Nerves and Eyes Flashcards
What is accommodation?
The changing of the lens’ shape
Which parts of the eye control the lens’ shape?
The ciliary muscles and the suspensory ligaments
What happens to the eye when exposed to sudden very bright light?
The light triggers a reflex that makes the pupil smaller, allowing less light in
What happens to the eye when exposed to dim light?
The brain tells the radial muscles to contract, making the pupils bigger and allowing more light in
What does a coordinated response require?
A stimulus, a receptor and an effector
Why are organisms able to respond to changes in their environment?
To increase their chances of survival
What do receptors do?
They detect a change in the environment (a stimulus)
What do effectors do?
They respond to a nerve impulse by either contracting (muscle) or releasing a chemical (gland)
What does the coordinator (CNS) do?
It receives the nerve impulses from the sensory neurone. It coordinates information received and send out nerve impulses
What does a motor neurone do?
It receives nerve impulses from the CNS and transmits them onto the effector
What does a sensory neurone do?
It receives the nerve impulse from the receptor and transmits it onto the coordinator (CNS)
In what order does a detected nerve impulse reach the muscle?
Receptor Sensory neurone Coordinator (CNS) Motor neurone Effector
What is a synapse?
A gap between neurones where chemicals are released to start up an electrical impulse in the next neurone
What does the iris control?
The diameter of the pupil and therefore how much light enters the eye
What does the lens do?
It focuses the light on the retina (the light-sensitive part of the eye - covered in rods and cones)
