A&P Ch. 6 PPT Integumentary System PDF

Chapter 6 Integumentary System  Words To Know Derm/o = skin Sub= under, below Epi= above Lip/o= fat Cutane/o= skin Py/o= pus Melan/o= black  Integumentary System The integumentary system consists of the skin and its derivatives. – Nail...

Chapter 6 Integumentary System  Words To Know Derm/o = skin Sub= under, below Epi= above Lip/o= fat Cutane/o= skin Py/o= pus Melan/o= black  Integumentary System The integumentary system consists of the skin and its derivatives. – Nails, hair, sweat glands, sebaceous glands The integument is the skin covering the body. – Also known as the cutaneous membrane – Barrier to the outside world – Visual indicator of our physiology and health – Its scientific study and treatment termed dermatology  Properties of the Integument The integument – Body’s largest organ – Protects internal body structures – Accounts for 7-8% of body weight – Area ranges between 1.5-2.0 m2 – Thickness ranges between 1.5 mm and 4.0 mm – A postage stamp sized sample of skin ~ 280 cm of blood vessels ~ 220 cm of nerves ~ 60 oil glands ~ 900 sensory receptors (10 000 on finger tips) ~ 2 million cells.  Composition of the Integument Integument composed of all tissue types – Surface covered by an epithelium – Underlying connective tissue: provides strength and resilience contains smooth muscle associated with hair follicles – Nervous tissue: provides information about touch, pressure, temperature, and pain  Integument Epidermis Dermis Subcutaneous layer  Composition of the Integument Layers of the integument  Epidermis  stratified squamous epithelium  Dermis  deeper layer  primarily dense irregular connective tissue  Subcutaneous layer  Deep to dermis  Layer of alveolar and connective tissue  Termed subcutaneous layer or hypodermis  Not part of the integumentary system  Closely involved with structure and function of skin  Layers of the Integument (Figure 6.1) Hair shaft Sweat pore Epidermis Epidermal ridge Dermal papilla Papillary layer Integument Arrector pili muscle Sebaceous (oil) gland Dermis Sweat gland duct Reticular layer Merocrine sweat gland Vein Artery Subcutaneous layer Adipose connective tissue Hair follicle Tactile Areolar Sensory (sensory) connective tissue nerve fiber receptors  Composition of the Integument: Epidermis The epithelium of the integument – Termed epidermis – Keratinized, stratified squamous epithelium – Consists of specific layers, or strata Epidermis  Composition of the Integument: Epidermis The epithelium of the integument – Layers from superficial to deep: stratum corneum stratum lucidum stratum granulosum stratum spinosum stratum basale – most superficial two layers with dead keratinocytes – Bottom three layers with living keratinocytes  Composition of the Integument: Epidermis Stratum basale – Also known as stratum germinativum or basal layer – Three cell types: Keratinocytes (basal) – Most abundant in epidermis – Found in all layers – Divide to regenerate new cells Melanocytes – Scattered among the keratinocytes – Produce and store pigment (melanin) in response to UV light tactile cells (few) – AKA Merkel cells – Sensitive to touch – When compressed, release chemicals » stimulate sensory nerve endings  Composition of the Integument: Epidermis Stratum spinosum – Also known as spiny layer – Keratinocytes – Epidermal dendritic cells (Langerhans cells) Often present in stratum spinosum and stratum granulosum Immune cells that help initiate immune response Responsive to pathogens and epidermal cancer cells  Composition of the Integument: Epidermis Stratum granulosum – Also known as granular layer – First layer of keratinization process where keratinocytes fill with keratin causes nucleus and organelles to disintegrate fully keratinized cell dead but structurally sound process not complete until more superficial layers  Composition of the Integument: Epidermis Stratum lucidum – Only in thick skin – Translucent layer also known as clear layer – Filled with a translucent protein, eleidin intermediate product in keratin maturation – Cells are dead  Composition of the Integument: Epidermis Stratum corneum – Also known as the hornlike layer – Anucleate – Surface unsuitable for the growth secretions of exocrine glands also helping prevent growth – Cells are dead  Composition of the Integument: Epidermis Stratum corneum Migration of keratinocytes – Originate from stem cells in stratum basale – Migrate through strata to stratum corneum over two weeks undergoing structural changes – Remain in stratum corneum another two weeks – Are shed  Thick Skin Stratum corneum High Magnification Epidermis Stratum lucidum Stratum granulosum Stratum spinosum Dermis Stratum basale  Epidermal Strata (Figure 6.2) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Dead keratinocytes Stratum corneum Sweat gland duct Sweat gland duct Stratum lucidum Stratum granulosum Living keratinocyte Stratum spinosum Melanocyte Stratum basale Epidermal dendritic cell Basement membrane Dermis Tactile cell Sensory nerve ending LM 25x (a) (b) a: © Ed Reschke/Peter Arnold Images  Composition of the Integument: Epidermis Variations in the epidermis – Variations between different body regions – Variations between individuals – Variations in thickness, color, and skin markings  Composition of the Integument: Epidermis Variations in the epidermis Thick