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150 Cards in this Set
- Front
- Back
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Extracellular Fluid
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Watery, internal environment of multicellular organisms, surrounds cells, stable composition
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Intracellular Fluid
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Fluid Within Cells
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Pseudounipolar Neurons
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Sensory Neuron- Small. short dendrites, long axon. During development dendrite fused with axon. Myelinated.
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Bipolar Neurons
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Sensory Neuron- Have two relatively equal fibers extending off central cell body. Dendrites covalescing into one long dendrite before cell body.
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Anaxonic Neuron
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Interneuron- short axons and dendrites which are indistinguishable. In the brain.
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Multipolar Neuron (Interneuron)
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High branched but lack long extensions. Receive lots of info.
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Mulitpolar Neuron (Efferent/Effector)
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Myelinated, motor neuron, several dendrites and branched axon.
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Oligodendrocyte
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Equivalent to Schwann cells but in CNS, support and insulate axon, one forms myelin around portions of several axons
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Astrocyte
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highly branched, 50% cells in brain, communicate with neurons and modify chem. signals, hold neurons in place, get nutrients for neurons, digest parts of dead neurons
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Microglia
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Specialized immune cells in CNS, remove damaged cells and invaders
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Ependymal
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create selectively permeable epitheal layer which separates fluid compartments of the CNS, source of neural stem cells
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Membrane Potential
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-60mv
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Hyperpolarization
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Negative Shift Vm
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Depolarization
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Positive Shift Vm
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Cell Membrane
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Act as capacitor (insulator between two conductors)
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ICF K+ (mm)
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125
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ICF Na+
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12
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ICF Cl-
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10
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ICF Ca2+
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0.0002
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ICF A-
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130
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ECF K+
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5
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ECF Na+
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120
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ECF Cl-
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125
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ECF Ca2+
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2
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ECF A-
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low
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Resting Permeability K+
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high
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Resting Permeability Na+
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low
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Resting Permeability Cl-
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very low
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Resting Permeability Ca2+
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ultra low
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Resting Permeability A-
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none
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Equilibrium Potential
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Vm where movement of ion down it's concentration gradient is balanced by opposing electrical potential force
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Maintaining Vm
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K+ permeable and leaves cell, draws A- to membrane (but A- cannot cross), A- pulls K+ back and stops at equilibrium, no net movement
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NernstEquation
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Calculating Equilibrium Potential
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Vion K+
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-90mV
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Vion Na+
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60mV
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Vion Cl-
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-70mV
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Vion Ca2+
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120mV
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Vm with no channels open?
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0mV
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Na+/K+ ATPase
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maintains gradient, does not contribute directly to resting potential
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Goldman Equation
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Calculating Vm
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RT/F at 37degrees
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26.73
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Perm.K
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1
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Perm.Na
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1/15
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Perm. Cl
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1/100
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Action Potential
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Rapid Change in Vm due to coordinate action of certain voltage gated channels, not graded, all or nothing event, code info and trigger movement of glands
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Large Stimulus (AP)
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More APs
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AP Duration Neuron
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1-5ms
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AP Duration Heart
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300-400ms
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AP Threshold
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-55mV
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Voltage Sensor
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transmembrane amino acids, sensitive to Vm
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At rest, voltage gated Na+channel
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Activation gate closed
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Activation- deploarization
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Activation gate open, Na+ enters down concentration and electrical gradients
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Inactivation
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Na+ inactivation gate closes, despite depolarization
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Recovery
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Returns to rest, activation gate closes and inactivation gate opens, takes time
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K+ Resting
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Gate Closed
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Activation K+
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Delayed, depol from Na+ entry opens gate, K+ leaves down concentration gradient, Vm goes towards VionK
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De-activation K+
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Chan closes to rest. Turns itself off over time.
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TTX and procaine
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Block Na+ channels, no Action Potential
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Absolute Refractory Period
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Absolutely no AP, Na+ gates inactivated
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Relative Refractory Period
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strong stimulus, smaller APs, some channels recovered
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Hillock
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APs are initiated here, highest Na+ channel density
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AP Propagation
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One way due to refractory period, APs regenerated along axon, no decrement or distortion
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Local Current
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wave of electric current that spreads throughout the cytoplasm
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Large Diameter Axons
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Propagate APs fast, low internal resistance to local current
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Node of Ranvier
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Bare axon, high density of Na+ channels
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Myelinated Axon
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Fast propagation
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Saltatory Conduction
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AP at each node of ranvier, large local current spreads rapidly, myelin insulates current leap
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Synapse
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where electrical signals are transferred from one cell to another
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At synapse, presynaptic APs cause
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Ca2+ rushes into presynaptic terminal, Ca2+ dependant transmitter exocytosis
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Short Synaptic Delay
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Release takes 100-200us
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Presynaptic Terminal, Ca2+
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Binds fusion proteins
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Synaptotagmin
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Ca2+ sensor
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SNARE complex
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Docks vesicle at membrane, nce Ca2+ binds, rearranges to promote fusion
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Termination of Transmitter action
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Uptake by terminal of glia, enzymatic breakdown, diffusion from cleft (into bloodstream or elsewhere)
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Postsynaptic Potentials (PSPs)
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Fast transmittance for daily NS function, mediated by low molecular weight neurotransmitters, response of Vm to ligand-gated channels, graded
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Glutamate
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Na+ in and K+ out, depolarizes (excite)
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Acetylcholine
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Na+ in and K+ out, depolarizes (excite)
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Glycine
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Cl-in, hyperpolarizes (inhibit)
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GABA
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Cl-in, hyperpolarizes (inhibit)
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ACH, Glu, Glyc, GABA
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Recycled and repackaged at the terminal. Enables rapid signalling.
