Sensory receptors in the skin, eyes, ears, tongue and nose detect various stimuli like light, sound, chemicals and pressure. These receptors convert the stimuli into electrical signals that are transmitted by sensory neurons to the brain. The brain then interprets these signals to form the perceptions of sight, hearing, smell, taste and touch. Sensory receptors include photoreceptors in the eyes, hair cells in the ears, taste buds in the tongue and olfactory receptors in the nose. The brain integrates information from sensory receptors to build an understanding of the external environment.

1. Sensory Mechanisms

2. Sensory receptors and the brain Sensation Perception Action potentials transmitted by sensory receptors to the brain Sensory receptors Specialized neurons/epithelial cells Extero- and interoreceptors Convert energy to changes in membrane potentials and transmit to brain Functions: transduction, amplification, transmission, and integration Interpretation of the stimuli by the brain Ex. colors, taste, sound, smell

4. 1. Follow the movement of the rotating pink dot with your eyes. 2. Stare at the cross in the center. 3. Concentrate on the cross at the center for a long period of time.

5. Is the blue side in the front or back of the cube?

7. Types of sensory receptors

8. Vision and photoreceptors * All have pigment molecules that absorb light

9. Structure of the human eye Ciliary body Iris Suspensory ligament Cornea Pupil Aqueous humor Lens Vitreous humor Optic disk (blind spot) Central artery and vein of the retina Optic nerve Fovea (center of visual field, most cones) Retina with rods and cones Choroid Sclera

11. Hearing and equilibrium in invertebrates Statocysts in invertebrates Ciliated receptor cells Cilia Statolith Sensory nerve fibers 1 mm Tympanic membrane

12. Hearing and equilibrium in mammals Pinna Auditory canal Eustachian tube Tympanic membrane Stapes Incus Malleus Skull bones Semicircular canals Auditory nerve, to brain Cochlea Tympanic membrane Oval window Eustachian tube Round window Vestibular canal Tympanic canal Auditory nerve Bone Cochlear duct Hair cells Tectorial membrane Basilar membrane To auditory nerve Axons of sensory neurons 1 Overview of ear structure 2 The middle ear and inner ear 4 The organ of Corti 3 The cochlea Organ of Corti Outer ear Middle ear Inner ear

13. Chemoreceptors and taste Sensilla in insects Taste buds in mammals

14. Chemoreceptors and smell Brain Nasal cavity Odorant Odorant receptors Plasma membrane Odorant Cilia Chemoreceptor Epithelial cell Bone Olfactory bulb Action potentials Mucus

15. Mechanoreceptors and pain receptors in the skin