science test nervous system/ lenses Flashcards
what are neurons?
They are cells of the brain, spinal cord and nerves.
what do neurons do
They transmit nerve impulses.
what are neurons composed of
a cell body surrounded by a cell membrane that contains organelles, and a nucleus in the middle.
what are dendrites? and what do they do?
Dendrites are small branches that receive nerve impulses from neurons or sensory nerves.
what is the axon and what does it do
The axon sends nerve impulses out of the cell body and is tipped with nerve endings.
what is the myelin sheath?
its an insulator for the axon that protects and channels the nerve impulses.
what does the lens of the eye do
causes light rays to converge in order to focus on the retina.
what happens When light passes through the transparent structure of the eye,
it refracts (bends).
explain what happens when light hits the eye
Image is projected on retina when light passes through transparent structure.
The image is flipped by the lens but the brain interprets it as if it was right side up.
Rodes and cones of the retina turn light rays into nerve impulses.
Impulses are transmitted through the optic nerve and sensory neurons until they reach the visual arc of the brain.
