Role of the integumentary system in protecting the body
Introduction
Human body, like all higher order vertebrates, relies on multiple organ systems for maintenance of homeostasis, the integumentary system is but one of them. Anatomically, the integumentary system has two components :the cutaneous membrane(the skin) and its accessory structures. The skin comprises of the dermis and epidermis whereas the later include hair, nails, and exocrine glands located in the dermis. Interestingly, both the cutaneous and accessory structures share a common embryological origin: The ectoderm (Martini 2005, p.151). With respect to functioning, the skin is involved in a variety of physiologic functions, the most obvious being protection of the underlying cells from damage and dehydration. Other functions include excretion, synthesis of vitamin D, nutrient storage, thermoregulation, and sensation (Bhise 2008, p, 121). This paper focuses on the protection function of the skin as discussed under mechanical protection; protection from dehydration; the body defense role of the skin , protection via sensation; and protection against premature aging and skin cancer.
Integumentary and Mechanical protection as a role of the skin
The integumentarysystem perse is involved in mechanical protection of the underlying tissues such as muscles, bones, and internal organs. This role will be discussed in the light of protection against mechanical and chemical harm. In connection to the accidental trauma to the skin through physical means such as abrasion is inevitable. Additionally, human get into contact with numerous chemical agents that have potential to corrode the skin. However, few are the times that physical and chemical harm result despite the many hazards, courtesy of the most superficial layer of the epidermis called stratum corneum, which is composed of non-living remnants of keratinocytes. Besides, this layerhelps protect against dehydration. It is therefore prudent to analyse its functional unit:Keretin(Clark &Pflinger 2004,p.2). It is also important to recognise the dermis, which is the layer of skin between the epidermis and subcateneous tissues. It is vital in thermoregulation.
Formation And Functions Of Stratum Corneum
Stratum corneum is a keratin-rich layer that helps protect against minor physical trauma and corrosion. Keratin is a tough and durable fibrous protein that is also water resistant. This layer of cornified cells is regenerative : Keratinocytes are continually formed from large stem cells dividing in the innermost layer of the epidermis called stratum germinativum. According to Martin et al. (2009.p.153) it takes 15-30 days for a cell to move from fom stratum germinativum to stratum corneum; in between the two are stratum spinosum, stratum granulosum and Stratum lucidum in the order of innermost to outermost layer. In fact, the transition of a cell from the terminative layer to the outermost layer underlies the process of keratinization, which also underlies the natural death of skin cells(Robert 2009, p.392).
Every dividing stem cell in stratum germinativum produces a daughter cell that is pushed into the next layer, the stratum spinosum. Keratinocytes in this layer are bound by desmosomes. With time, these cells are displaced into the stratum granulosum layer; the Keratinocytes also ceases to divide and instead the cell nuclei and other cell organelles begin to degenerate. Besides, the cells also begin producing a protection called keratohyalin, which is a keratin precursor. Soon after, the cells reach the stratum lucidum and begin to produce eliding, a closer keratin precursor. Ultimately, the cells lose all organelles (dies) and becomes thinner and flatter. Subsequently, dehydration produces a tightly interlocked keratin layer. The Keratinocytes are now in the stratum corneum, which comprises of 15-30 layers of cornfield cells. These Keratinocytesgradually become shed-off or washed away with two weeks. It therefore suffices to say that he stratum corneum forms a protective barrier to the epithelium and underlying tissues(Longo et al. 2012,pp.392-393)
Role Of The Skin In Protection From Dehydration
The role of Keratin
As earlier hypothesized, the protection function of the skin against dehydration also lies in the stratum corneum layer. Keratin is not only tough and durable but also water resistant(Lewis, Heikkeniger&Dirkisin 2008, p. 476). This phenomenon allows protection against dehydration emanating from complication in burns, a disorder in which the cornfield layer is damaged. Perhaps, dehydration would be inevitable were it not for the stratum corneum layer if the approximate 500 ml daily physiologic water loss is anything to go by. This physiologic lose is termed as insensible perspiration; the rate of insensible perspiration drastically increases if the stratum corneum is damaged.
The role of sebaceous glands
Moreover, the sebaceous glands also play a synergistic role in protection against dehydration. Sebaceous glands are holocrine communication with hair follicles; they secrete an oily secretion called sebum. Sebum consists of a mixture of cholesterol, triglycerides, electrolytes and proteins. Importantly, presence of the first components makes sebum primarily oily in nature. Release of sebum into the lumen of the glands involves a combination of holocrine secretion and contraction of the arrectorpili muscles. The later forces the secretion onto the skin surface via hair follicle. Upon reaching the skin surface, sebum lubricates keratin on both the skin and hair follicles. Lubricating the cornified layer enhances its protective function against dehydration (Martinin et al.2009,p.153).
