AP 2401 Professor Young LSCS chap 13
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| Peripheral Nervous System (PNS) description | all neural structures outside the brain and spinal cord | ||||
| The PNS includes _______ (4) | Includes sensory receptors, peripheral nerves, associated ganglia, and motor endings | ||||
| Sensory Receptors facts | Structures specialized to respond to stimuli Activation of sensory receptors results in depolarizations that trigger impulses to the CNS The realization of these stimuli, sensation and perception, occur in the brain | ||||
| Receptor Classification by Stimulus Type | Mechanoreceptors thermoreceptors photoreceptors chemoreceptors nociceptors | ||||
| Mechanoreceptors | respond to touch, pressure, vibration, stretch, and itch | ||||
| Thermoreceptors | sensitive to changes in temperature | ||||
| Photoreceptors | respond to light energy (e.g., retina) | ||||
| Chemoreceptors | respond to chemicals (e.g., smell, taste, changes in blood chemistry) | ||||
| Nociceptors | sensitive to pain-causing stimuli | ||||
| Exteroceptors | Respond to stimuli arising outside the body Found near the body surface Sensitive to touch, pressure, pain, and temperature Include the special sense organs | ||||
| Interoceptors | Respond to stimuli arising within the body Found in internal viscera and blood vessels Sensitive to chemical changes, stretch, and temperature changes | ||||
| Proprioceptors | Respond to degree of stretch of the organs they occupy Found in skeletal muscles, tendons, joints, ligaments, and connective tissue coverings of bones and muscles Constantly “advise” the brain of one’s movements | ||||
| Complex receptors are _______ organs | Special Sense | ||||
| Most receptors are _____ and include _____ and _____varieties | simple encapsulated unencapsulated | ||||
| Simple Receptors: Unencapsulated (facts) | Are everywhere very abundant in epithelia and connective tissues free dendritic nerve endings respond chiefly to **temperature and pain** | ||||
| Simple Receptors: Unencapsulated examples | Merkel (tactile) discs – light touch Hair follicle receptors | ||||
| Simple Receptors: Encapsulated examples | Meissner’s corpuscles (tactile corpuscles) – hairless areas Pacinian corpuscles (lamellated corpuscles) – first applied, picks up vibrations Ruffini’s corpuscles, Muscle spindles, and Golgi tendon organs, Joint kinesthetic receptors | ||||
| The three main levels of neural integration in the somatosensory system are: | Receptor level – the sensor receptors Circuit level – ascending pathways Perceptual level – neuronal circuits in the cerebral cortex | ||||
| The receptor must have _______ for the stimulus energy | specificity | ||||
| The receptor’s _______ must be stimulated | receptive field | ||||
| Stimulus energy must be converted into a ____________ – receptor potential, a process called _________. | graded potential transduction | ||||
| A _____ _______ in the associated sensory neuron must reach threshold | generator potential | ||||
| The faster the impulses the _________ the stimulus | stronger | ||||
| ________ occurs when sensory receptors are subjected to an unchanging stimulus | Adaptation | ||||
| During adaptation _____________ become less responsive and _________ decline in frequency or stop. | Receptor Membranes become less responsive and receptor potentials decline | ||||
| ______ – cordlike organ of the PNS consisting of ________ enclosed by __________ | Nerve Peripheral axons connective tissue | ||||
| Endoneurium | loose connective tissue that surrounds axons | ||||
| Perineurium | coarse connective tissue that bundles fibers into fascicles | ||||
| Epineurium | tough fibrous sheath around nerve | ||||
| Nerves are classified into ______ and _____ divisions | Sensory and Motor | ||||
| ________ (_______) nerves carry impulse TO the CNS | Sensory (afferent) | ||||
| _______ (________) nerves carry impulses FROM the CNS | Motor (efferent) | ||||
| ______ nerves have sensory and motor fibers and are the most common | Mixed | ||||
| Mixed nerves carry ______ and _______ impulses | Somatic and autonomic | ||||
