We went into more detail about the action potential of a neuron in this class. There are chemically regulated and voltage regulated ion channels. chemically regulated channels open with the binding of a chemical NT. This allows a controlled number of ions to influx. Whereas voltage regulated channels are activated at a certain depolarizing voltage and allows a massive influx of ions. this massive influx creates a positive feedback system opening more VR channels.
When the positive charge reaches the synaptic bulb calcium channels open and push the synaptic vesicles to the membrane where they are released into the synaptic cleft. the amount of NT released into the SC depends on the amount of calcium in the ECF, which is regulated by astrocytes. There are many factors that determine if a neuron reaches action potential. The total excitatory effects must be greater than the inhibitory effects to a degree that the neuron is able to reach its threshold (Spacial summation). The neuron could also be stimulated by rapid and frequent release of NT (temporal summation).
Schwan cells are also important to the speed of the conduction. They wrap around the axons of the neurons in the PNS. One schwan cell around one axon and and there are multiple schwan cells that wrap around the neuron. Schwan cells insulate the axon creating a fast signal conduction. When an axon becomes damaged in the PNS the schwan cells go through mitosis extending the axon so it can repair its connection. The neuron cells of the CNS are wrapped by oligodendrocytes. one oligodendrocyte wraps many CNS neurons. because of this the neurons of the CNS are not able to repair axons when they are damaged.
I can see how carpal tunnel syndrome occurs. the nerves to the hand become damaged or inflamed from the repetitive movements and you start to lose feeling, movement or strength. that's why the brace helps. it gives your nerves time to heal without further damage. but I' not sure how the stretches would help.
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Val,
ReplyDeleteNice job on both of these blogs! You are twenty points richer! The stretching is probably more about the immune system and inflammation than about the nervous system. The stretching would aid the movement of fluid from the ECF of the damaged cells into the lymphatic system. This would reduce the overall inflammation,i.e, swelling and the pain.
I'm pretty sure we all know someone who has Carpal Tunnel Syndrome (CTS). It seems to be a pretty common ailment to those who have worked office jobs with a high demand on repetitive movements. My former boss had carpal tunnel syndrome, which she had surgery to repair. My sister is a massage therapist and I asked her how the stretches would help CTS. She said that stretches are more of a preventative method rather than a way to repair already damaged muscles. She said the way CTS works is when you perform repetitive hand movements (such as computer typing) over a long period of time, the flexor muscles in your wrist become irritated and apply pressure to the nerves, causing pain. Massaging the flexor muscles and performing stretches can prevent the muscles from becoming irritated and becoming too tight. Once CTS is at a severe stage, surgery seems to be the only realistic option, whereas massages would be used before the pain becomes too severe.
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