Group+1+NS

2.Imagine the case of a boat with a small leak below the water line. In order to keep the boat afloat, the small amount of water entering through the leak has to be pumped out, which maintains a lower water level relative to the open sea. Neurons do the same thing, but they pump out positively charged sodium ions. In addition, they pump in positively charged potassium ions (potash to the gardeners out there!!) Thus there is a high concentration of sodium ions present outside the neuron, and a high concentration of potassium ions inside. The neuronal membrane also contains specialised proteins called channels, which form pores in the membrane that are selectively permeable to particular ions. Thus sodium channels allow sodium ions through the membrane while potassium channels allow potassium ions through. OK, so far so good. Now, under resting conditions, the potassium channel is more permeable to potassium ions than the sodium channel is to sodium ions. So there is a slow //outward// leak of potassium ions that is larger than the //inward// leak of sodium ions. This means that the membrane has a charge on the inside face that is negative relative to the outside, as more positively charged ions flow out of the neuron than flow in. This difference in the concentrations of ions on either side of the membrane gives rise to the membrane potential and the membrane is said to be polarised. >
 * A **__Neuron__**is a nerve cell and the basic structure of the nervous system. What are the parts of a neuron and what do they do? (GIVE SEVERAL NOT JUST 3 - but what are the 3 most important parts for this class? Highlight them for sure) 1. Neurons conduct electrical impulses by using the Action Potential . This phenomenon is generated through the flow of positively charged ions across the neuronal membrane.
 * What are neurotransmitters / What do they do?
 * **Neurotransmitters** are the chemicals which allow the transmission of signals from one neuron to the next across synapses. They are also found at the axon endings of motor neurons, where they stimulate the muscle fibers. And they and their close relatives are produced by some glands such as the pituitary and the adrenal glands. In this chapter, we will review some of the most significant neurotransmitters.
 * NEUROTRANSMITTERS are the brain chemicals that communicate information throughout our brain and body. They relay signals between nerve cells, called “neurons.” The brain uses neurotransmitters to tell your heart to beat, your lungs to breathe, and your stomach to digest. They can also affect mood, sleep, concentration, weight, and can cause adverse symptoms when they are out of balance. Neurotransmitter levels can be depleted many ways. As a matter of fact, it is estimated that 86% of Americans have suboptimal neurotransmitter levels. Stress, poor diet, neurotoxins, genetic predisposition, drug (prescription and recreational), alcohol and caffeine usage can cause these levels to be out of optimal range.


 * **__ Nerves __** are bundles of axons or dendrites bound together by connective tissue. They are composed of several neurons. There are three main types (check you text book) of neurons. What are they and how are they different from each other?
 * Motor nereves are nerves that carries impluses from the central nevous system which triggers muscules to contract.
 * Sensory neurons respond to tactile stimuli and can activate motor neurons in order to achieve muscle contraction.
 * Automic
 * Automic


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