Essential Idea:
Living organisms are able to detect
changes in the environment
Understandings:
- Receptors detect changes in the environment
- Rods and cones are photoreceptors located in the retina
- Rods and cones differ in their sensitivities to light intensities and wavelengths
- Bipolar cells send the impulses from rods and cones to ganglion cells
- Ganglion cells send messages to the brain via the optic nerve
- The information from the right field of vision from both eyes is sent to the left part of the visual cortex and vice versa
- Structures in the middle ear transmit and amplify sound
- Sensory hairs of the cochlea detect sounds of specific wavelengths
- Impulses caused by sound perception are transmitted to the brain via the auditory nerve
- Hair cells in the semicircular canals detect movement of the head
Applications:
- Red-green colour-blindness as a variant of normal trichromatic vision
- Detection of chemicals in the air by the many different olfactory receptors
- Use of cochlear implants in deaf patients
Skills:
- Labelling a diagram of the structure of the human eye
- Annotation of a diagram of the retina to show the cell types and the direction in which light moves
- Labelling a diagram of the structure of the human ear