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UI BIOL 1140 - Sensory Organs
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BIOL 1140 1st Edition Lecture 21Outline of Last LectureI. Nervous system Has Two Principal PartsII. Neurons Make Action PotentialsIII. Sodium-Potassium Pump Maintains resting potentialIV. Graded Potentials Alter the Resting PotentialV. An Action Potential Is a Sudden Reversal of Membrane VoltageVI. Action Potentials are All-or-None VII. Information is Transferred from a Neuron to its TargetVIII. Neurotransmitter is ReleasedIX. Neurotransmitters Exert Excitatory or Inhibitory EffectsX. Postsynaptic Neurons Integrate and Process InformationXI. Peripheral Nervous System Relays Info Between Tissues and CNSXII. Sensory Neurons Provide Info to the CNSXIII. The Somatic Division Controls Skeletal MusclesXIV. Neuroglia Cells Support and Protect NeuronsXV. Disorders Associated with Degeneration of Myelin SheathsXVI. The Autonomic Division Controls Automatic Body FunctionsXVII. The Sympathetic and Parasympathetic Divisions Oppose Each OtherOutline of Current LectureI. The Brain and Spinal Cord Constitute the CNSII. The Spinal Cord Relays InfoIII. The Brain Processes and Acts on InfoIV. Receptors Receive and Convert StimuliV. Receptors are Classified According to StimulusVI. CNS Interprets Nerve Impulses Based on Origin and Frequency of ImpulsesVII. Some Receptors Adapt to Continuing StimuliVIII. Somatic Sensations and Special Senses Provide Sensory InfoIX. Thermoreceptors Detect TemperatureX. Mechanoreceptors Detect Limb Position, Muscle Length, and TensionXI. TasteXII. SmellXIII. HearingXIV. The Outer Ear Channels Sound WavesXV. Middle Ear Amplifies SoundCurrent Lecture These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.II. The Brain and Spinal Cord Constitute the CNSa. CNS protectioni. Bone: skull and vertebraeii. Meninges: protective membranes1. Dura mater, arachnoid, and pia materiii. Cerebrospinal fluid: bathes the brain, spinal cord1. Shock absorber2. Produced within the ventricles of the brainiv. Blood-brain barrier: prevents entry of certain chemicals and pathogensIII. The Spinal Cord Relays Infoa. Spinal cord is a superhighway for action potentials between the brain and the rest of the body b. White matteri. Outer portion of spinal cordii. Consists of myelinated ascending (sensory) and descending (motor) nervetractsc. Grey matteri. Center portion of spinal cordii. Contains cell bodies, dendritesIV. The Brain Processes and Acts on Infoa. Brain i. Command center of the bodyb. Four major anatomical/functional divisionsi. Hindbrain1. Coordinated basic, automatic, and vital tasksii. Midbrain1. Coordinates muscle groups and responses to sight and soundiii. In-between brain (diencephalon)1. Relays sensory info to the forebrainiv. Forebrain1. Receives, integrates input, determines complex behaviorV. Receptors Receive and Convert Stimulia. Stimulus:i. Sensory input that causes some change within or outside the bodyii. Heat, pressure, sound waves, light, chemicalb. Receptor: i. Structure that detects stimuli and converts its energy into another formc. Different kinds of receptorsVI. Receptors are Classified According to Stimulusa. Mechanoreceptorsi. Respond to mechanical energyb. Thermoreceptorsi. Respond to heat or coldc. Pain receptorsi. Respond to tissue damage or excessive heat or pressured. Chemoreceptorsi. Respond to presence of chemicalse. Photoreceptorsi. Respond to lightVII. CNS Interprets Nerve Impulses Based on Origin and Frequency of Impulsesa. Nerve impulses are transmitted from a given receptor to specific portions of the brainb. Stronger stimulii. Activate a greater number of receptorsii. Trigger a greater frequency of action potentials in sensory neuronsVIII. Some Receptors Adapt to Continuing Stimulia. Sensory adaption i. Sensor neuron stops sending impulses even though the original stimulus is still presentii. Allows the CNS to concentrate on important stimuli and ignore noncriticalones to maintain homeostasisb. Receptors that adapti. Light touch, pressure, and smellc. Receptors that do not adapti. Pain, joint, and muscle monitoring receptorsIX. Somatic Sensations and Special Senses Provide Sensory Infoa. Somatic sensationsi. Arise from receptors located throughout the bodyii. Temperature, pressure, touch, vibration, pain, awareness of body positionsb. Special sensesi. Arise from receptors restricted to specific areas of the bodyii. Taste, smell, hearing, balance, visionX. Thermoreceptors Detect Temperaturea. Thermoreceptors near skin surface provide info about external environmenti. Surface Thermoreceptors adapt quicklyb. Thermoreceptors in thoracic and abdominal organs monitor core temperaturei. Core temperature receptors do not adapt quickly XI. Mechanoreceptors Detect Limb Position, Muscle Length, and Tensiona. Mechanoreceptorsi. In joints: detect joint positionii. In skeletal muscles: muscle spindlesb. Specialized mechanoreceptors for monitoring muscle length, which relay info about limb positioni. In tendons: detect tensionXII. Taste: a. Taste budsi. Chemoreceptors bind with dissolved substancesii. Most are distributed around edge, front, back of tongueb. Taste categoriesi. Sweet, salty, sour, bitter, umamiXIII. Smella. Olfactory receptor cellsi. Chemoreceptors that bind with odorantsii. Detect > 1,000 different odorantsb. Correlation between taste and smelli. Chewed food releases chemicals that come in contact with olfactory receptorsXIV. Hearinga. Properties of sound and sound wavesi. Loudness1. Related to amplitude of sound waves2. Measured in decibelsii. Pitch1. Related to frequency a. Higher frequency = higher pitchb. Lower frequency = lower pitchXV. The Outer Ear Channels Sound Wavesa. Pinna: outer visible portion of ear, directs sound waves to auditory canalb. Auditory canal: directs sound waves to the tympanic membranec. Tympanic membrane (ear drum): separates outer ear from middle ear, vibrates inresponse to sound waves and passes along vibrations to the malleus bone (hammer) in inner earXVI. Middle Ear Amplifies Sounda. Air-filled space with three small bonesi. Malleus (hammer), incus (anvil), stapes (stirrup)b. Tympanic membrane vibrates and passes this through the three bones to the inner earc. Several-fold amplification of soundd. Auditory tube (Eustachian tube)i. Connects to throatii. Equalizes


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UI BIOL 1140 - Sensory Organs

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