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118 Cards in this Set
- Front
- Back
Peripheral Nervous System (PNS)
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All parts of the NS except brain + spinal cord. Includes sensory receptors, peripheral nerves, associated ganglia, and motor endings. Provides links to and from the external environment.
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Ganglia
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Cluster/group of neuronal cell bodies outside of CNS
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Endoneurium
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Surrounds each axon
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Fascicles
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Are bundles of axons
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Perineureum
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Surrounds each fascicle
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Epineureum
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Surrounds the whole nerve
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Sensory receptors
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Are specialized to respond to changes in their enviornment called stimuli.
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Stimuli
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Changes in enviornment
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Define neuron
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A nerve cell
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Define nerve fiber
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An axon and its various sheaths
(In PNS, always have SC and often have myelin sheath) |
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Define nerve
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Collection of nerve fibers and their specialized CT sheaths (epineurium, perineurium, endoneurium)
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Sensory receptors by stimulus:
Mechanoreceptors |
Touch, pressure, vibration, or stretch
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Sensory receptors by stimulus:
Thermoreceptors |
Temperature (internal or external)
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Sensory receptor by stimulus:
Photoreceptor |
Light (eyes-retina)
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Sensory receptor by stimulus:
Chemoreceptors |
Chemicals (blood ph, salt levels)
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Sensory receptor by stimulus:
Nociceptors |
Pain
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Sensory receptor by location:
Exteroreceptors |
Sensitive to external stimuli (pain, pressure, temperature, light)
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Sensory receptor by location:
Interoreceptors |
Responds to internal stimuli (chemicals, temperature, stretch)
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Sensory receptor by location:
Proprioceptors |
Responds to positon; found in muscles, tendons, joints, ligaments
(where body part is + state of connective tissue) |
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Free or naked nerve endings
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Are present every where in body + responds primarily to pain + temperature
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Incapsulated dendritic endings:
Meissner's corpusles |
Are receptors for discrimminatory + light touch in hairless areas of body
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Incapsulated dendritic endings:
Pacinan or lamellated corpuscles |
Are stimulated when deep pressure is first applied
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Incapsulated dendritic endings:
Muscle spindles |
Detects when a muscle is being stretched + initiates reflex that resists stretch
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Incapsulated dendritic endings:
Golgi tendon organs |
Are stimulated when associated muscle stretches the tendon
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Incapsulated dendritic endings:
Joint kinesthetic receptors |
Monitors the stretch in articular capsules of synovial joints.
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Cranial nerves
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Emerges from brain
First 2 nerves sensory, rest are mixed 12 pairs |
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Spinal nerves
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Emerges from spinal cord
31 pairs |
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Cranial nerve I
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Olfactory
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Cranial nerve II
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Optic
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Cranial nerve III
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Oculomotor
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Cranial nerve IV
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Trochlear
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Cranial nerve V
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Trigeminal
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Cranial nerve VI
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Abducens
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Olfactory
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(Sensory) Receptors are in olfactory epithelium
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Olfactory damage:
Anosmia |
Fracture of ethmoid (perception of smell)
Actual damage to olfactory receptor (loss of smell) |
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Optic
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(Sensory) Receptors in retina of eye
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Olfactory nerve passes through
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Cribriform plate of ethmoid to olfactory bulb
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Optic nerve passes through
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Optic foramen, partially crosses over at the optic chiasma
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Optic defect:
Anopsias |
Visual defects
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Oculomotor
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(Mixed) mainly motor nerves to 4 of the 6 eye muscles, eyelid, iris, and lens
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Oculomotor nerve passes through
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Superior orbital fissure of the ethmoid
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Oculomotor defect:
Ptosis |
Eyelids droop
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Oculomotor defect:
External strabismus |
Eyes rotate laterally, eyes don't move together - focusing becomes difficult
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Trochlear
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(Mixed) Mainly motor nerves to superior oblique muscle of eye
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Trochlear damage:
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Results in inability to rotate eye inferiolaterally
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Trigeminal
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(Mixed) Largest cranial nerve with 3 divisions
