Intro zoology week 6 notes
Intro zoology week 6 notes BIOL 1114, 001
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This 3 page Class Notes was uploaded by Hannah Kirby on Sunday February 28, 2016. The Class Notes belongs to BIOL 1114, 001 at University of Oklahoma taught by Dr.Lee in Spring 2016. Since its upload, it has received 26 views.
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Date Created: 02/28/16
Week 6 notes zoo Ch. 27 The senses “Outside world” receptor potentials action potentials synaptic transmissions “sensation” Blocking pain receptors inhibit opening of Ca at axon terminals of presynaptic neurons; inhibit closing of K; block receptors on post synaptic neurons; inhibit Na from entering synaptic neuron (block signals from reaching the post synaptic neuron) Nervous system peripheral vs central Central nervous system brain, spinal cord Peripheral nerves, etc Interneurons abundant Sensory neurons detect Motor neurons contractions or secretions Subdivisions of the nervous system Autonomic nervous system (subset of PNS) During emergencies and stressful situations increase heart rate, dilate arteries to muscles, constrict arteries to GI (gastrointestinal tract) When resting decrease heart rate, constrict arteries to muscles, and send more blood to GI Sympathetic nervous system: fight or flight Parasympathetic nervous system: rest and digest, calm down Contrasting roles of nervous system Senses general senses, proprioception, special senses General senses all over the body: touch, temperature, pain Special sense cephalization: hearing and equilibrium, vision, smell, taste Adaptational advantages doesn’t take long to reach the brain Mechanoreceptors and free nerve endings Receptor potentials are graded potentials that occur in sensory receptor cells What is desensitization? Sensory adaptation getting used to a constant stimulus over time Sensory receptors generate fewer action potentials under continuous stimulation Pain is not normally desensitized General senses table 27.1 Proprioception ears, balance, body in space Chemicals are especially important for animal communication. Ex: many spiders and scorpions taste for mates scorpions use pectins, tap around on ground to find mate Chemoreceptors in nose and tongue respond to chemicals Sense of taste gustation 100150 taste buds on each papillae about 10,000 total tastebuds, change throughout life so taste preferences change Tastebuds are specialized Specialized taste buds for specific chemicals sweet, salty, sour, bitter, umami (delicious, meaty, savory) Detecting saltyAbundant Na+ in salty meals can directly enter through ion channels to depolarize salty receptors Detecting sour abundant H+ directly enter ion channels to depolarize salty receptors Bitter, sweet, and umami molecules physically bind to ligandgated receptors to depolarize the cell Detecting sweet how sweet something is=how well the substance binds to sweet receptors Smell: Olfaction Airborne molecules must be absorbed before we can smell it chemoreceptors Olfactory bulb “scent” has to enter nose, go through nasal cavity and attach to “fingers” on the olfactory bulb When smelling you are essentially tasting a sample of air Mucus layer inside of nose, with olfactory receptor cells. Odorant molecules bind to the nerve endings to generate action potentials that are sent to the brain Vision: light detection Stage 1simple eyes light and dark Stage 2 direction of light Stage 3 more photoreceptors and cups, crude images Stage 4 complex tasks, sharp clear vision Light passes through cornea, pupilfocused by lens, fovea Blind spot optic nerves have to go to brain, so light cannot be reflected in that spot Normal sight rays focus on retinas Nearsightedness oblong shape eyes, rays focus in front of retina, corrective lenses focus rays further back Rod cells provide black and white vision in dim light Cone cells detect color Pigment molecules (conopsin & rhodopsin) activated (change shape) when they absorb lightreceptor potential generated Visible spectrum ROYGBIV Opponent processing theory certain color coded cones will get tired and other colors will in a way take over (flag example) Forms of eyes: Eyes cups Compound eyes mosaic vision; lens, photoreceptor cells, ommatidium Single lens eyes (stage 4) Human eye (stage 4) Product of human evolution blind spot, glaucoma (pressure can impact optic nerve and damage vision) Detection of infrared vision using technology Green tree pit viper infrared vision, high concentration of highly sensitive TRP proteins Ears Hearing converts sound waves from mechanical to electrical signals Echolocation using hearing as vision Vibrations are funneled through auditory canal toward eardrum eardrum vibrates bones (hammer, anvil, stirrup) amplify and shake oval window which vibrate fluid around cochlea. Cochlea fluid filled; basilar and tectorial membranes sound waves deflect the membrane and move the cilia inside cochlear canal. Cilia fire action potentials toward brain that interprets sound Location of deflection along the cochlea= pitch Greater deflection= louder sound intensity Balance and equilibrium Proprioception vestibular apparatus consists of two pouches and three semicircular canals. Flow of fluid in semicircular canals Semicircular canals detect rotating and tilting motions of the head Utricle detects horizontal acceleration and head tilt (using gravity) Saccule detects vertical acceleration