The Nervous System and the Eye Flashcards
What is the reflex arc?
Stimulus - receptor - sensory neurone - relay neurone - motor neurone - effector - response
What neurones are in the peripheral nervous system?
Motor neurones and sensory neurones
What is the spinal cord?
long and thin tubular bundle of nerves
Extension of the CNS from the brain
Enclosed by the vertebral column
What are the two main parts of the CNS?
brain and spinal cord
What happens in the transmission of a nerve impulse across a synapse?
The nerve impulse travels along the axon in the form of an electrical signal. The vesicles containing neurotransmitter move to the membrane. The neurotransmitter is emptied into the synapse. It diffuses across the synapse. The neurotransmitters bind to the receptor on the surface of the dendrite, triggers a new nerve impulse.
What does the iris do to change the size of the pupil?
To make the pupil bigger, the radial muscles contract and the circular muscles relax.
What are rods responsible for?
Dim light vision
What are cones responsible for?
Colour vision
How does the lens help us focus?
The lens refracts the light onto the retina upside down and our brain flips the image
What shape of the lens is used for focusing on a distant object? Why?
The lens needs to be flatter, because the light comes in nearly parallel.
What shape of the lens is used for focusing on things close to us? Why?
The lens is rounder, so it can bend the light more to hit one point on the retina.
What do the ciliary muscles do to make the lens flatter?
Ciliary muscles relax, suspensory ligaments are pulled tight
