Sensory Physiology PDF

Sensory Physiology Pseudounipolar neurons: cell body between two axons; no dendrites Peripheral branch and central branch Impulse transferred to ascending tracts LO: Explain how the stimulus modality is perceived Reading: pp. 266-267 Introduction to Sensory Receptors Sensory receptors...

Sensory Physiology Pseudounipolar neurons: cell body between two axons; no dendrites Peripheral branch and central branch Impulse transferred to ascending tracts LO: Explain how the stimulus modality is perceived Reading: pp. 266-267 Introduction to Sensory Receptors Sensory receptors change energy impulse into nerve impulses. Neural pathway depends on sensation (sound, light, pressure) Energy impulse is same, receptors differ, need brain to differentiate Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 4 Sensory Receptors can be classified based on: 1. Type of stimulus 2. How they respond to a stimulus 3. Type of information they give 4. Origin of that information Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 5 Categories of Sensory Receptors 1. Type of Stimulus: Chemoreceptors: sense chemicals in environment (taste, smell) or blood (baroreceptors, osmoreceptors) Photoreceptors: sense light Thermoreceptors: respond to internal temp Mechanoreceptors: mechanical deformation of receptor (touch, hearing) Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 6 Categories of Sensory Receptors 2. Response to stimulus – Phasic and Tonic 1) Phasic receptor: activity burst, quickly adapt - decrease response Examples - smell, touch, temperature 2) Tonic receptor a) Maintain high firing rate as long as stimulus is applied. b) Example: pain Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7 Categories of Sensory Receptors Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 8 Categories of Sensory Receptors 3. Type of information 1) Proprioceptors: Body position and fine muscle control. a. Muscles, tendons, joints 2) Cutaneous (skin) receptors a. Touch, temp, pain 3) Special senses a. Sight, hearing, smell, taste Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 9 Categories of Sensory Receptors 4. Origin of information: Exteroceptors: stimuli from outside the body Cutaneous receptors, special senses (more superficial) Interoceptors: internal stimuli; found in organs Monitor BP, osmolality, pH, and O2 conc. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 10 LO: Describe the organs involved and the function of the special senses (sight, hearing, taste, smell, touch) Reading: pp. 268-277, 281-305 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 11 Touch - Cutaneous Receptors Touch, pressure, pain, cold, and heat receptors mediated by dendrites of sensory neurons. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 12 Taste Taste Cells of Taste Buds Specialized epithelial cells Microvilli contact chemicals. Each taste bud has gustatory cells for each category of tastes: Salty, sour, sweet, bitter, and umami (meaty) Cells behave like neurons - depolarize and produce action potentials. Cells release neurotransmitters onto sensory neurons. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 13  Smell (Olfaction) Olfactory Apparatus Olfactory receptors in olfactory epithelium of nasal cavity. Receptors = neurons with dendrite projecting into nasal cavity ending in ciliated knob 1 odorant molecule to 1 cilia protein to 1 sensory neuron Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 14  Hearing External Ear Waves funneled into external auditory meatus, to tympanic membrane (eardrum). Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 15 Middle Ear Air-filled cavity between tympanic membrane and cochlea Vibrations transmitted, amplified along 3 bones (malleus, incus and stapes) to oval window. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 16  The Cochlea Sound Transmission Vibrations displace perilymph, pass through endolymph leave via round window. 3500 mechanosensory hair cells (stereocilia) on basilar membrane, each with 6-20 sensory neurons. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 17 General pathway of light through the eye Passes through cornea into anterior chamber Through pupil, can change dia. (due to pigmented iris muscle). Through lens, can change shape to focus image. Through posterior and vitreous chambers Retina, interact with photoreceptors, absorbed by choroid layer. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 18 Dilation and Constriction of the Pupil Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 19  Rods and Cones Rods: black-and-white vision in low light Dark adaptation: after 20 minutes more photopigments produced Cones: less sensitive to light, allow color vision and greater visual acuity Response depends on wavelength and intensity Short – blue Medium – green Long - red Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 20