BIOLOGY, SUMMER SCHOOL, DAY 6

The following post contains a link to the latest set of Cornell Notes in Mr. Hatfield's classes.  These include the structure and function of the neuron, the type of cell that makes up most of the tissues in the nervous system.

Here are the notes on neuron structure and function.    Today's class built on yesterday's notes on cells and their organelles. 

The morning session focused on cell membrane structure and function, with special attention to how the neuron uses its membrane to create a difference in electrical potential, which becomes the basis of the nerve impulse.   At the end of class, students were shown a 20-minute video which describes some of the events that take place in the development of a human infant's brain.   A worksheet based on this video was distributed in class.

Here is that video, broken into a pair of segments:





Students who are interested in watching other videos in this series can find them on the following YouTube channel: 

https://www.youtube.com/user/flixwest?feature=watch



And, just in case you lose the worksheet given in class, a PDF file copy is available HERE.


Students: The ACTION POTENTIAL, covered on pages 898-900 of your text, is one of the more challenging topics in the course, but a very effective way of illustrating aspects of cell membrane function.

To assist with your understanding for Wednesday's class, here is a video, shown in class, that summarizes the events in a single action potential:




Notice that the resting potential is negative (-70mv) while the action potential is positive (+40mv).

Notice that the change in potential is generated by the motion of positively-charged sodium (Na+) and potassium (K+) ions across the axon membrane.

Before the nerve fires, sodium is in high concentration OUTSIDE the axon membrane, while potassium is in high concentration WITHIN the membrane.  In the video, the sodium channel is shown in green while the potassium channel is shown in blue.   There are also 'leak' channels shown in purple.

The graph shown in the video is commonly used in college-level courses to convey a great deal of information about the various stages of the action potential (resting potential, depolarization, repolarization, hyperpolarization, etc.) and uses significant vocabulary and concepts not found in your text.   You will not be responsible for knowing the graph, but as it may help you to understand the concepts behind the video, I enclose a version of that graph here: