The Nervous System, Part 1: Crash Course A&P #8

Sensory receptors located in the skin or internal organs, for example, and send them to the central

nervous

system

. Most sensory neurons are unipolar neurons. Although motor or efferent neurons perform the opposite function, most are multipolar and transmit impulses from the central

nervous

system

to the muscles and glands of the body. Then there are intermediate or association neurons, which live in the central nervous system and transmit impulses between sensory neurons and motor neurons. Intermediate neurons are the most abundant in the body and most of them are multipolar. Well, it's time to apply the knowledge. Let's review everything we have learned so far with the example of the spider on your knee.

These eight crawling legs activate unipolar sensory neurons in the skin of the knee when they detect something crawling on the body. The signal then travels through an axon lined with Schwann cells to the spinal cord, where it passes to several multipolar intermediate neurons. Some intermediate neurons can send a signal directly through a group of multipolar neurons to the quadriceps muscles, prompting you to kick your legs before you realize what's happening. Other intermediate neurons will pass that signal to neurons that transmit it to the brain through the spinal cord. Here the body realizes for the first time that it is a spider, and the connections between the neurons interpret and divide the signal, either so that you can start screaming and wave your arms in fear, or so that you can keep calm. calm down and walk away.

Spider your body with dignity. It all depends on the connections between neurons. Does this raise a new question? as? Jean-Martin Charcot How do neurons use chemistry and electricity to communicate with each other? This is one of the most fascinating and complex aspects of the nervous system and literally our entire lives, and it's what we'll cover in our next episode. Today you learned how sensory input, integration, and motor output from the nervous system control your world. We talked about the central and peripheral systems and their functions, and we talked about the role of different glial cells in the function of nervous tissue, and about the role of different types of neurons and their structural structures and their function in the body structurally and functionally and about what happens when you find a spider crawling on your skin.

Thanks for watching, especially to our Subbable subscribers who make Crash Course content available to them and everyone around the world. To learn more about how you can support us, visit subbable.com. This episode was written by Kathleen Yale, edited by Blake de Pastino, consulted by Dr. Brandon Jackson, directed and edited by Nicholas Jenkins and Michael Aranda, and illustrated by the Thought Café team.