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Trigeminal:
V1 Opthalmic division |
Passes through the superior orbital fissure
Fibers come from nasal cavity, cornea, lacrimal gland Tested by attempting to evoke corneal reflex |
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Trigeminal:
V2 Maxillary divison |
Passes through foramen rotundum
Fibers from nasal cavity, palate, upper teeth, cheeks, lower eyelid Tested with pin pricks + hot/cold objects |
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Trigeminal:
V3 Mandibular divison |
Passes through the foramen ovale
To/from tongue lower teeth, chin Tested by strength of jaw opening + closing, + lateral jaw movement |
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Trigeminal damage:
Tic doulereux |
Inflammation of the trigeminal
Results in severe pain from slight stimuli Partly treatable with drugs, in severe case nerve is severed |
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Abducens
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(Mixed) Primarily motor to lateral rectus muscle of eye
Single muscle of eye |
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Abducens defect:
Internal strabismus |
Eye cant move laterally
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Facial
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(Mixed) Somatic motor nerves run through internal acoustic meatus then stylomastoid foramen of temporal to muscls of facial expression, palate, tongue, salivary gland (sense of taste)
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Facial:
Parasympathetic motor nerves |
To lacrimal, nasal, salivary glands
Snesory nerves from anterior part of tongue |
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Facial damage:
Bell's palsy |
Loss of taste, inability to tear, asymmetry of face
Paralysis of facial muscles, usually on 1 side, eyelid droops (results of herpes virus) |
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Vestibulocochlear
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(Sensory) Cochlear divison transmits sound impulses
Vestibular division, equilibrium |
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Vestibulocochlear damage:
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Deafness, dissiness, loss of balance, nausea
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Glossopharyngeal
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(Mixed) To/from pharnyx and part of tongue
Chemoreceptors for blood CO2 + O2 levels |
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Glossopharyngeal damage:
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Damages gag and swallowing reflexes, impairment of taste
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Vagus
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(Mixed) Only cranial nerve that extends below neck
Autonomic regulation of heart, lungs, organs of abdominal cavity |
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Vagus damage:
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Impaired peristalsis, difficult swallowing, death.
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Accessory
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(Mixed) Only cranial nerve that consists of cranial and spinal roo
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Accessory:
Cranial root |
Helps vagus control the muscles of the larynx and pharynx
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Accessory:
Spinal root |
Controls some of the major neck muscles
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Accessory damage:
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Causes head to turn to side, shoulder elevation becomes difficult
(Ask patient to move neck back) |
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Hypoglossal
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(Mixed) Mostly motor to the tongue
Involved in speech + swallowing |
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Hypoglossal damage:
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Inability to protrude tongue or tongue leaning to one side
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Spinal Nerve
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31 pairs - spinal nerves arise from spinal cord
Except for thoracics, ventral rami join together to form nerve plexuses |
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Spinal nerve connects to spinal cord
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By dorsal + ventral root
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Rami
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Lie distal to + are lateral branches of spinal nerves that carry both motor + sensory nerves
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Dorsal rami
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Innevervated in back
Lie in point of origin from spinal column |
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Ventral rami
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Only in thorax
Arranged in simple segmental pattern that corresponds to dorsal rami |
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Cervical plexuses
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Formed by ventral rami of first four cranial nerve
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Brachial plexuses
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Stimulated partly in neck + axilla
Gives rise to virtually all nerves that inervate the upper limb |
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Sacral + lumbar plexuses
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Overlap because many fibers of lumbar plexus contributes to sacral plexus via the lumbosacral trunk
The two plexuses are often referred as lumbosacral plexus |
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Dermatones
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Area of skin innervated by cutaneous branches of single spinal nerve
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Hinton's law
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States that any nerve serving a muscle that produces movement at a joint also innervates the joint + skin over joint
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Somatic
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Conscious
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Visceral
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Internal organs
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Referred pain 1
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Some visceral afferent nerves ravel along the same pathways as the somatic nerves
The brain can interpret the impulses from the visceral nerves as being from skin + muscles |
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Referred pain 2
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Heart is innervaed by T1-T5
Heart problems are mistakenly interpreted as coming from left arm |
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Reflex
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Unlearned, rapid, predictable motor responses to stimulus + occur over highly specific neural pathways called reflex arcs
Response doesn't necessarily require brain |
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Reflex arc process
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Receptor sends afferent impulses via sensory neuron to CNS.
