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Spinal Cord
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It is continuous with the medulla oblongata Extends from the foramen magnum of the occipital bone to the upper boarder of L2 2 main Functions: – Impulse conduction Communication to and from the brain through tracts of white matter – Reflex integration Reflexive movements as opposed to those initiated voluntarily
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There are 31 pairs of spinal nerves – C1-C8 – T1-T12 – L1-L5 – 5 sacral nerves
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Gray & White Matter Gray Matter: – Nerve cell bodies, neuroglia, axon terminals, and unmyelinated association neurons (interneurons) White matter – Bundles or tracts of myelinated fibers of sensory and motor neurons
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Horns Ventral Horn – Cell bodies and dendrites of the Somatic motor neuron cell bodies and dendrites Dorsal Horn – Somatic & Autonomic: sensory axons from the sensory nerve roots Lateral Horn – Present only in thoracic, lumbar, and sacral segments of the cord – Contain cell bodies of the autonomic motor neurons and interneurons
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Figure 11.1 Nervous System
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Reflex Arc Figure 13.14 Receptor 1 2 3 4 Sensory neuron Integration center 5 Effector Motor neuron Stimulus Skin Spinal cord (in cross-section) Interneuron
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Denticulate ligament – Formed by lateral extensions of pia mater – Attaches the spinal cord to the dura mater – Anchors spinal cord in place
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Reflexes Fast, predictable, automated responses to changes in the environment Somatic reflexes involve contraction of skeletal muscles There are automatic or visceral reflexes which we are not usually conscious of
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Reflex Arc Pathway followed by nerve impulses that produce a reflex – 5 functional components 1.Sensory receptor 2.Sensory neuron 3.Integrating center (in gray matter where sensory and motor neuron synapse) 4.Motor neuron 5.Effector (part of body that responds to the motor impulse
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Reflex Arc Figure 13.14 Receptor 1 2 3 4 Sensory neuron Integration center 5 Effector Motor neuron Stimulus Skin Spinal cord (in cross-section) Interneuron
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Somatic Reflexes Stretch Reflexes – Involves only two neurons and one synapse (monosynaptic reflex arc) – Stretch reflexes can be elicited at the elbow, wrist, knee and ankle joints – Examples: Patella or knee-jerk reflex Achilles or ankle-jerk reflex – (Dorsiflex the ankle and tap the Achilles tendon
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Stretch Reflex Figure 13.17 ____
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Superficial cord reflexes: – (abdominal, cremaster, and plantar) result from pain and temperature changes – Example: Plantar reflex Stimulate cutaneous receptors on the sole of the foot Babinski’s reflex: damage to pyramidal (corticospinal) tract
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Nervous Physiology Extra Credit Complete these activities in lab book (listed in your outline) Have to answer questions from the activity to get credit can do all these at home: – Reaction time from a learned stimulus (with the ruler) p.345 Act.9 – Two-point discrimination p356 Act.2 – Adaptation of touch receptors p.357 Act. 5 – Determination of blind spot p. 371 Act. 5 From Outline- Write a really short paragraph about what happened – “B-r-r-r, That’s Hot” 2 points for each assignment completed
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Ear 2 Important Functions – Hearing The conversion of sounds waves (mechanical and fluid) into action potentials (electrical) – Equilibrium Ability to subconsciously detect changes in head position, rotational movement and acceleration/deceleration Reflexes maintain the body in a stable position in spite of any changes or movements
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Ear is divided into 3 regions External Ear – Collect sound waves and channels them Middle Ear – Conveys sound vibration Inner Ear – Labyrinth that houses receptors for hearing and equilibrium
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External Ear Pinna or auricle – Flap of elastic cartilage External auditory canal (or meatus) Ceruminious glands (blue on model) – Secrete earwax (cerumen) Tympanic membrane (eardrum)
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Middle Ear Ear Ossicles – Malleus, Incus, Stapes – (MAiling, INCludes, STAmps) Auditory tube (phayngotympanic tubes) – Duct connecting middle ear to throat Oval Window – Creates fluid waves within cochlea Round window – Equalizes pressure created by vibration of oval window
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Inner Ear Bony chambers called osseous or bony labyrinth – Cochlea (hearing) – Vestibule (equilibrium) Consists of 2 sacs: Utricle & saccule – House equilibrium receptor regions: maculae – Semicircular canals (equilibrium) Respond to rotational movement in head Ampulla – Base of semicircular canals – Houses equilibrium receptor (crista ampullaris)
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Inner Ear Figure 15.27
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Cochlea Scala vestibuli – Provides brain with info concerning position Scala tympani Cochlear duct Tectorial membrane – Where hair cells are embedded
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Auditory Transduction Video https://www.youtube.com/watch?v=PeTriGTE Noc https://www.youtube.com/watch?v=PeTriGTE Noc
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