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112 Cards in this Set
- Front
- Back
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What is another name for a leakage channel?
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Non gated channel
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_________ – gated channels respond to a direct change in the membrane potential
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Voltage
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_________ gated channels respond to a specific chemical stimulus
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Ligand
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_________ gated ion channels respond to mechanical vibration or pressure
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Mechanically
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_______________ ______________ __________ is where a neuron is not actively passing an action potential
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resting membrane potential
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What kind of ions are along the inside of a cell membrane and what kind are along the outside?
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Negative is along the inside, Positive along the outside
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What is the potential energy difference at rest for a voltage gated channel?
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-70 mV
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At resting potential what is the extracellular fluid rich with?
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Na+ and Cl-
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What is the name of the intracellular fluid in cell membrane?
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Cytosol
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What is the cytosol filled with?
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K+, organic phosphate, and amino acids
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K+ is _______ more permeable than Na+
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50-100
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The inward flow of ______ can’t keep up with outward flow of _____
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Na+, K+
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What is another name for the Na+/K+ pump?
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bilateral dual pump
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Hyperpolarization
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cell has become more negative
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Depolarization
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membrane has become more positive
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There is a ______ relationship between strength of stimulus and size of voltage change
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direct
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Why do we need a Na+ pump?
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Because we have leakage channels that throw off the equilibrium so the pump brings it back to equilibrium
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Where do graded potentials occur most often?
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dendrites and cell body of a neuron
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The influx of Na+ produces the _________ phase of the action potential
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Depolarization
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What is an action potential?
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Series of rapidly occurring events that change and then restore the membrane potential of a cell to its resting state
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What is an all or none principal?
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with stimulation, either happens one specific way or not at all
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How fast does an all or none principal happen?
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1/1000 of a second
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When K+ rushes out the cell ______
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Repolarizes
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What does propagation mean?
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spreading out
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Which channel has two gates?
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Na+
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Na+ has how many gates? What are/is their/it's name(s)?
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2 activation and inactivation
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Whether the gate is activated or not depends solely on the ________ gate.
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activation
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What is peak voltage?
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+30mV
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Once peak voltage is reached, what happens next?
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K+ gate opens and K+ rushes in causing cell to become more negative
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What is the absolute refractory period?
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in the repolarizing phase 3 this means no other action potential can occur because the inactivation gate is closed
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What is the relative refractory period?
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it is possible for an activation potential to occur but it will require a lot more energy because the K+ channel is still open figure 4
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What is the biggest axon, middle axon, smallest axon?
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Biggest: A
Middle: B Smallest: C |
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Axons _ & _ are myelinated.
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A & B
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What are the Nodes of Ranvier?
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breaks in the mylenation along the axon
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What is continuous conduction?
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where axons that are not mylenated
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What fiber is unmyelinated sensory and autonomic motor
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C
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What fiber is myelinated visceral sensory and autonomic preganglionic
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B
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What fiber is myelinated somatic sensory and motor to skeletal muscle
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A
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Agonist
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anything that not only mimics but enhances a transmitter effects
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Antagonist
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anything that blocks the action of a neurotransmitter
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Competitive antagonist
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gets there faster than what is supposed to go there and sits on the receptor such as CO
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Trigger zone
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area in the axon hillock where the axon tapers off and goes to the cell body
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_____________ & ___________ prevent opening of voltage – gated Na+ channels
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Local anestetics and some neurotransmitters
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What happens when Ca+ goes into the synaptic bulbs?
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it triggers a cascade of events
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Receptors
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structures to which chemical messengers can bind in a lock and key fashion
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Bind
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act of a chemical messenger occupying the binding site of a receptor
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Spatial summation
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1 postsynaptic neuron receiving a message from 2 or more presynaptic neurons
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Temporal summation
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1 postsynaptic neuron receiving a message from 1 presynaptic neuron
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Intensity of impulses can be seen in what two ways?
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frequency and single big blast
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Diverging circuit
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single cell stimulates many others ex: can be found in visual circuitry
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Converging circuit
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one cell stimulated by many others ex: bipolar cells of the eye converging unto ganglion cell
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Oscillatory or Reverberating circuit
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impulses from later cells repeatedly stimulate early cells in the circuit (short – term memory) coordinating muscle activities, waking, sleeping, and breathing
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Parallel after discharge circuit
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single cell stimulates a group of cells that all stimulate a common postsynaptic cell
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Can repairs be made to the CNS?
