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Chapter 8
Neurons
| Question | Answer |
|---|---|
| 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 |
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mramir06
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