What is the Dermis?


The dermis is a tough fibroelastic tissue of collagen and elastic fibers. It contains epidermal appendages (sweat glands, hair follicles and arrector pili muscles) and blood vessels that distribute blood to the skin and remove toxins.


Nurses observe the skin of their patients daily and need to understand its structure and key functions. This article and the accompanying self-assessment will help nurses do just that.

The Epidermis

The epidermis is the outermost layer of skin. It functions to protect against pathogens, chemicals and UV radiation. It also helps regulate body temperature, provides a sense of touch, and produces sweat to help regulate the skin’s chemistry.

The first layer of the epidermis is called the stratum basale. This is where the majority of cells found in the epidermis are located. These cells are mitotically active and constantly produce new keratinocytes which then move toward the surface of the skin, pushing old cells up in the process. The cells in the stratum basale are flat with a cuboidal to columnar appearance and connect to each other by desmosomes and hemidesmosomes.

Once these keratinocytes reach the top of the epidermis, they lose their nuclei and transform into keratinized squames. These squames then become corneocytes, which are a keratinized brick-like cell with a phospholipid membrane. This membrane is very durable and helps to protect the lower layers of your skin.

During the transformation process, these corneocytes also produce a lipid-rich secretion that helps keep your skin hydrated. Several other types of cells are found in the epidermis including Merkel cells which send signals to the brain that get translated as your sense of touch and melanocytes which are responsible for producing the pigmentation of your skin and hair. Overactive melanocytes can result in uneven skin pigmentation.

The Papillary Layer

The papillary layer of the dermis is a thin, loose, connective tissue layer that 대전피부과 lies beneath the epidermis and attached to it. It contains thin elastic fibres and fine collagen fibrils, as well as a number of blood vessels. It is a highly vascularized layer compared to the deeper reticular layer. This layer helps to regulate the movement of nutrients and fluids through your skin and is responsible for maintaining the health and appearance of the epidermis.

The papillae, or rete ridges, that extend into the epidermis from this layer are finger-like structures which contain sensory nerve endings, cytoplasms and a network of blood capillaries. The papillae help to sense and detect foreign materials that have penetrated the epidermis. They also assist in removing waste products from the surface of the skin. The papillae are more pronounced in areas of thicker skin such as the palms, soles and digits.

In this layer we can find melanocytes (the cells that produce the colour of our skin), hair follicles, sweat glands and sebaceous glands. It is also the site of some of the specialized functions that our skin performs such as insulation (absorption and retention of heat), shock-absorption, fat storage and communication (release of visual and pheromonal signals such as blushing and nervous sweating). The thickness of the dermis varies across the body and between individuals. It is thinner over the eyelids and thicker on the back of the body.

The Reticular Layer

The reticular layer is the thickest of the two dermal layers and houses most of the skin’s blood vessels, glands and fat cells. This layer gives the skin its strength and elasticity, but can also wrinkle as a result of reduced tissue volume over time. Its most notable features are a network of blood vessels that offer support and nutrients, sweat glands, hair follicles and lymphatics. It is also home to nerves that sense temperature, touch and pain.

Unlike the loosened, evenly distributed collagen fibers in the papillary layer, the dense irregular connective tissue in the reticular layer is visible as a net-like pattern under H&E staining. It contains fewer fibroblasts and less ground substance, and has more elastin fibers than the papillary layer.

Notice the fingerlike projections (also called dermal papillae) that protrude from this layer and into the epidermis. The papillae increase the strength of the connection between the epidermis and dermis. These papillae contain capillaries and sensory touch receptors known as Meissner’s corpuscles, which can sense light touches. Pacinian corpuscles, which can sense vibration and pressure, are found in the deeper dermis, just below the reticular layer. Sweat glands, which are simple coiled tubules, are also seen here. The secretory portions of the sweat glands are clustered in the hypodermis, which is largely adipose tissue.

The Blood Vessels

Blood vessels supply oxygen, nutrients, and other essential substances to cells throughout the body. This is a very important process. If you were to lay out all the blood vessels in your body in a straight line, they would cover nearly 60,000 miles—enough to circle the earth almost three times! The blood vessels consist of arteries that transport blood away from the heart; arterioles, which branch into ever-smaller blood vessels that are called capillaries, where oxygen and water products are exchanged; and finally, venules, which are small blood vessels that combine with those that exit the capillaries to form veins, which carry blood back toward the heart.

The dermis provides a strong connective tissue layer that supports and protects the epidermis, hair follicles, glands, and blood vessels. The dermis is also a home for many different cell types, including fibroblasts, mast cells, histiocytes, and adipocytes.

One interesting feature of the dermis is that it has little blood vessels on its own, called vasa vasorum. These tiny blood vessels supply the skin with blood and help it stay moisturized. Blood vessels in the dermis also have tiny muscles, called arrector pili muscles, that can contract and cause goosebumps in response to cold temperatures or fear. This function assists with thermoregulation by causing sweating and dilating the blood vessels to increase the volume of blood near the surface, which releases heat. The vessels then contract again to prevent loss of heat as the blood returns to the core.