Skin. Let’s have a closer look.

The skin is the largest organ of the human body, and it serves as a physical barrier between the internal organs and the external environment.

The skin is composed of three primary layers:

• Epidermis: This is the outermost layer of the skin, and it is made up of several sub-layers. The cells of the epidermis are constantly being shed and replaced by new cells from the lower layers.
• Dermis: This is the middle layer of the skin, which contains hair follicles, sweat glands, and blood vessels. It is responsible for providing support and nutrients to the epidermis.
• Subcutaneous tissue (also called the hypodermis): This is the deepest layer of the skin, and it is composed of connective tissue and fat. It serves as a cushion for the other layers and helps to regulate body temperature.

The epidermis is further divided into four sub-layers, and it is responsible for the skin barrier function, which prevents water loss and protects the body from harmful external factors.

Starting from the outermost layer, these sub-layers are:

• Stratum corneum: This is the topmost layer of the epidermis and is made up of dead skin cells called corneocytes. Its primary function is to act as a barrier to protect the skin from environmental stressors such as UV radiation, chemicals, and bacteria.
• Stratum lucidum: This layer is only found in thick skin, such as the soles of the feet or palms of the hands. It is made up of translucent cells that lack nuclei and other organelles.
• Stratum granulosum: This layer is responsible for the production of keratin, a tough, fibrous protein that helps to protect the skin from damage. The cells in this layer also secrete lipids that help to waterproof the skin.
• Stratum basale (also called the basal cell layer): This is the deepest layer of the epidermis and is responsible for the production of new skin cells. The cells in this layer divide and differentiate, eventually moving up to the upper layers of the epidermis.

Skincare products can be absorbed into the skin up to the level of the dermis, which is the second layer of the skin. The dermis contains blood vessels and lymphatic vessels, which can transport some of the active ingredients in skincare products to other parts of the body.

The extent to which a skincare product can penetrate the skin and be absorbed into the body depends on several factors, including the molecular size of the active ingredient, the way used to deliver the active ingredients in a product to the skin, and the condition of the skin.

For example, smaller molecules can penetrate the skin more easily than larger molecules, and the use of certain ingredients like penetration enhancers can increase the absorption of a product. Additionally, if the skin has been compromised due to injury, inflammation, or disease, it may be more permeable to skincare products.

  However, it is worth noting that not all skincare products are designed to penetrate deeply into the skin. Some products, such as moisturisers and sunscreens, are designed to form a protective barrier on the surface of the skin to prevent water loss and protect against UV radiation, respectively.