versus thin skin – Thick skin on the palms of hands, soles of feet, and surfaces of fingers and toes has all five layers of epidermal strata has sweat glands has no hair follicles or sebaceous glands from 0.4 to 0.6 mm thick Thick Skin Thin Skin  Thick Skin Stratum corneum High Magnification Epidermis Stratum lucidum Stratum granulosum Stratum spinosum Dermis Stratum basale  Composition of the Integument: Epidermis Variations in the epidermis Thick versus thin skin – Thin skin covers most of the body lacks a stratum lucidum has sweat glands, hair follicles, and sebaceous glands from 0.075 to 0.150 mm thick  Thin Skin Stratum corneum High Magnification Stratum Epidermis granulosum Stratum spinosum Stratum Dermis basale  Thick Skin and Thin Skin (Figure 6.3) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Stratum corneum Epidermis Stratum granulosum Stratum spinosum Stratum corneum Epidermis Stratum basale Stratum lucidum Dermis Stratum granulosum LM 40x LM 75x Stratum spinosum Stratum basale (a) Thick skin (b) Thin skin a: © Carolina Biological Supply Company/Phototake b: © Carolina Biological Supply Company/Phototake  Composition of the Integument: Epidermis Variations in the epidermis Coloring from hemoglobin – Hemoglobin: an oxygen binding compound present in red blood cells – Bright red color upon binding oxygen – Gives blood vessels in dermis a reddish tint – Seen most easily in fair skinned individuals – More visible if blood vessels dilate  Composition of the Integument: Epidermis Variations in the epidermis Coloring from melanin – Pigment produced and stored in melanocytes – Occurs in black, brown, tan, yellow-brown shades – Transferred to keratinocytes in stratum basale – Amount in skin varies according to heredity and light exposure UV light stimulating melanin production – All people with same number of melanocytes – Activity and color varying among individuals darker skinned producing more and darker colored melanin  Production of Melanin by Melanocytes (Figure 6.4) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Vesicle filled Epidermis with melanin Melanin pigment in keratinocyte Stratum basale with melanin pigment Melanin pigment Melanocyte Dermis LM 124x Stratum basale (a) (b) b: © John Burbidge/Photo Researchers, Inc.  Composition of the Integument: Epidermis Variations in the epidermis Coloring from carotene – Yellow-orange pigment – Acquired from yellow-orange vegetables – Accumulates inside subcutaneous fat and keratinocytes of stratum corneum – Converted to vitamin A within the body – Plays important roles: in vision in reducing free radicals in immune function  Composition of the Integument: Epidermis Variations in the epidermis Nevus – Commonly called a mole – Harmless overgrowth of melanin forming cells – Rarely may become malignant should be monitored for changes suggesting malignancy Freckles – Yellowish or brown spots – Represent localized areas of increased melanocyte activity – Degree of pigmentation based on sun exposure and heredity  Composition of the Integument: Epidermis Variations in the epidermis Hemangioma – Skin discoloration due to benign blood vessel tumor – Capillary hemangiomas appear in skin as bright red to deep purple nodules usually present at birth and disappear in childhood known as strawberry-colored birthmarks – Cavernous hemangiomas involve larger dermal blood vessels may last a lifetime known as port-wine stains  Composition of the Integument: Epidermis Variations in the epidermis Ridge patterns of the skin – Small conical pegs in thin skin – Complex arches and whorls on finger, palms, soles, and toes called friction ridges formed from large folds and valleys of dermis and epidermis help increase friction on contact each individual with a unique pattern of friction ridges allows for personal identification  Friction Ridges of Thick Skin (Figure 6.5) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Arch Whorl Loop Combination Composition of the Integument: Epidermis Which type of skin lacks a stratum lucidum and is found covering most of the body? Thin skin  Composition of the Integument: Dermis The dermis – Deep to the epidermis – Ranges in thickness from 0.5 mm to 3.0 mm – Composed of connective tissue Dermis Dermis and Dermal Papillae Dermis Dermal papillae  Composition of the Integument: Dermis Components of the dermis – Primarily collage with elastic and reticular fibers – Motile dendritic cells serving an immune function – Blood vessels, sweat glands, sebaceous glands – Hair follicles, nail roots, sensory nerve endings, arrector pili – Divided between the papillary layer and deeper reticular layer  Composition of the Integument: Dermis Papillary layer of the dermis – Superficial region of the dermis – Directly adjacent to epidermis – Composed of areolar connective tissue – Derives name from projections of the dermis termed dermal papillae contain capillaries and sensory nerve endings – Projections of epidermis interdigitating with papillae termed epidermal ridges – Interlock and increase the area of contact between layers  Composition of the Integument: Dermis Reticular layer of the dermis – Deeper, major portion of the dermis – Extends from papillary layer to subcutaneous layer – Consists primarily of dense irregular connective tissue – Contains large bundles of collage fibers fibers interwoven into a