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BIO201-CH13-PNS&ARCS

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

QuestionAnswer
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.
Created by: Ladystorm on 2007-06-24



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