The natural shape of the lens is strong and rounded
• The ciliary muscle pulls the lens to a flatter, weaker shape
?
Describe organization of the retina
Innermost layer
under choroid
Consists of: • Outer pigment cells • Rods and cones • Axons of visual nerve fibres
• RD
Which cells are the sensory neurons? Which are the specialized transducer cells?
d ???
Describe the role of the PNS and SNS for focusing? What muscle are involved?
• Process of focusing called Accommodation
– Change in strength of lens
– Fast: takes only 350 ms to change focus from far to
near.
– Accomplished by action of autonomic nervous system on
CILIARY MUSCLE. (parasympathetic; ACh)
• The natural shape of the lens is strong and rounded
• The ciliary muscle pulls the lens to a flatter, weaker shape
Describe the role of the PNS vs SNS for accommodation? What muscles are acted upon?
• Main action of accommodation is via
parasympathetic nervous system (ACh)
• ACh causes contraction of ciliary muscle,
and constriction of the ring.
– Leads to increasing lens curvature for close
objects
– Decreasing parasympathetic tone relaxes
muscle, causes a flatter lens for distant objects
– Sympathetic nervous system does not play a
major role (unlike pupil dilation/constriction
process)
Describe the process of phototransduction, use the words above.
- is the process by which animals convert light energy into electrical signals
- in humans, phototransduction takes place when light hits the retina, the sensory organ of the eye
- the retina develops from the same embryonic tissue as the brain, & (as in the cortex of the brain) neurons in the retina are organized into layers
- there are 5 types of neurons in the retinal layers: photoreceptors, bipolar cells, ganglion cells, amacrine cells, & horizontal cells
??
Differentiate between rods and cones.
RODS: • More. • Grayscale vision. • High sensitivity. – Night vision. – Low acuity. • More convergence onto ganglion cells. • Mainly located in peripheral retina.
CONES: • Fewer. • Color vision (at least three varieties) • Lower sensitivity. - High acuity. - Day vision. • Less convergence • Mainly located in the fovea.
Why is our vision in the nighttime black and white?
rods (grayscale) prioritize for situations with low light (night vision) ?
What is the blind spot
b/c the optic disk has no photoreceptors, images projected onto this region cannot be seen, creating what is called the eye’s blind spot
The ciliary muscle helps to
A) control the amount of light reaching the retina.
B) control the shape of the lens.
C) control the production of aqueous humor.
D) move the eyeball.
E) none of the above
B ?
The amount of light reaching the retina is controlled by the A) lens. B) iris. C) optic disk. D) ciliary muscle. E) more than one of the above
A ?
Photoreceptors secrete the neurotransmitter A) acetylcholine. B) norepinephrine. C) glutamate. D) dopamine.
C ?
Greater visual acuity results from convergence of __________ numbers of cells onto
retinal ganglion cells.
A) higher
B) lower
B ?
