Integumentary system - wikipedia Integumentary system `` Integumentary '' redirects here. For the part of the female reproductive system of seed plants, see Ovule. Integumentary system Cross-section of all skin layers Identifiers Code TH H3. 12.00. 0.00001 TA A16. 0.00. 001 FMA 72979 Anatomical terminology ( edit on Wikidata ) The integumentary system comprises the skin and its appendages acting to protect the body from various kinds of damage, such as loss of water or abrasion from outside. The integumentary system includes hair, scales, feathers, hooves, and nails. It has a variety of additional functions ; it may serve to waterproof, cushion, and protect the deeper tissues, excrete wastes, and regulate temperature, and is the attachment site for sensory receptors to detect pain, sensation, pressure, and temperature. In most land vertebrates with significant exposure to sunlight, the integumentary system also provides for vitamin D synthesis. Contents 1 Skin 1.1 Epidermis 1.2 Dermis 2 Hypodermis 3 Functions 4 Clinical significance 5 References 6 External links Skin The skin is the largest organ in the body. In humans, it accounts for about 12 to 15 percent of total body weight and covers 1.5 - 2m of surface area. The human skin ( integument ) is composed of at least two major layers of tissue : the epidermis and dermis. ( The hypodermis or subcutaneous layer is not part of the skin. ) The epidermis is the outermost layer, providing the initial barrier to the external environment. Beneath this, the dermis comprises two sections, the papillary and reticular layers, and contains connective tissues, vessels, glands, follicles, hair roots, sensory nerve endings, and muscular tissue. The deepest layer, the hypodermis, is primarily made up of adipose tissue. Substantial collagen bundles anchor the dermis to the hypodermis in a way that permits most areas of the skin to move freely over the deeper tissue layers. Epidermis Main article : Epidermis ( skin ) Epidermis and dermis of human skin The epidermis is the top layer of skin made up of epithelial cells. It does not contain blood vessels. Its main functions are protection, absorption of nutrients, and homeostasis. In structure, it consists of a keratinized stratified squamous epithelium comprising four types of cells : keratinocytes, melanocytes, Merkel cells, and Langerhans ' cells. The major cell of the epidermis is the keratinocyte, which produces keratin. Keratin is a fibrous protein that aids in protection. An overwhelming amount of keratin can cause disease and infection as well as some eruptions from the skin that will protrude out of the skin and lead to death. Keratin is also a waterproofing protein. Millions of dead keratinocytes rub off daily. The majority of the skin on the body is keratinized. The only skin on the body that is non-keratinized is the lining of skin on the inside of the mouth. Non-keratinized cells allow water to `` stay '' atop the structure. The protein keratin stiffens epidermal tissue to form fingernails. Nails grow from a thin area called the nail matrix ; growth of nails is 1 mm per week on average. The lunula is the crescent - shape area at the base of the nail, this is a lighter color as it mixes with the matrix cells. Also, the stratum corneum is the top part of the epidermis. Dermis Main article : Dermis The dermis is the middle layer of skin, composed of dense irregular connective tissue and areolar connective tissue such as a collagen with elastin arranged in a diffusely bundled and woven pattern. The dermis has two layers. One is the papillary layer which is the superficial layer and consists of the areolar connective tissue. The other is the reticular layer which is the deep layer of the dermis and consists of the dense irregular connective tissue. These layers serve to give elasticity to the integument, allowing stretching and conferring flexibility, while also resisting distortions, wrinkling, and sagging. The dermal layer provides a site for the endings of blood vessels and nerves. Many chromatophores are also stored in this layer, as are the bases of integumental structures such as hair, feathers, and glands. Hypodermis Main article : Hypodermis The hypodermis, otherwise known as the subcutaneous layer, is a layer beneath the skin. It invaginates into the dermis and is attached to the latter, immediately above it, by collagen and elastin fibres. It is essentially composed of a type of cell known as adipocytes specialised in accumulating and storing fats. These cells are grouped together in lobules separated by connective tissue. The hypodermis acts as an energy reserve. The fats contained in the adipocytes can be put back into circulation, via the venous route, during intense effort or when there is a lack of energy providing substances, and are then transformed into energy. The hypodermis participates, passively at least, in thermoregulation since fat is a heat insulator. Functions The integumentary system has multiple roles in homeostasis. All body systems work in an interconnected manner to maintain the internal conditions essential to the function of the body. The skin has an important job of protecting the body and acts as the body 's