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| 357582710 | Peripheral Nervous System (PNS) | All neural structures outside the brain, sensory receptors, peripheral nerves and associated ganglia that also includes sensory receptors. | 0 | |
| 357582711 | Sensory Receptors | Specialized to respond to changes in their environment (stimuli), activation results in graded potentials that trigger nerve impulses and sensation (awareness of stimulus) and perception (interpretation of the meaning of the stimulus) occur in the brain. | 1 | |
| 357582712 | Classification of Receptors | Based on stimulus type, location, and structural complexity. | 2 | |
| 357582713 | Mechanoreceptors | Respond to touch, pressure, vibration, stretch, and itch. | 3 | |
| 357582714 | Thermoreceptors | Sensitive to changes in temperature. | 4 | |
| 357582715 | Photoreceptors | Respond to light energy (e.g., retina). | 5 | |
| 357582716 | Chemoreceptors | Respond to chemicals (e.g., smell, taste, changes in blood chemistry). | 6 | |
| 357582717 | Nociceptors | Sensitive to pain-causing stimuli (e.g. extreme heat or cold, excessive pressure, inflammatory chemicals). | 7 | |
| 357582718 | Exteroceptors | Respond to stimuli arising outside the body, receptors in the skin for touch, pressure, pain, and temperature; used in most special sense organs. | 8 | |
| 357582719 | Interoceptors (visceroceptors | Respond to stimuli arising in internal viscera and blood vessels and sensitive to chemical changes, tissue stretch, and temperature changes. | 9 | |
| 357582720 | Proprioceptors | Respond to stretch in skeletal muscles, tendons, joints, ligaments, and connective tissue coverings of bones and muscles plus inform the brain of one's movements. | 10 | |
| 357582721 | complex receptors (special sense organs) | Vision, hearing, equilibrium, smell, and taste. | 11 | |
| 357582722 | simple receptors for general senses: | Tactile sensations (touch, pressure, stretch, vibration), temperature, pain, and muscle sense and unencapsulated (free) or encapsulated dendritic endings. | 12 | |
| 357582723 | Thermoreceptors | This is unencapsulated by cold receptors (10-40ºC); in superficial dermis and heat receptors (32-48ºC) in deeper dermis. | 13 | |
| 357582724 | Nociceptors | Unencapsulated that respond to: pitching, chemicals from damaged tissue, temperatures outside the range of thermoreceptors and capsaicin. | 14 | |
| 357582725 | Light touch receptors | Unencapsulated is tactile (merkel) discs and hair follicle receptors. | 15 | |
| 357582726 | Encapsulated Dendritic Endings | All are mechanoreceptors. | 16 | |
| 357582727 | Meissner's (tactile) corpuscles | Discriminative touch | 17 | |
| 357582728 | Pacinian (lamellated) corpuscles | Deep pressure and vibration | 18 | |
| 357582729 | Ruffini ending | Deep continuous pressure | 19 | |
| 357582730 | Muscle spindles | Muscle stretch | 20 | |
| 357582731 | Golgi tendon organs | Stretch in tendons | 21 | |
| 357582732 | Joint kinesthetic receptors | Stretch in articular capsules | 22 | |
| 357582733 | Sensation to Perception | Survival depends upon sensation and perception, sensation is the awareness of changes in the internal and external environment plus perception of the conscious interpretation of those stimuli. | 23 | |
| 357582734 | Sensory Integration | Input comes from exteroceptors, proprioceptors, and interoceptors and input is relayed toward the head, but is processed along the way. | 24 | |
| 357582735 | Receptor level | The sensor receptors | 25 | |
| 357582736 | Circuit level | Ascending pathways | 26 | |
| 357582737 | Perceptual level | Neuronal circuits in the cerebral cortex. | 27 | |
| 357582738 | Processing at the Receptor Level | Receptors have specificity for stimulus energy, stimulus must be applied in a receptive field, transduction occurs, and stimulus energy is converted into a graded potential called a receptor potential. | 28 | |
| 357582739 | Special Sense Organs | Stimulus, receptor potential in receptor cell, release of neurotransmitter, generator potential in first-order sensory neuron, and action potentials (if threshold is reached). | 29 | |
| 357582740 | Adaptation of Sensory Receptors | Adaptation is a change in sensitivity in the presence of a constant stimulus, receptor membranes become less responsive, and receptor potentials decline in frequency or stop. | 30 | |
