Why the dermal papillae interlock with the epidermis

Corns are a specialized form of calluses. They are formed due to the abrasion on the skin as a result of an elliptical-type motion. The papillary layer is made up of areolar connective tissue and the underlying reticular layer is composed of dense irregular connective tissue.

This dermal part of the skin organ is vasculated has blood vessels and is innervated has nerves. As described earlier, the dermis is sparsely populated with fibroblasts that produce collagen and elastin fibers in the extracellular matrix. This leads to a strong and elastic tissue structure. The matrix can also contain mast cells involved in allergic reactions.

The fibroblasts are dispersed within the collagen and elastin fibers of the areolar tissue loose connective tissue of the papillary layer. This forms a loose mat, which contains an abundance of small blood vessels.

The dermal papillae with blood capillaries interdigitate become interlocked with the epidermal ridges of the stratum basale. In addition, the papillary layer contains phagocytes — defensive cells that help fight bacteria or other infections that have breached the skin.

This layer is also interspersed with lymph vessels and sensory receptors. Fibrocytes form the bundles of collagen that extend into the papillary layer and the hypodermis, making these layers hard to distinguish. The flexible collagen provides structure and strength, while elastin lends limited elasticity to the skin. Collagen also binds with water, keeping the skin hydrated.

Dehydration causes a loss of turgor; if the skin of a dehydrated person is pinched it remains domed and does not immediately flatten out. Collagen injections and Retin-A creams help restore skin turgor by introducing collagen externally in the former case or by stimulating blood flow and repair of the dermis in the latter case.

The hypodermis also called the subcutis or subcutaneous layer functions to connect the integument epidermis and dermis to the underlying muscles and organs. The hypodermis is not considered part of the skin, but has several important functions.

Like the dermis, the hypodermis is made up of areolar tissue, collagen, and elastic fibers, providing it with some elasticity. Additionally, it contains adipose tissue, which functions as a mode of fat storage.

The hypodermis is vascular and contains arteries, veins, and blood capillaries. Adipose tissue present in the hypodermis accumulates fat, which serves as an energy reserve, insulates the body, and prevents heat loss. The fat distribution changes as our bodies mature and age. It is also hormone-dependent. Men tend to accumulate fat in different areas neck, arms, lower back, and abdomen than do women breasts, hips, thighs, and buttocks.

Physical inactivity due to a lack of exercise and sedentary jobs, combined with the consumption of high-calorie foods, has resulted in the highest rates of obesity ever seen in our country. While accumulation of fat provided an evolutionary advantage to our ancestors, who experienced unpredictable bouts of famine, it is now considered a major health threat.

When there is an irregular accumulation of melanocytes in the skin, freckles appear. Moles are larger masses of melanocytes, and although most are benign, they should be monitored for changes that might indicate the presence of cancer Figure 5. A total lack of melanin is caused by the genetic disorder called albinism See Disorders of the…Integumentary System below. Albinism is a genetic disorder that affects completely or partially the coloring of skin, hair, and eyes.

The defect is primarily due to the inability of melanocytes to produce melanin. Individuals with albinism tend to appear white or very pale due to the lack of melanin in their skin and hair. Recall that melanin helps protect the skin from the harmful effects of UV radiation. Individuals with albinism tend to need more protection from UV radiation, as they are more prone to sunburns and skin cancer. They also tend to be more sensitive to light and have vision problems due to the lack of pigmentation on the retinal wall.

Treatment of this disorder usually involves addressing the symptoms, such as limiting UV light exposure to the skin and eyes. In vitiligo , the melanocytes in certain areas lose their ability to produce melanin, possibly due to an autoimmune reaction. This leads to a loss of color in patches Figure 5. Neither albinism nor vitiligo directly affects the lifespan of an individual. Other changes in the appearance of skin coloration can be indicative of diseases associated with other body systems.

Tumors of the pituitary gland can result in the secretion of large amounts of melanocyte-stimulating hormone MSH , which results in a darkening of the skin. A sudden drop in oxygenation can affect skin color, causing the skin to initially turn ashen white. This happens when the oxygen supply is restricted, as when someone is experiencing difficulty in breathing because of asthma or a heart attack. This ABC video follows the story of a pair of fraternal African-American twins, one of whom is albino.