first line of defense against infection, temperature change, and other challenges to homeostasis. Functions include : Protect the body 's internal living tissues and organs Protect against invasion by infectious organisms Protect the body from dehydration Protect the body against abrupt changes in temperature, maintain homeostasis Help excrete waste materials through perspiration Act as a receptor for touch, pressure, pain, heat, and cold ( see Somatosensory system ) Protect the body against sunburns by secreting melanin Generate vitamin D through exposure to ultraviolet light Store water, fat, glucose, vitamin D Maintenance of the body form Formation of new cells from stratum germanium to repair minor injuries Protect from UV rays. Regulates body temperature It distinguishes, separates, and protects the organism from its surroundings. Small - bodied invertebrates of aquatic or continually moist habitats respire using the outer layer ( integument ). This gas exchange system, where gases simply diffuse into and out of the interstitial fluid, is called integumentary exchange. Clinical significance Possible diseases and injuries to the human integumentary system include : Rash Yeast Athlete 's foot Infection Sunburn Skin cancer Albinism Acne Herpes Herpes labialis, commonly called cold sores Impetigo Rubella Cancer Psoriasis Rabies Rosacea References Jump up ^ Integumentary System at the US National Library of Medicine Medical Subject Headings ( MeSH ) Jump up ^ Marieb, Elaine ; Katja Hoehn ( 2007 ). Human Anatomy & Physiology ( 7th ed. ). Pearson Benjamin Cummings. p. 142. Jump up ^ `` The Integumentary System ''. Encyclopedia.com. Retrieved 3 June 2013. Jump up ^ Martini & Nath : `` Fundamentals of Anatomy & Physiology '' 8th Edition, pp. 158, Pearson Education, 2009 ^ Jump up to : The Ageing Skin - Structure of Skin Jump up ^ Pratt, Rebecca. `` Integument ''. AnatomyOne. Amirsys, Inc. Retrieved 2012 - 09 - 28. External links The Wikibook Human Physiology has a page on the topic of : Integumentary System Library resources about Integumentary System Resources in your library Human systems and organs Musculoskeletal Skeletal system Bone Carpus Collar bone ( clavicle ) Thigh bone ( femur ) Fibula Humerus Mandible Metacarpus Metatarsus Ossicles Patella Phalanges Radius Skull Tarsus Tibia Ulna Rib Vertebra Pelvis Sternum Cartilage Joints Fibrous joint Cartilaginous joint Synovial joint Muscular system Muscle Tendon Diaphragm Circulatory system Cardiovascular system peripheral Artery Vein Lymphatic vessel Heart Lymphatic system primary Bone marrow Thymus secondary Spleen Lymph node CNS equivalent Glymphatic system Nervous system Brain Spinal cord Nerve Sensory system Ear Eye Integumentary system Skin Subcutaneous tissue Breast Mammary gland Immune system Myeloid Myeloid immune system Lymphoid Lymphoid immune system Respiratory system Upper Nose Nasopharynx Larynx Lower Trachea Bronchus Lung Digestive system Mouth Salivary gland Tongue upper GI Oropharynx Laryngopharynx Esophagus Stomach lower GI Small intestine Appendix Colon Rectum Anus accessory Liver Biliary tract Pancreas Urinary system Genitourinary system Kidney Ureter Bladder Urethra Reproductive system Female Uterus Vagina Vulva Ovary Placenta Male Scrotum Penis Prostate Testicle Seminal vesicle Endocrine system Pituitary Pineal Thyroid Parathyroid Adrenal Islets of Langerhans Skin and related structures Skin Epidermis Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale Basement membrane Basal keratinocyte Lamina lucida Lamina densa Dermis Papillary Dermal papillae Reticular Subcutaneous tissue Panniculus / Pannus ( Panniculus adiposus Panniculus carnosus ) Membranous layer Loose connective tissue Superficial fascia Adnexa Skin glands Sweat glands : Apocrine sweat gland Eccrine sweat gland Sebaceous Hair Root sheath Outer root sheath Inner root sheath Henle 's layer Huxley 's layer Hair shaft Cuticle Cortex Medulla Bulb with matrix cells Hair follicle Muscle Arrector pili muscle Pilosebaceous unit Hair sebaceous gland Nail Nail matrix Nail plate Lunula Eponychium Paronychium Hyponychium Retrieved from `` https://en.wikipedia.org/w/index.php?title=Integumentary_system&oldid=818806206 '' Categories : Integumentary system Organ systems Hidden categories : All articles with unsourced statements Articles with unsourced statements from January 2018 Articles with unsourced statements from March 2017 Talk Contents Help About Wikipedia Alemannisch Aragonés অসমীয়া Asturianu Azərbaycanca বাংলা Bân - lâm - gú Беларуская Беларуская ( тарашкевіца ) ‎ Български Català Čeština Cymraeg Deutsch Ελληνικά Español Esperanto Euskara فارسی Français Gaeilge Galego 한국어 Hrvatski Ido Bahasa Indonesia Interlingua Íslenska Italiano עברית Basa Jawa Latina Limburgs Luganda Nederlands नेपाल भाषा 日本 語 Norsk nynorsk Occitan پنجابی Polski Português Русский සිංහල Simple English Slovenčina Slovenščina کوردی Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska Tagalog தமிழ் ไทย Türkçe Українська Tiếng Việt Winaray 中文 Edit links This page was last edited on 5 January 2018, at 18 : 06. 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Question: what are the two parts of the integumentary system
Answer: the skin