| 357582741 | Phasic (fast-adapting) receptors | Signal the beginning or end of a stimulus and examples include receptors for pressure, touch, and smell. | 31 | |
| 357582742 | Tonic receptors | Adapt slowly or not at all examples include nociceptors and most proprioceptors. | 32 | |
| 357582743 | Processing at the Circuit Level | Pathways of three neurons conduct sensory impulses upward to the appropriate brain regions. | 33 | |
| 357582744 | First-order neurons | Conduct impulses from the receptor level to the second-order neurons in the CNS. | 34 | |
| 357582745 | Second-order neurons | Transmit impulses to the thalamus or cerebellum. | 35 | |
| 357582746 | Third-order neurons | Conduct impulses from the thalamus to the somatosensory cortex (perceptual level). | 36 | |
| 357582747 | Perception Of Pain | Warns of actual or impending tissue damage, stimuli include extreme pressure and temperature, histamine, K+, ATP, acids, and bradykinin;Impulses travel on fibers that release neurotransmitters glutamate and substance, and some pain impulses are blocked by inhibitory endogenous opioids. | 37 | |
| 357582748 | Structure of a Nerve | Cordlike organ of the PNS and bundle of myelinated and unmyelinated peripheral axons enclosed by connective tissue. | 38 | |
| 357582749 | Endoneurium (nerve) | Loose connective tissue that encloses axons and their myelin sheaths. | 39 | |
| 357582750 | Perineurium (nerve) | Coarse connective tissue that bundles fibers into fascicles. | 40 | |
| 357582751 | Epineurium (nerve) | Tough fibrous sheath around a nerve. | 41 | |
| 357582752 | Classification of Nerves | Most nerves are mixtures of afferent and efferent fibers and somatic and autonomic (visceral) fibers and pure sensory (afferent) or motor (efferent) nerves are rare. | 42 | |
| 357582753 | Types of fibers in mixed nerves | Somatic afferent and somatic efferent plus visceral afferent and visceral efferent. Peripheral nerves classified as cranial or spinal nerves. | 43 | |
| 357582754 | Ganglia | Contain neuron cell bodies associated with nerves. | 44 | |
| 357582755 | Dorsal root ganglia | sensory, somatic | 45 | |
| 357582756 | Autonomic ganglia | motor, visceral | 46 | |
| 357582757 | Regeneration of Nerve Fibers | Mature neurons are amitotic, if the soma of a damaged nerve is intact: axon will regenerate, CNS oligodendrocytes bear growth-inhibiting proteins that prevent CNS fiber regeneration. | 47 | |
| 357582758 | Macrophages | removes debris | 48 | |
| 357582759 | Schwann cells | form regeneration tube and secrete growth factors | 49 | |
| 357582760 | Axons | regenerate damaged part | 50 | |
| 357582761 | Cranial Nerves | Twelve pairs of nerves associated with the brain and most are mixed in function and two pairs are purely sensory. | 51 | |
| 357582762 | Olfactory Nerves | I - Sensory -Smell: Arise from the olfactory receptor cells of nasal cavity, pass through the cribriform plate of the ethmoid bone, fibers synapse in the olfactory bulbs, and pathway terminates in the primary olfactory cortex and it is purely sensory (olfactory) function. | 52 | |
| 357582763 | The Optic Nerves | II-Sensory-Optic: arise from the retinas, pass through the optic canals, converge and partially cross over at the optic chiasma, optic tracts continue to the thalamus, where they synapse, and optic radiation fibers run to the occipital (visual) cortex and is sensory. | 53 | |
| 357582764 | The Oculomotor Nerves | III-Motor-Eye: Fibers extend from the ventral midbrain through the superior orbital fissures to the extrinsic eye muscles, functions in raising the eyelid, directing the eyeball, constricting the iris (parasympathetic), and controlling lens shape. | 54 | |
| 357582765 | The Trochlear Nerves | IV-Motor-eye(down &out): Fibers from the dorsal midbrain enter the orbits via the superior orbital fissures to innervate the superior oblique muscle, primarily a motor nerve that directs the eyeball. | 55 | |
| 357582766 | The Trigeminal Nerves | V-Sensory &motor for face: Largest cranial nerves; fibers extend from pons to face, three divisons: Ophthalmic (V1) passes through the superior orbital fissure, Maxillary (V2) passes through the foramen rotundum, Mandibular (V3) passes through the foramen ovale and convey sensory impulses from various areas of the face (V1) and (V2), and supplies motor fibers (V3) for mastication. | 56 | |
