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The outer covers of our body, known as skin, are often taken for granted despite their crucial functions. Not only does our skin act as a cover for the human body, but it also plays a vital role in protecting us from external damage. From regulating body temperature to providing a sense of touch, the skin functions as a multi-tasking organ that deserves our attention and care. Our skin not only provides protection but also regulates body temperature and allows us to experience touch.
Let’s explore the anatomy and functions of healthy skin and learn how to maintain its optimal health and beauty.
Skin structure
The skin, which is the body’s outer covering, is among the largest organs, covering an area of 1.5-2.3 square meters and weighing up to 15% of the total body mass. From a histological perspective, it is divided into two layers:the epidermis and dermis. Additionally, the dermis also includes the hypodermis (the subcutaneous tissue), although sometimes this is considered to be a separate skin layer. This is because the dermis and hypodermis do not have clear boundaries and instead merge with each other. These layers differ in structure and function, but they share the overall purpose of acting as a barrier against mechanical and chemical injuries, UV radiation, and pathogens.
Anatomy, histology and immunohistochemistry of normal human skin
The epidermis is the topmost layer of the skin, comprising multiple sub-layers of cells that serve as a water-resistant barrier and safeguard the body from external harm. It lacks blood vessels and receives nourishment and oxygen from the underlying dermis.
The dermis is the layer of skin situated beneath the epidermis. It consists of collagen and elastin fibers that provide durability, flexibility, and structural support. The dermis houses blood vessels, sweat glands, sebaceous glands, hair follicles, and nerves, and is responsible for regulating body temperature and conveying sensory information.
The hypodermis, also known as the subcutaneous tissue, is the layer of fat and connective tissue located beneath the dermis. It serves as an energy reserve, provides insulation and cushioning to the body, and connects the skin to underlying muscle and bone.
The dermis and hypodermis are interconnected layers of the skin that blend into each other without a distinct separation point. This is possible because of the collagen and elastin fibers that serve as an anchor between the two layers, resulting in a seamless integration.
Basic histological structure and functions of facial skin
Epidermis
The epidermis is composed of five distinct layers, each containing different types of cells and performing specific functions.
The five layers of the epidermis are:
- Stratum basale: the innermost layer where new skin cells are produced.
- Stratum spinosum: the layer where cells form keratin, which helps provide strength and structure to the skin.
- Stratum granulosum: the layer where cells die and produce granules of keratin.
- Stratum lucidum: a thin, clear layer found only in areas of thick skin like the palms and soles.
- Stratum corneum: the outermost layer of dead skin cells that acts as a protective barrier against the environment.
The predominant cells in the epidermis are keratinocytes, found in the basal layer (stratum basale). These are responsible for producing keratin and lipids to form the epidermal barrier. They also participate in the absorption of calcium and the activation of vitamin D precursor, helping to synthesize vitamin D through exposure to the sun.
Dermatologists often encounter a condition called keratosis pilaris – a thickening of the epidermis or “goosebumps” – which is considered to be an inherited disease. However, integrative nutrition suggests that the underlying cause of this skin problem is the dysfunction of the gallbladder or deficiency of fat-soluble vitamins. Thus, some instances of keratosis pilaris may not be inherited, and normalization of the digestive system can be crucial to maintaining healthy skin instead of relying on hormonal creams and other topical measures.
Anatomy, Skin (Integument), Epidermis
Dermis
The dermis is the layer of skin located beneath the epidermis and above the subcutaneous tissue (hypodermis). It consists of two main layers: papillary and reticular.
The papillary layer is a thin upper layer consisting of loose connective tissue, which helps to support and nourish the epidermis. It also contains blood vessels, lymphatic vessels, and sensory nerve endings, responsible for the sense of touch.
The reticular layer is a thicker, lower layer of dermis consisting of dense connective tissue, which provides structural support to the skin. This layer contains collagen and elastin fibers that give the skin its elasticity and strength. The reticular layer also contains blood vessels, lymphatic vessels, and sensory nerve endings responsible for detecting pressure and vibration.
The dermis plays a vital role in regulating body temperature, as it contains blood vessels, allowing blood to be exposed to external temperatures to cool down. It also contains sebaceous glands, sweat glands, and hair follicles. These structures help to lubricate and protect the skin, as well as excrete waste products.
