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57 Cards in this Set
- Front
- Back
myasthenia gravis
cause and treatment |
Auto-immune disease in which antibodies attack neuromuscular junctions that bind ACh receptors together in clusters. Fiber becomes less sensitive to ACh.
Treatments are: cholinesterase inhibiters immunosuppressive agents thymus removal plasmapheresis |
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myosin and actin
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contractile proteins and occur in all cells
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triceps surae
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gastrocnemius and soleus
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sacromere
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basic unit of contraction in muscle
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sacromere: components
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z band: provides anchorage for thin filaments and elastic filaments
sacromers is z disc to z disc I band - gap between thick filaments (light) A band - where thick and thin filaments overlap (dark) H band - gap of only thick filaments |
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most common type of neuron
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multipolar neuron
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neuron structure
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can have multiple dendrites but no more than 1 axon
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axonal transport
retrograde vs anterograde |
anterograde - movement down the axon away from the soma
retrograde - movement up the axon toward the soma |
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neuroglia
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neuroglia more numerous than neurons in the brain
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action potential from axon
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more dramatic change produced by voltage-regulated ion gates in the plasma membrane
only occur where there is enough density of high voltage gates action potential is generated in the Trigger Zone rapid up and down change in membrane voltage |
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functions of muscles
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Movement - move from place to place, movement of body parts and body contents in breathing, circulation, feeding and digestion, defecation, urination, and childbirth
role in communication – speech, writing, and nonverbal communications Stability - maintain posture by preventing unwanted movements antigravity muscles – resist the pull of gravity and prevent us from falling or slumping over stabilize joints Control of openings and passageways - sphincters – internal muscular rings that control the movement of food, bile, blood, and other materials Heat production by skeletal muscles as much as 85% of our body heat |
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deepest abdominal muscle
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transverse abdominal
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This muscle has parallel fibers
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Rectus Abdominus
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This is a bi-pennate muscle
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Rectus Femoris
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Phrenic nerve
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supplies the diaphragm
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antagonist vs synergist
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synergist - muscle that aids the prime mover
stabilizes the nearby joint modifies the direction of movement antagonist - opposes the prime mover relaxes to give prime mover control over an action preventing excessive movement and injury antagonistic pairs – muscles that act on opposite sides of a joint |
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carpal tunnel--what causes it?
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prolonged, repetitive motions of wrist and fingers can cause tissues in the carpal tunnel to become inflamed, swollen, or fibrotic
puts pressure on the median nerve of the wrist that passes through the carpal tunnel along with the flexor tendons tingling and muscular weakness in the palm and medial side of the hand pain may radiate to arm and shoulder treatment – anti-inflammatory drugs, immobilization of the wrist, and sometimes surgery to remove part or all of flexor retinaculum |
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rotator cuff muscles
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“SITS” muscles
supraspinatus infraspinatus teres minor subscapularis |
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characteristics of skeletal muscle
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voluntary, striated muscle attached to one or more bones
striations - alternating light and dark transverse bands results from an overlapping of internal contractile proteins voluntary – usually subject to conscious control muscle cell, muscle fiber, (myofiber) as long as 30 cm |
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characteristics of cardiac muscle
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striated like skeletal muscle, but myocytes (cardiocytes) are shorter and thicker
each myocyte is joined to several others at the uneven, notched linkages – intercalated discs appear as thick dark lines in stained tissue sections electrical gap junctions allow each myocyte to directly stimulate its neighbors mechanical junctions that keep the myocytes from pulling apart sarcoplasmic reticulum less developed, but T tubules are larger and admit supplemental Ca2+ from the extracellular fluid damaged cardiac muscle cells repair by fibrosis a little mitosis observed following heart attacks not in significant amounts to regenerate functional muscle |
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characteristics of smooth muscle
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composed of myocytes that have a fusiform shape
one nucleus, located near the middle of the cell no visible striations reason for the name ‘smooth muscle’ thick and thin filaments are present, but not aligned with each other z discs are absent and replaced by dense bodies well ordered array of protein masses in cytoplasm protein plaques on the inner face of the plasma membrane cytoplasm contains extensive cytoskeleton of intermediate filament attach to the membrane plaques and dense bodies provide mechanical linkages between the thin myofilaments and the plasma membrane sarcoplasmic reticulum is scanty and there are no T tubules |
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Muscular Dystrophy
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muscular dystrophy - group of hereditary diseases in which skeletal muscles degenerate and weaken, and are replaced with fat and fibrous scar tissue
Duchenne muscular dystrophy is caused by a sex-linked recessive trait (1 of 3500 live-born boys) most common form disease of males – diagnosed between 2 and 10 years of age mutation in gene for muscle protein dystrophin |
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isotonic muscle contraction
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muscle changes in length with no change in tension
concentric contraction – muscle shortens while maintains tension eccentric contraction – muscle lengthens as it maintains tension |
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isometric muscle contraction
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muscle is producing internal tension while an external resistance causes it to stay the same length or become longer
can be a prelude to movement when tension is absorbed by elastic component of muscle important in postural muscle function and antagonistic muscle joint stabilization |
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Red Fibers
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slow oxidative (SO), slow-twitch, red, or type I fibers
abundant mitochondria, myoglobin and capillaries - deep red color adapted for aerobic respiration and fatigue resistance relative long twitch lasting about 100 msec soleus of calf and postural muscles of the back |
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White Fibers
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fast glycolytic (FG), fast-twitch, white, or type II fibers
fibers are well adapted for quick responses, but not for fatigue resistance rich in enzymes of phosphagen and glycogen-lactic acid systems generate lactic acid causing fatigue poor in mitochondria, myoglobin, and blood capillaries which gives pale appearance SR releases & reabsorbs Ca+2 quickly so contractions are quicker (7.5 msec/twitch) extrinsic eye muscles, gastrocnemius and biceps brachii |
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Threshold
