anatomy and physiology of the integumentary system pdf

Anatomy And Physiology Of The Integumentary System Pdf

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Nurses need to understand the skin and its functions to identify and manage skin problems. This article comes with a self-assessment enabling you to test your knowledge after reading it. Nurses observe the skin of their patients daily and it is important they understand the skin so they can recognise problems when they arise.

Ultrastructure of Skin

Nurses need to understand the skin and its functions to identify and manage skin problems. This article comes with a self-assessment enabling you to test your knowledge after reading it. Nurses observe the skin of their patients daily and it is important they understand the skin so they can recognise problems when they arise.

This article, the first in a two-part series on the skin, looks at its structure and function. Citation: Lawton S Skin 1: the structure and functions of the skin.

Nursing Times [online]; , 12, Nurses will observe the skin daily while caring for patients and it is important they understand it so they can recognise problems when they arise. The skin and its appendages nails, hair and certain glands form the largest organ in the human body, with a surface area of 2m2 Hughes, This article reviews its structure and functions.

The epidermis is composed mainly of keratinocytes. Beneath the epidermis is the basement membrane also known as the dermo-epidermal junction ; this narrow, multilayered structure anchors the epidermis to the dermis. The layer below the dermis, the hypodermis, consists largely of fat. These structures are described below. The epidermis is the outer layer of the skin, defined as a stratified squamous epithelium, primarily comprising keratinocytes in progressive stages of differentiation Amirlak and Shahabi, Keratinocytes produce the protein keratin and are the major building blocks cells of the epidermis.

As the epidermis is avascular contains no blood vessels , it is entirely dependent on the underlying dermis for nutrient delivery and waste disposal through the basement membrane.

At the same time, it prevents the loss of water and maintains internal homeostasis Gawkrodger, ; Cork, The epidermis is composed of layers; most body parts have four layers, but those with the thickest skin have five. The layers are:. The epidermis also contains other cell structures. Keratinocytes are formed by division in the stratum basale. As they move up through the stratum spinosum and stratum granulosum, they differentiate to form a rigid internal structure of keratin, microfilaments and microtubules keratinisation.

The outer layer of the epidermis, the stratum corneum, is composed of layers of flattened dead cells corneocytes that have lost their nucleus. Between these corneocytes there is a complex mixture of lipids and proteins Cork, ; these intercellular lipids are broken down by enzymes from keratinocytes to produce a lipid mixture of ceramides phospholipids , fatty acids and cholesterol.

The stratum corneum can be visualised as a brick wall, with the corneocytes forming the bricks and lamellar lipids forming the mortar. As corneocytes contain a water-retaining substance — a natural moisturising factor — they attract and hold water. The high water content of the corneocytes causes them to swell, keeping the stratum corneum pliable and elastic, and preventing the formation of fissures and cracks Holden et al, ; Cork, This is an important consideration when applying topical medications to the skin.

These are absorbed through the epidermal barrier into the underlying tissues and structures percutaneous absorption and transferred to the systemic circulation. The stratum corneum regulates the amount and rate of percutaneous absorption Rudy and Parham-Vetter, One of the most important factors affecting this is skin hydration and environmental humidity. In healthy skin with normal hydration, medication can only penetrate the stratum corneum by passing through the tight, relatively dry, lipid barrier between cells.

When skin hydration is increased or the normal skin barrier is impaired as a result of skin disease, excoriations, erosions, fissuring or prematurity, percutaneous absorption will be increased Rudy and Parham-Vetter, Melanocytes are found in the stratum basale and are scattered among the keratinocytes along the basement membrane at a ratio of one melanocyte to 10 basal cells.

They produce the pigment melanin, manufactured from tyrosine, which is an amino acid, packaged into cellular vesicles called melanosomes, and transported and delivered into the cytoplasm of the keratinocytes Graham-Brown and Bourke, The main function of melanin is to absorb ultraviolet UV radiation to protect us from its harmful effects. Skin colour is determined not by the number of melanocytes, but by the number and size of the melanosomes Gawkrodger, It is influenced by several pigments, including melanin, carotene and haemoglobin.

