Chapter 29 - BIOL1320
Chapter 29 - BIOL1320 BIOL 1320
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This 8 page Class Notes was uploaded by Ailia Owen on Wednesday March 25, 2015. The Class Notes belongs to BIOL 1320 at University of Houston taught by Brian C Mahon in Spring2015. Since its upload, it has received 169 views. For similar materials see General Biology in Natural Sciences and Mathematics at University of Houston.
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Date Created: 03/25/15
Chapter 29 The senses 32515 924 PM Bats Echolocation 0 High pitched sound produced in larynx o Emitted from mouth and nose 0 Brains process the time delay and spatial arrangement of the echoes to determine size shape location speed and direction of objects in the environment Marine mammals dolphins whales Ultrasonic clicking noises in nasal passageways 0 Focus the sound by bouncing it off of skull bone and an oil filled structure in the forehead 0 Receive echo in a narrow window of bone behind the jaw SENSORY RECEPTION Sensory receptors sense originate specialized cells or neurons that are tuned to the 0 Conditions of external world 0 Internal organs 0 Detect stimuli all stimuli are a form of energy 0 Sensory transduction detect stimuli and convert to electrical signals 0 o All sensory receptors 0 Trigger and action potential 0 Send information to the central nervous system 0 Sensations depends on part of the brain the receives action potential 0 Sensory receptors in a taste bud detect sugar 0 Sugar molecule enters taste bud gt bind to sweet detectors specific protein molecules embedded in a taste receptor cell membrane gt binding triggers signal transduction pathway that causes some ion channels to open and others to close gt changes in flow of ions create a graded change in membrane potential receptor potential Stronger stimulus more neurotransmitters released by receptor cell and more frequently the sensory neuron transmits action potential to the brain 0 Sensory adaptation repeated stimuli cause the sensory receptors to become less sensitive 5 categories 0 Pain receptors detect dangerous stimuli high heat and pressure Only receptor in epidermis o Thermoreceptors detect heat or cold 0 Mechanoreceptors respond to Mechanical energy Touch Pressure Sound 0 Chemoreceptors respond to chemicals Sensory receptors in nose and taste buds o Electromagnetic receptors respond to Electricity Magnetism Light sensed by photoreceptors HEARING AND BALANCE 0 Human ear channels sound waves 0 Outer ear pinna flap like gt auditory canal gt eardrum separates outer ear from middle ear gt chain of bone in middle ear malleus incus stapes gt fluid in cochlea inner ear gt Eustachian tube connect pharynx to middle ear for pressure equalization 0 Pressure waves transmitted to fluid of cochlea 0 Bend hair cells in organ of Corti against basilar membrane 0 Triggering nerve cells in the brain 0 Louder sounds generate more action potentials 0 Various pitches stimulate different regions of the organ of Corti 0 Outer ear 0 Pinna o Auditory canal Eardrum separates outer and middle ear 0 Middle ear concentration in the middle ear 0 Hammer 0 Anvil o Stirrup Oval window separates middle and inner ear 0 Inner ear organ of Corti stimulated o Cochlear canals Upper Middle Lower o 3 organs detect body position and movement 3 semicircular canals detect changes in head s rotation or angular movement 2 chambers detect position of the head with respect to gravity n Utricle n Saccule All function on same principle bending of hairs on hair cell 0 Deafness loss of hearing 0 Causes inability to detect sounds from Middleear infections Ruptured eardrum Stiffening of middle ear bones Damage to sensory receptors or neurons 0 Progressive and permanent Motion sickness conflicting signals between eyes and inner ear 0 Can be reduced by Closing eyes Limiting head movement Focusing on stable horizon Sedatives Dramaminebonine Longlasting drug containing skin patches VISION the ability to detect light 0 Photoreceptors contain pigment molecules that absorb light 0 Light receptors are based on these cells 0 Eye cup simplest light detecting organ 0 Planarians 0 Sense light intensity and direction 0 2 major types of image forming eyes 0 Compound eyes insects Ommatidia light detectors several thousand Function as acute motion detector Excellent color vision 0 Singlelens eyes Pupil small opening in the front center of the eye Iris controls pupil Lens dislike structure that light passes through Retina light focused here u Contains many photoreceptors Rods contain visual pigment rhodopsin o Absorb dim light can detect shades of grey Cones contain visual pigment photopsin o Absorb bright colored light see color in bright light When absorb light 0 Chemical change alters the permeability of the cell s membrane 0 Resulting receptor potential triggers a change in the release of neurotransmitters from the synaptic terminals 0 Initiates complex integration process in retina Fovea center of focus a Highly concentrated photoreceptors Evolved independently in vertebrates but are similar in structure Human eyes single lens that focus by changing position or shape 0 Sclera outer surface of tough white connective tissue At front of eye sclera becomes the n Cornea lets light into the eye and helps focus light Surrounds the n Choroid pigmented layer Anterior choroid forms the iris eye color 0 Lens and ciliary body divide the eye into 2 chambers Large chamber behind the lens filled with n Vitreous humor jellylike substance Small chamber in front of lens filled with n Aqueous humor thinner substance Humors help maintain shape of eyeballs and circulate nutrients and oxygen to lens cornea and iris Conjunctiva lines the inner surface of the eyelid and folds back over the whites of the eyes but not the cornea Conjunctivitis imflammation of conjunctiva by bacteria or virus 0 Gland above eye secretes tears that clean and moisten 0 Lens focuses light in the retina by bending light rays 2 ways a Back and forth squid fish a Changing shape using mammals Muscles attached to choroid Ligaments that suspend the lens 0 Near vision accommodation light from near objects diverging rays Ciliary muscle contracted Ligaments slacken 0 Distance vision light from distant objects parallel rays Ciliary muscles relax Ligaments pull on lens 0 Visual acuity ability of the eyes to distinguish fine details Measured by reading standardized eye charts from 20 feet 2020 ability to see normally 0 Common vision problems corrective lenses can bend light rays to compensate for these problems Nearsighted inability to focus on distant objects a Eyeball too long Farsighted inability to focus on near objects a Eyeball too short Astigmatism blurred vision a Misshapen lens or cornea 32515 924 PM Describe the essential roles of sensory receptors Explain how electromagnetic receptors help the hammerhead shark perceive its world Define sensory transduction receptor potential and sensory adaptation and provide examples of each Describe the five general categories of sensory receptors found in animals and provide examples of each List the structures of the ear in the sequence in which they participate in hea ng Explain how body position and movement are sensed in the inner ear Explain what causes motion sickness and what can be done to prevent it Compare the structures and functions of the eye cups of planarians the compound eyes of insects and crustaceans and the singlelens eyes of humans Describe the parts of the human eye and their functions Compare the structures functions distributions and densities of rods and cones Describe the role of the central nervous system in sensory perception 32515 924 PM
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