| 357582767 | The Abducens Nerves | VI-Motor: Fibers from the inferior pons enter the orbits via the superior orbital fissures, primarily a motor, innervating the lateral rectus muscle. | 57 | |
| 357582768 | The Facial Nerves | VII-Motor-Sensory:Fibers from the pons travel through the internal acoustic meatuses, and emerge through the stylomastoid foramina to the lateral aspect of the face, chief motor nerves of the face with five major branches, motor functions include facial expression, parasympathetic impulses to lacrimal and salivary, sensory taste from the anterior two-thirds of the tongue. | 58 | |
| 357582769 | The Vestibulocochlear Nerves | VIII-Sensory, some motor-Hearing and Balance : Afferent fibers from the hearing receptors (cochlear division) and equilibrium receptors (vestibular division) pass from the inner ear through the internal acoustic meatuses, and enter the brain stem at the pons-medulla border, and mostly sensory function; small motor component for adjustment of sensitivity of receptors. | 59 | |
| 357582770 | The Glossopharyngeal Nerves | IX-Mixed- Gag Reflex: Fibers from the medulla leave the skull via the jugular foramen and run to the throat, motor functions: innervate part of the tongue and pharynx for swallowing, and provide parasympathetic fibers to the parotid salivary glands, sensory functions: fibers conduct taste and general sensory impulses from the pharynx and posterior tongue, and impulses from carotid chemoreceptors and baroreceptors. | 60 | |
| 357582771 | The Vagus Nerves | X-Mixed: The only cranial nerves that extend beyond the head and neck region, fibers from the medulla exit the skull via the jugular foramen, most motor fibers are parasympathetic fibers that help regulate the activities of the heart, lungs, and abdominal viscera, and sensory fibers carry impulses from thoracic and abdominal viscera, baroreceptors, chemoreceptors, and taste buds of posterior tongue and pharynx. | 61 | |
| 357582772 | The Accessory Nerves | XI-Motor: Formed from ventral rootlets from the C1-C5 region of the spinal cord (not the brain), rootlets pass into the cranium via each foramen magnum, accessory nerves exit the skull via the jugular foramina to innervate the trapezius and sternocleidomastoid muscles. | 62 | |
| 357582773 | The Hypoglossal Nerves | XII-Motor: Fibers from the medulla exit the skull via the hypoglossal canal and innervate extrinsic and intrinsic muscles of the tongue that contribute to swallowing and speech. | 63 | |
| 357582776 | Spinal Nerves | • 31 pairs of mixed nerves named according to their point of issue from the spinal cord: 8 cervical (C1-C8), 12 thoracic (T1-T12), 5 Lumbar (L1-L5), 5 Sacral (S1-S5), and 1 Coccygeal (C0). | 64 | |
| 357582777 | Spinal Nerves: Roots | Each spinal nerve connects to the spinal cord via two roots and dorsal and ventral roots unite to form spinal nerves, which then emerge from the vertebral column via the intervertebral foramina. | 65 | |
| 357582778 | Ventral roots | Contain motor (efferent) fibers from the ventral horn motor neurons and fibers innervate skeletal muscles. | 66 | |
| 357582779 | Dorsal root | Contain sensory (afferent) fibers from sensory neurons in the dorsal root ganglia and conduct impulses from peripheral receptors | 67 | |
| 357582780 | Spinal Nerves: Rami | • Each spinal nerve branches into mixed rami by: dorsal ramus, larger ventral ramus, meningeal branch, and rami communicates (autonomic pathways) join to the ventral rami in the thoracic region. | 68 | |
| 357582781 | Spinal Nerves: Rami | • All ventral rami except T2-T12 form interlacing nerve networks called plexuses (cervical, brachial, lumbar, and sacral) and the back is innervated by dorsal rami via several branches. | 69 | |
| 357582782 | Ventral rami of T2-T12 as intercostal nerves which: | Supply muscles of the ribs, anterolateral thorax, and abdominal wall. | 70 | |
| 357582783 | Cervical Plexus | Formed by ventral rami of C1-C4 and innervates skin and muscle of the neck, ear, back of head, and shoulders. | 71 | |
| 357582784 | Phrenic nerve | Major motor and sensory nerve of the diaphragm (receives fibers from C3-C5). | 72 | |
| 357582785 | Brachial Plexus | Formed by ventral rami of C5-C8 and T1 (and often C4 and T2) and it gives rise to the nerves that innervate the upper limb. | 73 | |
| 357582786 | Roots (Brachial Plexus) | five ventral rami (C5-T1). | 74 | |
| 357582787 | Trunks (Brachial Plexus) | upper, middle, and lower. | 75 | |
