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CSU - BC 103 - Class Notes - Life103-Week 15 Notes

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CSU - BC 103 - Class Notes - Life103-Week 15 Notes

School: Colorado State University
Department: Biology
Course: Biology of Organisms-Animals and Plants
Professor: Jennifer Dewey
Term: Fall 2016
Tags:
Name: Life103-Week 15 Notes
Description: These notes cover Sensing the Environment, Behavior and Social Structures, and Conservation and Global Change.
Uploaded: 05/06/2016
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background image Life 103 Notes  Adapted from the lecture notes of Dr. Tanya Dewey  Sensing the Environment  •  Sensory Pathways  -Reception: sensory receptor (cells, organs, part of cells) detects a 
stimulus 
-Transduction: converts the energy from a stimulus to a membrane 
potential (charge) 
-Transmission: the stimulus travels as nerve impulses 
-Perception: the brain interprets the transmission 
-Sensory receptor (cells, organs, parts of cells) detects a stimulus 
(reception), which results in a change of membrane potential in the 
receptor (transduction) 
-Graded response: magnitude of membrane potential change is influenced 
by stimulus intensity 
-Transduction converts the energy from a stimulus to a membrane 
potential (charge) 
-Membrane Potential: A difference in charge between the inside and 
outside of a cell (see textbook figure 48.6) 
 
~i.e. voltage difference; positive outside and negative inside  -Selectively permeable membrane 
-Active transport and selective permeability maintains membrane potential 
-Perception is the processing of stimuli in the brain 
-Synesthesia: stimulation of one sensory or cognitive pathway leads to 
automatic, involuntary experiences in a second sensory or cognitive 
pathway 
•  Amplification  -Sensory stimuli are strengthened during transduction either via accessory 
structures (middle ear bones, for example) or enzyme catalysis of 
secondary messengers in cells 
•  Sensory adaptation  -Receptors decrease responsiveness with continued stimulation  •  Sensory receptors  -Mechanoreceptors respond to mechanical energy such as pressure, 
touch, stretch, motion, and sound 
 
~Example: Lateral line system (see textbook figure 50.14)      -Hair cells detect motion (see textbook figure 50.11)      -Direction of movement changes the trajectory and pattern of       the membrane potential (action potential)    ~Example: mammalian hearing (see textbook figure 50.10)      -Outer/middle/inner ear      -Vibrations in air cause vibration of tympanic membrane      -Tympanic membrane contacts middle ear bones      -Middle ear bones amplify and transmit vibrations to inner       ear fluid in cochlea      -Vibrations detected by hair cells in basilar membrane    ~Example: echolocation-detecting reflected sound      -Note differences in ear (pinna) shape and size 
background image     -Ear shape determines what frequencies of sound are most        efficiently detected-both reflected sound and direct sound  -Chemoreceptors respond to chemical stimuli (smell or taste) 
 
~Gustation: taste (see textbook figure 50.24)    ~Taste receptors in taste buds    ~Olfaction: smell (see textbook figure 50.25)    ~Thousands of odorant receptors    ~Each detects a single odorant    ~Over 3% of human genes    ~Dogs have 300 million olfactory receptors while humans only have      6 million olfactory receptors    ~Vomeronasal organ (Jacobson’s organ): detects pheromones,  detects molecules at very low concentration 
 
~Flehmen and “tasting” the environment  -Electromagnetic receptors detect electromagnetic energy such as 
visible light, electricity, and magnetism 
 
~Single evolutionary origin of vision indicated by shared genes that        control photoreceptor development    ~Photoreceptor: cell that converts light into stimulus via             photosensitive proteins (visual pigments)    ~Example: simple eyes detect light (see textbook figure 50.15)    ~Example: compound eyes (see textbook figure 50.16)      -Many ommatidia (light detectors), each with a lens    ~Example: vertebrate vision (see textbook figure 50.17)      -Iris and pupil      -Lens focuses light      -Retina lined with photoreceptors      -Rods are more sensitive to light and cones detect color      -Retinal: light absorbing molecule      -Opsin: associated protein      -Light absorption changes retinal arrangement and activates        opsin      -Activating rhodops causes signal transduction via enzyme        cascade      -Changing membrane potential    ~Example: detecting magnetic fields      -Magnetite crystals in tissues orient to Earth’s magnetic field      -Birds, bats, whales, others    ~Example: detecting natural electrical fields, such as those            produced by muscle contractions      -Primarily in aquatic animals because water is an excellent       conductor      -Evolved from mechanoreceptors (lateral line system)      -Passive electroreception vs. active electroreception      -Electric “echolocation”  -Thermoreceptors detect heat or cold and help regulate body 
temperature by signaling surface and body core temperature 

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School: Colorado State University
Department: Biology
Course: Biology of Organisms-Animals and Plants
Professor: Jennifer Dewey
Term: Fall 2016
Tags:
Name: Life103-Week 15 Notes
Description: These notes cover Sensing the Environment, Behavior and Social Structures, and Conservation and Global Change.
Uploaded: 05/06/2016
6 Pages 14 Views 11 Unlocks
  • Better Grades Guarantee
  • 24/7 Homework help
  • Notes, Study Guides, Flashcards + More!
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