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133 Cards in this Set
- Front
- Back
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What is are some examples of direct integrating systems?
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Gap junctions, cell adhesions, and tight junctions.
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What role do direct integrating systems play?
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ions increase in one cell can be tranported through connexins, or tranpsorted through cAMP. Can go directly from cyplasmic contact to the outside environment.
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How does paracrine and autocrine signalling work?
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through extra cellular fluid. signaling to nearby cells. I.E. cytokines and eicosonoids -- cause pain
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What is the difference between endocrine glands and exocrine glands?
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Endocrine glands are ductless and exocrine secrete outside the body, like pheramones.
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What are some characteristics of a hydrophilic chemical messenger?
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Must have a special transporter, therefore packed in intracellular vesicles and released via exocitosis, otherwise would dissolve in the Extracellular fluid. Has transmembrane receptor and is fast acting.
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What are some characteristics of a hydrophobic chemical messenger?
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Only synthesized on demand, thus it is slower to transport and diffuse. Short distances can travel alone, but long distances need a carrier protein.
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Peptide messengers
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Released by exocitosis; made in rough ER; packed into vesicles. I.E. Vasopresin (ADH)
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Steroid Messengers
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Made from cholesterol. Hormones, autocrine, paracrine, carrier because hydrophobic.
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Biogenic amines
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Neurotransmitters NH2, C, also paracrine, dopamine, thyroid hormone,
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Lipid
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Paracrine and NT, eicosanoids -- pain reception
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What chemical messengers aid in blocking pain?
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leukotrienes and prostoglandings which are lipid based.
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Purines
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adenosine, AMP, ATP, guanine,, nucleotides, NT neuromodulators, paracrine.
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Adenosine prompts what?
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Calming in the brain
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Gases
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NO, NT Nueromodulator and paracrine. Vessel dialator via smooth muscle relaxation.
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How do ligand-receptor interactions control communications?
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The presence of a receptor determines the cellular response. If there is no extyson receptor on a cell then it doesnt matter how much ectysone is present, the cell won't respond.
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How do agonists work?
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Binding of a ligand to a receptor activates the receptor. Upregulating and down regulating is important for amplification for example caffeine binds to adenosine receptor --> and inhibits it.
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How do antagonists work?
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binding of a ligand to a receptor does nota ctivate the receptor --> for example, heroin downregulates receptors in order to try and maintain homeostasis.
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Receptors
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Large proteins composed of several domains one will be the lgand binding domain
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Isoforms
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there can be one or two different forms of a receptor.
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Synergism
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When one hormone amplifies the effect of another one
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Antagonism
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when one hormone opposes the effect of another one
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Permissiveness
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presence of one hormone is required for the second to act
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What are some effects of chronic stress?
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muscle wasting and hypertension, atrophy of neurons in hippocampus, which can cause decrease in memory and cognistion, can decrease reproduction.
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Describe the effect that glucocorticoids have on seasonal variance.
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Increase during breeding season and required for some behaviors. Glucocorticoids can modify behavior.
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What is the primary role for glucocorticoids?
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Prime the immune system and nervous system in anticipation for stressors
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Explain the scientific method.
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Observations, hypothesis, experiment, predictions, results, support/reject hypothesis.
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Describe the basic neural circuit
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Sensory input, integration, output, response.
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What are the two ways to control the nervous system?
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sequential control, feedback control; sensory and endocrine work together to control cell and animal function and ensure smooth and coordinated response.
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What is the most primitive nervous system?
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Jellyfish, they have a nerve net, no brain.
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What type of nervous system to flat worms have?
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Primitive brain and a nerve cord
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The PNS is split into what two branches?
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Afferent sensory neurons and efferent motor neurons.
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What are afferent neurons?
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Sensory neurons, going toward the brain.
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What are efferent neurons?
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motor neurons, going away from the brain.
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The CNS is split into what two branches?
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somatic and autonomic
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The autonomic system is split into what two branches, and what do they mean?
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Sympathetic "fight or flight" and Parasympathetic "rest and digest"
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What does the neuron doctrine state?
