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BIO201 - Ch 13 - Peripheral Nervous Sys. & Reflex- Marieb/Hoehn - Rio Salado- AZ

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5 classes of receptors are?   (1) Mechanoreceptors (touch,pressure), (2) thermoreceptors (temp), (3) photoreceptors (light), (4) chemoreceptors (chemicals in solution), & (4) nociceptors (pain).  
Nociceptors sense what?   Stimuli that can damage body - elicits pain as response.  
3 classifications of receptors by location.   (1) Exteroceptors (outside body), (2) interoceptors (w/in body), (3) proprioceptors (in ligaments, joints, muscles, & CT).  
Simple receptors   Modified dendritic endings of senosry neurons  
Complex receptors   Sense organs (vision, hearing, equilibrium, smell & taste).  
Unencapsulated (naked) dendric endings   Unmyelinated - C fibers - knoblike swellings @ ends. Temp, pain, itch (histamine) - Merkel discs & hair follicles.  
Encapsulated dendric endings   1 or more fiber terminals of sensory neurons enclosed in CT capsule.  
Give some examples of encapsulated dendric endings   Mechanoreceptors - Meissner's, Pacinian, Ruffini, muscle spindles, golgi tendon & joint kinesthetic.  
Messner's Corpuscles   Tactile - encapsulated, exteroceptors - light pressure - in dermal papillae of hairless skin.  
Merkel (tactile) discs   Tactile - unencapsulated, exteroceptor - light pressure - basal layer of epidermis.  
Pacinian Corpuscles (lamellated)   Resembles cut onion - pressure - encapsulated, exteroceptor & mechanoreceptor - pressure, vibration, stretch - dermis & hypodermis  
Hair follicle receptor   Hair deflection - exteroceptor & mechanoreceptor  
Ruffini endings   Deep & continuous pressure - exteroceptor & proprioceptor - encapsulated - deep in dermis, hypodermis, & joint capsules.  
Muscle Spindles   Muscle stretch & length - proprioceptor & mechanoreceptor - encapsulated - in skeletal muscles of extermities.  
Golgi tendon organs   Tendon stretch & tension - proprioceptor & mechanoreceptor - encapsulated - in tendons.  
Joint Kinesthetic Receptors   Synovial joint capsules - proprioceptor, mechaoreceptors, nociceptors - encapsulated - syovial joints.  
Fusiform   "Spindle-shaped"  
Intrafusal Fibers   Bundle of modified skeletal muscle fibers - make muscle spindles - enclosed in CT  
Golgi tendon organs consist of __.   Small bundles of tendon (collagen) fibers.  
When Golgi tendon organs are activated, the contracting muscle __.   Is inhibited, which causes it to relax.  
Which 4 receptor types contribute to joint kinesthetic receptors?   Pacinian, ruffini, free nerve endings, & Golgi-like organ.  
Somatosensory System   That part of sensory system serving body wall & limbs that receives input from receptors & transmits info.  
3 main levels of neural integration in somatosensory system.   (1) Receptor level, (2) Circuit level (ascending pathways), & (3) Perceptual level (neuronal circuits in cerebral cortex).  
Phasic receptors   Fast adapting receptors often giving bursts of impulses @ beginning/end of stimulus - Pacinian & Meissner's.  
Tonic Receptors   Sustained response w/little or no adaptation - nociceptors & most proprioceptors.  
The task at the circuit level is to __.   Deliver impulses to appropriate region of cerebral cortex for stimulus location & perception.  
Ascending sensory pathways typically consist of __.   A chain of 3 neurons - 1st, 2nd, & 3rd order sensory neurons.  
Axons of 1st order sensory neurons __.   Link receptor & circuit levels of processing - cell bodies in dorsal root or cranial ganglia.  
Impulses reach conscious awareness in the __.   Sensory Cortex  
Fibers in the nonspecific ascending pathways __.   Transmit pain, temp, & coarse touch impulses. Emotional aspects of perception (pleasure/pain)  
Specific ascending pathways are involved in __.   Discriminative aspects of touch (tactile), vibration, pressure, & conscious proprioception (limb & joint position)  
"Noxious Stimuli"   Anything damaging to tissues.  
Body's pain-producing chemicals   Prostaglandins & bradykinins  
Pain-producing chemicals activate __.   Specific receptors on small-diameter C fibers, & initiates pain signals.  
Surface, somatic localized pain transmitted on __.   Myelinated A delta fibers.  
Deep somatic pain always indicates __.   Tissue Damage - unmyelinated C fibers.  
The pain neurotransmitter   Substance P & glutamate  
Hyperalgesia   Pain amplification  
Nerve   Parallel bundles of peripheral axons enclosed by successive wrappings of CT.  
