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49 Cards in this Set
- Front
- Back
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Basic function of the nervous system
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Functions:
-Sensory input -monitoring stimuli occuring inside & outside the body. -Integration- interpretation of sensory input -Motor output- response to stimuli by activating effector organs. |
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CNS
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-Brain & Spinal cord
-Integration & command center |
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PNS
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-Paired spinal & Cranial nerves
-Carries messages to & from the spinal cord & brain. 2 DIVISIONS: AFFERENT & EFFERENT. |
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PNS (2 Functional divisions)
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Sensory (afferent) - sensory afferent fibers carry impulses from skin skeletal muscles & joints to the brain.
Motor (efferent) - transmits impulses from the CNS to effector organs |
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Somatic nervous system
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concscious control of skeletal muscles
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Autonomic nervous system
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Regulates smooth muslces, cardiac muscle & glands.
DIVISIONS: SYMPATHETIC & PARASYMPATHETIC (ALWAYS BATTLING TO KEEP HOMEOSTASIS) |
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Neuroglia
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Supporting cells.
Provide supporive scaffolding for neurons Segregate & insulate neurons Guide young neurons to the proper connections Promote Health & growth. |
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Sympathetic NS
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Fight or Flight response.
No digestion |
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Parasympathetic NS
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Relaxation
Conserve Energy Digestion |
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Myelin Sheath
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Whitish, fatty segmented sheath around most long axons.
FUNCTIONS: protect the axon, eletrically insulate fibers from one another, & increase the speed of the nerve impulse transmission. |
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Nodes of Ranvier
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Gaps in the myelin sheath between adjacent schwann cells
They are the sites where axons collaterals can emerge. |
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Neural Classification
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Multipolar- 3 or more processes.
Bipolar- 2 processes ( axon & dendrite ) Unipolar- single short process |
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Graded Potential
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Short lived local changes in membrane potential.
Decrease in intensity w/ distance. Their magnitude varies directly w/ the strength of the stimulus. Sufficiently strong graded potentials can inititate action potentials. Voltage changes in graded potential are decremental. Current is quickly dissipated due to the leaky plasma membrane. can only travel over short distances |
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Action Potential
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Brief reversal of membrane potential w/ a total amplitude of 100 mV
Only generated by muscle cells & neurons. do not decrease in strength over distance principal means of neural communication an action potential in the axon of a neuron is a nerve impulse. |
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Salatory Conduction
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Current passes through a myelinated axon only at the nodes of Ranvier.
Voltage gated channels are concentrated at these nodes (Na+) action potentials are triggered only at the nodes & jump from one node to the next. much faster than conducting along unmyelinated axons. |
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Electrical Synapses
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are less common than chemical synapses.
correspond to gap junctions found in other cell types. ARE IMPORTANT TO THE CNS: arousal from sleep, mental attention, emotions & memory, ion & water homeostasis. |
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Chemical Synapses
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Specialized for the release & reception of neurotransmitters.
2 parts: axonal terminal of the presynaptic neuron, which contains synaptic vesicles. & recepter region on the dendrite(s) or soma of the post synaptic neuron. |
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Serial processing
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input travels along 1 pathway to a specific destination.
works in an all or none manner ex: spinal reflexes |
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Parralell processing
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input travels along several pathways
pathways are integrated in differ. CNS systems. one stimulus promotes numerous reponses. ex: a smell may remind of the odor & associated experiences. |
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Myelin Sheath Formed by:
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Alegodendroctyes.
AXONS that are unmyelinated is gray matter. White areas are axons that are myelinated. |
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Basal Nuclei
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Masses of gray matter found deep w/ in the cortical white matter.
FUNCTIONS: Influence muscular activity, Regulate attention & cognition, Regulate intesity of slow or stereotyped movements, Inhibit antagonisitc & unnecessary movement. |
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Limbic system
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Structures located on the medical aspects of cerbral hemis. & diencephalon.