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Neurons are discrete cells, not meshwork. Basically, one neuron is one cell.
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Dendrite
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neuron receptor
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soma
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neuron body
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synapse
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neuron joint
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axon
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end of the neuron
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Glia
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cells that surround nervous tissue
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Neuroglia
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cells that glue neurons
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What are the four types of neuroglia?
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astrocytes, microglial cells (only located in the brain for an immune response), shwann cells (increase condictivity), and oligodendrocytes
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Unipolar neurons
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CNS, inverts, 1 process
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Bipolar
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sensory, 2 processes
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Multipolar
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CNS, invetebrates, many axons and dendrites 3 + processes.
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Current
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net movement of charge
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voltage
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separation of positive and negative charges
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Resistance
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inverts of voltage -- descrives how current flow is limited
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Charge rules
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carried by ions, opposite charges attract, energy required to keep them apart and overall positive and negative charges are equal in the body.
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What in the body is a natural insulator and what is a natural conductor?
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Pohspholipid bilayer is a natural insulator but water and ion channels are good conductors.
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Ohm's Law
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I=V/R, where I=current, V=Potential Difference in volts, and R=Resistance. If R is high, then charge separation is great.
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Resting membrane potential
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inside of membrane is negative
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polarization
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change in membrane potential such that positive is on the inside and negative on the outside. The voltage is zero.
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Oubain
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knowcks out Na+/K+ ATPas that is maintaining resting membrane potential
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hyperpolarization
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slight overcompensation for an action potential
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Nerst Equation
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E=RT/zF logCout/Cin E=voltage potential R=gas constant T=temperature F=farrdale constant z=valence
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refractory period
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no other action potential can occur
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What is responsible for the resting membrane potential?
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Mainly the K+ ion gradient -- equilibrium occurs when electrical force exactly balances chemical force of an ion
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recovery phase
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voltage-gated channels still open, working on closing, leaky Na+ channels still open.
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What are the channels doing during a resting membrane potential?
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PK>PNa; The K+ leak channel is leaky, the voltage gated Na+ and K+ channels are both closed.
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What are the channels doing during the rising phase of an action potential?
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PNa>PK; The K+ leak channel is leaky, voltage-gated Na+ channel is open allowing Na+ into the cell, voltage gated K+ channel is closed.
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What are the channels doing during the falling phase of an action potential?
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AKA refractory, PK>PNa; The K+ leak channel is leaky, the voltage-gated Na+ channel is inactivated and the voltage-gated K+ opens to release K+ out of the cell.
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What are the channels doing during the recover phase of an action potential?
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PK>PNa; Everything moves toward an equilibrium. The K+ leak channel is leaky, the voltage-gated Na+ channel is closed, and the voltage-gated K+ channel allows K+ to move freely toward an equilibrium.
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What is a graded potential?
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Small stimuli that don't reach action potential
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What is the importance of a refractory period?
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prevents re-excitation of the cell, prevents bi-drectional firing, prevents continual firing.
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What affects conductivity?
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Axon length (longer the faster), myelination, and temperature.
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What are the importance of synapses?
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They are similar to gap junctions, they cause no delay, and they are found in nervous systems where speed is important.
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What are some responses of a chemical synapse?
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Fast, slow, excititory, inhibitory, one-way signaling, amplify signaling.
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Describe the release of a neurotransmitter
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presynaptic cell (neuron) stimulates a post-synaptic cell (muscle cell, or another neuron) via membrane depolarization. This triggers voltage-gate sodium channels to open, and since Ca2++ is low on the inside, high on the outside, it triggers exocytosis of the neurotransmitters. Neurotrsmitter receptor and receptor number are important!
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Dynamin
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tags vesicles for re-uptake
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Oligodendrocytes
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connects two axons via schwann cells, eveloping the axons of the neurons
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astrocytes
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act as metabolic intermediaries between capilaries of neurons -- take up neruotransmitters in intercellular space.
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microglial cells
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aid in immune responses in neural tissue and may act as phagocytes
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capacitance
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properties exhibited due to the insulating properties of the lipid bilayer.