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Chemical Identity
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One primary fast transmitter per neuron, many neurons may have secondary transmitters (co-transmitters)
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Spatial Summation
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integration of inputs from multiple synapses at different locations
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Temporal Summation
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integration of more thanone input from a single synapse over time
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Slow chemical synaptic transmission
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metabotropic/g-protein coupled receptors
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Slow transmission, postsynaptic
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slow but amplified and prolonged response
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Slow transmission, neurotransmitter
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1st messenger, binds to mR
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metabotropic receptor
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interacts with G-protein
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G-protein
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binds GTP and links receptor to effector
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membrane bound enzymes
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effectors
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membrane bound enzymes/effectors
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convert substrate to 2nd messenger
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Adenylate Cyclase
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converts ATP to cAMP
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cAMP
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turns on PKA, opens and closes membrane channels
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PKA
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phosphorylates proteins, turns on and off genes
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Phospholipase C
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converts PIP2 to IP3 and DG
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DG
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turns on PKC
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PKC
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phosphorylates proteins
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IP3
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Turns on smooth ER, lease of Ca2+ into cytosol, turns on calmodulin, Ca2+ opens and closes channels and turns on and off genes
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Effector: Channels + Metabotropic Receptors
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-sometimes G-protein can directly open or close channel, only receptor operated channels, slower than ionotropic Rs
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Fast Transmitter
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made at axon terminal
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Neuro-peptides
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made in soma, sent to terminal
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GABA, Glycine, Glutamate,ACH, ATP, serotonin
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iono and meta receptors
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Peptides, dopamine, norepinephrine, epinephrine and histamine
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only meta receptors
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Gap Junction
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cells connected by non-selective channel, current of solutes pass directly cell-to-cell
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Gap Junction high conductane
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mass pass solutes of 1kD of less
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6 connexin proteins from each neuron
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1 connexon
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many connexons
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gap junction
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Sympathetic
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fight or flight
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Parasympathetic
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rest and digest
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Hypothalamus, Pons, Medulla
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Autonomic control centre
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Brain Stem, Spinal cord, autonomic ganglia
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ANS proper
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targets, effectors ANS
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smooth and cardiac muscle, glands
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2 neurons synapse at
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autonomic ganglia
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No postgang neurons, sympathetic input to
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adrenal glands
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sympathetic input to adrenal glands
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epinephrine secretion into bloodstream
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sympathetic CNS origin of preganglionic cells
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thoracic and lumbar spinal cord
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sympathetic ganglia
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in chain close to SC
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parasympathetic CNS origin of pregang
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brainstem of sacral spinal cord
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parasympathetic ganglia
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in or near targets
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Preganglion sympathetic and parasympathetic neurotransmitter
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Acetylcholine
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preganglionic ACH receptors
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nicotinic receptors
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nicotinic receptors
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ionotropic receptors
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sympathetic postganglionic neurotransmitter
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norepinephrine
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parasympathetic postganglionic transmitter
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achetylcholine
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parasympathetic postganglionic ACH receptor
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muscarinic receptors
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sympathetic postganglionic norepinephrine receptor
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adrenergic receptor
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adrengergic receptor
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metabotropic receptors
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muscarinic receptor
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metabotropic receptors
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Preganglionic Transmission
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fast transmission, drives APs in postganglionic neurons, ionotropic receptors, EPSP
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Postganglionic Transmission
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slow transmission to muscle/glands, changes biochemistry of Vm of target cells
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Adrenergic mRs
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Alpha 1 and 2, beta 1, 2 and 3
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Muscarinic mRs
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m1, 3, 5 and m2 and 4
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a1 Rs
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Increase IP3 and DG
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a2 Rs
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decrease cAMP
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b1, b2, b3
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increase cAMP
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m1,3 and 5
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increase IP3 and DG
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m2 and 4
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decrease cAMP
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Sympathetic Heart Response
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increases rate/concentration
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Sym. Arteriole Control
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constricts
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Sym. Lung control
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dilate bronchioles
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Sym. adrenal glands control
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secrete epinephrine
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Para heart control
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decrease rate
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Para arteriole control
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not innervated
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Para lung control
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constrict bronchioles
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Para adrenal gland control
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not innervated
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Symp. Heart Control
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NorE-beta Rs-Adenylate cyclase, increases cAMP, PKA, Ca2+ chanels and Ca2+ release
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Para. Heart Control
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ACH-m2Rs- turn on adenylate cyclase, g-protein inhibits AC, decrease cAMP, PKA, etc
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Phosphodiesterase converts cAMP back to AMP (to be turned back to ATP)
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caffeine stops it.
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Sym. Control of Airway Smooth Muscle
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NE-beta Rs-cAMP-turns on PKA, turns off myosin light chain kinase, muscle relaxes
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Para Control of Airway Smooth Muscle
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ACH turns on:
1) Dg-PKC on-turns on calponin-muscle contracts 2)IP3-Ca2+ release from smooth ER-calmodulin on-turns on myosin light chain kinase-muscle contracts |
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Homeostasis
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Dynamic Balance between Sym. and Para
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