The body defence role of the skin: A function of sebaceous gland and keratin
Importantly, sebaceous glands also confer an immunologic advantage because sebum has an antiseptic property that inhibits bacterial growth other than that of skin’s normal flora. In fact, this immunologic role acts alongside the mechanical defence role of keratin in the cornified layer. Mechanical defence occurs because Keratin is a layer of dead cells that requires abrasion for living cells underneath to be reached. Besides, the waxy nature of sebum increases the integrity of the skin. For an infection to occur (even involving the normal flora), this skin integrity must be broken(Martini et al.2008,p161). This explains why frequent shampooing predisposes an individual to bacterial skin infections like carbuncles, which involves Staphylococcus aureus, anormal flora(Lewis, Heitkeniger & Dirkisin 2008, p.477).
Additionally, the rationale behind stopping the of hand brushes during surgical scrubbing lies in the same school of thought: Breaking the skin integrity and hence exposing practitioners to potentially infectious patients’ secretions (Lewis, Heitkeniger & Dirkisin 2008, p.479). Interestingly, the Stratum spinosum layer of the skin also harbors Langerhans cells: Macrophages cells mediate in the events of immunologic response by getting rid of the worn out and infected cells and debris in the event that any microorganisms penetrate the first three layer of the skin. In fact, these defence and immunologic roles of the skin are together termed as the first line defence mechanisms of the body (Martini et al. 2009,p.154).
The sensory function of the skin in protection
Additionally, the skin has an elaborate sensory function that helps detect noxious agents well before they cause harm. This is a function of sensory receptors in the dermis of the skin, which include nociceptors (pain receptors), thermo receptors, and mechanoreceptors. However, nociceptors appear to-also-play the role of the last two because they are sensitive to temperature extremes, mechanical damage, and dissolved chemicals precisely (Martini, nath ,& Bartholomew 2012), skin mechanoreceptors include free nerve endings for touch and pressure; tactile receptors for touch, pressure, and vibration; Meissner’s corpuscles for fine touch; Merkel’s cells for fine touch and pressure; Ruffini cells for pressure; and Pacinian corpuscles for high frequency vibrations. Together, all these receptors help protect the body against chemical, mechanical, and thermal damage, often via withdrawal reflexes (Martini et al. 2009, p. 157).
However, nociceptors appear to- also-play the role of the last two because they are sensitive to temperature extremes, mechanical damage, and dissolved chemicals precisely (Martini et al. 2009,p.158)., skin mechanoreceptors include free nerve endings for touch and pressure; tactile receptors for touch, pressure, and vibration; Meissner’s corpuscles for fine touch; Merkel’s cells for fine touch and pressure; Ruffini cells for pressure; and Pacinian corpuscles for high frequency vibrations. Together, all these receptors help protect the body against chemical, mechanical, and thermal damage, often via withdrawal reflexes (Martini et al. 2009, p. 157).
Protection against premature aging and skin cancer: The role of Melanocytes
The skin also functions to protect the body against non-infectious diseases, precisely skin cancer and premature wrinkling. This function is achieved through melanocytes found in the startumbasale. Melanocytes utilize tyrosine to synthesize a dark pigment called melanin, which is then stored in intracellular vesicles that are then injected into Keratinocytes in startumbasale and later startumspinosum (Lewis, Heitkeniger&Dirkisin 2008, p. 476). Melanin concentrates around the nucleus of cells in these two layers and thereby protects their nucleus against UV radiation. Otherwise, continued exposure to UV would easily damage fibroblasts leading to premature wrinkling. Moreover, UV may also damage chromosomes in melanocytes and germinitive cells and therefore cause skin cancer
Protection via thermoregulation
Finally, thermoregulation function of the skin is also protective because temperature extremes (hypothermia and hyperthermia) would denature enzymes in the body (Martini & Bartholomew 2012, p.99). In either of these conditions, normal physiologic process would stall; conditions of extreme hypothermia(below35°C) and hyperthermia(above 38°C) indeed fatal. Thermoregulation is achieved through increased sweating,
Arteriolar vasodilation and relaxation of the erector pili muscles. Evaporation of sweat causes latent heat loss while vasodilation increases via convection as blood flows more superficially. On the other hand, relaxation of erector pili muscles keeps hair follicles: This reduces the ability to “insulate” the skin with a pre-warmed layer of air is also known as vasoconstriction (Robert 2009, p. 397).
Conclusion
The skin is not only the largest organ of the integumentary system but also a very important organ for various physiological processes. Amongst the protective roles of the skin include protection from dehydration, infection, and physical trauma. The Keratinized epidermal layer, sebaceous glands, and sensory receptors help achieve these roles. In conclusion, this paper has sought to explain in detail all the protective features of the skin. It’s crucial role being acting as a physical barrier which protects the body from pathogens which exists in the external environment and also regulation of other various physiological processes in our bodies.
Reference list
Martini, f., nath, j. L., &bartholomew, e. F. (2012). Fundamentals of anatomy & physiology. San
Francisco, Benjamin Cummings.
