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Phys Lect 8
Question | Answer |
---|---|
Why is synaptic transmission vital in the body? | B/c cells need to be able to communicate with eachother via recieving input, integrating that input, and sending output to other cells (effectors or regulators). |
Electrical synapses | are created through gap junctions (intercalated discs in the heart) and allow signal/current propogation from one cell to the next directly |
What Proteins make up gap juncitons | 6 Connexins make up a Connexon. These Connexons are permeable to ions and conduct the electrical current b/w the 2 cells. |
Cell types that have electrical synapses (gap junctions) | 1.Neurons. 2.Myocardia. 3.Smooth Muscle. |
Why are electrical synapses important in Myocardia? | They allow appropriate ventricular sync so they beat together and pump BL effectively |
What causes connexons to close? | 1.Decreased pH. 2.Increased Ca2+. |
Explain the mechanism acting on connexons during Ischemia | With a lack of Oxygen to the myocardia, CO2 and lactic acid will build up in the tissue, causing the connexons to close which terminates the electrical synapse. As result the heart beats out of sync. |
How is a neurotransmitter released in the chemical synapse? | As the signal/ion current reaches the terminal bouton, it activates voltage-gated Ca channels which stimulate the release of the neurotransmitter into the synaptic cleft. |
What ion is responsible for the fusion and release of neurotransmitter from the presynaptic cell into the synaptic cleft? | Ca2+ |
2 ways Neurotransmitter is removed from the synaptic cleft | 1.Enzymatic degradation. 2.Re-uptake into the pre-synaptic cell **This Terminates chemical transmission. |
What determines the effects generated in the post-synaptic cell of a chemical synapse? | 1.Type of Neurotransmitter. 1.Receptor type. |
3 ways drugs can affect chemical synapses? | 1.Inhibit re-uptake of neurotransmitter (generates greater response). 2.Inhibit enzymatic degredation of neurotransmitter (generates greater response). 3.Inhibit the post-synap receptors (prevents a response) |
Postsynaptic Ionotropic Receptors | FAST response. Ligand gated ion channels. Ex: Nicotinc receptors in skeletal muscle. |
Postsynaptic Metabotropic Receptors | SLOW response. G-protein/2ndary messager receptors. Ex: Muscarinic receptors in the heart. Regulates HR |
Inhibitory Neurotransmitters | 1.GABA (Brain). 2.Glycine (Spinal cord). **Cause an efflux of K+ or influx of Cl- which make the Em more negative (farther away from the threshold). |
ANS neurotransmitters | 1.Norepi. 2.Epi. 3.NO. 4.ACh. |
3 Neurotransmitters found in the brain | 1.Dopamine. 2.Histamine. 3.Serotonin |