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Chapter 8

Neurons

QuestionAnswer
Schwann cells wrap around.. axon and form insulating myelin sheaths
Nodes of Ranvier are.. gaps in insulation
Satellite cells form... supportive capsules in a ganglion (pl. ganglia)
Gap junctions are between... and help... Schwann cells and help them communicate
Oligodendrocytes form... myelin sheath
what takes up and releases chemicals, feed neurons, water-K+ balance, and part of blood-brain-barrier? Astrocytes
What in the central nervous system provides immune defense? Microglia
Ependymal cell are a source of stem cells
True or False: When an axon is cut, the section attached to the cell body continues to live. True
True or false: the nervous system consist of the brain and spinal cord. True
What 2 systems are involved in the peripheral nervous system? Somatic and autonomic nervous systems
True or False: Sensory division of the PNS takes information from the CNS to target cells via efferent neurons. False
True or False: Efferent division of the PNS sends information to the CNS through afferent neurons. False
Synapse: the region where an axon terminal communicates with its postsynaptic target cell.
Pseudounipolar neurons have.... During development... a single process called the axon. the dendrite fused with the axon
Bipolar neurons have.. two relatively equal fibers extending off the central cell body.
Anaxonic CNS interneurons have no... apparent axons
Multipolar CNS interneurons are highly... branched but lack long extensions
Resisting membrane potential determines primarily by.. K+ concentration gradient Cell's resisting permeability to K+, Na+, and Cl-
graded potential use what kind or signal Imput signal
the types of gated ion channels involved in graded potential are.... Mechanically, chemically, or voltage-gated channels
Graded potential occurs where ? usually dendrites and cell body
Na+, K+, and Ca2+ are usually involved in what potential ? Graded
what type of signals are involved in graded potential? depolarizing or hyperpolarizing
True or false: the strength of signal in graded potentially depends on initial stimulus; can be summed True
what initiates the signal in graded potential? entry of ions through gated channels
no minimum level requires to initiate 2 signals coming close together in time will sum Initial stimulus strength is indicated by frequency of a seris of action potential are all unique characteristics that describe which potential graded
true or false: the refractory period prevents backward conduction true
what signal does action potential have? regenerating conduction signal
action potential occurs when... trigger zone through axon
what type of channels are involved in action potential? voltage-gated channels
Na+ and K= are involved in what potential? action potential
True or false: Depolarizing is the type of signal involved in action potential. false
True or false: in action potential the strength of a signal depends on initial stimulus; cannon be summed False All or none phenomenon
what initiates the signal in action potential? Above threshold graded potential at the trigger zone opens ions channels.
Speed of action potential in neuron is influence by: diameter of axon: the larger the axon the faster resistance of an axon membrane to ion leakage out of the cell: Myelinated axons are faster. Saltatory conduction between nodes of Ranvier
Threshold stimulus require to initiate Refractory period: 2 signals too close together in time cannot sum there are unique characteristics that belong to what potential Action
graded potentials lose strength as they move through the cell due to: current leak and cytoplasmic resistance
True or false: if strong enough, action potentials reach the trigger zone in the axon hillock and initial segment. False: graded potential
Cell's excitability is the ability to: fire an action potential
Conduction is...(definition) the high-speed movement of a action potential along an axon
what is the resting membrane potential of a neuron? -70mV
True or false: during the rising phase, voltage-gated Na+ and K+ channels open True
Rapid Na+ entry does what to the cell? depolarizes
True or false: when at peak during action potential K= channels close and slower Na+ channels open. False: Na+ channels close and slower K+ channels open
True or false: Potential delay of 1-2 msec between action potentials independent of intensity of trigger True
True or False: Absolute refractory period is due to K+ gates resetting False: Na+
What follows the refractory period? relative refractory period
Electrical synapses pass electrical signals... through gap junctions
Chemical synapses use ________________________ that cross synaptic clefts. neurotransmitters
Neurotransmitters and neuromodulators act at______________ ___________________. short distances
Neurotransmitter are ________ acting. fast
Neuromodulators are ________ acting. slow
Neurohormones act _________ distance. long
Receptor-channels also known as ______________ receptors. ionotropic
True or False: all neurotransmitters bind to specific receptors True
What does the Kiss-and run pathway consist of? vesicles fuse with membrane at the fusion pore neurotransmitters pass through a channel vesicles pull back from fusion pore
In a __________ pathway, one presynaptic neuron branches to affect a larger umber of postsynaptic neurons. divergent
Ina ____________ pathway, many presynaptic neurons provide input to influence a smaller number of postsynaptic neurons. convergent
The cell body of a ___________ motor neuron is nearly covered with synapses providing input from other neurons somatic
Created by: mramir06