H.A. 101: Epithelial Tissue


The foundation of Human life can be categorized into numerous groups, each larger than the last. First, we identify atoms that make molecules. Things such as Oxygen, Carbon, and Nitrogen are critical atoms that create the foundation of molecules. Molecules are combinations of atoms that result in the creation and foundation of cells, the smallest life form. Groups of Cells can combine to create one of four primary tissues (Epithelial, Connective, Muscle, and Nervous). Together, a group of tissue will function to create an organ such as the stomach, brain, and kidney. Finally, organs work together to create organ systems that provide the functions of an organism.

Epithelial Characteristics

Epithelial tissue has characteristics that make it completely different from other tissues. These Characteristics include Cellularity, Polarity, Attachment, and Avascularity.

Cellularity is the characteristic that cells are bound closely together and there is no intercellular space.

Polarity means that the cells have structural and functional differences based on the area of the cell. The apical surface of an epithelial cell is exposed and has things such as cilia and microvilli for absorption.

The basal surface is attached to deeper tissue to stabilize the cell. This is also called Attachment and the epithelial cell’s basal layer is attached to the basal lamina.

Finally, avascularity is the characteristic that epithelial tissue does not contain blood vessels.

Epithelial Function

The functions of Epithelial tissue vary based on the shape, polarity, and many other factors. The main functions include:

  1. Physical protection from abrasion, dehydration, and destruction
  2. Controlling permeability
  3. Provides sensations (Neuroepithelia)
  4. Produces secretions with special gland cells

Within Epithelial cells, there are specializations when it comes to the apical surface. The major specializations are Microvilli, Stereocilia, and Ciliated Epithelium. Microvilli help increase surface area to increase absorption of nutrients and materials. They are often found in the urinary and digestive tracts. Stereocilia are long microvilli found in the inner ear and male reproductive tract. In the ear, they help with balance and hearing. Finally, Ciliated Epithelium helps transport material along the apical surface to another location. These are found in the lining of the respiratory tract and are used to push mucus out of your airways.

Maintaining Integrity of Epithelium

Epithelial cells are often small, fragile, and numerous. So, how do they keep their shapes and overall integrity to perform their functions? Three major factors are involved in this:

  1. Intercellular Connections
  2. Attachment to the basal lamina
  3. Self-perpetuated epithelial maintenance and renewal

Intercellular Connections are extensive connections present between epithelial cells that hold them together and prevent the passage of chemicals and pathogens. Some examples of Intercellular Connections include Cell junctions and CAMs (Cell adhesion molecules)

Attachment to the Basal Lamina is created between the cell membrane and the basement membrane. Within this connection, there are typically two layers called the Basal Lamina and Reticular Lamina. The Basal Lamina is the layer closest to the epithelial cell and connects to the Plasma membrane. The Reticular Lamina is the next layer and attaches to the underlying tissue. These two layers help create a boundary between the Connective Tissue and Epithelial cells.

Maintaining Epithelium is extremely important to assure all functions are operating properly. They are replaced frequently because of exposure to enzymes, toxic chemicals, abrasion, and pathogens. So, how are these cells replaced? Epithelial cells are replaced through stem cell division located near the basal lamina.

#45 Podcast With Pre-PA Clinic

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#44 Where Have We Been?

For the last month, you may have noticed that My Biology Experience has been inactive with no new content. So, what have we been up to and what is to come in the following months?

First, we would like to say thank you to all the subscribers, followers, creators, and whoever else may be supporting our journey. Without people supporting this website, we would have a lot less to show for it. If you are not subscribed or following us on social media, make sure you subscribe using an email or by hitting the follow button to make sure you get the most up-to-date content.

The past month has been a hectic time for me. I just finished up my Junior year of college where I did extremely well! I have also been finishing my applications to graduate school! I finished my applications just the other day and it is a huge relief and stress taken away from my life. The major thing that has caused the inactivity of My Biology Experience was a trip to the United Kingdom that I took. During this past semester (Spring 2022), I took a Global Field Studies (GFS) course called CSI UK. A GFS course is a class in which you study a topic of another country or even something within the United States. You then use what you have learned in the classroom to apply it in the real world. For my class, we studied the differences between forensic science in the United States and the United Kingdom.

The trip we took was amazing! It was a 15-day trip in which we traveled to four major cities. The first of these cities was Glasgow Scotland. This was one of my favorite cities for its personal and small city feel.

Arthurs Seat in Edinburgh Scotland

The second city we visited was Edinburgh Scotland. This city felt more like a tourist town since it is the capital of Scotland. We went to places like Parliament and the High Court. This was my favorite city because of its beauty, small city feel, and atmosphere. While in Edinburgh we traveled to Dundee for a day to do a research exchange. This opportunity was very unique because I was able to listen to graduate students of my own class and graduate students of another university exchange new information and ideas that were very interesting.

The last city that we stayed in was London. To be honest, I was not the biggest fan of London. It felt as if someone took New York City and placed it in another country. While staying here I didn’t feel like I was in another country. I felt like I was home in New York at times.

In regards to applications to graduate school, I plan on coming out with a post explaining my experiences, recommendations, and a general overview of the CASPA application. I am also working on ideas for the Study Biology section of My Biology Experience. This section has been a work in progress for almost six months now but, after considering different aspects of this integral part of the website we have decided to go a different route. I will be coming out with a post explaining this as well.

We are glad to be back posting on My Biology Experience and I can not wait to share the next part of my journey with you!