Nervous system physiology

This course is a part of NCLEX-RN, a 21-course Topic series from Khan Academy.

There are about 85 billion neurons in your brain, and they’re sending electrical signals in your body right now! They tell your eyes to move across this page, interpret the words that you read, maintain your posture...all in a fraction of a second. In this section we’ll explore this vast, complex system from the cellular to the sensory level.

This course contains 4 segments:

Neural cells

3A: Neurons transmit information to one another through electrochemical signals. They make up the motor nerves that allow you to type an essay, the sensory nerves that let you feel a fluffy dog, and your brain, allowing to remember the content of this module. They have a number of helper cells, ranging from astrocytes, to microglia, to ependymal cells as well. You will come to appreciate the structure and function of neurons and the comrade cells which help to maintain the optimal function of the nervous system.

Neuron membrane potentials

3A: As you visually process this webpage, countless action potentials are taking place across the neurons in the occipital lobe of your brain. An action potential is an extremely quick change in the membrane potential of the neuron that can propagate toward other neurons. It’s like one neuron is telling another neuron “Hey, wake up! We have work to do!” You will soon gain an appreciation for the mechanism of the action potential, which allows for communication between neurons of all flavors in your body- from those responsible for the maintenance of memory to those functioning in sensation.

Neuronal synapses

3A: Synapses are the means by which neurons, just like other cells of the body, communicate with each other as well as other cells, like muscles and glands. They are the equivalent of neural telephone lines allowing for the transmission of a neurotransmitter, that is, the message. Thus, you are able to tell a dog from a cat. and a ball from a rock. Without all this cross-talk, you might look at an object without truly seeing or hear a sound without actually listening.

Biosignaling

3A: The human body is composed of about 100 trillion cells (this is not counting your bacterial buddies, who actually outnumber your cells 10 to 1!) Your cells must speak to each other to coordinate this massive symphony of life. In this tutorial, you will learn about the molecular basis of cellular signaling that makes this vast network speedy and efficient.