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Passive electrical properties
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cconditions in which the membrane resistance does not change--govern how voltages change over space and time along neuronal axons. Don't explain generation of action potentials.
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Resting Membrane potential
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polarity is negative on the inside of the membrane compared to the positive outside charge.
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Membrane Resistance
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The Positive and negative charges aligning the membrane cause a resistance of ions to pass freely through the membrane
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Depolarization
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decrease in absolute value of membrane potential toward zero (becomes less negative inside the cell)
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Hyperpolarization
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Increase in the aboslute value of membrane potential away from zero (becomes more negative inside the cell)
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passive spread/electrotinic conduction
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voltage change decreases exxponentially with distance from the source producing it.
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Electrochemical equilibrium
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reacheced when the tendency for K+ ions to diffuse out of the cell is exactly blaanced by their tendency to move in
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Function of Na+/K+ ATPase Pump
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Actively transports Na+ out of the cell and K+ into it because Na+ leaks into the cell and K+ leaks out of it. 3 Na+ ions for every 2 K+ ions. Makes inside more negative. This produces outward ionic current.
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Gibbs-Donnian Equilibrium
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Cl- ions are in passive equilibrium although they are more concentrated outside of the cell.
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ionic hypothesis
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concentrations of ions inside and outside a cell are maintained in a steady state by a mixture of active-transport processes and passive transport processes
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electroneutral pump
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equal quantities of charge inward and outward across a membrane
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electrogenic pump
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unequal quantities of charges inward and outward across a membrane
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Action potential
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Mementary reversal of membrane portential from about -65 mV (inside negative) to about +40 mV (inside positive) that last about 1 ms, followed by resoration of original membrane potential.
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Voltage threshold
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critical value of depolarization that allow AP to occur.
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what do action potentials result from?
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intense, localized increases in permeabilites to specific ions, increases that are both voltage and tine-dependenct. Permeability increases are selective for specific ions, Sodium and potassium
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Why do action potentials not greatly interfere with ion concentrations?
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Action potentials require a very small concentration of ions, also the Na+/K+ pump maintains a constant ratio of ions within the cell. Presumably, their firing rates will not excede the limit of the Na+/K+ ATPase pump.
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nonspiking neurons
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neurons that produce only graded membrane potential changes in response to a stimulus or synaptic input because they lack voltage-gated sodium channels. these include photoreceptors, bipolar cells, and horizolntal cells of the vertebre and retina.
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pacemaker potentials
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some cells are spontaneously active, generating action potentials without depolarization of another cell. vertebrate cardiac muscle fibers, I.e. depolarization ramps another action potential
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Connexons
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Form channels from postsynaptic cell and presynaptic cll that connect the cytoplasm. Consist of 6 connexins. Exist in electrical synapses
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synaptic vessicles
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store neurotransmitters
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How do chemical synapses work?
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presynaptic neuron releases neurotransmitter molecules in response to an arriving AP. Neurotransmitter is synthesized in presynaptic neuron and stored in synaptic vesicles until release. Neurotransmitter is released by calcium dependent exocytosis-fusion of the synaptic vesicles to the presynaptic membrane. The rleased neurotransmitter molecules bind to treceptor proteins embedded in the postsynamptic membrane. Neurotransmitter receptors are transmembrane proteins that are effectors for change in the postsynaptic cell, usually producing a change in post synaptic membrane potential.
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Ioinotropic receptors
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Work fast to change membrane potentials. Single molecule constitutes both the receptor and athe ion channel. Receptors bind and neurotransmitter they open to allow ion flow.
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Metabotropic receptors
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produce metabolic change in the postsynaptic cell. Slow, long-lasting modulatory effects on synaptic processes.
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What are some advantaged to chemical synapses?
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Amplify current flow, can be excitatory or inhibitory, one-way flow, much more modifiable in their properties.Use makes them stronger, disuse makes them weaker.
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synaptic potential
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transitory, graded change in the resting potential of the membrane of the synapse. Can cause excititory or inhibitory responses.