Additionally, the dermis contains immune cells, such as macrophages and lymphocytes, which help to protect the body against infection and disease.
The dermis is composed mainly of collagen, which provides strength and support to the skin, making it resistant to tearing and deformation. Collagen is a protein produced naturally by the body and is an essential component of the skin. However, consuming bone broth can aid the body in increasing its collagen content, leading to improved skin health. Here we provide a simple recipe for a bone broth.
Bone broth recipe:
Ingredients:
- 3-4 pounds of beef bones (marrow, knuckle, or joint bones)
- 1 onion, chopped
- 2-3 carrots, chopped
- 2-3 celery stalks, chopped
- 2 cloves garlic, minced
- 1-2 bay leaves
- 1 tablespoon apple cider vinegar
- Salt and pepper to taste
- Water (enough to cover the bones)
Instructions:
- Preheat the oven to 375°F. Place the beef bones on a baking sheet and roast them in the oven for about 30-40 minutes, until they are golden brown.
- Transfer the roasted bones to a large pot or a slow cooker. Add the chopped onion, carrots, celery, garlic, and bay leaves.
- Pour enough water to cover the bones and vegetables by about 1-2 inches. Add the apple cider vinegar and a pinch of salt and pepper.
- Bring the mixture to a boil, then reduce the heat to low and let it simmer for at least 12-24 hours. You can simmer it for up to 48 hours for a more concentrated broth.
- Skim any foam or impurities that rise to the surface of the broth.
- Once the broth is done simmering, remove the bones, vegetables, and spices.
- Strain the broth, let it cool and store in the refrigerator for 7 days. It can also be frozen and stored for up to 3 months.
- You can either drink bone broth on its own or use it as a base for preparing soups, sauces, and porridges.
Hypodermis
Although the hypodermis is not regarded as a distinct layer of skin, it differs significantly from the dermis in terms of structure and functions. The hypodermis, also called subcutaneous adipose tissue or subcutaneous fascia, is mainly composed of fat with some fibrous connective tissue. Adipocytes (fat cells) are the dominant cells in the hypodermis, responsible for storing fat reserves.
The hypodermis plays a crucial role in accumulating and storing nutrients, water, energy, and fat-soluble vitamins. Additionally, it contributes to the production of female sex hormones, thermoregulation, and mechanical protection of the skin.
Skin derivatives (appendages)
Skin derivatives, also known as appendages, are structures that develop from the skin during embryonic development. Some of the main types of skin derivatives include:
Hair
Hair is a filament primarily composed of the protein keratin that grows from hair follicles embedded in the skin. It serves to protect the skin and regulate body temperature. Human hair can have different colors due to the presence of melanin, a dark pigment, in varying concentrations. The more pigment, the more intense the color. Accordingly, as the amount of pigment decreases, hair turns gray.
Some believe that premature gray hair is inherited, but integrative nutrition explains this phenomenon as resulting from a deficiency of protein and iron, or insufficient amounts of antioxidants in food.
Nails
Nails are hard, flattened structures made of keratin that grow from the tips of fingers and toes. They serve to protect the tips of the digits, and fingernails further aid in fine motor tasks. The nails consist of 89% keratin, 10% water, and 1% fat.The condition of nails depends on the amount of protein available in the body and B vitamins in the diet. That’s why it is crucial to maintain a healthy diet, rich in the following products:
- Mammalian meat, including offal
- Poultry
- Fish
- Nuts
- Seeds
- Greens
- Sprouts of seeds
- Deactivated nutritional yeast
Sweat glands
Sweat glands are small tubular structures that produce sweat, which is released onto the skin surface through pores. Sweat helps to regulate body temperature and excrete waste products.
Sebaceous glands
Sebaceous glands are small glands that secrete sebum, an oily substance that lubricates and protects the skin.
Mammary glands
Mammary glands are highly specialized sweat glands that produce milk for nourishing newborn children.
Ceruminous glands
Ceruminous glands are another kind of modified sweat gland found in the ear canal. They produce earwax (cerumen) to protect the ear canal from foreign particles and microorganisms.
All of these skin derivatives play important roles in protecting and maintaining the health of the skin and the body as a whole.
Skin functions
The skin is the largest organ of the body and performs a variety of functions that are essential for maintaining overall health and wellbeing. Some of the key functions of the skin include:
- Protection: The skin acts as a barrier between the external environment and the body, protecting against physical, chemical, and microbial damage.
