The Integumentary System PDF

At the end of the session, the students should be able to:  Describe the structure and layer of the skin and its function 1. epidermis 2. dermis 3. subcutaneous layer  Describe the supporting layer of the skin  Explain the basis for skin color function and variation  D...

At the end of the session, the students should be able to:  Describe the structure and layer of the skin and its function 1. epidermis 2. dermis 3. subcutaneous layer  Describe the supporting layer of the skin  Explain the basis for skin color function and variation  Describe the structure and functions of the accessory structure of the skin 1. Hair 2. Skin glands 3. Nails  Discuss the function of the skin  The integumentary make up from the skin and glands, hair, nails and other structures  Contact with the external environment as it is outside of the body  It is the largest organ of the body in surface area & weight - is about 2 square meters (22 square feet) and weighs 4.5–5kg (16% of body weight)  Dermatology is the medical specialty that deals with diagnosing and treating skin disorders  It is 0.5–4 mm thick, thinnest on the eyelids, thickest on the heels  We lose almost a kg of skin epithelium a year that becomes a major part of household “dust”  The surface area distribution is estimated by ‘rules of nines’  Useful in assessing the area of skin involved in burns Distribution of body surface  Head & neck - 9 %  Each upper limb – 9%  Front of trunk – upper 9 %, lower 9 % (whole of anterior trunk 18%)  Back of trunk including buttocks – upper 9 %, lower 9 % (whole of posterior trunk 18 %)  Each lower limb – posterior 9 %, anterior 9 % (whole of each lower limb 18 %) The skin has 3 major layers:  Epidermis  Dermis  Subcutaneous layer or hypodermis  Most outer layer of skin & avascular  Composed of keratinized stratified squamous epithelium  Divided into 4 -5 layers of cell - stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum and stratum basale Stratum corneum  Most superficial layer & much ticker  Consists of dead cells known as squames  The cells are continuously shed & replaced by cell from deeper layer  It is waterproof & serve as an effective barrier against light & heat waves, bacteria and many chemicals Stratum lucidum  Only present in non- hairy skin (fingers, palms, and soles)  Absent in thin skin  Appear thin, clear & translucent – homogenous region between stratum granulosum & stratum corneum  Consists of several rows of flat, dead cells Stratum granulosum  contains keratin & lamellar granules  Keratinization begin in this layer Stratum spinosum  layer of 8-10 keratinocytes  provides strength and flexibility to the skin  contains dendritic cells which aid the immune response Stratum basale  Deepest layer of the epidermis next to basement membrane  Closest to the blood supply  Contains stem cells that able to go for cell division to form new cells  Contain melanocytes & tactile epithelial cells (sensory receptor)  Melanocytes – produce melanin  Dandruff is an excess of keratinized cells shed from the scalp  Psoriasis is a chronic skin disorder characterized by a more rapid division and movement of keratinocytes through the epidermal strata Prolonged exposure to the harmful radiation in sunlight lead to 3 types of skin cancer 1. Basal cell carcinoma – UV exposure damages cell in the stratum basale 2. Squamous cell carcinoma – due to exposure to UV or carcinogen such as tar and oil chemicals. Appear like ulcer-like sore 3. Malignant melanoma – due to radiation damage to melanocytes. May developed from an existing mole  New skin cannot regenerate if injury destroy stratum basale  A skin graft is the transfer of a patch of healthy skin taken from donor site from the same individual  Contain blood cells, lymphatic, nerves, hairs, nails & glands  Functions - provides temperature stability and prevents dehydration  Had 2 regions/layer – papillary region & reticular region Papillary region  Lies just below the epidermis  Contain of blood vessels, free nerve ending, hair follicles, dermal papillae & corpuscles of touch (meissner corpucles) Reticular region  Consists of dense irregular connective tissue containing collagen and elastic fibers, adipose cells, hair follicles, nerves, sebaceous (oil) glands, and sudoriferous (sweat) glands  Provide skin with strength, extensibility (ability to stretch)& elasticity (ability to return to normal shape after stretching)  Epidermal ridges reflect contours of the underlying dermal papillae and form the basis for fingerprints (and footprints) – different individually  Function to increase firmness of grip by increasing friction  Skin overstretched in the dermis- cause rupture of elastic fiber result in permanent striae (in pregnancy & obesity)  Lines of cleavage are “tension lines” in the skin that indicate the predominant direction of underlying collagen fibers  Plastic surgeons make their incisions parallel to the normal cleavage lines in order to minimize scarring  It is not a part of the skin  Also called the hypodermis, and it attaches the skin to underlying tissues and organs  It contains blood vessels and nerves in transit to the more superficial layers  Lamellated (pacinian) corpuscles - nerve that detect external pressure applied to the skin Functions  Serves as a fat storage area – used for energy when necessary  An area for blood vessel passage  An area of pressure nerve endings  Cushion the underlying organ from mechanical shock & act as heat insulator in temperature regulation  The skin contains different types of sensory receptors to differentiate between the different tactile (“touch”) sensations  Light touch, pressure, vibration, itch and tickle  These sensory receptors are found in different layers:  Superficially Merkel discs, free nerve endings (detect many stimuli), Meissner corpuscles, and hair root plexuses  Deep Pacinian corpuscles Degree of burn  The color of skin and mucous membranes can provide clues for diagnosing certain conditions  Main factor affecting skin color –melanin, hemoglobin & carotene Melanin  Produced by melanocytes in the stratum basale  The amount of melanin causes the skin’s color to vary from pale yellow to red to tan to black  Located mostly in the epidermis, where it absorbs UV radiation  Exposure to UV light stimulates melanin production  Repeatedly exposing the skin to UV light causes skin cancer Hemoglobin  It is oxygen-carrying pigment in the red cells  The level of oxygenation of haemoglobin and the amount blood circulating in the dermis give the skin its pink to red color Carotenes  Yellow-orange pigment that give egg yolk & carrots their color  Found in the stratum corneum, dermis, and subcutaneous layer  Freckles are accumulation of melanin in patch which triggered by exposure to sunlight  Having more freckles is a genetic trait  Erythema - redness of the skin, is caused by engorgement of capillaries in the dermis with blood due to skin injury, exposure to heat, infection, inflammation, or allergic reactions  Jaundice – build up yellow pigment bilirubin in the skin & whites of the eyes – indicate liver disease  Pallor or paleness of the skin, may occur in conditions such as shock and anemia  Albinism is a congenital disorder characterized by the complete or partial absence of pigment in the skin, hair, and eyes due to a defect of an enzyme involved in the production of melanin  Vitiligo is a chronic disorder that causes depigmentation patches in the skin  The precise cause, is not known, but is most likely a combination of genetic factors coupled with a disorder of the immune system (autoimmune disease)  Nevi (“birthmarks” or moles) are chronic lesions of the skin – they are, by definition, benign  Malignant melanoma is a cancer of melanocytes  Tattooing - permanent coloration of the skin in which a foreign pigment is deposited with a needle into the dermis  Body piercing - the insertion of jewellery through an artificial opening. Potential complications - infections, allergic reactions, and anatomical damage (such a nerve damage or cartilage deformation) Consists of  Hair  Sebaceous glands  Nails  Sweat glands Anatomy of Hair  Shaft – superficial portion above the surface  Root - penetrates the dermis and subcutaneous layer & a hair follicle  Hair matrix – produce new hairs by cell division  Associated with hairs are sebaceous (oil) glands, arrectores pili muscles & root plexuses  Papilla of the hair - contains blood vessels and provides nourishment for the growing hair  Hair removal - electrolysis uses an electric current to destroy the hair matrix  Hair Growth - growth cycle consists of a growing stage and a resting stage & can be altered by illness, diet, high fever, surgery, blood loss, severe emotional stress, and gender  Hair Color - due primarily to the amount and type of melanin  gray hair - due to decline in the synthesis of melanin  white hair – is results from accumulation of air bubbles in the hair shaft  Types of hair  Lanugo - is a fine, nonpigmented hair that covers the fetus  Vellus hair - is a short, fine hair that replaces lanugo - scattered over most of the body surface  Terminal hair -hairs are heavy, more deeply pigmented, and usually longer – over the head, eyebrows, eyelashes, axillary hairs & pubic hairs  Course pigmented hair appears in response to androgens  Functions of hair - protection, decrease in heat loss, and sensing light tough  Androgens - hormones influence the growth and loss of hair The arrector pili  It is a smooth muscle fibres attached to the hair follicles  Contraction makes the hair stand erect and raises the skin around the hair, causing ‘goose flesh’  The muscles are stimulated by sympathetic nerve fibres in response to fear and cold  This is an efficient warming mechanism especially when accompanied by shivering, i.e. involuntary contraction of the skeletal muscles.  