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9 Cards in this Set
- Front
- Back
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The synapse is.....
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a specialized region of contact between two or more cells, at which a message is transmitted from one cell to the next.
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Two kinds of synapses
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1. Electrical Synapses
2. Chemical Synapses. |
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1. Electrical Synapses
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Synaptic transmission occurs as a result of the intercellular flow of current (electrical coupling, electrical synapses, or electrotonic transmission).
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Chemical Synapses.
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Synaptic transmission is chemically mediated (as between most neurons or between neurons and muscle cells).
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gap junctions
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Specialized structures that allow electrical current to pass directly between neighboring cells.
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Gap junction channels can close in response to:(3)
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a. high intracellular [Ca +
] in one of the coupled cells; b. high intracellular [H ] in one of the coupled cells (i.e., low intracellular pH); c. depolarization of one of the cells |
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Characteristics of transmission at electrical synapses
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1. Transmission can be bi-directional
2. Faster transmission 3. High degree of certainty that an impulse in the presynaptic cell will give rise to another in the postsynaptic cell. Vital for propagation of the cardiac action potential in heart 4. They allow large numbers of (small) cardiac and smooth muscle cells to contract synchronously. 5. Gap junctions may allow neighboring cells to interact metabolically. The large size of gap junction channel allows ATP, NADH, and IP3 to pass from one cell to its neighbor. |
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4 processes of chemical synaptic transmission
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1. Release of a chemical transmitter from the presynaptic nerve terminal.
2. Diffusion of the transmitter to the postsynaptic membrane. 3. Binding of the transmitter to the postsynaptic receptor and response 4. Inactivation or removal of the transmitter. |
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what are the 2 types of chemical synapse ?
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1. excitatory (increase the probability of action potentials in the postsynaptic cell)
2. inhibitory (reduce the probability of postsynaptic APs). |