| List 4 types of mixed nerves | Somatic afferent and somatic efferent Visceral afferent and visceral efferent | ||||
| If the soma of a damaged nerve remains intact, damage **can/can't** be repaired | can | ||||
| Regeneration of a nerve cell involves ____ to remove debris, ________ to form a regeneration tube and secrete growth factors, and ____ to regenerate damaged part | Macrophages, schwann cells, axons | ||||
| ___ pairs of cranial nerves arise from the brain | 12 | ||||
| ______ cranial nerves carry parasympathetic fibers that serve muscles and glands | 4 | ||||
| Cranial Nerve I: Olfactory | Arises from the olfactory epithelium Functions solely by carrying afferent impulses for the sense of smell | ||||
| Cranial Nerve II: Optic | Arises from the retina of the eye Functions solely by carrying afferent impulses for vision | ||||
| Cranial Nerve III: Oculomotor | Fibers extend from the ventral midbrain, pass through the superior orbital fissure, and go to the extrinsic eye muscles Functions in raising the eyelid, directing the eyeball, constricting the iris, and controlling lens shape | ||||
| Cranial Nerve IV: Trochlear | Fibers emerge from the dorsal midbrain and enter the orbits via the superior orbital fissures; innervate the superior oblique muscle Primarily a motor nerve that directs the eyeball | ||||
| Cranial Nerve V: Trigeminal | Fibers emerge from the pons to face Largest of cranial nerves Sensory fibers to the face and motor fibers to the chewing muscles | ||||
| Cranial Nerve VI: Abducens | Fibers leave inferior pons and enter orbit via superior orbital fissure to run to eye Controls the extrinsic eye muscle that abducts the eyeball (turns it laterally) | ||||
| Cranial Nerve VII: Facial | Mixed nerve with five major branches Motor functions include facial expression, and the transmittal of autonomic impulses to lacrimal and salivary glands Sensory function is taste from the anterior two-thirds of the tongue | ||||
| Cranial Nerve VIII: Vestibulocochlear | inner ear, pass through the internal acoustic meatus, and enter the brainstem at the pons-medulla border Two divisions – cochlear (hearing) and vestibular (balance) Functions are solely sensory – equilibrium and hearing | ||||
| Cranial Nerve IX: Glossopharyngeal | Motor – innervates part of the tongue and pharynx, and provides motor fibers to the parotid salivary gland Sensory – fibers conduct taste and general sensory impulses from the tongue and pharynx | ||||
| Cranial Nerve X: Vagus | The only cranial nerve that extends beyond the head and neck Fibers emerge from the medulla via the jugular foramen Most motor fibers are parasympathetic fibers to the heart, lungs, and visceral organs Its sensory function is in taste | ||||
| Cranial Nerve XI: Accessory | Primarily a motor nerve Supplies fibers to the larynx, pharynx, and soft palate Innervates the trapezius and sternocleidomastoid, which move the head and neck | ||||
| Cranial Nerve XII: Hypoglossal | Fibers arise from the medulla and exit the skull via the hypoglossal canal Innervates both extrinsic and intrinsic muscles of the tongue, which contribute to swallowing and speech | ||||
| Spinal Nerves (number) | 8 cervical (C1-C8) 12 thoracic (T1-T12) 5 Lumbar (L1-L5) 5 Sacral (S1-S5) 1 Coccygeal (C0) | ||||
| Dermatomes | area of skin innervated by the cutaneous branches of a single spinal nerve All spinal nerves except C1 participate in dermatomes | ||||
| Hilton’s law: | Hilton’s law: any nerve serving a muscle that produces movement at a joint also innervates the joint itself and the skin over the joint | ||||
| A ________ is a rapid, predictable motor response to a stimulus | reflex | ||||
| Reflexes may be inborn(_______) or learned (_______) and involve only _________ nerves and the ________. | Be inborn (intrinsic) or learned (acquired) Involve only peripheral nerves and the spinal cord Involve higher brain centers as well | ||||
| 5 components of the reflex arc | Receptor Sensory Neuron Integration Center Motor Neuron Effector |
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Created by:
hkrawietz
on 2011-07-05