File Name: skin structure and function .zip
The Structure and Function of Skin, Third Edition is devoted to all matters pertaining to the structure and function of the skin. Drawing upon the accumulated data derived from embryology, histology, anatomy, physiology, biochemistry, and pharmacology, this book presents an overview of skin, with emphasis on human skin. Topics range from the biological functions of the dermis to the histochemical and microchemical properties of the epidermis; the effects of protein deficiency on hair growth; cutaneous innervation; nail regeneration and growth; sebaceous glands; and eccrine sweat glands.
Nutrition influences skin structure; however, a systematic investigation into how energy and macronutrients protein, carbohydrate and fat affects the skin has yet to be conducted. We evaluated the associations between macronutrients, energy intake and skin structure in mice fed 25 experimental diets and a control diet for 15 months using the Geometric Framework, a novel method of nutritional analysis. Skin structure was associated with the ratio of dietary macronutrients eaten, not energy intake, and the nature of the effect differed between the sexes. In males, skin structure was primarily associated with protein intake, whereas in females carbohydrate intake was the primary correlate.
DermNet provides Google Translate, a free machine translation service. Note that this may not provide an exact translation in all languages. The skin of an adult occupies an area of 1. It varies in thickness from 0.
The thinnest sites are the eyelids a few cells thick and scrotum. The thickest are the soles and palms about 30 cells thick. Normal skin Diagram showing structural. These layers are modified according to the needs of the specific area of the body. For example, the scalp is covered with thick hair , the palms have particularly thick epidermis and the face contains large numbers of sebaceous glands.
Acid mantle Skin has an average pH value of 5. This is the result of acidic substances such as amino acids , lactic acid and fatty acids in perspiration, sebum and the hormones.
There are resident protective microflora bacteria and yeasts but the acid mantle repels pathogenic micro- organisms and reduces body odour. Epidermis The epidermis is a dynamic structure acting as a semi- permeable barrier with a layer of flat anuclear cells at the surface stratum corneum. The epidermis regenerates in orderly fashion by cell division of keratinocytes in the basal layer , with maturing daughter cells becoming increasingly keratinised as they move to the skin surface.
Immune cells within the epidermis recognise and process small molecules penetrating the skin surface. Pigment cells in the basal layer melanocytes protect the skin from ultraviolet radiation. The basement membrane zone is the communication channel between epidermis and dermis.
The epidermis has a complex structure designed to protect from the environment. It has an undulating surface with cross-crossing ridges and valleys, with invaginations due to follicles and sweat duct ostia. Epidermis is thickest on palms and soles, and thinnest on eyelid and scrotum. Friction ridges Ridges are particularly well developed on the fingers and toes where they are known as friction ridges with characteristic patterns commonly referred to as fingerprints.
The science of ridgeology has been well developed for forensic purposes. Friction ridges Friction ridges.
The speed of renewal is greater if the epidermis is injured and in certain skin diseases particularly psoriasis. Keratinocytes are created in the basal layer and gradually move towards the surface, flattening out and becoming more differentiated towards the anuclear horny cell of the stratum corneum.
The appearance and structure of normal skin varies according to the site of origin of the tissue and the age, sex and ethnicity of the subject. Take the Structure of the epidermis quiz. See smartphone apps to check your skin. DermNet NZ does not provide an online consultation service.
If you have any concerns with your skin or its treatment, see a dermatologist for advice. Principles of dermatological practice. The prevalence of skin diseases. Structure of the epidermis quiz. Modern evaluative friction ridge identification — pdf file download Books about skin diseases Books about the skin Dermatology Made Easy book. Columnar cells derived from ectoderm. Stain with haematoxylin i. Produce protein keratin and lipids. Produce inflammatory cytokines including interleukin Express adhesion molecules.
Attached to surrounding cells by desmosomes. Dividing cells with a roughly day cycle. Daughter cells move to surface to form stratum corneum 28 to days. Dendritic cells with clear cytoplasm and small dark-staining nuclei.
Derived from neural crest. Ratio to basal keratinocytes is Produce melanin in melanosomes. Dendritic processes allow transfer of melanin to adjacent keratinocytes by pinocytosis tips of dendrites pinched off and engulfed. Similar number of melanocytes in all races but melanogenesis is variable. White skin: melanin mainly in basal layer.
