What Is the Stratum Corneum?
The term “stratum” comes from the Latin word “struma”, which means skin. A layer of dead cells (called a “fibroblast”) covers our bodies. These fibroblasts are called the stratum corneum. They protect us from harmful bacteria, viruses, and other foreign substances that may enter into our body through various openings such as wounds or broken skin.
When we breathe, air enters our lungs and travels through the body. Some of it gets trapped inside our lungs. If there is no room left for all the air, some of it leaks out of our lungs into the outside world. However, if too much air leaks out of your lung, you will get pneumonia or even death due to suffocation.
If too little air leaks out of your lungs, you will not get any symptoms at all. You could even die because your lungs cannot hold enough oxygen. The reason why some people do not feel any symptoms when they have too little air in their lungs is because the amount of air inside them is small compared to what would leak out if there was too much. The amount of air inside us is so large compared to the air leaking out that we do not feel any symptoms at all. This is also why when we exercise, our lungs are able to hold more air inside them.
If the amount of air leaking out of our lungs increased by the same ratio our lung size increased by, then we would suffocate because our lungs could no longer hold enough oxygen.
The amount of air in your lungs is measured in a unit called a “partial pressure”. The partial pressure of oxygen (abbreviated as P O2) in your blood is the amount of oxygen you are breathing divided by the total amount you can breathe. If the P O2 is more than a certain level, then oxygen will be able to diffuse into your blood. If the level is too low, then you will suffocate. You can increase the partial pressure of oxygen in your blood by increasing the amount of air leaking out of your lungs.
This is why you feel short of breath when you exercise, as more air leaks out of your lungs to increase the partial pressure of oxygen in your blood.
The P O2 level in your blood is important because it determines how much oxygen is absorbed into your blood. If a certain structure in your body needs oxygen, then that structure will let more oxygen diffuse into your blood. If it does not need any oxygen, then it will not let any more oxygen diffuse into your blood. This is why you don’t feel short of breath while you sleep. Your body does not need to use much energy while you sleep, so it does not let much oxygen diffuse into your blood.
The stratum lucidum layer is a layer of the skin located directly below the stratum corneum layer. It contains mostly glycogen and lipids. It has a clear/yellow appearance under the microscope, hence the name. It can be found in areas where there is frequent friction or pressure against the skin. In other words, it can be found in the hands, feet, and lips.
What Is the Stratum Lucidum Used For?
The stratum lucidum layer is a protective barrier for the rest of the skin. Just like the rest of the skin, it helps protect the body from bacteria, viruses, chemicals, and other external threats to the body.
The stratum lucidum prevents some materials from entering the skin. This is especially true for things that are not lipid soluble, like water. It is not effective at preventing lipid soluble things (like many drugs) from entering into the skin.
There are no common products that are made using the stratum lucidum. It is mainly used in scientific experiments.
Research on the Stratum Lucidum
The stratum lucidum can be used to test how lipophilic and hydrophilic chemicals interact with skin. Chemicals that are hydrophilic (like water) will pass through the stratum lucidum, and only a small amount will diffuse into the skin. However, chemicals that are lipophilic (like oil) will not diffuse into the skin very much, but instead will pass through the stratum lucidum and remain on the skin.
The stratum lucidum can also be used to test how effective a product is at preventing water loss. Many cosmetics manufacturers use this process when developing new products. This process is called “keratinocyte migration assay”. It involves putting cells from the skin onto a microscope slide and testing different products on the cells to see which prevent water loss the best.
The stratum lucidum can be used to test how much energy your body absorbs and uses when you are doing physical activity. It does this by measuring the amount of oxygen in your blood before, during, and after exercise. This process is called “oxymeter testing”. Many sports teams and physical education teachers use this process to determine how good each student’s endurance is, and what they can do to improve it.
The stratum lucidum layer is located below the stratum granulosum layer.
Sometimes the stratum lucidum layer is missing from certain parts of the skin. This condition is called ichthyosis. With ichthyosis, the skin can be dry and flaky all over the body. It is thought to be caused by a problem with how the stratum lucidum forms when a baby is developing inside the mother’s womb.
The stratum lucidum is the only layer of the epidermis that does not contain any dead cells.
The stratum lucidum contains small amounts of lipid rich materials.
The stratum lucidum is fairly thick in skin that has frequent contact with the outside world, such as the hands and feet. It is also fairly thick in skin that has to withstand a lot of friction, such as the soles of the feet.
Sources & references used in this article:
Preparation of isolated sheets of human stratum corneum by AM KLIGMAN, E CHRISTOPHERS – Archives of dermatology, 1963 – jamanetwork.com
Human stratum corneum lipids: characterization and regional variations. by MA Lampe, AL Burlingame, JA Whitney… – Journal of lipid …, 1983 – ASBMB
Electrical properties of the epidermal stratum corneum by T Yamamoto, Y Yamamoto – Medical and biological engineering, 1976 – Springer
Factors which influence the water content of the stratum corneum by IH Blank – Journal of Investigative Dermatology, 1952 – core.ac.uk
Stratum corneum defensive functions: an integrated view by PM Elias – Journal of Investigative Dermatology, 2005 – Elsevier
Stratum corneum moisturization at the molecular level by AV Rawlings, IR Scott, CR Harding… – Journal of investigative …, 1994 – Elsevier
Decreased level of ceramides in stratum corneum of atopic dermatitis: an etiologic factor in atopic dry skin? by G Imokawa, A Abe, K Jin, Y Higaki… – Journal of Investigative …, 1991 – Elsevier