1. A.P. Biology
Sense Organs

2. Sensory Reception Mechanoreceptor Thermoreceptor Pain Receptor
Type of Sensory Receptor
Mechanoreceptor
Thermoreceptor
Pain Receptor
Chemoreceptor
Photoreceptor
Stimulus
Pressure, position, acceleration (balance)
Heat
Tissue damage
Chemicals (taste, smell)
Light (vision)

3. Brain’s assessment of a stimulus depends on:
Which nerve pathway is carrying the stimulus (i.e. optic nerve—assessed as vision)
Frequency of action potentials (receptors “fire” more frequently for a “stronger” stimulus)
Number of axons stimulated (stronger stimulus recruits more receptors)

4. Sense Organs = concentrations of sensory receptors
Examples: Eye, Ear, Nose etc.

5. Taste—Chemoreceptors in taste buds on the tongue
Chemicals bind to receptors on taste cells, generating nerve impulses in sensory neurons

6. Smell—Chemoreceptors in the nose
Smell—Chemoreceptors in the nose (olfactory cells) detect chemicals (odors)

8. Two types of Photoreceptors—Located in the Retina
Rod Cells—B/W vision
Cone Cells –Color vision

9. Stimulation of the photoreceptors generates nerve impulses  optic nerve  brain

10. Lens focuses images onto the retina
Muscles/ ligaments change the shape of the lens

11. Vision Problems and their Corrections

13. Hearing & Balance Hearing Sound waves enter auditory canal
Vibrate the Tympanic Membrane
Malleus, Incus, Stapes
Vibrates Oval Window
Moves fluid in the Cochlea
Hair cells move, stimulating nerve cells in the auditory nerve (mechanoreceptors)

15. Balance/Movement
Fluid movement in the Semi-circular Canals