Plates slid past each other
A Nerve electrical impulse only travels in one direction. There are several reasons nerve impulses only travel in one direction. The most important is synaptic transport.
In order for a "nerve impulse" to pass from cell to cell, it must cross synaptic junctions. The nerve cells are lined up head to tail all the way down a nerve track, and are not connected, but have tiny gaps between them and the next cell. These tiny gaps are called synapses.
When you get a nerve firing, you have probably heard that it is an electrical impulse that carries the signal. This is true, but it is not electrical in the same way your wall outlet works. This is electrochemical energy. Neurotransmitters are molecules that fit like a lock and key into a specific receptor. The receptor is located on the next cell in the line. When the neurotransmitter hits the receptor on the next cell in line, it signals that cell to begin a firing as well.
This will continue all the way down the length of the nerve track. In a nutshell, a nerve firing results in a chain reaction down the nerve cell's axon, or stemlike section. Sodium (Na+) ions flow in, potassium (K+) ions flow out, and we get an electrochemical gradient flowing down the length of the cell. You can think of it as a line of gunpowder that someone lit, with the flame traveling down the length of it. Common electrical power is more like a hose full of water, and when you put pressure on one end, the water shoots out the other.
Therefore, nerve impulses cannot travel in the opposite direction, because nerve cells only have neurotransmitter storage vesicles going one way, and receptors in one place.
The four characteristics of a mineral are:
1. Cleavage- the way it breaks, whether flat or roughly.
2. Luster- the way light reflects off of it, i.e. pearly, shiny, etc.
3. Streak- the color that its powder is
4. Hardness, for example, diamond is the hardest mineral, this is usually measured on the Mohs scale.
We use samples to perform experiments. When sampling, we take test subjects from a larger group often known as "<em>population</em>" or at times "<em>universe</em>".
Sampling is a term we use to describe the process of selecting a small representitive group from a larger population. Sampling can often be divided in its simplest form into:
- <u>Random Samples</u>
- <u>Non-Random Samples.</u>
Which as their names imply, represent first a sample that is chosen by not specific method and whose probability is equal for the entire <em>population</em>, and secondly a sample chosen based on specific parameters.
Sampling can then become more complex, being divided into more complex methods such as:
- <u>Systematic sampling
</u>
- <u>Stratified sampling
</u>
- <u>Cluster sampling</u>
etc.
The one thing all of the sampling methods have in common is the fact that they will all draw their samples from one place. This place or aspect from which samples are drawn is known as the <em>population</em> <em>group </em>or sometimes coined as the <em>universe</em>, to represent the group in its entirety.
To learn more visit:
brainly.com/question/350477?referrer=searchResults
