Neuroscience Fundamentals - Module 1: The Cell

The first step to understanding any part of the body is to define its most basic building block - the cell.

Defining the cell

The cell is defined by the Oxford dictionary as the smallest structural and functional unit of an organism. You may have heard this common explanation in a middle school biology class: “All body tissues are made up of collections of cells. Groupings of tissue make up organs. Groups of organs make up organ systems, and the organ systems together make up the whole body.”

But, what does being the smallest functional unit in the body actually MEAN? What do cells actually DO other than be small that makes them so special?

Well, the first step to discussing this is to break down their structural components and basic functions.

To begin, please view this explanation of the basic animal cell structure from 2 Minute Classroom on YouTube. You do not need to memorize all of the structures but you will benefit from gaining a working understanding of how cells generally look and operate. If you’d like, you can pair this video with this printable diagram. The linked website has both labeled and unlabeled copies of a basic animal cell diagram worksheet available for download and use. Referencing the worksheets or practicing filling in the structure labels might help with understanding if you find any of this information overwhelming, especially if you are a visual learner. Again don’t feel you have to do this to engage with this course - it is just here as an option for those who would like to use it.

There are different types of cells in the body

While cells in the human body generally share the common characteristics shared above, they are differentiated into many types that have slight variations in structure, concentrations of organelles, or other specialized elements that set them apart. This allows cells to form different body structures and to perform specialized functions. For example, the cells that make up muscles tend to be long and thin and have high concentrations of fibrous internal structures which allow them to form muscle structures and perform the functions of contraction and elongation necessary for movement. Meanwhile, skin cells are much smaller, flattened out similarly to a coin, and are full of specialized proteins which allow them to form a protective barrier against water, germs, UV radiation, and other external threats.

Types of cells in the nervous system

There are many types of cells in the nervous system, but at the most basic level these can be divided into two groups: neurons, and glial cells.

Neurons

Neurons are the main focus of many neuroscience and neurology conversations since these are the cells that send and receive signals. Please view the video “The Neuron” from 2 Minute Neuroscience to learn about the neuron’s specialized structure. You may also enjoy the similar video “Anatomy of a Neuron” from Khan Academy. It is longer at 6 minutes but some may find the pace easier to follow. An optional companion labeling/coloring worksheet is available here.

Glial cells

There are many types of glial cells in the nervous system, but all of them serve to support neurons in some way. This can be through literally supporting neurons by providing an external structure for them to live within, by delivering nutrients, helping to balance neurotransmitters, providing protection against threats, insulating neuronal axons, and more. This video provides a brief overview of the different types of glial cells and their specific functions. A brief (although not exhaustive) reference list is also provided below:

astrocytes: provide structural support for neurons and form the blood-brain barrier

oligodendrocytes and schwann cells: insulate neuronal axons in order to protect the cells and aid in action potential transmission (cell signaling)

microglia: provide immune support

ependymal cells: cerebrospinal fluid homeostasis, removing waste

satellite cells: provide protection and nutrients for peripheral nervous system neurons

Summary and application

The cell is the basic building block of the body, and there are many specialized types which make up specific tissues. There are several types of specialized cells that make up the nervous system, of which the neuron is identified as especially important as its function is to send and receive signals.

Understanding the structure of cells in the body, and especially of the neuron, will help you to understand how these cells make up the larger structures in the nervous system and carry out important functions.

What’s next?

Now that you understand the structure of the neuron, you are ready to learn about the action potential. This refers to how neurons send signals through the body. Come back to learn about this in module 2!