Includes: rhinecephalon, amygdala, hypothalmus, anterior nucleus of the thalmus. Parts especially imp. in emotions: Amygdala- anger, danger, fear. Puts emotional responses to odors. (eg: skunks smell bad). Interacts w/ the prefrontal lobes. (emotionally to conscious understandings) |
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Reticular Formation
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Composed of 3 broad columns along the length of the brain stem.
RAS & MOTOR FUNCTION: sends impulses to the cerebral cortex to keep it conscous & alert. Filters out repetitive & weak stimuli. Motor function: helps control coarse motor movements & autonomic centers regulate visceral motor functions |
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Brain Waves
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Alpha waves- regular & rhythmic, low amplitude, "idling brain."
Beta waves- rhythmic, more irregular waves, occuring during the awake & mentally alter state. Theta waves- more irregular the alpha waves, common in children but abnormal in adults. Delta waves- High amplitude waves seen in deep sleep & when reticular activating system is damped. |
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Sleep
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Stage 1 (NREM) -one can be easily aroused. eyes are closed and relaxation begins.
Stage 2 (NREM)- EEG pattern is irregular w/ sleep spindles; arousal is more difficult. Stage 3 (NREM)- sleep deepens, theta & delta waves appear, vital signs decline, & dreaming is common Stage 4 (NREM)- EEG pattern is dominated by delta wave; skeletal muscles are relaxed & arousal is difficult REM OCCURS REM SLEEP: EEG pattern reverts through NREM stages to the stage 1 pattern, vital signs increase, skeletal muscles are inhibited ( except ocular muscles) most dreaming takes place. |
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STM
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working memory is a fleeting memory of the events that continually happen.
STM Lasts seconds to hours and is limited to 7 or 8 pieces of information. |
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LTM
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limitless capacity.
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Protection of the brain
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BY: bone, meninges & cerebrospinal fluid.
Harmful substances are shielded from the brain by the blood-brain barrier. |
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Dura Mater, Arachnoid Mater, & Pia Mater
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DM- dural septa extend inward & limit excessive movment of the brain.
AM-Middle meninx which forms loose brain covering, seperated by the dura mater & the subdural space. PM-deep meninx composed of delicate connective tissue that clings tightly to the brain. |
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Protection of the spinal cord
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CNS tissue is enclosed w/ in the vertebral column from the foramen magnum to L1
Povides a 2 way communication to & from the brain. Protected by bone, meninges, & CSF Epidural space: space between the vertebrae & the dural sheath (Dura mater) filled w/ fat and a network of veins. |
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General classification of sensory receptors
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Stimulus type, Exteroceptors, Interoceptors, Proprioceptors, structrual complexity, uncapsulated, encapsulated.
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Adaptation of sensory receptors
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Adaptation occurs when sensory rec. are subjected to an unchanging stimulus.
R. responding to pressure, touch & smell adapt quickly, pain receptors and proprioceptors do no exhibit adapation |
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Nerve
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a cordlike organ of the PNS consisting of perpherial axons enclosed by connective tissue.
REGENERATION: damage to nerve tissue is serious because mature neurons are amitotic. If the soma of a damaged nerve remains intact, damage can be repaired. Regeneration involves coordinated activity among: marcophages, schwann cells, & axons. |
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Cranial nerves (and their roles)
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Cranial nerve 1: OLFACTORY.- impulses for the sense of smell.
Cranial nerve 2: OPTIC- functions solely by carrying afferent impulses for vision. Cranial nerve 3: OCULOMOTOR- functions in raising the eyelid, directing the eyeball, constricting the iris, & controlling the lens shape. Cranial nerve 4: TROCHLEAR- primarily a motor nerve that directs the eyeball. Cranial nerve 5: TRIGEMINAL- conveys sensory impulses from various ares of the face and supplies motor fibers for mastification Cranial nerve 6: ABDCUENS- primarily a motor nerve innervating the lateral rectus muscle. cranial nerve 7: FACIAL- sensory function is taste from the anterior 2 thirds of the tongue.(if nerve is damaged you get bells palsy) cranial nerve 8: VESTIBULOCOCHLEAR- 2 divisions: cochlear (hearing) & vestibular (balance.) Functinos: are solely sensory - equilibrium & hearing. cranial nerve 9: GLOSSOPHARYNGEAL- motor- innervates part of the tongue & pharynx, & provdes motor fibers to the parotid salivary gland. & sensory-fibers conduct taste & general sensory impulses from the tongue & the pharnyx. cranial nerve 10: VAGUS- its sensory function is taste( LARGER NERVES OF THE PNS- MOST IMPORTANT!) Cranial nerve 11: ACCESSORY: primarily a motor nerve- supplies fibers to the larnyx, pharynx, & soft palate. Cranial nerve 12; HYPOGLOSSAL- innervates both extrinsic & intrinsic muscles of the tongue, which contribute to swallowing & speech. |
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Nerve Plexus
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Fibers travel to the periphery via several different routes.