The CNS, the integration center has neurons which recieve the information + stimulate a motor neuron to send an efferent impulse to effector (skeletal muscle) |
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Reflexes can be
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Somatic (skeletal muscle) or autonomic
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Spinal reflexes
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Somatic reflexes mediated by spinal cord
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Reflex damage:
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Exaggerated, distorted, or absent reflexes indicate nervous system disorder
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Stretch reflexes
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Designed to prevent overstretching of muscles, connective tissues
Triggered by tapping on tendons attatched to muscles at elbow, wrist, knee + ankle joints (Knee jerk) |
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Stretch reflexes:
Monosynaptic process |
Muscle spindles detect slight stretch
Muscle spindle generates impulses to sensory neuron to posterior root of spinal nerve Sensory neuron synapses with motor neuron in gray matter of spinal cord Ach at NMJ triggers contraction of skeletal muscle |
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Stretch reflex:
Knee jerk |
Stretches quadriceps as quickly as possible sends to dorsal root
(Sensory fiber goes in) Designed to prevent overstretching or damage |
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Flexor (withdrawl) reflex process
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Pain sensitive sensory neuron stimulated
Impulse propagates into spinal cord Sensory neuron activated interneuron + signal sent to several segments Several motor neurons activated + motor impulse propagates toward several NMJs Ach released into synaptic cleft causes flexor muscles to contract, withdrawing body part from painful stimulus |
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Stretch reflex diagnosis
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Absence or hypoactivity can indicate ventral horn signal or peripheral nerve damage,
diabetes mellitus, nerosyphilis, hyperactivity as seen in damage parts of corticospinal tract which sends inhibitory impulses. |
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Diabetes mellitus
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Controls glucose levels
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Neurosyphilis
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STD
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Plantar relfexes
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A blunt object drawn along the sole of the foot normally causes curling of toes
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Plantar reflexes:
Babinski's sign |
1 degree motor cortex or corticospinal cord damage
Big toe dorsiflexes and the other toe fans laterally (normal in infants) |
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Autonomic Nervous system
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Part of peripheral nervous system
COnsists of neurons that innervate involuntary muscle and glands Also called: Involuntary NS, General visceral NS |
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Architecture of ANS
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Functional unit of ANS is almost always a two neuron chain
(CNS) Preganglionic neuron (PNS) Postganglionic neuron Effector organ |
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Architecture of ANS:
Axons |
Axons tend to be relatively slow
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Architecture of ANS:
Preganglionic axon |
Thin and lightly myelinated axon
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Archiitecture of ANS:
Postganglionic axon |
Thinner and unmyelnated
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SNS
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Produces voluntary movements
Responds to consciously percieved sensory input |
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ANS
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Produces involuntary movements (cardiac/smooth muscle + glands)
Responds to unconscious sensory input |
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ANS reflex arcs
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Regulates activity of smotth, cardiac muscle + many glands
Continual flow of nerve impulses from autonomic sensory neurons in visceral organs + blood vessels propagates into integrating centers of CNS Impulses in autonomic motor neurons propagate to various effector tissues Can excite or inhibit activities of effector tissues ANS activity is regulated by hypothalamus + brain stem of CNS |
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Parasympathetic divison
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Most organs have dual innervation
Transmis opposing nerve impulses Operates involuntary functions |
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Norepinephrine (NE)
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speeds up or slows down
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Cholinergenic
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Neurons release acetylcholine
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Adrenergenic
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Neurons relase norepinephrine
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Presympathetic
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Starts at nerves (thoracolumbar location)
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Parasympathetic
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Starts at nerves (Craniosacral)
Normal body functions |
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Blood vessels only have
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Parasympathetic NS
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Glycogenolysis
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Polysaccharide
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Lypolysis
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Breakdown of fats
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Sympathetic Division promotes
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"Fight or flight"
Allows more blood flow to heart + skeletal muscle Speeds heart rate + strength of contraction Promotes glycogenolysis, lipolysis Stimulates arrector pilli muscles + sweat glands |
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Effects of sympathetic NS are longer lasting than the effects of parasympathetic NS
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NE is inactivated more slowly than Ach
NE takes longer to exert its effect on postsynaptic cells Adrenal medulla strengthens + helps maintain sympathetic effects |
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Adrenal medulla
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Innervated by preganglionic neuron.
When sympathetic NS is activated, responds by releasing hormones, epinephrine + norepinephrine |
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Adrenal medulla is actually a cluster of
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Modified postganglionic neurons.
Instead of releasing neurotransmitter NE to specific target, It relases NE + epinephrine as hormones that circulate the blood. The effect is slower but longer lasting |
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Sympathetic
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Dominates during "fight or flight" - extreme physical or emotional stress
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Parsympathetic
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Enhances rest + digest activities
Favors activities that support body functions that conserve + restore energy during rest + recovery SLUDD: salivation, lacrimation, urination, digestion, defecation Decreases: heart rate, diameter of airways, diameter of pupils. |