The skin is the largest organ of the body. Measuring between 1.5 and 2.0 square metres in an adult, it forms an extensive contact area with the environment. This contact presents a variety of important challenges, which the skin must meet in order to protect the body. It also provides important opportunities, which the skin uses to maintain homeostasis.
Consider the challenges and opportunities posed by contact with the environment and relate them to the major functions of the skin.
The integumentary system, consisting of skin, hair and nails, act as a barrier to protect the body from the environment. Some challenges and opportunities posed to the skin by the environments are; exposure to sunlight/UV Rays, bacteria, mechanical damage, chemical damage and thermal damage.
The integumentary system acts as a barrier in three ways: a chemical barrier, a physical barrier and a biological barrier. The integumentary system works with the immune system to create a biological barrier. Specialized cells in the skin find and destroy foreign bacteria.
A physical barrier consists of hard, keratinized cells in the nails, skin and hair. These cells especially in skin and nails help protect the internal organs and blood system from external environmental factors. Hair helps to minimalise insects from crawling on the skin, protect the scalp from physical trauma and regulate heat.
A chemical barrier is also due to skin. The skin has sweat glands which secrete substances onto the skin that stop the reproduction of bacteria. The skin also produces melanin which acts to protect ultraviolet rays from the sun however despite melanin’s protective factors excessive sun exposure will eventually damage the skin.
Explain how the structures of the skin contribute to its functions.
The skin is the largest organ in the integumentary system and has 2 major components: the cutaneous membrane or skin and the accessory structures.
The cutaneous membrane has 2 components: the epidermis and the dermis. The epidermis is the outer layer of the skin and the dermis is a layer of skin between the epidermis and subcutaneous tissues.
The accessory structures consists of hair, nails and multicellular exocrine glands.
The epidermis consists of 5 layers; the stratum basale, spinosum, granulosum, lucidum and corneum. The Stratum basale is the outer layer of skin, the stratum spinosum is a layer of the epidermis found between the stratum granulosum and stratum basale. This layer helps to prevent dehydration, the stratum granulosum is the layer between the stratum lucidum and stratum spinosum, the stratum lucidum is a thin, clear layer of dead skin cells. It is found only in areas of thick skin, most noticeably on the palms of the hands and the soles of the feet and finally the stratum corneum is the outermost layer and is filled with keratin, which is made up of dead cells.
The dermis is responsible for the strength of skin. Its main functions are to regulate temperature and to supply the epidermis with nutrient-saturated blood. Much of the body’s water supply is stored within the dermis. The dermis contains most of the skin’s specialized cells and structures, including: Blood vessels, lymph vessels, hair follicles, sweat glands, sebaceous, or oil, glands, nerve endings, collagen and elastin.
The dermis layer is made up of two sublayers, the papillary layer, which contains a thin arrangement of collagen fibers. The papillary layer supplies nutrients to select layers of the epidermis and regulates temperature. The second is the reticular layer which is thicker and made of thick collagen fibers that are arranged in parallel to the surface of the skin. The reticular layer strengthens the skin, providing structure and elasticity.
A layer of tissue that lies immediately below the dermis is the hypodermis or subcutaneous tissue. The hypodermis consists primarily of loose connective tissue and lobules of fat and acts as an energy reserve. It contains larger blood vessels and nerves than those found in the dermis. The hypodermis contains: elastic fibers, fibrous bands, fat, blood vessels, lymphatic vessels, hair follicle roots, nerves and muscle.
The skin includes the following functions; protection, sensation, heat regulation, control of evaporation, storage and synthesis, absorption, water resistance.
The structures of the skin all work together to maintain the important functions.
You are exercising on a hot day. Explain two ways in which the integumentary system acts to preserve homeostasis
Two ways in which the integumentary system acts to preserve homeostasis are sweating and vasodilation.
Homeostasis is a term for your body’s ability to regulate your internal state, and sweating is an example of this. If your body temperature gets too high, one of the homeostatic mechanisms used to bring your temp back to normal is sweating.
Eccrine sweat glands are the major sweat glands of the human body, found in virtually all skin. Sweat is clear secretion that is primarily water and salt (sodium chloride).
Sweat reaches the skin via a duct that opens externally as a funnel shaped pore. Eccrine sweat glands are a highly efficient part of the heat regulating system, they are supplied with nerve endings that cause them to secrete sweat when the body’s temperature gets too high. When sweat evaporates off the skins surface it takes body heat with it. On a hot day you could lose up to 7 litres of body water.
Another way the integumentary system acts to preserve homeostasis is vasodilation. Blood vessels supplying blood to the skin can swell or dilate – called vasodilation. This causes more heat to be carried by the blood to the skin, where it can be lost to the air however if the external environment is as hot as or hotter than the body the only way to release heat is through evaporation of perspiration.
This is an efficient source of heat loss as long as the air is dry, if it is humid evaporation occurs at a much slower rate leaving the person hot and irritated.
When the body cools down the hypothalamus through the autonomic nervous system tells the ‘heat loss’ centre to switch off.
Indicate how ageing affects the skin and explain how these changes affect its normal function.
As people age their epidermal cell replacement slows therefore the skin begins to thin resulting in an increase of bruising and other types of injury. The lubricating substances provided by the skin glands that provides young looking and soft skin start to become less efficient, resulting in dry itchy skin. Elastic fibers and collagen fibers become fewer and stiffer so the skin has much less elasticity resulting in wrinkles.
The decrease in numbers of melanocytes and langerhans cells produced can enhance the risk of skin cancer in older age, especially if alot of ultraviolet rays are absorbed.
UV rays are a major contribution to the rapidity of skins aging. Over time, the sun’s rays damage certain fibers in the skin called elastin. The breakdown of elastin fibers causes the skin to sag and take longer to heal.
Ageing also affects things below the skin; loss of fat below the skin may result in loosening skin, bone loss after the age of 60 can cause puckering of the skin around the mouth, cartilage loss in the nose causes drooping of the nasal tip.
Smokers also tend to have more wrinkles than non-smokers of the same age.
Skin changes associated with ageing pose particular problems for nurses caring for elderly people.
Outline the nursing principles involved in skin care in the elderly.
Elderly patients are prone to skin tears, ulcers, abrasions, irritation and infection especially if they are diabetic. If proper skin care is not adhered to, it can result in sores, dry/painful skin and even gangrene.
When an elderly patient is bathing the temperature of the water should be warm rather than hot as elderly people’s skin does not contain as much oil as it once did, if all the oil is washed away, their skin is more susceptible to breaking, which can lead to infection.
A mild soap should always be used as it is not harsh on their skin and helps prevent it from becoming dry.
Due to the loss of natural oils in the skin, it is necessary to apply a moisturizing lotion after a bath and multiple times through the day. Using a moisturizer helps reduce the itchiness, and the likelihood of infection.
It is not uncommon for some elderly patients to be confined to their bed 24 hours a day. This is when skin care is vital, especially if they are incontinent of bowel and bladder, washing and drying the area regularly can reduce the risk of a fungal infection forming.
Elderly skin must be observed regularly to check for changes such as moles.
Workbook 3 Integumentary system
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