Receptors and Senses

1. Receptors and Senses Amelia Hoyt

2. Relationship Between Receptors & Senses The senses are a result of receptors -they are used to identify changes in the environment -detecting/processing sensory information and generating motor responses is the physiological basis for all animal behavior

4. Pathways Four basic functions: 1 sensory reception 2 transduction 3 transmission 4 perception -the ultimate effect of the wide range of sensory receptors is to open/close ion channels

5. 1) Sensory Reception receptor: -a sensory cell or organ -a subcellular structure that interacts directly with stimuli types of receptors: -mechanoreceptors -chemoreceptors -electromagnetic receptors -thermoreceptors -pain receptors

6. 2) Transduction -sensory transduction: conversion of a physical or chemical stimulus to a change in the membrane potential of a sensory receptor -receptor potential: change in the membrane potential itself

7. 3) Transmission -for many receptors, transducing the energy in a stimulus into a receptor potential initiates transmission of action potentials to the Central Nervous System

8. 4) Perception -color, smell, sound, taste, touch -constructions formed in the brain: do not exist outside of it

9. Sensory Systems -hearing -sight -taste and smell

10. Hearing -result of mechanoreceptors -related to perception of body equilibrium (balance) -mechanoreceptor cells produce receptor potentials when settling particles or moving fluid causes deflection of cell-surface structures

14. Sight -ability of animals to detect light and other electromagnetic radiation -underlying mechanism for capturing light is the same despite the use of a diverse set of organs -all contain photoreceptors: cells that contain light-absorbing pigment molecules -genes for vision present among diverse groups

16. Taste and Smell -gustation: taste -olfaction: smell -both depend on chemoreceptors that detect specific chemicals in the environment -for terrestrial animals, taste=detection of tastants and smell=detection of odorants -no distinction between taste and smell in aquatic animals

17. Senses in Cnidarians -Cnidarians lack image-forming eyes -rely on chemoreceptors to recognize the smell and taste of prey -rely on mechanoreceptors to recognize the pressure and vibration of prey

18. Senses in the Annelida (polychaetes) -receptors detect light, chemicals, pressure -have ciliated structures believed to be chemoreceptors -have eyes, which can form compound images -some species have statocysts

20. Senses in the Arthropoda (insects) -modified cuticles into a diverse number of receptors -setae -pressure sensors -antennae -compound eyes and ocelli -some species have statocysts

22. Senses in Mammalia (humans) -hearing & equilibrium closely related -five types of tastants: sweet, sour, salty, bitter, umami -vision is well-processed to form images in color and eyes have the ability to focus by changing the shape of the lens -individual taste cells contain receptors that only recognize one specific tastant

26. Hearing Disorders Otosclerosis: -unknown causes, but likely a genetic link -result of an abnormal sponge-like bone growing in the middle ear, preventing it from vibrating in response to sound waves -symptoms: progressively worse hearing, better hearing in noisy rather than quiet environments, sometimes tinnitus (ringing) -diagnosis: audiometry/audiology, or temporal bone CT -Treatment: hearing aid, fluoride, calcium, or vitamin D, surgery (stapedectomy or stapedotomy)

27. Age-related hearing loss -cause: the tiny hairs in the ear becoming damaged or dying; result of accumulation of factors -symptoms: certain sounds seeming overly loud, difficulty hearing in noisy areas, high-pitched sound distinction difficulty, voices seeming slurred, tinnitus -diagnosis: audiometry/audiology -treatment: hearing aids, alternate means of communication, surgery (cochlear implant)

28. Vision Disorders -myopia: "nearsighted" result of too long eyeball length or too steep cornea -symptoms: poor ability to see at a distance -diagnosis: vision test -treatment: glasses, contacts, refractive surgery

29. -hyperopia: "farsighted"; result of too short eyeball or too flat cornea, hereditary condition -symptoms: difficulty seeing objects up close -diagnosis: vision test -treatment: glasses, contacts, refractive surgery

30. Taste and Smell Disorders -Anosmia: loss of smell, wide range of causes including infection, deformed nasal bones, tumors, malnutrition, surgery, certain nasal sprays, etc. -symptoms: loss of smell -diagnosis: inability to detect odors for an extended period of time -treatment: has to be for underlying causes; no treatment for the condition itself

31. -Aguesia: loss of or impaired ability to taste; may be general, partial, or specific to some tastants; potentially caused by: loss of smell, infection, nerve damage, etc. -symptoms/diagnosis: loss of taste to some or all tastants, sometimes loss of smell -treatment: must be geared towards underlying cause

32. Conclusion Benefits of having a sensory system: -detection of danger -detection of prey -greater awareness of surroundings -sexual selection

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