Layers of CT around nerve, inferior to superior.   Endoneurium - perineurium - epineurium.  
Ganglia   Collections of cell bodies of nerves in PNS - afferent & efferent.  
Wallerian Degeneration   Axon & myelin sheath distal to injury of neuron begins to disintegrate w/o nutrients.  
Regeneration of a peripheral nerve.   (1) Fragmentation of axon, (2) Macrophages destroy axon, (3) Axon filaments grow w/in regeneration tube formed by Schwann cells, (4) regenerated axon & formation of new myelin sheath.  
CAMs   Cell adhesion molecules that encourage growth of axon & from regeneration tube.  
Regeneration Tube   System of cellular cords that guide regenerating axon "sprouts" across gap & to original contacts.  
There are __ pairs of cranial nerves.   12  
Cranial Nerves Pneumonic Tool?   Oh, once one takes the anatomy final, very good vacations are here!  
First 3 O's of cranial nerves?   Olfactory, optic, & oculomotor.  
4th & 5th cranial nerve T's?   Trochlear, Trigeminal  
Which cranial nerve for taste?   Facial - VII  
The planners & coordinators of complex motor activities?   Cerebellum & Basal Nuclei  
Lowest to highest - levels of motor hierarchy.   Segmental, projection, & precommand  
Segmental Level   Lowest of motor hierarchy - spinal cord circuits.  
Central Pattern Generators (CPGs)   Control locomotion & often-repeated motor activities - networks of inhibitory/excitatory neurons - alternating patterns of movements.  
Projection Level of motor control   Upepr motor neurons of motor cortex - direct (pyramidal) system, brain stem nuclei - reticular formation.  
Direct system of brain stem motor areas.   Pyramidal system - voluntary movement  
Indrect system of brain stem motor areas.   Multineuronal - reflex & CPG-controlled actions.  
Precommand level of motor control   Cerebellum & basal nuclei - precisely start/stop movements, coordinate postsure, block unwanted movement, & monitors muscle tone - CONTROL OUTPUTS  
The keycenter from "online" sensorimotor integration & control is the __.   Cerebellum - acts on motor pathways through projection areas of brainstem & motor cortex via thalamus.  
Basal nuclei receives inputs from all __.   Cortical areas - in advance of willed movements.  
The cortex says, "I want to do this" & lets the __ take over & provide timing & patterns to execute.   Precommand areas.  
Somatosensory Cortex   Somatic sensations are processed by this outermost layer of gray matter - here is area of interneurons organized like maps of individual parts of body.  
Taste & smell are __ senses.   Chemical - they start @ chemoreceptors.  
Spinal reflexes   Somatic reflexes mediated by spinal cord.  
Spinal Shock   All functions controlled by spinal cord are immediately depressed.  
__ provide tension info of muscle & __ the length.   Golgi tendon organs, muscle spindles  
Type 1a fibers of muscle spindles.   Innervate spindle center - detect rate & degree of stretch.  
Type 2 fibers of muscle spindles.   Innervate spindle ends - detect degree of stretch.  
Stretch reflex   Makes sure muscle stays at correct length - knee-jerk - maintains muscle tone - posture muscles.  
Patellar/knee-jerk reflex helps keep __.   Knees from buckling when standing upright. Causes quads to contract w/o thinking.  
Stretch stimulus causes __ to relax so they cannot resist shortening of stretched muscle during reflex arc.   Antagonists  
Most familiar clinical example of stretch reflex.   Knee-jerk.  
All stretch reflexes are __ & __.   Monosynaptic & ipsilateral  
Ipsilateral   Same side of body  
Reflex arc are __.   Polysynaptic - stimulate one & inhibit antagonist.  
a-y coactivation   Motor impulses are simultaneously sent to the large extrafusal fibers & muscle spindle intrafusal fibers.  
A gymnast must have highly sensitive __ or she'll fall.   Muscle spindles  
Golgi tendon organs help avoid __.   Tearing of muscles & tendons by relaxing muscle & lengthening in response to tension.  
Flexor reflex   Withdrawl reflex - automatic withdrawl of threatened body part from stimulus - protective reflexes.  
Crossed-extensor reflex   Contralateral (other side) responds to support the body part experiencing flex reflex.  
Plantar reflex   L4-S2 - sole of foot (plantar) stimulated & downward flexion (curling) of toes.  
Babinski's Sign   When sole of foot stimulated, great toe dorsiflexes & smaller toes fan laterally.  
Abdominal reflexes   Tests cord & ventral rami T8-T12  
Skeletal muscles derive from?   Paired blocks of mesoderm.  


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