Melanin is transferred into the keratinocytes via a melanosome; the colour of the skin therefore depends of the amount of melanin produced by melanocytes in the stratum basale and taken up by keratinocytes. Skin colour is also influenced by exposure to UV radiation, genetic factors and hormonal influences Biga et al, Langerhans cells.

These are antigen micro-organisms and foreign proteins -presenting cells found in the stratum spinosum. Merkel cells. These cells are only present in very small numbers in the stratum basale. They are closely associated with terminal filaments of cutaneous nerves and seem to have a role in sensation, especially in areas of the body such as palms, soles and genitalia Gawkrodger, ; White and Butcher, This is a narrow, undulating, multi-layered structure lying between the epidermis and dermis, which supplies cohesion between the two layers Amirlak and Shahabi, ; Graham-Brown and Bourke, It is composed of two layers:.

The lamina lucida is the thinner layer and lies directly beneath the stratum basale. The thicker lamina densa is in direct contact with the underlying dermis. It undulates between the dermis and epidermis and is connected via rete ridges called dermal papillas, which contain capillary loops supplying the epidermis with nutrients and oxygen. This highly irregular junction greatly increases the surface area over which the exchange of oxygen, nutrients and waste products occurs between the dermis and the epidermis Amirlak and Shahabi, The dermis forms the inner layer of the skin and is much thicker than the epidermis mm White and Butcher, Situated between the basement membrane zone and the subcutaneous layer, the primary role of the dermis is to sustain and support the epidermis.

The main functions of the dermis are:. The network of interlacing connective tissue, which is its major component, is made up of collagen, in the main, with some elastin.

Scattered within the dermis are several specialised cells mast cells and fibroblasts and structures blood vessels, lymphatics, sweat glands and nerves. The epidermal appendages also lie within the dermis or subcutaneous layers, but connect with the surface of the skin Graham-Brown and Bourke, The papillary dermis is the thinner layer, consisting of loose connective tissue containing capillaries, elastic fibres and some collagen.

The reticular dermis consists of a thicker layer of dense connective tissue containing larger blood vessels, closely interlaced elastic fibres and thicker bundles of collagen White and Butcher, It also contains fibroblasts, mast cells, nerve endings, lymphatics and epidermal appendages.

Surrounding these structures is a viscous gel that:. Specialised dermal cells and structures. The fibroblast is the major cell type of the dermis and its main function is to synthesise collagen, elastin and the viscous gel within the dermis. Mast cells contain granules of vasoactive chemicals the main one being histamine. They are involved in moderating immune and inflammatory responses in the skin Graham-Brown and Bourke, Blood vessels in the dermis form a complex network and play an important part in thermoregulation.

These vessels can be divided into two distinct networks:. The lymphatic drainage of the skin is important, the main function being to conserve plasma proteins and scavenge foreign material, antigenic substances and bacteria Amirlak and Shahabi, Free sensory nerve endings are found in the dermis as well as the epidermis Merkel cells and detect pain, itch and temperature.

The autonomic nerves supply the blood vessels and sweat glands and arrector pili muscles attached to the hair Gawkrodger, The hypodermis is the subcutaneous layer lying below the dermis; it consists largely of fat. It provides the main structural support for the skin, as well as insulating the body from cold and aiding shock absorption. It is interlaced with blood vessels and nerves. Within this, it performs several important and vital physiological functions, as outlined below Graham-Brown and Bourke, This is achieved by alterations to the blood flow through the cutaneous vascular bed.

The secretion and evaporation of sweat from the surface of the skin also helps to cool the body. This is important for patients with a skin condition, as pain and itching can be extreme for many and cause great distress. Also touch is important for many patients who feel isolated by their skin as a result of colour, disease or the perceptions of others as many experience the fact that they are seen as dirty or contagious and should not be touched.

The skin is an important immunological organ, made up of key structures and cells. Depending on the immunological response, a variety of cells and chemical messengers cytokines are involved. These specialised cells and their functions will be covered later.

