B9 Flashcards
Cornea
Transparent lens that reflects (bends) light as it enters the eye
Iris
Controls how much light enters the eye
Lens
Transparent disc that can change shape to focus light onto the retina
Retina
Contains light receptor cells - rods(detect light intensity) and cones (detect colour
Optic Nerve
A sensory neurone that carries impulses between the eye and the brain
Fovea
area in which all 3 types of cone cells are found
Accommodation for near objects
- contraction of ciliary muscle
- relaxation of suspensory ligament
- lens becomes thicker and curved
- focal length shortens
- light is refracted more
Accommodation for far objects
- our ciliary muscle is relaxed
- the elastic lens tends to become thin
- ligaments become tight
- lens pulled into a thin shape and less curved
- long focal length
Bright light
-Radial muscles relax
-Circular muscles contract
-Pupil contracts
-Less light enters the eye
Dim light
-Radial muscles contract
-Circular muscles relax
-Pupil dilates
-More light enters the eye
Gravitropism
response in which parts of a plant grow towards or away from gravity.
Phototropism
a response in which parts of a plant grow towards or away from the direction from which light is coming
Homeostasis
maintenance of a constant internal environment.
Negative feedback
Negative feedback is a process that happens when your systems need to slow down or completely stop a process that is happening. Outgoing impulses counteract the effects which produce the incoming pulses.
Hormone
A hormone is a chemical substance, produced by a gland or organ, carried by the blood, which alters the
activity of one or more specific target organs
