The epidermis is composed of keratinized stratified squamos epithelium, that consists of four different cell types and four of five layers. The cell types include kerationocytes, melanocytes, Merkel cels, and Langerhan's cells. The outer portion of the skin is exposed to the external environment and functions in protection. Since the epidermis is the top layer of skin, you shed skin every day without even knowing it! In the epidermis, there are different layers within it. The first is the Stratum Basale layer, usually just known as the Basal layer. It is the deepest epidermal layer, attached firmly to the dermis, and also consists of a single row of the youngest keratinocytes. The cells in the Basal Layer undergo rapid division. The next layer in the epidermis is the Stratum Spinosum, a.k.a the Prickly Layer. The cells in this layer have a weblike system of intermediate filaments attached to desmosomes. Melanin granules and Langerhans' cells are really big in this layer. The layer after that is the Stratum Granulosum (Granular Layer). This layer is a very thin layer that has three to five cell layers in which major changes in keratinocyte appearance happens. Keratohyaline and lamellated granules build up in the cells of this layer. Next is the Stratum Lucidum a.k.a as the clear layer. This layer is a very thin, transparent band superficial to the stratum granulosum. It is a few rows of dead, flat keratinocytes. It is only present in thick skin. The last layer of the epidermis is the Stratum Corneum a.k.a the Horny Layer, yes i know that is a funny name. This layer is the outermost layer of keratinized cells, and it accounts for three quarters of the thickness of the epidermis. It's functions include: protection from abrasion and penetration, waterproofing, and rendering the body relatively insensitive to biological, chemical, and physical assaults.
The next major layer below the epidermis is the Dermis that has strong, and flexible connective tissue. The cels in this layer include fibroblasts, macrophages, and sometimes have mast cells and white blood cells. This layer consists of two layers, papillary and reticular. The papillary layer has Areolar connective tissue with collagen and elastic fibers. Its surface has peg like projections called dermal papillae. Dermal papillae contains capillary loops, Meissner's corpuscles, and free nerve endings. The reticular layer accounts for about 80% of the thickness of the skin, and has collagen fibers that add strength and resiliency to the skin. Elastin fibers provide stretch-recoil properties.
The Hypodermis is the deepest layer of your skin, and it is composed of adipose and areolar connective tissue.
Have you ever wondered why your skin is the color that it is? There are three different pigments that contribute to your skin color. Melanin is one of them. Melanin is a yellow to reddish-brown to black pigment that is responsible for darker skin colors. That's why when you see melanoma cancer, the spots are really dark. Freckles and pigmented moles are also build ups of melanin. Carotene is another pigment that is yellow to orange, and is usually most obvious in the palms and soles of your feet. Hemoglobin is a reddish pigment that is responsible for the pinkish look of the skin.
Sweat glands are a pretty big part of the body, and there are different types that prevent overheating of the body that can secrete cerumen and milk. The eccrine sweat glands are found in the palms, the soles of the feet, and the forehead. Apocrine sweat glands are found in axillary and anogenital areas. The Ceruminous glands are modified apocrine glands that are in the external ear canal, and secrete cerumen. This may be surprising, but the mammary glands are actually specialized sweat glands that secrete milk. Sebaceous glands are simple glands that are found all over your body. They soften your skin when stimulated by hormones, and secrete an oily secretion called sebum.
Now that you know the normal functions of the skin, lets talk about the things that can go wrong with your skin. I'm going to talk about Albinism. Albinism occurs when one of several genetic defects makes the body unable to produce or distribute melanin, which is a natural substance that gives color to your hair, skin, and the iris of your eye. It results in little or no color in your hair, skin, or eyes. The defects of albinism may be passed down through families. There are two different types of albinism: Type 1 albinism, and Type 2 albinism. Type 1 albinism is caused by defects that affect production of the pigment, melanin. Type 2 albinism is due to a defect in the "P" gene. People with this type of albinism have slight color at birth, but the most severe type of albinism is called oculocutaneous albinism. People with this type of albinism have white or pink hair, skin, iris color, and vision problems. Another type is ocular albinism type 1 (OA1), which affects only the eyes. everything is usually in the normal range, but if an eye exam was taken, it would show that there is no coloring in the retina. HPS- Hermansky-Pudlak syndrome is a form of albinism caused by one single gene. It can occur with a bleeding disorder, as well as with lung and bowel diseases. The symptoms a person with albinism will have are:
If you are worried that you have albinism, genetic testing offers the most accurate way to diagnose albinism. It would be very helpful if your family has a history of albinism.