The skin is involved in several biochemical processes. The liver converts cholecalciferol to calcidiol, which is then converted to calcitriol the active chemical form of the vitamin in the kidneys. How an individual is perceived by others is important. People make judgements based on what they see and may form their first impression of someone based on how that person looks.

Throughout history, people have been judged because of their skin, for example, due to its colour or the presence of a skin condition or scarring. Skin conditions are visible — in this skin-, beauty- and image-conscious society, the way patients are accepted by other people is an important consideration for nurses.

This article gives an overview of the structure and functions of the skin. Part 2 will provide an overview of the accessory structures of the skin and their functions. Tagged with: Newly qualified nurses: systems of life. Sign in or Register a new account to join the discussion. You are here: Dermatology. Skin 1: the structure and functions of the skin. This article has been double-blind peer reviewed Scroll down to read the article or download a print-friendly PDF here if the PDF fails to fully download please try again using a different browser Assess your knowledge and gain CPD evidence by taking the Nursing Times Self-assessment test Read part 2 of this series here.

Biga LM et al Anatomy and Physiology. The integumentary system 5. Cork MJ The importance of skin barrier function. Edinburgh: Churchill Livingstone. London: Mosby.

Chapter 4: The skin, hair and nails

Common integument refers to skin and subcutaneous tissue, hair, nails, and breast. The last-named is described with the upper limb. The skin cutis provides a waterproof and protective covering for the body, contains sensory nerve endings, and aids in the regulation of temperature. The skin is important, not only in general medical diagnosis and surgery, but also as the seat of many diseases of its own. The study of these is called dermatology Gk derma, skin. The area of the body surface is about 2 sq m.

5.1 Layers of the Skin

What do you think when you look at your skin in the mirror? Do you think about covering it with makeup, adding a tattoo, or maybe a body piercing? The integumentary system refers to the skin and its accessory structures, and it is responsible for much more than simply lending to your outward appearance.

Accessory structures of the skin include hair, nails, sweat glands, and sebaceous glands. These structures embryologically originate from the epidermis and can extend down through the dermis into the hypodermis. Hair is a keratinous filament growing out of the epidermis. It is primarily made of dead, keratinized cells.

This article, which forms part of the life sciences series, examines the anatomy and physiology of skin, also termed the integumentary system. Skin is composed of two main layers, the epidermis and dermis. The structure of the epidermis and dermis are described and their functions are discussed. Accessory structures, such as nails and hair are also considered. Although many diseases of the skin exist, two common conditions — psoriasis and decubitus ulcers — are described in this article.


Although you may not typically think of the skin as an organ, it is in fact made of tissues that work together as a single structure to perform unique and critical functions. The skin and its accessory structures make up the integumentary system , which provides the body with overall protection. The skin is made of multiple layers of cells and tissues, which are held to underlying structures by connective tissue Figure 5. The most superficial layer of the skin is the epidermis which is attached to the deeper dermis. Accessory structures, hair, glands, and nails, are found associated with the skin.

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Сохраняя ледяное спокойствие, Сьюзан ткнула указательным пальцем в твердокаменную грудь Хейла и заставила его остановиться. Хейл в шоке отпрянул, поняв, что она не шутит: Сьюзан Флетчер никогда еще до него не дотрагивалась, даже руки не коснулась. Правда, это было не то прикосновение, какое он рисовал в воображении, представляя себе их первый физический контакт, но все же… Хейл долго с изумлением смотрел на нее, затем медленно повернулся и направился к своему терминалу. Одно ему было абсолютно ясно: распрекрасная Сьюзан Флетчер бьется над чем-то очень важным, и можно поклясться, что это никакая не диагностика. ГЛАВА 28 Сеньор Ролдан восседал за своим столом в агентстве сопровождения Белена, чрезвычайно довольный тем, как умело обошел глупую полицейскую ловушку. Немецкий акцент и просьба снять девушку на ночь - это же очевидная подстава. Интересно, что они еще придумают.

Accessory Structures of the Skin

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The Skin. • The integument system consists of the skin (cutaneous membrane) and its accessory organs. • The skin is composed of three layers of tissue: the.


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