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72 Cards in this Set
- Front
- Back
transmembrane potential (TMP)
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difference in voltage between inside and outside of cell
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resting membrane potential (RMP)
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when the cell is not electrically active
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graded potential
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any charge that brings a cell out of rest
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action potential
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generated when graded potential reaches threshold
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depolarization
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making the membrane more positive
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repolarization
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returns membrane to resting potential
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hyperpolarization
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results when potassium ions move out, inside of cell becomes more negative, , making the charge differential
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threshold for axon
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depolarization of 10-15 mV
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all or nothing
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You send an impulse via nerve to the motor endplate, where the neurons meets up with the skeletal muscle fiber. If this excitation (via release of ACh) is enough to cross the threshold in the postsynaptic cell (the motor fiber). If this stimuli is strong enough, it will cause a depolarization of the muscle, which causes the sarcoplasmic reticulum to release calcium and cause a series of reactions within the muscle to make it contract. Thusly, if a muscle fiber is activated with a strong enough impulse, it will contract. This contraction is the same strength regardless of the intensity of the neuronal signaling (after it has crossed the threshold for excitation), so the fiber contracts. Your muscle fibers only have one strength, on or off. To vary your lifting, say a heavy object versus a lighter one, you recruit fewer muscle fiber bundles, rather than have all of the muscle fibers contract at a lesser intensity. they can't contract at a lesser intensity, so it is said to be all or none.
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afferent division is divided into what two divisions
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somatic and visceral sensory
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efferent division is divided into what two divisions
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somatic nervous system and autonomic nervous system
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multipolar neuron services what organ
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brain
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bipolar neuron services what organs
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sensory organs
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unipolar services what parts of the body
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sensory neurons of the PNS
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name three nueron functions
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sensory nueron, internueron, motor neuron
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function of sensory neuron
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carries information from receptor to CNS
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internueron function (association nueron)
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link between sensory and organ neurons
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motor nueron function
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carries information from brain to effectors
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passive (leak) channel
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permanently open
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three types of active channels and how they're activivated
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mechanical- activitated by pressure/vibration
ligand/chemical- activated by neurons voltage- activated by charge |
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name 3 states of gated channels
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1) closed but can be opened by stimulus
2) open, activated 3) closed, cannot be activated |
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four types of glial cells in the CNS
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astrocytes, ependymal, oligodentrocytes, microglia
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astrocytes
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maintains blood brain barrior
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ependymal cells
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produce CSF
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oligodentrocytes
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myelinate axons
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microglia
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fight infections
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2 types of glial cells in peripheal nervous system
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satellite cells and schwann cells
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satellite cells
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regulates O2, CO2, nutrient and nuerotransmitter levels around neurons
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schwann
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provides myelination to axons
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threshold for axon
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depolarization of 10-15 mV
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5 stages of generation of action potential
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1) depolarization to threshold
2) activation of Na+ gated channels and rapid depolarization 3) inactivation of Na- channels and activation of K+ channels 4) return to normal permeability 5) refractory period |
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where is action potential propagated
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axon
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where are potentials passed onto the next cell
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synaptic terminals
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relative refractory period
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initiation of a second action potential is inhibited but not impossible
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refractory period
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the amount of time it takes for an excitable membrane to be ready for a second stimulus once it returns to its resting state following an excitation
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absolute refractory period
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cannot execute muscle contraction at all
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continuous propagation of impulse (action potential)
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local currents depolarize adjacent areas of membrane so that action potentials continue to form along the membrane
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saltatory propagation of impulse
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propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials without needing to increase the diameter of an axon.
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where is action potential generated
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axon hillock
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this part of the skeletal muscle cell releases calcium when stimulated by the T tubultes
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terminal cisterns of sarcoplasmic reticulum
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what type of synapse dominates the nervous system?
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chemical
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band of connective tissue that surrounds muscles
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epimysium
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graded potentials can involve either depolarization or hyperpolarization, true or false
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T
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two types of synapses
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electrical and chemical
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electrical synapse
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no gap between the presyn. and post-synaptic cells, the 2 cells are joined by connexons
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2 types of post-synaptic potentials
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excitatory post-synaptic potential and inhibitory
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excitatory post-synaptic potential
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graded depolarization caused by arrival of neurotransmitter at the postsyn. membrane- results from openings of chemically gates membrane channels that lead to depolarization
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inhibitory post-synaptic potential
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graded hyperpolarization- its inhibited because while hyperpolarization continues, the nueron is inhibited and requireds a larger than usual depolarizing stimulus
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2 kinds of summation
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spatial and temporarl
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spatial summation
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potentials arrive at different locations at the same time
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temporal summation
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potentials arrive at ONE location in rapid succession
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in electrical synapses, 2-way transmission of impulses is possible, T or F
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T
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where can electrical synapses be found?
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the brain, including the vestibular nuclei, the eye, and in one pair of PNS ganglia (ciliary ganglia)
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function of neurotransmitters
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to open or close ion channels that influence membrane that influence membrane permeability
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hierarchical arrangement of skeletal muscle
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Z-line
z-line sandwiching H-zone A and I bands sarcomers myofibrils muscle fibers fascicles skeletal muscle |
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each muscle fiber is surrounded by
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sarcolemma
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myofibrils have how many sarcomers
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10,000
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muscle fibers are made up of
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myofibrials
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what role does the elastic prtein titin have in muscle contraction
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pulls thin filament towards the M-line in the A band, the I--band (area between successive A-bands) shorten, but the A band remains the same. contraction stops when the Z-line touches the ends of teh thick filaments, at which point the I-band disapears
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sarcome is the area between
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2 successive z-lines
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a sarcomere has how many myofilaments
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2, the thick and thin
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thin filament has what proteins
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actin, nebulin, troponin, tropomyosin
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M line
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situated in middle and divides the sarcomere into equal halves
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thick filaments are attached to the
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M-line
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thin filaments are attached to the
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z-lines
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titin connects:
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head of the thick to teh z-line which creates 3 zones where the major myofilaments can be found
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A-band
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runs entire lenght of the thick filamanet on either side of the M-line- has a part where thick and thin overlap
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what role does troponin have in muscle contraction
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arriving AP stimulates sarcoplasmic reticulum into relasing Ca2+ into sarcoplasm, the extra Ca2+ binds to troponin
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a cross-bridge is formed when
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a myosin head binds to an active site on the thin filament (f-actin)
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twitch
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single stimuls-contraction-relaxation sequence in a muscle fiber
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twitch can be divided into
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latent period
contraction phase relaxation phase |
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treppe
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if a skeletal muscle is stimulated a 2nd time immediately after relaxation phase, the contraction will develop a slightly higher maximum tension than at the first stimulus. amount of tension produced remains constant, Because the tension rises in stages, its called treppe
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