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yes, extremely slow and minimal repairs
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Repair to the axon of a neuron in the PNS can happen as long as what?
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the damage doesn't reach past the first node
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Chromatolysis
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nissl bodies break up into fine granular masses
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Wallerian degeneration
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degeneration of the distal portion of the axon and myelin sheath
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What factors prevent neurogenesis in CNS?
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inhibition by neuroglial cells, absence of growth stimulating factors, lack of neurolemmas, and rapid formation of scar tissue
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Schwann cell mitosis
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neurolemma on each side of injured axon repairs tube
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What happens about 10-20 days after an injury to a neuron?
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chromatolysis
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What happens about the 3rd to 5th day after an injury to a neuron?
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Wallerian degeneration
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Retrograde degeneration of the proximal portion of the fiber extends only to what portion of the axon?
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the first neurofibral node.
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What are the three ways that neurotransmitters can be removed?
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diffusion, enzymatic degradation, and uptake by nerons or glia cells
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Inhibitory postsynaptic potential results from what?
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Results from the opening of ligand – gated Cl- or K+ channels
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Excitatory postsynaptic potential results from what?
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Results from the opening of ligand – gated Na+ channels
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A depolarizing postsynaptic potential
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Excitatory postsynaptic potential
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What axonal flow moves organelles and materials along surface of microtubules?
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Fast
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What axonal flow transports in either direction?
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Fast
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How many mm per day can a fast axonal flow cover?
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200-400
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Which axonal flow moves in one direction only – away from cell body?
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Slow
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How many mm per day can a slow axonal flow cover?
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1-5
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separates charges and put the like ones on one side together resulting in electrical pressure
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Potential difference
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What type of fluid is on the inside of the membrane?
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Cytosol
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At resting potential of an excitable cell which parts are negative? positive?
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Inner negative, outer positive
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What is nicknamed the second brain?
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Gut
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What are the three types of neurons based on function?
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Sensory neurons (Afferent) pathways, Motor neurons (Efferent), Intermediate/relay/interneuron
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What does somatic refer to?
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body
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Approximately how many neuroglia are there per cell?
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9
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All sensory neurons are _____polar
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uni
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Where is the cell body on a sensory neuron?
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Middle of the axon
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Where is the cell body on a motor neuron?
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At the end
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What kind of neuron is this?
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Purkinje
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What type of neuron is this?
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Pyramidal
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What type of neuron is this?
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sensory
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What kind of neuron is this?
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motor
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What kind of neurons are these?
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BIpolar, unipolar, multipolar
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What maintains the BBB?
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Astrocytes
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What creates scaffolding for the CNS?
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Astrocytes
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What performs repairs, guiding neuron development?
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Astrocytes
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What controls composition of the extracellular fluid?
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Astrocytes
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What conducts the myelination of neurons in the CNS?
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Oligodendrocytes
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What are the specialized immune cells of the CNS?
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Microglia
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What cells line the chambers and passage filled with CSF?
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Ependymal cells
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What cells assist in the circulation of CSF?
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Ependymal cells
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What cells aid in myelination of neurons in the PNS?
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Schwann cells
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How many Schwann cells are needed to myelinate one axon?
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1
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In the CNS what is the white matter composed of?
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myelinated axons
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In the CNS what is the gray matter composed of?
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everything but myelinated axons
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True or False:
In the spinal cord, gray matter is central. |
True
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True or False:
White matter is central in brain |
True
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Enteric plexuses help regulate what body system?
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digestive
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What receptors monitor changes in the internal or external environment.
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sensory
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What is the function of sensory neurons?
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to sense changes in the internal and external environment through sensory receptors
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What is the function of interneurons?
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to analyze the sensory information, store some aspects, and make decisions regarding appropriate behaviors.
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What is the function of motor neurons?
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to respond to stimuli by initiating action
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What is the most common glia cell type?
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Neuroglia
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What does the sympathetic division of the autonomic nervous system do?
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speeds up heart rate
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What does the parasympathetic division of the autonomic nervous system do?
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slows down heart rate
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How far can graded potentials and action potentials travel?
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graded: local membranes, action: long distances
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Where do graded potentials occur most often?
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dendrites and cell body
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step-by-step depolarization of each portion of the length of the axolemma
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continuous conduction (unmeylenated)
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depolarization only at nodes of Ranvier where there is a high density of voltage-gated ion channels
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saltatory conduction
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