| 357582788 | Divisions (Brachial Plexus) | anterior and posterior. | 76 | |
| 357582789 | Cords (Brachial Plexus) | lateral, medial, and posterior. | 77 | |
| 357582790 | Axillary (Brachial Plexus) | Innervates the deltoid, teres minor, and skin and joint capsule of the shoulder. | 78 | |
| 357582791 | Musculocutaneous (Brachial Plexus) | innervates the biceps brachii and brachialis and skin of lateral forearm | 79 | |
| 357582792 | Median (Brachial Plexus) | innervates the skin, most flexors and pronators in the forearm, and some intrinsic muscles of the hand | 80 | |
| 357582793 | Ulnar (Brachial Plexus) | supplies the flexor carpi ulnaris, part of the flexor digitorum profundus, most intrinsic muscles of the hand, and skin of medial aspect of hand | 81 | |
| 357582794 | Radial (Brachial Plexus) | innervates essentially all extensor muscles, supinators, and posterior skin of limb | 82 | |
| 357582795 | Lumbar Plexus | Arises from L1-L4 and innervates the thigh, abdominal wall, and psoas muscle. | 83 | |
| 357582796 | Femoral nerve | innervates quadriceps and skin of anterior thigh and medial surface of leg | 84 | |
| 357582797 | Obturator nerve | passes through obturator foramen to innervate adductor muscles | 85 | |
| 357582798 | Sacral Plexus | Arises from L4-S4 and serves the buttock, lower limb, pelvic structures and perineum. | 86 | |
| 357582799 | Sciatic Nerve | Longest and thickest nerve of the body, innervates the hamstring muscles, adductor magnus, and most muscles in the leg and foot and composed of two nerves: tibial and common fibular. | 87 | |
| 357582800 | Dermatome | the area of skin innervated by the cutaneous branches of a single spinal nerve | 88 | |
| 357582801 | Innervation of Skin-Dermatome | All spinal nerves except C1 participate in this and most of theses overlap, so destruction of a single spinal nerve will not cause complete numbness. | 89 | |
| 357582802 | Hilton's law | Any nerve serving a muscle that produces movement at a joint also innervates the joint and the skin over the joint | 90 | |
| 357582803 | Motor Endings | PNS elements that activate effectors by releasing neurotransmitters | 91 | |
| 357582804 | Innervation of Skeletal Muscle | Takes place at a neuromusclular junction and ACH is a neurotransmitter. | 92 | |
| 357582805 | ACh binds to receptors, resulting in | Movement of Na+ and K+ across the membrane, depolarization of the muscle cell, an end plate potential, which triggers and action potential. | 93 | |
| 357582806 | Innervation of Visceral Muscle and Glands | Autonomic motor endings and visceral effectors are simpler than somatic junctions, branches form synapses en passant via varicosities, acetylcholine and norepinephrine act indirectly via second messengers, and visceral motor responses are slower than somatic responses. | 94 | |
| 357582807 | Levels of Motor Control | Segmental, projection, and precommand level. | 95 | |
| 357582810 | Segmental Level | The lowest level of the motor hierarchy, central pattern generators (CPGs): segmental circuits that activate networks of ventral horn neurons to stimulate specific groups of muscles and controls locomotion and specific, oft-repeated motor activity. | 96 | |
| 357582813 | Projection Level | Consists of: upper motor neurons that direct the direct (pyramidal) system to produce voluntary skeletal muscle movements, brain stem motor areas that oversee the indirect (extrapyramidal) system to control reflex and CPG-controlled motor actions, projection motor pathways keep higher command levels informed of what is happening. | 97 | |
| 357582817 | Precommand Level | Neurons in the cerebellum and basal nuclei, regulate motor activity, precisely start or stop movements, coordinate movements with posture, block unwanted movements, monitor muscle tone, and perform unconscious planning and discharge in advance of willed movements. | 98 | |
| 357582824 | Cerebellum | Acts on motor pathways through projection areas of the brain stem and acts on the motor cortex via the thalamus. | 99 | |
| 357582826 | Basal nuclei | Inhibit various motor centers under resting conditions. | 100 | |
| 357582827 | Inborn (intrinsic) reflex | a rapid, involuntary, predictable motor response to a stimulus. | 101 | |
| 357582828 | Learned (acquired) reflexes | Result from practice or repetition (ex. driving skills). | 102 | |
