BSC 2085 Exam 2 Study Guide Lesson 7 The Integumentary System I Describe the components of the integumentary system a The integument largest system of the body is made up of two parts i Cutaneous membrane the skin 1 The outer epidermis is superficial epithelium epithelial tissues 2 The inner dermis consists of connective tissues ii Accessory structures 1 Originate in the dermis and extend through the epidermis to the skin surface including hair nails and multicellular exocrine glands b What are the accessory structures What are their functions i Hair protects and insulates also guarding openings against particles and insects ii Nails protect fingers and toes They are made of dead cells packed with keratin Nail production occurs in the nail root iii Exocrine glands 1 Sebaceous glands oil glands a Simple branched alveolar glands are associated with hair follicles and coat the hair b Sebaceous follicles are not associated with hairs but act to protect hairs These discharge directly onto skin surface The sebum contains lipids and other ingredients and functions to lubricate and protect the epidermis and inhibit bacteria 2 Apocrine sweat glands a Found in armpits around nipples and groin b These secrete products into hair follicles and produce sticky cloudy secretions Odor is caused by bacteria breaking down the secretions c Apocrine sweat glands are surrounded by myoepithelial cells which squeeze apocrine gland secretions onto skin surface d THESE SECRETIONS ARE RELEASED VIA THE MEROCRINE MODE DESPITE THE NAME 3 Merocrine eccrine sweat glands a These are widely distributed on body surface especially on palms and soles sensible perspiration b These discharge directly onto skin surface and participates in c Functions excrete water and electrolytes cool skin and flush microorganisms and harmful chemicals from skin II Explain how the integumentary system is linked to the cardiovascular and nervous system a b Linked to the cardiovascular system by blood vessels in the dermis Linked to the nervous system by sensory receptors that detect stimuli for pain touch and temperature III Describe the main functions of the cutaneous membrane a Protection of underlying tissues and organs b Excretion of salts water and organic wastes via glands c Maintenance of body temperature insulation and evaporation d Production of melanin keratin Vitamin D3 and storage of lipids e Detection of touch pressure pain and temperature IV Describe the major layers of skin a Epidermis avascular and dominated by keratinocytes keratin protein Thin skin 4 layers of keratinocytes most of body thick skin 5 layers and covers palms and soles of feet b Stratum Basale i Attached to the basement membrane by hemidesomosomes ii Forms a strong bond between the epidermis and dermis as well as epidermal ridges the basis of fingerprints iii Dermal papillae are tiny mounds that increase the area of the basement membrane and strengthen attachment between epidermis and dermis iv Here the main cells are basal cells also known as germinative cells v Merkel cells are found in hairless skin and respond to touch to trigger the vi Melanocytes contain the pigment melanin and are scattered throughout the nervous system stratum basale c Stratum Spinosum the spiny layer i This layer is produced by division of the stratum basale ii This layer is made up of 8 10 layers of keratinocytes bound together by desomosomes iii The cells shrink until cytoskeletons stick out but continue to divide to increase the thickness of the epithelium iv Dendritic Langerhans cells are present here which are active in the immune system d Stratum Granulosum the grainy layer i Division stops in this layer and production begins 1 Keratin production keratin is a tough fibrous protein making up hair and nails As keratin accumulates the cell flattens and its plasma membrane thickens and becomes less permeable 2 Keratohyalin production keratohyalin are dense granules that cross link keratin fibers ii Cells of the stratum granulosum produce protein fibers dehydrate and die But these cells create tightly interlocked layers of keratin surrounded by keratohyalin e Stratum Lucidium the clear layer i Found only in thick skin ii Covers stratum granulosum iii Cells here are flattened densely packed with keratin and are devoid of organelles because they are all dead iv These cells do not have organelles and the cells do not survive much longer f Stratum Corneum the horn layer i This is the exposed surface of skin and is made up of 15 to 30 layers if keratinized cells ii This layer is water resistant but not water proof iii This layer is shed and replaced every two weeks iv All exposed skin surfaces except the anterior of the eyes undergo cornfication kertanization which is the formation of protective superficial layers of cells filled with keratin g How are fingerprints formed Why are they important i The basis of fingerprints are formed in the stratum basale These ridges are important because they increase surface are and friction which ensures a secure grip These are determined by genetics and uterine environment during fetal development V Explain the difference between insensible and sensible perspiration a Insensible perspiration is interstitial fluid lost by evaporation through the stratum corneum This is perspiration you lose by just sitting around b Sensible perspiration is water excreted by sweat glands You can actively feel this perspiration It is basically sweating VI Explain how carotene and melanin affect skin color a What are the differences between these two pigments i Carotene is an orange yellow pigment that is found in orange vegetables It accumulates in epidermal cells and fatty tissues of the dermis It can be converted to vitamin A which is used for maintenance of epithelia and photoreceptor function ii Melanin is a yellow brown or black pigment produced by melanocytes in stratum basale Melanin is stored in transport vesicles and transferred to keratinocytes b Explain how different conditions can affect skin color i Jaundice is caused by a buildup of bile produced by the liver It gives the skin a yellow color ii Cyanosis bluish skin tint which is caused by severe reduction in blood low or oxygenation iii Pituitary tumors are caused by excess melanocyte stimulating hormone production giving an extremely bronze tan iv Addison s disease is a disease of the pituitary gland characterized by increased release of adrenocorticotropic hormone which has a similar effect on
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