Blacks: melanin throughout epidermis. Tanning: melanin shifts into keratinocytes, production increased. Touch sensory-mechanical receptors. Scarce small round cells found only using electron microscopy. Most numerous in palms and soles. Probably neural crest derived, possibly from keratinocytes. Attached to keratinocytes by desmosomes.
Daughter cells produced by basal cells progress outwards. Communicate with surrounding keratinocytes, melanocytes and Langerhans cells.
Derived from bone marrow. Antigen -presenting cell: collects contact antigens and presents them to sensitised T lymphocytes. Circulate via dermal lymphatics to regional lymph nodes. Attached to cell membrane opposite similar complex on adjacent cell. Tonofilaments connect the keratinocyte cytoplasm with the desmosome.
In the intercellular space there is a lattice-work transmembrane linker. Desmosomes make and break as keratinocytes move from basal layer to surface. Migrating neutrophils , eosinophils , lymphocytes, erythrocytes can be present in epidermis transiently in diseased states. Thin homogeneous eosinophilic area no organelles visible. Cytoplasm contains keratin filaments. Most obvious in areas of friction e. Vertical stacks of flat cells move outwards over 14 days.
At base, adherent cell membranes. At top, cells loosen and fall off. Readily absorb and lose water. Eccrine glands. Sweat glands produce hypotonic solution of water, sodium chloride, urea, ammonia and uric acid. Abundant, except vermilion of lips, labia minora, glans penis, prepuce. Most dense on palms, soles, axillae and forehead.
Sweat on palms and soles enhances grip. Secretory coil deep in dermis, duct opens directly onto skin surface. Duct composed of two layers of small cuboidal cells. Immune function: secrete IgA. Hypothalamic control via specific nerve fibres results in increased production with heat, emotional stress and spicy foods.
Develop tolerance to high ambient temperatures by increased sweat production and increasing hypotonicity. Apocrine glands. Scent glands that become active after puberty. Mainly found in axillae and perianal regions. Primary secretion is thick and odourless; smell derives from bacterial colonisation. Terminal hair on scalp; vellus hair on body surface short, thin, light coloured. None on palms and soles. Root sheath buds downward from epithelium at a consistent angle, depending on site.
Growth phase anagen with pointed tip lasts several years; short involutional phase catagen ; resting phase for several months, with clubbed or bulbous tip telogen.
Hair cortex is produced at a rapid metabolic rate from medulla loose cuboidal cells within hair bulb. Cortex contains densely packed keratin with extra sulphur and cystine. Cortex surrounded by cuticle : a single layer of shingle-like cells.
Anatomy and physiology of hair Structure of hair bulb Phases of hair cycle. Most concentrated on scalp and face where circulating androgens induce increased secretion at puberty. Several lobules lead into common excretory duct, mostly opening into outer portion of hair follicle.
Opens directly onto skin surface on labia, prepuce, nipple and areola. Produce sebum: triglycerides , phosopholipids, esterified cholesterol.
If your institution subscribes to this resource, and you don't have a MyAccess Profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus. Please consult the latest official manual style if you have any questions regarding the format accuracy. The skin is the site of many complex and dynamic processes as demonstrated in Figure and Table These processes include barrier and immunologic functions, melanin production, vitamin D synthesis, sensation, temperature regulation, protection from trauma and aesthetics. The epidermal barrier protects the skin from microbes, chemicals, physical trauma, and desiccation due to transepidermal water loss. The keratinocytes of the epidermis are produced and renewed by stem cells in the basal layer resulting in replacement of the epidermis approximately every 28 days. It takes 14 days for these cells to reach the stratum corneum and another 14 days for the cells to desquamate.
Abstract · 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.
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.
Danby, Michael J. Cork, Georgios N. Skin physiology is dynamically changing over the first years of postnatal life; however, ethnic variations are still unclear.
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c: Sweat pores fed by sweat glands open to the cristae cutis (arrows). 1. Structure and Function of the Skin. The skin is the human body's its largest organ, covering.Reply
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The human skin is the outer covering of the body and is the largest organ of the integumentary system.Reply
Its most obvious job is to protect our insides from the outside, but there is much more to the skin than that.Reply