Ever Wonder What Your Skin Is Made Of?

Your extraordinary skin is a composite, microstructural, supple membrane,¹  mostly made of water, proteins, lipids, and minerals.²  Fundamentally, skin is energy organized as matter in the form of atoms, molecules, cells, and tissues. By understanding your skin in this context, you can better appreciate its complexity and functionality.

All that lives and exists in our physical space-time³ environment, is highly structured and organized. Our biological world can be viewed as a collection of systems that cooperate symbiotically, exchanging energy and information.⁴  Organic life can generally be hierarchically categorized, on a continuum of biological scales, based on size and complexity.

These biological scales, from the smallest and simplest to the largest and most complex, are the: subatomic particle,⁵  atom, molecule, macromolecule, organelle, cell, tissue, organ, organ system, organism, population, community, ecosystem, biome, and biosphere.⁶  Our biosphere is like a set of nesting dolls.⁷

The Building Blocks of Skin

Subatomic particles, also known as elementary particles, are self-contained units of energy (e.g., electrons, gluons, and quarks^{8, 9})¹⁰  They are the building blocks of all visible matter in the universe. As far as scientists know, these subatomic particles cannot be broken down into smaller components.

Subatomic particles can organize and form atoms.⁹  Differing quantities and arrangements of subatomic particles cause the atom to have differing chemical properties.¹¹  There are over 100 types of atoms.¹² 

In the natural world, every atom is accounted for as an element.¹³  One element is one type of atom.¹⁴  All known elements are organized on the periodic table.¹⁵

Scientists have detected at least 60 elements in the human body, however only about 25 of them are known to be essential to life.¹⁶  The most prevalent elements in our body are: oxygen (O), carbon (C), hydrogen (H), nitrogen (N), calcium (Ca), phosphorus (P), potassium (K), sulfur (S), sodium (Na), chlorine (Cl), and magnesium (Mg).^{17, 18}  Your body takes these atoms in from the air you breathe, food you eat, and liquids you drink.¹⁹  Your body’s atoms were previously in the air, plants, animals, and minerals. The great majority of atoms in your body are replaced continuously at different rates.²⁰

Atoms can come together and form molecules. A molecule is comprised of two or more atoms of the same element, or different elements, bonded together.¹⁴  Examples of molecules important to the human body are: water (H₂O), oxygen (O₂),²¹  carbon dioxide (CO2), sodium chloride (NaCl), and glucose (C₆H₁₂O₆₎ .²²  Molecules are sometimes referred to as micromolecules. Important micromolecules in cells include amino acids, fatty acids, and nucleotides.²³

Molecules can join together and form giant molecules. In your body, these giant molecules are called biological macromolecules. There are four categories of biological macromolecules: proteins (e.g., hemoglobin, collagen, and enzymes), carbohydrates (simple and complex carbohydrates), lipids (e.g., triglycerides, phospholipids, steroids, and squalene), and nucleic acids (DNA and RNA).²⁴

Macromolecules can bond together and form organelles.²⁵  Organelles perform specific functions and can be thought of as tiny organs within a cell.²⁶  Some examples of organelles are the nucleus, mitochondria, Golgi apparatus, and plasma membrane.^{27, 28}

From Cells to Tissues

Organelles organize and work together to form a cell.  A cell is a membrane-bound group of organelles that work together to allow the cell to function.²⁹  Your body is comprised of roughly 37 trillion cells. Scientists estimate there are 200 to 500 different types of cells in the adult human body.^{30, 31, 32, 33}  You have stem cells, red blood cells, keratinocytes, melanocytes, and Langerhans cells, to name just a few.

Organized groups of cells that work together to carry out a specific function form tissue.³⁴  Your body has four main types of tissue: epithelial tissue, connective tissue, muscle tissue, and nervous tissue.³⁵ 

The following are some common types of epithelial tissue: simple squamous epithelium, simple columnar epithelium, non-keratinized stratified squamous epithelium, and keratinized stratified squamous epithelium.³⁶  Some examples of connective tissue are: adipose, cartilage, bone, blood, and lymph.³⁷ 

Two or more tissue types working together to perform one or more specific physiological function(s) form an organ.³⁸  Your skin is an organ. Your skin is comprised of epithelial tissue and connective tissue that work closely with muscle tissue and nervous tissue to perform unique and critical functions.³⁹   

The Layers of Your Skin

Your skin can be divided into two main layers, each of which vary significantly in their anatomy and function. The epidermis is a thin, protective layer of keratinized stratified squamous epithelial tissue. Beneath it lies the dermis, a thick, elastic layer of dense fibrous connective tissue.^{40, 41}

In the literature, the hypodermis (or subcutis) is often listed as a third layer of skin, below the dermis. There is ongoing debate and confusion regarding the nomenclature of the hypodermis (or subcutis) and its classification as a distinct layer of the skin. The term "hypodermis" may lack specificity, leading to ambiguity in its usage. Historically, what is now recognized as the dermal white adipose tissue layer was referred to as both subcutis and hypodermis.^42.

Below the dermis lies a layer of subcutaneous white adipose tissue (sWAT).⁴³  This layer is not considered part of the skin.⁴⁴

Your skin is a dynamic and complex structure composed of countless interacting elements, ranging from the smallest subatomic particles to the organized tissues that form its layers. Delving into the microstructural composition of your skin allows for a deeper appreciation of its vital roles in protection, sensation, and overall health.

Recognizing the complexity and beauty of your skin encourages a greater understanding of why caring for it is essential. This includes maintaining hydration, ensuring proper nutrition, and protecting it from environmental stressors. As one of the largest organs in your body, your skin deserves thoughtful attention and care, reflecting the remarkable interplay of biology and chemistry that sustains your daily wellbeing.

References

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