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35 terms

Chapter 11 - Synapse & Neurotransmitters

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Synapse
A junction that mediates information transfer from one neuron to the next or from a neuron to an effector cell
Axodendritic Synapses
Synapses between the axon endings of one neuron and the dendrites of other neurons
Axosomatic Synapses
Synapses between axon endings of one neuron and cell bodies of other neurons
Presynaptic Neuron
The neuron conducting impulses toward the synapse
Postsynaptic Neuron
The neuron transmitting the electrical signal away from the synapse
Electrical Synapses
A less common variety of synapse, it consists of gap junctions like those found between certain other body cells. They contain protein channels, called connexons, that intimately connect the cytoplasm of adjacent neurons and allow ions and small molecules to flow directly from one neuron to the next.
Chemical Synapses
Synapses that are specialized for release and reception of chemical neurotranmitters. Made up of two parts: axon terminal and a receptor region
Synaptic Cleft
A fluid filled space approximately 30-50nm wide
Synaptic Delay
A delay that lasts 0.3-5.0 ms, making transmission across the chemical synapse the rate limiting step of neural transmission.
Excitatory Synapse
Synapses where the neurotransmitter binding causes depolarization of the postsynaptic membrane
Inhibitory Synapse
A synapse that reduces a postsynaptic neuron's ability to generate an AP.
Temporal Summation
A summation that occurs when one or more presynaptic neurons transmit impulses in rapid fire order and burst of neurotransmitter are released in quick succession
Spatial Summation
A summation that occurs when the postsynaptic neuron is stimulated at the same time by a large number of terminals from the same or more commonly, different neurons
Synaptic Potentiation
Repeated or continuous use of a synapse enhances the presynaptic neuron's ability to excite the postsynaptic neuron, producing larger than expected postsynaptic potentials
Presynaptic Inhibition
It occurs when the release of excitatory neurotransmitter by one neuron is inhibited by the activity of another neuron via an axoanxonic synapse
acetylcholine, biogenic amines, amino acids, peptides, purines, gases and lipids
What are the classes of a neurotransmitter?
Acetylcholine
Found at all neuromuscular junction with skeletal muscle; widespread throughout the cerebral cortex, hippocampus and brain stem
Biogenic Amine
A neurotransmitter broadly distributed in the brain, where they play a role in emotional behavior and help regulate the biological clock
Neuropeptides
Strings of amino acids that act as a neurotransmitter. Inhibits pain by inhibiting substance P.
Purines
ATP recognized as a major neurotransmitter in both the CNS and PNS. Produces a fast excitatory response at certain receptors.
Gases and Lipids
Nitric oxide and carbon monoxide, neurotransmitters that are synthesized. Can be used to stimulate the synthesis of cyclic GMP.
Neuromodulator
A term used to describe a chemical messenger released by a neuron that does not directly cause EPSPs or IPSPs but instead affects the strength of synaptic transmission
Channel Linked Receptors
Ligand gated channels that mediate direct transmitter action.As the ligand binds to one receptor subunits, the protein change shape. Channel opens, membrane potential changes.
G Protein Linked Receptors
Activity is indirect, complex, slow and often prolonged- ideas a s a basis for some types of learning. Control the production of cAMP, cGMP, diacyglycerol, Ca2+.
Neural Integration
Neuronal pools and their patterns of communicating with other parts of the nervous system
Neuronal pools
Billions of neurons in the CNS are organized into this. It is a functional group of neurons that integrate incoming information received from receptors or different things and then forward the process information to other destinations
Circuit
The patterns of synaptic connections in neuronal pools, determine the pool's functional capabilities
Diverging CIrcuits
One incoming fiber triggers response in ever increasing number os neurons farther and farther along in the circuit. Amplifying circuits.
Converging Circuits
the Pool receives inputs from several presynaptic neurons, and the circuit has funneling, or concentrating, effect.
REverberating (oscillating) Circuits
Incoming signal travels through a chain of neurons, each of which makes collateral synapses with neurons in a pervious part of the pathway
Parallel after discharge circuits
Incoming fiber stimulates several neurons arranged in parallel arrays that eventually stimulate a common output cell
Serial Processing
The whole system works in a predictable or or nothing manner. One neuron stimulates the next, which stimulates the next, and so on, eventually causing a specific anticipated response.
Reflexes
Rapid, automatic responses to stimuli, in which a particular stimulus always causes the same response
Reflex arc
Neural pathways over which reflexes occur. the 5 essential components are: receptor, sensory neuron, CNS integration center, motor neuron, and effector
Parallel Processing
Inputs that are segregated into many pathways and information delivered by each pathway is dealt with simultaneously by different parts of the neural circuitry