- Sensation: The skin contains millions of nerve endings that detect pressure, temperature, and pain, allowing us to sense our surroundings and react to potential threats.
- Temperature regulation: The skin helps regulate body temperature through sweating and blood vessel dilation and constriction, ensuring that the body maintains a stable internal temperature.
- Vitamin D synthesis: The skin produces vitamin D when exposed to sunlight, which is important for maintaining b bones and a healthy immune system.
- Immune defense: The skin contains immune cells that help defend against infection and disease.
- Excretion: The skin excretes waste products such as urea and lactic acid through sweat glands, helping to maintain the body’s internal balance.
- Absorption: The skin can absorb certain substances, such as medications, through its pores and hair follicles.
Research indicates that the skin serves a purpose similar to a big factory, making and changing things like proteins or fats. Skin is also a part of our body’s defense, feeling, and hormone systems.
What is the ‘true’ function of skin
Overall, the skin plays a vital role in maintaining our health and wellbeing, and it is important to take care of it through good hygiene, proper nutrition, and protection from harmful environmental factors.
What conditions and disorders affect the skin
Our skin condition is not only affected by external factors and visible skin diseases, but also by the functioning of internal organs. The health of our skin is intricately linked to the functioning of our digestive tract, which includes the stomach, gallbladder, liver, pancreas, and intestines.
Skin disorders
There are many skin conditions and disorders that can affect the appearance of the skin, ranging from mild and temporary to severe and chronic. These include:
Acne: a common skin condition that occurs when hair follicles become clogged with oil and dead skin cells, resulting in pimples, blackheads, and whiteheads.
Eczema: a chronic skin condition that causes red, itchy, and inflamed patches on the skin.
Psoriasis: a chronic autoimmune disorder that causes thick, scaly patches of skin to form.
Rosacea: a chronic skin condition that causes redness, flushing, and visible blood vessels on the face.
Dermatitis: an inflammation of the skin that can be caused by a variety of factors, including allergies, irritants, and infection.
Skin cancer: a type of cancer that develops in the skin cells and can be caused by exposure to UV radiation from the sun or other sources.
Fungal infections: skin infections caused by fungi, such as ringworm, athlete’s foot, and nail fungus.
Viral infections: skin infections caused by viruses, such as cold sores, warts, and shingles.
Bacterial infections: skin infections caused by bacteria, such as impetigo and cellulitis.
There are many other skin conditions and disorders that can affect the skin, and treatment options vary depending on the specific condition and its severity. It is important to consult with a healthcare provider if you have concerns about your skin health.
Digestive tract
Here are some ways in which each our internal organs can impact our skin health:
Stomach: The stomach serves to break down food into smaller particles that can be absorbed by the body. When the stomach is not functioning properly, it can lead to nutrient deficiencies, such as low levels of proteins, vitamin B12 and iron, which are essential for healthy skin.
Gallbladder: The gallbladder produces bile, which helps to break down fats in the small intestine. Issues with gallbladder function can disrupt the normal uptake of fat-soluble vitamins, such as vitamins A, D, and E, which are important for skin health.
Liver: The liver primarily serves to detoxify the body and regulate hormone levels. When the liver is overloaded with toxins or not functioning properly it can lead to hormonal imbalances that can trigger skin conditions such as acne and eczema.
Pancreas: The pancreas produces enzymes that help to break down food in the small intestine. Improper pancreas function leads to poor absorption of nutrients, which can impact skin health. In addition, pancreatic issues can lead to fat malabsorption, resulting in dry and itchy skin.
Intestines: The intestines are responsible for absorbing nutrients from the food we eat and for eliminating waste products. When the intestines are not functioning properly, it can lead to nutrient deficiencies, malabsorption, and an imbalance in gut bacteria, which can all impact skin health.
In summary, our digestive tract plays a crucial role in maintaining healthy skin. It is important to eat a balanced diet, stay hydrated, and ensure that all our digestive organs are functioning properly to support optimal skin health.
Thyroid gland
Another important internal organ that affects skin health is the thyroid gland. It plays a vital role in regulating many bodily functions, including metabolism and the production of hormones. When the thyroid gland is not functioning properly, it can have a significant impact on skin health.
