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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