Watch this video to learn about the challenges these children and their family face. Which ethnicities do you think are exempt from the possibility of albinism?

The skin is composed of two major layers: a superficial epidermis and a deeper dermis. The epidermis consists of several layers beginning with the innermost deepest stratum basale germinatum , followed by the stratum spinosum, stratum granulosum, stratum lucidum when present , and ending with the outermost layer, the stratum corneum. The topmost layer, the stratum corneum, consists of dead cells that shed periodically and is progressively replaced by cells formed from the basal layer.

The stratum basale also contains melanocytes, cells that produce melanin, the pigment primarily responsible for giving skin its color. Melanin is transferred to keratinocytes in the stratum spinosum to protect cells from UV rays.

The dermis connects the epidermis to the hypodermis, and provides strength and elasticity due to the presence of collagen and elastin fibers.

It has only two layers: the papillary layer with papillae that extend into the epidermis and the lower, reticular layer composed of loose connective tissue. The hypodermis, deep to the dermis of skin, is the connective tissue that connects the dermis to underlying structures; it also harbors adipose tissue for fat storage and protection. The skin consists of two layers and a closely associated layer.

The epidermis provides protection, the dermis provides support and flexibility, and the hypodermis fat layer provides insulation and padding. They appear to be sloughing off. What determines the color of skin, and what is the process that darkens skin when it is exposed to UV light?

Cells of the epidermis derive from stem cells of the stratum basale. Describe how the cells change as they become integrated into the different layers of the epidermis. Skip to content Learning Objectives By the end of this section, you will be able to: Describe the layers of the skin and the functions of each layer Identify the components of the integumentary system Describe the layers of the skin and the functions of each layer Describe the layers of the epidermis and dermis Identify and describe the hypodermis and fascia Describe the role of keratinocytes and their life cycle Describe the role of melanocytes in skin pigmentation.

External Website View this animation to learn more about layers of the skin. Figure 5. Everyday Connection — Lipid Storage The hypodermis is home to most of the fat that concerns people when they are trying to keep their weight under control. Disorders of the…Integumentary System. The first thing a clinician sees is the skin, and so the examination of the skin should be part of any thorough physical examination.

Most skin disorders are relatively benign, but a few, including melanomas, can be fatal if untreated. Because it helps heal all types of tissues and skin that got burned. How can damage to a bone affect other human body systems?

Fat tissue from the bone marrow can leak into the blood, causing fat embolism syndrome, which can cause lung problems and seizures. If the skin breaks open fracture , pathogens can enter the body and cause an infection. What is the dermal papillae responsible for? Category: medical health skin and dermatology. You should notice that the dermis extends up into the epidermis in structures called dermal papillae. These have two functions. First, they help adhesion between the dermal and epidermal layers.

Second, in areas of thick skin like this, they provide a large surface area, to nourish the epidermal layer. What is the dermal layer of skin? How deep is the dermal layer? What happens if the hair papilla is destroyed? What do Merkel cells do? What color is the dermis? How thick is the epidermis? How many layers of skin do I have? It extends up into the epidermis in small projections called dermal papillae. This region also contains Meissners corpuscles, which are touch receptors, as well as free nerve endings non-myelinated that are sensitive to temperature.

The collagen bundles are woven into a coarse network. This layer contains fibroblasts, macrophages and fat cells. The arteries supplying the skin are deep in the hypdermis. Branches from the arteries pass upwards to form a deep and a superficial plexus.

It supplies the fatty tissue of the hypodermis, and the deeper parts of the dermis, including the capillaries for hair follicles, deep sebaceous glands and sweat glands. The superficial subpapillary plexus lies just beneath the dermal papillae, and supplies the capillaries in the dermal papillae. The pink colour of skin is mainly due to the blood seen in venules of this plexus. There are many arteriovenous anastomoses in the dermis, which can prevent blood from entering the superficial cutaneous plexus.

This strategy is used as a response to cold as a way of conserving heat. The danger is that if the epidermis loses its blood supply for too long, it will die frostbite! Alternatively, when it is hot, more blood is allowed into the superficial plexus, and the skin flushes. The blood in the superficial capillaries is cooled by the evaporation of sweat of the surface of skin. Skin functions and Layers Some facts about skin Skin is the largest organ of the body.