Thyroid hormone action on skin
Here are some ways in which thyroid issues can affect the skin:
Dry skin: Hypothyroidism, a condition in which the thyroid gland is underactive, can lead to dry skin. This is because the reduced metabolic rate associated with hypothyroidism can lead to decreased oil production in the skin, resulting in dryness.
Hair loss: Both hypothyroidism and hyperthyroidism (a condition in which the thyroid gland is overactive) can cause hair loss. This is because the hormones produced by the thyroid gland help to regulate hair growth.
Changes in skin texture: Thyroid issues can also lead to changes in the texture of the skin. In hypothyroidism, the skin may become rough and dry, while in hyperthyroidism, the skin may become thin and fragile.
Acne: Hyperthyroidism can lead to an increase in sebum production, which can contribute to the development of acne.
Delayed wound healing: Hypothyroidism can lead to delayed wound healing, which may result in longer-lasting scars.
If you are experiencing any of these skin symptoms along with other symptoms such as fatigue, weight gain or weight loss, and mood changes, it is important to talk to your healthcare provider to rule out thyroid issues as the underlying cause. Thyroid issues can often be managed effectively with medication and lifestyle changes. Addressing the underlying thyroid issue may help to improve skin health as well.
Stress
Stress is another significant factor that has an impact on many areas of health, including skin health. Studies have demonstrated that stress can cause skin inflammation, itching, weaken the skin’s ability to act as a barrier, slow down wound healing, and reduce the body’s ability to fight against diseases.
Stress and Skin: An Overview of Mind Body Therapies as a Treatment Strategy in Dermatology
Here are some ways in which stress can affect the skin:
Acne: Stress can trigger the release of hormones that increase oil production in the skin, leading to the development of acne.
Wrinkles and fine lines: Chronic stress can lead to the breakdown of collagen in the skin, which can result in the development of wrinkles and fine lines.
Dryness: Stress can also impact the skin’s ability to retain moisture, leading to dryness and flakiness.
Inflammation: Stress can contribute to inflammation throughout the body, including in the skin. This can exacerbate skin conditions such as psoriasis, eczema, and rosacea.
How can I protect my skin
Nutrition plays a critical role in maintaining healthy skin. A balanced diet that provides adequate amounts of nutrients is essential for healthy skin. Here are some ways in which nutrition can affect skin health:
- Hydration: Proper hydration is essential for maintaining healthy skin. Dehydration can lead to dryness, flakiness, and even wrinkles. Drinking enough water and consuming hydrating foods such as fruits and vegetables can help to keep the skin hydrated and healthy.
- Macronutrients: Adequate intake of macronutrients such as protein, carbohydrates, and healthy fats is essential for maintaining healthy skin. Protein is particularly important in the production of collagen, which is a key component of healthy skin.
- Micronutrients: Certain micronutrients, such as vitamins A, C, and E, as well as minerals such as zinc and selenium, are important for skin. These nutrients play a role in protecting the skin from damage and in supporting collagen production.
- Deficiencies: Deficiencies in certain nutrients can have negative effects on skin health. For example, a deficiency in vitamin C can lead to scurvy, which is characterized by skin changes such as roughness, hyperkeratosis, and petechiae. Similarly, a deficiency in vitamin A can lead to dry, scaly skin.
A balanced diet that includes a variety of fruits, vegetables, whole grains, lean proteins, and healthy fats can help to ensure that the body is receiving the nutrients it needs to support healthy skin. In some cases, supplements may be necessary to address specific nutrient deficiencies.
When dealing with skin problems, it is important to look for the underlying causes, as they are often the basis for the emergence of problems, rather than cosmetic and external factors. Consulting with a healthcare professional or a registered dietician can help to determine the reason for skin problems and choose the best correction strategy and supplementation if necessary.
References
- Anatomy, histology and immunohistochemistry of normal human skin
- Basic histological structure and functions of facial skin
- Anatomy, Skin (Integument), Epidermis
- Histology, Dermis
- Histology, Skin Appendages
- What is the ‘true’ function of skin
- Gut–Skin Axis: Current Knowledge of the Interrelationship between Microbial Dysbiosis and Skin Conditions
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7916842/
- Thyroid hormone action on skin
- Stress and Skin: An Overview of Mind Body Therapies as a Treatment Strategy in Dermatology