The goal for treatment of albinism is to relieve the symptoms, but the treatment you do depends on the seriousness of the disorder. It is very helpful to protect the skin and eyes from the sun. When exposed to the sun, use sunscreen and cover up completely with clothing, use sunscreen with the highest SPF, and use UV protected sunglasses.
Sources:
The next major layer below the epidermis is the Dermis that has strong, and flexible connective tissue. The cels in this layer include fibroblasts, macrophages, and sometimes have mast cells and white blood cells. This layer consists of two layers, papillary and reticular. The papillary layer has Areolar connective tissue with collagen and elastic fibers. Its surface has peg like projections called dermal papillae. Dermal papillae contains capillary loops, Meissner's corpuscles, and free nerve endings. The reticular layer accounts for about 80% of the thickness of the skin, and has collagen fibers that add strength and resiliency to the skin. Elastin fibers provide stretch-recoil properties.
The Hypodermis is the deepest layer of your skin, and it is composed of adipose and areolar connective tissue.
Have you ever wondered why your skin is the color that it is? There are three different pigments that contribute to your skin color. Melanin is one of them. Melanin is a yellow to reddish-brown to black pigment that is responsible for darker skin colors. That's why when you see melanoma cancer, the spots are really dark. Freckles and pigmented moles are also build ups of melanin. Carotene is another pigment that is yellow to orange, and is usually most obvious in the palms and soles of your feet. Hemoglobin is a reddish pigment that is responsible for the pinkish look of the skin.
Sweat glands are a pretty big part of the body, and there are different types that prevent overheating of the body that can secrete cerumen and milk. The eccrine sweat glands are found in the palms, the soles of the feet, and the forehead. Apocrine sweat glands are found in axillary and anogenital areas. The Ceruminous glands are modified apocrine glands that are in the external ear canal, and secrete cerumen. This may be surprising, but the mammary glands are actually specialized sweat glands that secrete milk. Sebaceous glands are simple glands that are found all over your body. They soften your skin when stimulated by hormones, and secrete an oily secretion called sebum.
Now that you know the normal functions of the skin, lets talk about the things that can go wrong with your skin. I'm going to talk about Albinism. Albinism occurs when one of several genetic defects makes the body unable to produce or distribute melanin, which is a natural substance that gives color to your hair, skin, and the iris of your eye. It results in little or no color in your hair, skin, or eyes. The defects of albinism may be passed down through families. There are two different types of albinism: Type 1 albinism, and Type 2 albinism. Type 1 albinism is caused by defects that affect production of the pigment, melanin. Type 2 albinism is due to a defect in the "P" gene. People with this type of albinism have slight color at birth, but the most severe type of albinism is called oculocutaneous albinism. People with this type of albinism have white or pink hair, skin, iris color, and vision problems. Another type is ocular albinism type 1 (OA1), which affects only the eyes. everything is usually in the normal range, but if an eye exam was taken, it would show that there is no coloring in the retina. HPS- Hermansky-Pudlak syndrome is a form of albinism caused by one single gene. It can occur with a bleeding disorder, as well as with lung and bowel diseases. The symptoms a person with albinism will have are:
- Absence of color in the hair, skin, or iris of the eye
- Lighter than normal skin and hair
- Patchy, missing skin color
- Crossed eyes (strabismus)
- Light Sensitivity (photophobia)
- Rapid eye movements (nystagmus)
- Vision Problems or functional blindness
If you are worried that you have albinism, genetic testing offers the most accurate way to diagnose albinism. It would be very helpful if your family has a history of albinism.
The goal for treatment of albinism is to relieve the symptoms, but the treatment you do depends on the seriousness of the disorder. It is very helpful to protect the skin and eyes from the sun. When exposed to the sun, use sunscreen and cover up completely with clothing, use sunscreen with the highest SPF, and use UV protected sunglasses.
Sources:
- http://www.nlm.nih.gov/medlineplus/ency/article/001479.htm
- http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002450/
