Topic 3- Nervous System Flashcards
What is the cornea?
Clear part of sclera that allows light to enter and refracts light entering
What is the pupil?
Hole in the centre of the iris which allows light to enter
What is the lens?
Changes shape to focus light onto retina
What is the sclera?
Protective, tough white outer coat
What is the choroid?
A pigmented layer which absorbs light to prevent reflection, also contains blood vessels
What is the retina?
Light sensitive layer. An image is formed here. Impulses sent to the optic nerve.
What is the optic nerve?
Carries impulses from retina to brain
What is the blind spot?
Where the optic nerve leaves the eye, there are no light sensitive cells here
What is the central nervous system?
Brain/ spinal cord
What is each sense organ made up of?
Receptors
What do receptors do?
Collect info from surroundings and pass the info as electrical impulses along neurones to the central nervous system
What do the central nervous system do?
Store information or decide on a reaction
What are the three types of reflex actions?
Protective, automatic, fast
Describe the path taken by a nerve impulse from the receptor to the effector
The stimulus (heat) is detected by the receptors (skin)
The receptor responds and sends an electrical impulse along a sensory neurone to the coordinator (spinal cord)
The electrical impulse is passed to a relay neurone inside the spinal cord then on to the motor neurone.
Between each neurone there is a gap called the synapse
The motor neurone carries the impulse to the effector (muscle)
The muscle contracts and pulls the hand away from the stimulus. This is a response.
What is the iris?
Muscles that alter the size of pupil to control the amount of light entering