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the minimum voltage necessary to generate an action potential in the muscle fiber and produce a contraction
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synaptic knob
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little swelling that forms a junction (synapse) with the next cell
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synaptic cleft
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gap between neurons was discovered by Ramón y Cajal through histological observations
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tetanus
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a state of sustained muscle contraction produced by temporal summation as a normal part of contraction
40-50 stimuli per second produces complete tetanus |
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tropomyosin
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protein that makes up thin muscle filaments
block the active sites to prevent binding of myosin |
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troponin
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calcium binding protein, bound to tropomysoin molecules of thin filaments
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RMP
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Resting Membrane Potential
RMP exists because of unequal electrolyte distribution between extracellular fluid (ECF) and intracellular fluid (ICF) RMP results from the combined effect of three factors: ions diffuse down their concentration gradient through the membrane plasma membrane is selectively permeable and allows some ions to pass easier than others electrical attraction of cations and anions to each other |
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somatic sensory division
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carries signals from receptors in the skin, muscles, bones, and joints
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visceral sensory division
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carries signals from the viscera of the thoracic and abdominal cavities
heart, lungs, stomach, and urinary bladder |
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somatic motor division
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– carries signals to skeletal muscles
output produces muscular contraction as well as somatic reflexes – involuntary muscle contractions |
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visceral motor division
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carries signals to glands, cardiac muscle, and smooth muscle involuntary, and responses of this system and its receptors are visceral reflexes
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sympathetic
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tends to arouse body for action
accelerating heart beat and respiration, while inhibiting digestive and urinary systems |
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parasympathetic
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tends to have calming effect
slows heart rate and breathing stimulates digestive and urinary systems |
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efferent vs afferent
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efferent - motor
afferent - sensory |
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effectors
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cells and organs that respond to commands from the CNS
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Glial cells of CNS
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oligodendrocytes -form myelin sheaths in CNS each arm-like process wraps around a nerve fiber forming an insulating layer that speeds up signal conduction
ependymal cells - lines internal cavities of the brain cuboidal epithelium with cilia on apical surface secretes and circulates cerebrospinal fluid (CSF) clear liquid that bathes the CNS microglia - small, wandering macrophages formed white blood cell called monocytes thought to perform a complete checkup on the brain tissue several times a day wander in search of cellular debris to phagocytize astrocytes most abundant glial cell in CNS cover entire brain surface and most nonsynaptic regions of the neurons in the gray matter of the CNS |
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Glial cells of PNS
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Schwann cells
envelope nerve fibers in PNS wind repeatedly around a nerve fiber produces a myelin sheath similar to the ones produced by oligodendrocytes in CNS assist in the regeneration of damaged fibers satellite cells surround the neurosomas in ganglia of the PNS provide electrical insulation around the soma regulate the chemical environment of the neurons |
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myelin sheath
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composed mostly of lipids
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conduction speed
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fastest in large myelinated fiber
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Regeneration of Peripheral Nerves
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regeneration of a damaged peripheral nerve fiber can occur if:
its soma is intact at least some neurilemma remains fiber distal to the injury cannot survive and degenerates macrophages clean up tissue debris at the point of injury and beyond soma swells, ER breaks up, and nucleus moves off center due to loss of nerve growth factor from neuron’s target cell axon stump sprouts multiple growth processes severed distal end continues to degenerate regeneration tube – formed by Schwann cells, basal lamina, and the neurilemma near the injury regeneration tube guides the growing sprout back to the original target cells and reestablishes synaptic contact nucleus returns to normal shape |
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depolarization
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case in which membrane voltage shifts to a less negative value
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repolarization
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shifts the voltage back to negative numbers returning toward RMP
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hyperpolarization
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membrane voltage 1 or 2 mV more negative than the original RMP – negative overshoot
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Local Potentials
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disturbances in membrane potential when a neuron is stimulated
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Refractory Period
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refractory period – the period of resistance to stimulation
two phases of the refractory period absolute refractory period no stimulus of any strength will trigger AP as long as Na+ gates are open from action potential to RMP relative refractory period only especially strong stimulus will trigger new AP |
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Neurotransmitters
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they are synthesized by the presynaptic neuron
they are released in response to stimulation they bind to specific receptors on the postsynaptic cell they alter the physiology of that cell |
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spatial summation
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net effect of postsynaptic potentials
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facilitation
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a process in which one neuron enhances the effect of another one
combined effort of several neurons facilitates firing of postsynaptic neuron |
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temporal summation
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occurs when a single synapse generates EPSPs so quickly that each is generated before the previous one fades
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spatial summation
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occurs when EPSPs from several different synapses add up to threshold at an axon hillock
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neural coding
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the way in which the nervous system converts information to a meaningful pattern of action potentials
qualitative information depends upon which neurons fire labeled line code – each nerve fiber to the brain leads from a receptor that specifically recognizes a particular stimulus type quantitative information – information about the intensity of a stimulus is encoded in two ways: one depends on the fact that different neurons have different thresholds of excitation stronger stimuli causes a more rapid firing rate excitement of sensitive, low threshold fibers gives way to excitement of less sensitive, high-threshold fibers as intensity of stimuli increases other way depends on the fact that the more strongly a neuron is stimulated, the more frequently it fires |