BIOL 1F25 Lecture Notes - Central Nervous System, Axon Terminal, Dendrite

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carminecrocodile64

19 May 2013

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Axon: main conducting unit of cell (output region); conducts action potentials. Firing pattern (i. e. slow spikes vs. fast bursts) A connection between two nerve cells or the nerve cell and a target cell (e. g. gland or muscle) Distinct gap between two brain cells; ~20 nm across; gap called synaptic cleft. Synaptic vesicles in axon terminal contain chemicals, used as a message at the synapse; called neurotransmitters. A specialized morphological structure between two synaptic partner cells. Development of the central nervous system (cns) of mammals: ~10,000 synapses formed in as short a time as 15 minutes. During development it is essential that the growing axons of neurons find their way to the correct region of the brain. Once there, they need to identify and connect with the correct targets. During development, growing end of axon called a growth cone; path finding and selecting target cells. Studied mainly in cultured neurons (grown in a dish)

Related Questions

The junction specialized for the transmission between a neuron and another cell is called a (1) _____ ______. Usually, the signal being sent to the receiving cell is carried by chemical messengers called (2) _____. (3) _____ is an example of this type of chemical messenger, which diffuses across the synaptic cleft, combines with protein receptor molecules on the muscle cell membrane, and soon thereafter is rapidly broken down by enzymes. At an (4) ____ synapse, the membrane potential is driven toward the threshold value and increases the likelihood that depolarization and an action potential will occur. At an (5) ____ synapse, the membrane potential is driven away form the threshold value, and the receiving neuron becomes hyperpolarized and is less likely to achieve an action potential. A specific transmitter substance can have either excitatory or inhibitory effects depending on which type of protein channel it opens up in the (6) ____ membrane. (7) ____ are neuromodulators that inhibit perceptions of pain and may have roles in memory and learning, emotional states, temperature regulation, and sexual behavior. (8) ____ ________ at the cellular level is the moment-by-moment tallying of all excitatory and inhibitory signals acting on a neuron. Incoming information is (9) ____ by the cell bodies, and the charge differences across the membranes are either enhanced or inhibited. Some narrow-diameter neurons are wrapped in lipid-rich (10) _______ produced by specialized neuroglial called Schwann cells; each of these is separated from the next by a(n) (11) ________ ________ - a small gap where the axon is exposed to extracellular fluid. A (12) ____ is an involuntary sequence of events elicited by a stimulus. During a (13) _______ ________, a muscle contracts involuntary whenever conditions cause a stretch in length; many of these help you maintain an upright posture despite small shifts in balance. Imbalances can occur at chemical synapses; a neurotoxin produced by Clostridium tetani blocks the release of GABA and glycine, thus freeing the motor neurons from (14) _____ control, which may cause tetanus â a prolonged, spastic paralysis that can lead to death. A. Excitatory H. Stretch reflex B. Inhibitory I. Summed C. Myelin J. Neurotransmitters D. Chemical synapse K. Postsynaptic E. Synaptic integration L. Endorphins F. Exposed node M. Acetylcholine (ACh)

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BIOL 1F25 Lecture Notes - Central Nervous System, Axon Terminal, Dendrite

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