| 357582830 | Components of a reflex arc | 1. Receptor—site of stimulus action, 2. Sensory neuron—transmits afferent impulses to the CNS, 3. Integration center—either monosynaptic or polysynaptic region within the CNS, 4. Motor neuron—conducts efferent impulses from the integration center to an effector organ, 5. Effector—muscle fiber or gland cell that responds to the efferent impulses by contracting or secreting. | 103 | |
| 357582835 | Spinal somatic reflexes | Integration center is in the spinal cord, effectors are skeletal muscle and testing of somatic reflexes is important clinically to assess the condition of the nervous system. | 104 | |
| 357582838 | Stretch and Golgi Tendon Reflexes | For skeletal muscle activity to be smoothly coordinated, proprioceptor input is necessary, Muscle spindles inform the nervous system of the length of the muscle, and golgi tendon organs inform the brain as to the amount of tension in the muscle and tendons. | 105 | |
| 357582841 | Muscle Spindles | Composed of 3-10 short intrafusal muscle fibers in a connective tissue capsule, intrafusal fibers, noncontractile in their central regions (lack myofilaments), and wrapped with two types of afferent endings: primary sensory endings of type Ia fibers and secondary sensory endings of type II fibers. | 106 | |
| 357582845 | Muscle Spindles | Contractile end regions are innervated by gamma efferent fibers that maintain spindle sensitivity. • Note: extrafusal fibers (contractile muscle fibers) are innervated by alpha efferent fibers. | 107 | |
| 357582847 | Muscle Spindles:excited in what ways | 1. External stretch of muscle and muscle spindle, 2. Internal stretch of muscle spindle: activating the gamma motor neurons stimulates the ends to contract, thereby stretching the spindle, stretch causes an increased rate of impulses in Ia fibers. | 108 | |
| 357582851 | Muscle Spindles | Contracting the muscle reduces tension on the muscle spindle, sensitivity would be lost unless the muscle spindle is shortened by impulses in the gamma motor neurons, alpha-gamma coactivation maintains the tension and sensitivity of the spindle during muscle contraction. | 109 | |
| 357582854 | Stretch Reflexes | Maintain muscle tone in large postural muscles and cause muscle contraction in response to increased muscle length (stretch). | 110 | |
| 357582856 | Stretch Reflexes-how it works | Stretch activates the muscle spindle, IIa sensory neurons synapse directly with alpha motor neurons in the spinal cord, alpha motor neurons cause the stretched muscle to contract, all stretch reflexes are monosynaptic and ipsilateral. | 111 | |
| 357582860 | Stretch Reflexes | Reciprocal inhibition also occurs—IIa fibers synapse with interneurons that inhibit the alpha motor neurons of antagonistic muscles. Example: In the patellar reflex, the stretched muscle (quadriceps) contracts and the antagonists (hamstrings) relax. | 112 | |
| 357582862 | Golgi Tendon Reflexes | Polysynaptic reflexes, help to prevent damage due to excessive stretch and important for smooth onset and termination of muscle contraction plus produce muscle relaxation (lengthening) in response to tension. | 113 | |
| 357582870 | Flexor (withdrawal) reflex | Initiated by a painful stimulus, causes automatic withdrawal of the threatened body part, and ipsilateral and polysynaptic. | 114 | |
| 357582873 | Crossed extensor reflex | Occurs with flexor reflexes in weight-bearing limbs to maintain balance, consists of an ipsilateral flexor reflex and a contralateral extensor reflex, the stimulated side is withdrawn (flexed), and the contralateral side is extended. | 115 | |
| 357582877 | Superficial Reflexes | Elicited by gentle cutaneous stimulation and depend on upper motor pathways and cord-level reflex arcs. | 116 | |
| 357582879 | Plantar reflex | Stimulus: stroking lateral aspect of the sole of the foot Response: downward flexion of the toes Tests for function of corticospinal tracts | 117 | |
| 357582882 | Babinski's sign | Stimulus: stroking lateral aspect of the sole of the foot Response: dorsiflexion of hallux and fanning of toes Present in infants due to incomplete myelination and in adults, indicates corticospinal or motor cortex damage. | 118 | |
| 357582886 | Abdominal reflexes | Cause contraction of abdominal muscles and movement of the umbilicus in response to stroking of the skin, vary in intensity from one person to another, absent when corticospinal tract lesions are present. | 119 |
