Sense Organs Flashcards
Definition of sense organs
Groups of receptor cells responding to specific stimuli.
What do sense organs do?
Sense the external environment by containing sensory neurones which pass impulses to brain for processing
Examples of sense organs
- skin -> temperature, pain & pressure receptors -> feeling temperature + sense of touch
- nose -> chemicals -> sense of smell
- ears -> sense vibrations + balance -> sense of hearing
- tongue -> senses chemicals -> sense of taste
Draw diagram of the eye
—see book
Function of cornea
To refract light
Function of iris
To control how much light enters pupil
Function of lens
To focus light in retina
Function of retina
Contains light receptors, some sensitive to light of different colours
Function of Optic nerve
Carries impulses to brain
Explain pupil reflex
Light intensity - light levels are controlled by the CIRCULAR AND RADIAL MUSCLES surrounding the pupil in the iris of the eye which control the APERTURE (or diameter of the opening) in an ANTAGONISTIC fashion
Explain constriction and dilation of circular and radial muscles
To CONSTRICT the pupil, the CIRCULAR mucles CONTRACT and radial muscles relax
To DILATE the pupil, the CIRCULAR muscles relax and radial muscles contract.
Explain accomodation in the eye to view near and distant objects.
- for distant objects, the ciliary muscles relax and suspensory ligaments pull tights.
- for close objects, the ciliary muscles contract allowing the lens to go fat, thus bending the light more
What are rod and cone cells? Where are they? + function
Rod cells and cone cells are 2 types of light-sensitive cells found in the FOVEA. These activate sensory nerve cells that pass messages into the visual center of the brain.