Each msucle recieves a nerve supply from more than one spinal nerve. Damage to one spinal segment cannot completely paralyze a muscle. |
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Cervical plexus
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is formed by the ventral rami of C1-C4.
The phrenic nerve is the major motor & sensory nerve of the diaphram.* |
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Brachial plexus
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Formed by C6 -C8 & T1.
It gives rise to the nerves that innervate the upper limb. 4 MAJOR BRANCHES: ROOTS TRUNKS DIVISIONS CORDS BRANCHES (REAL TEENAGERS DRINK COLD BEER) |
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Brachial plexus
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Axillary (innervates the deltoid & teres minor)
Musculocutaneous (sends fibers to the biceps brachii & brachialis.) Median (braches to most of the flexor muscles of arm) Ulnar (supplies the flexor carpi ulnaris & part of the flexor digitorum profundus. Radial- innervates essentially all extensor muscles. |
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Lumbar Plexus
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arises from L1-L4 & innervates the thigh, abdominal wall & proas muscle.
The major nerves are the femoral & the obturator. |
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Sacral Plexus
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Arises from L4-S4 & serves the buttock ,lower limb, pelvic structures & the perineum.
Major nerve is the sciatic, the longest thickest nerve of the body. composed of 2 nerves: the tibial & the common fibular nerves. |
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Reflexes:
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Stretch & deep tendon -initiated by the muscle spindles must maintain healthy muscle tone.
Stretch reflex- stretching the muscle activates the muscle spindle. excited motor neurons of the spindle cause the stretched msucle to contract. Golgi tendon reflex- opp. of stretch reflex, contracting the muscle activates the gogi tendon reflex. as a result the contracting muscle relaxes & the antagonist contracts. Flexor & extensor relflex- initiated by a painful stimulus that causes automatic withdrawl of the threatened body part. 2 parts: stimulated side is withdrawn, contralater side is extended. Superficial reflexes: initated by gentle cutaneous stimulate. |
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Autonomic System
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Consists of motor neurons that innervated smooth & cardiac muscle & glands, make adjustments to ensure optimal support for body activities, operate via subconscious control, have vsicera as most of their effectors.
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ANS V. SNS
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effectors, efferent pathways, & target organ reponses.
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2 Divisions of the ANS is: sympathetic & parasympathetic
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Sympathetic: mobilizes the body during extreme situations.
Parasym- performs maintenance activies & conserves body energy. |
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Parasympathetic
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Body energy use low.
Involves: digestion, defecation, and diuresis. decrease heart rate & respitory rates, and allow for digestion & the discarding of wastes. erection of the penis |
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Sympathetic
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"Fight or Flight"
Involves exercise, excitement, emergency, and embarrasement. increase heart & respitory rates ejaculation of the penis. |
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Cholinergic Receptors
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2 types of receptors that bind to ACh are nictoinic & muscarinic.
These are named after drugs that bind to them and mimic ACh effects. |
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Adregergic Receptors
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2 types of adrenergic receptors are alpha & beta.
alpha receptors is generally stimulatory. beta receptors are inhibitory. a noteable exception: NE binding to beta receptors of the heart is stimulatory. |
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Sympathetic Tone
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(vascomotor tone**) constricts blood pressure to rise as needed.
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