Chemotheraphy – treatment of cancer with drugs. The drugs affect the matrix cell & cause hair loss  Hirsutism – excessive of body hair due to excessive of androgens in female or prepubertal males Consists of  Sebaceous (oil) glands  Sudoriferous (sweat) glands  Eccrine sweat glands  Apocrine sweat glands  Ceruminous glands Sebaceous (oil) glands  Connected to hair follicles  Secreting portions of glands located in the dermis  Absent in the palms and soles …sebaceous glands  Produce sebum, which moistens hairs, waterproofs and softens the skin, and inhibits bacterial growth  The gland’s activity increases at puberty  Blockage of the glands– cause blackheads  Acne results when sebaceous glands become inflamed Sudoriferous (sweat) glands – had 2 types 1. Eccrine sweat glands  Distributed all over the body especially skin of the forehead, palm & sole  Their ducts terminate at pores at the surface of the epidermis ….Eccrine sweat glands  Produce sweat about 600ml/day that help regulate body temperature through evaporation – stimulated by sympathetic nerve  Help eliminate wastes such as urea  Emotional sweating –release sweat due to fear/embarrassment  Start function after birth 2. Apocrine sweat glands  Located in the skin of the axilla, pubis, and areola  Secrete a slightly viscous sweat  Start function at puberty  Did not play a role in the regulation of body temperature  Secrete sweat during emotional stress and sexual excitement  Odorless but if interact with bacteria – cause body odor Ceruminous glands  Present in the external auditory canal (outer ear canal)  Secrete a yellowish secretion called cerumen or earwax  Cerumen, together with hairs in the external auditory canal, provides a sticky barrier that impedes the entrance of foreign bodies and insects  Cerumen also waterproofs the canal and prevents bacteria and fungi from entering cells  Too much of cerumen in the external auditory meatus or canal cause impaction and prevent sound waves from reaching the ear drum  Acne is an inflammation of sebaceous glands  Cause;  sebaceous follicles are colonized by bacteria  over production of oil (sebum)  Usually begins at puberty when the sebaceous glad are stimulated by androgens  Nails are plates of tightly packed, hard, dead, keratinized cells of the epidermis  Each nail consists of a nail body, a free edge, and a nail root  Nail body - portion of the nail that is visible  Free edge - part of the body that extends past the end of the finger or toe  Nail root - portion that is not visible  Lunula - whitish semilunar area near the nail root  Cell division of the matrix cells produces new nails  Function - nails help in grasping and manipulating small objects in various ways and provide protection against trauma to the ends of the digits  Regulates body temperature  Stores blood  Protects body from external enviroment  Defects cutenous sensations  Excretes & absorbs substances  Synthesis vitamin D What structures make up the integumentary system?  Skin and glands, hair, nails Epidermis is composed of what epithelial tissue?  stratified squamous epithelium What is the deepest layer of the skin?  Hypodermis What are the contain of hypodermis?  Blood vessels & nerve What is the 5 layer of epidermis?  stratum corneum , stratum lucidum , stratum granulosum , stratum spinosum , stratum basale Which layer of epidermis only in palms & sole?  stratum lucidum Which layer of epidermis produce waterproofing sealant ?  stratum granulosum What are the specific characteristic of dermis?  Extensibility & elasticity Sebaceous glands secrete  Sebum In what layer of the epidemis is melanin produced?  Stratum basale When eccrine sweat glands will start to function?  Start function after birth Where are the main location of apocrine sweat glands?  axilla, pubis, and areola When apocrine glands will secrete the sweat?  during emotional stress and sexual excitement Which layer of the skin that is responsible for finger prints?  Dermal papilla in papillary layer (within Dermis) What is the cause of acne?  Over production of sebum & blockage of sebaceous glands The production of melanin is stimulate by  Exposure to UV light What is the congenital disease characterized by the complete or partial absence ofmelanin?  Albinism Which part of the hair that produces new hair by cell division?  Hair matrix What is the nonpigmented hair that covers the fetus?  Lanugo