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spatial summation
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simultaneously occurring EPSPs produced by different nerves
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Neuronal integtration
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neruon's output is not the same as its input, instead an integral function of that input--resulting from spatial and temoral summation of EPSP and IPSPs
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Describe how a neuromuscular junction works
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Each muscle fiber is innervated by only one motor neuron. Functions as relay synap;se: Each action potential in the motor neuron evokes large EPSP in the muscle fiber, which reaches threshold and elicits anaction potential in the muscle. Muscle fiber AP propagates to all parts of muscle fiber, depolarizing its membrane and triggering contraction.
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In a synapse, why do ligand-gated channels open?
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In response to a neurotransmitter rather than in response to depolarization.
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EPSP
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only synaptic, voltage independent, not regenerative, not all-or-none, and not propogated.
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What are the two major differences between neuronal and neuromuscular EPSPs?
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Glutamate is common in CNS rather than ACh and neuromuscular junctions are much larger than neuronal junctions, therefore they release much more neurotransmitter.
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What is the difference between an IPSP and EPSP
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one is inhibiting and one is excititory, EPSP is hyperpolarizing and EPSP is typically depolarizing. IPSP result from CL- ions.
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What is the role of presynaptic depolarization?
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trigger Ca2+ entry
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What is the role of Ca2+ in a synapse?
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Aids in the secretion of the neurotransmitter
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quanta
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packets of neurotransmitters that are released from synapse
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synapsin
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detaches vesicle from cytoskeletin in order to migrate toward lipid bilayer
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dynamin
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promotes reuptake of vesicles
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Dale's principle
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A neuron releases usually only releases one neurotransmitter at all it's synapses, however, few exceptions exist. They do, however, respond to multiple neurotransmitters.
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Five criteria to be a neurotransmitter
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Located at presynaptic terminal, released upon repsynaptic stimulation, mimic the effects of presynaptic stimulation, there should exist a mechanism for removal, effect of drugs.
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What are some broad generalizations about neurotransmitters and their general modes of action?
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Most synapses in the CNS use amino acid neurotransmitters.Biogenic amines are found in relatively few neurons, but these neurons have widely projecting endings (slow).. Peptides are present in substantial minorities and can be co-released.
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How are neurotransmitters terminated?
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reuptake and enzymatic digestion
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ionotropic receptors
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produce effects directly ; neurotransmitter produces effect directly dthrough ligand gated channel; nicotonic
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metabotropic receptor
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initiates metabolic cascade and typically act to increase the concentration of a second messenger.
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synaptic current
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sum of the net ionic currents through all of the activated receptors
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G-protein coupled receptor
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activated membrane proteins called G proteins, Initiate metabolic cascades.
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Presynaptic inhibition
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specific inhibitory interaction in which one axon terminal ends on another axon terminal and causes a decrease in the amount of neurotransmitter that the second terminal releases per action potential. More common than post-synaptic inhibition
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synaptic plasticity
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changes in synaptic strength over time
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Synaptic facilitation
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increase in amplitude of postysynaptic potentials in response to successive presynaptic impulces
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Habituation
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decrease in intensity of a reflex response
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Sensitization
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prolonged enhancement of a reflex response to a stimulus when the stimulus is presented repeatedly
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Long-term potentiation
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long--lasting enhancement of synaptic transmission following intense stimulation -- involves changes in synapse strength. necessary component of learning.
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rhabdomeric photoreceptors
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collections of microvilli that increase the membrane surface area in order to sense vomeronasal organ
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vomeronasal organ
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receptor molecules are located in microvilli on a secondary epithelium
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How are sensory cells replaced?
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The nerve cells stimulates growth and renewal every 3 months or so
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Steroid Hormones
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Synthesized from cholesterol. I.E> AGonads and adrenal cortex secrete steroid hormones
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Peptide or protein hormones
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ADH, insulin, GH
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Amine hormones
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EP, Norepinephrine, and dopamine.
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How are steroid hormone synthesized
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On demand from cholesterol
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