Sensory Mechanisms

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 Four functions: transduction, amplification, transmission, and integration Interpretation of the stimuli by the brain Ex. colors, taste, sound, smell

1. Follow the movement of the rotating pink dot with your eyes. 2 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.

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

Types of sensory receptors Mechanoreceptors  Physical deformation  Stretch receptors in muscles and hair cells Pain receptors  Excess heat, pressure, presence of chemicals, prostaglandins  Naked dendrites called nociceptors Thermoreceptors  Heat or cold  Skin receptors and interoreceptors in the hypothalamus Chemoreceptors  Presence and concentrations of chemicals in the environment  Osmoreceptors in brain, gustatory and olfactory receptors, pheromone receptors in moth antennae  photoreceptors: infrared in snakes, electroreceptors in eels, rods and cones in humans  EM energy EM receptors

Vision and photoreceptors * All have pigment molecules that absorb light Eye cup of planarians Compound eyes of insects, crustaceans, polychaetes Ommatidia are sensitive to movement! Single lens eyes of jellyfish, polychaetes, spiders, mollusks Single lens eyes of vertebrates

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 Structure of the human eye

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

Hearing and equilibrium in mammals Pinna Auditory canal Eustachian tube Tympanic membrane Stapes Incus Malleus Skull bones Semicircular canals Auditory nerve, to brain Cochlea Oval window 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

Chemoreceptors and taste Sensilla in insects Taste buds in mammals

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