meshwork surrounding structures in dermis  Layers of the Dermis (Figure 6.6) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Epidermal ridges Dermal papillae Epidermis Papillary layer Dermis Reticular layer Tactile (sensory) receptor Artery Vein Subcutaneous layer Areolar connective tissue Adipose connective tissue  Composition of the Integument: Dermis Lines of cleavage, stretch marks, and wrinkles Collagen and elastic fibers oriented in parallel bundles – Alignment result of applied stress during routine movement – Bundles functioning to resist stress – Orientation indicated by lines of cleavage (tension lines) – Important consideration for surgery incisions parallel – more likely to heal quickly incisions perpendicular to cleavage lines – more likely to open due to cut elastic fibers  Composition of the Integument: Dermis Lines of cleavage, stretch marks, and wrinkles Fibers contribute to skin characteristics. – Collagen fibers imparting tensile strength – Elastic fibers allowing stretch and recoil – Sometimes skin stretched beyond its capabilities some collagen fibers torn stretch marks, termed striae, occur – Flexibility and thickness of dermis diminished by UV light and aging – may cause sagging or wrinkled skin  Lines of Cleavage (Figure 6.7) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. An incision perpendicular to cleavage lines may gape and delay healing. An incision parallel to cleavage lines is more likely to heal quickly and not gape open.  Composition of the Integument: Dermis Innervation and blood supply Dermis with extensive nerve fibers – Sensory nerve fibers detect pressure, vibration, and cold – Motor nerve fibers control blood flow and gland secretions Dermal blood vessels – Supply nutrients to epidermis and dermis – Play an important role in body temperature and blood pressure regulation  Composition of the Integument: Dermis Innervation and blood supply Dermal blood vessels (continued) – Vasoconstriction blood vessel diameters narrowed blood shunted from periphery toward deeper structures occurring when trying to conserve heat look pale when exposed to cold  Composition of the Integument: Dermis Innervation and blood supply Dermal blood vessels (continued) – Vasodilation blood vessel diameter increased more blood close to body surface occurs when needing to loose heat why people may become flushed during exercise Composition of the Integument: Dermis Clinical View: Tattoos – Permanent images produced on integument – Dye injected into dermis – Becomes permanent part of dermis layer – Usually impossible to completely remove a tattoo  Composition of the Integument: Subcutaneous Layer Subcutaneous layer – Not considered part of integument – Consists of areolar and adipose connective tissue – Termed subcutaneous fat in areas of more adipose tissue – Connective tissue fibers interwoven with those of reticular dermis – Pads and protects the body Subcutaneous Layer  Composition of the Integument: Subcutaneous Layer Subcutaneous layer – Acts as energy reservoir – Provides thermal insulation – Drugs often injected here – Sexes with different layer thickness and distribution women, generally thicker – primarily in breasts, buttocks, hips, and thighs men, generally thinner – primarily in neck, upper arms, abdomen, lower back, buttocks  ALE Think-Pair-Share What are the three layers of integument (generally speaking)? What is one feature unique to each layer? 56  Integumentary Structures Derived from Epidermis: Hair & Nails Functions of hair Protection – Protects scalp from sunburn and injury – Hair within nostrils trapping particles – Hair within ears protecting from foreign matter – Eyelashes protecting eyes – Eyebrows keeping sweat out of eyes Heat retention – Prevents loss of heat from scalp to air  Integumentary Structures Derived from Epidermis: Hair Functions of hair Sensory reception – Has associated tactile receptors Visual identification – Important in determining age, sex, specific individuals Chemical signal dispersal – Disperse pheromones chemical signals involved in attracting sexual partners secreted by specific sweat glands onto hairs in axillary and pubic regions  Integumentary Structures Derived from Epidermis: Exocrine Glands of the Skin Skin houses many types of exocrine glands Two most common: – sweat glands – sebaceous glands  Integumentary Structures Derived from Epidermis: Exocrine Glands of the Skin Sweat glands Two groups: merocrine and apocrine General structure – Coiled, tubular secretory portion in reticular dermis – Sweat gland duct carrying secretions – Opening of the gland duct on epidermal surface termed sweat pore – Contain myoepithelial cells contract to squeeze the gland discharge secretions in response to sympathetic stimulation  Figure 5.6 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Disintegrating Secretions cells becoming Secretory contents the secretion Pinching off of apical portion of Secretory secretory cell vesicle Nucleus Cells Nucleus of dividing Secretory vesicles secretory cell releasing their contents via exocytosis (a) Merocrine gland (b) Apocrine gland (c) Holocrine gland  Integumentary Structures Derived from Epidermis: Exocrine Glands of the Skin Sweat glands Merocrine sweat glands – Most numerous and widely distributed sweat glands – Simple, coiled tubular glands – Discharge their secretions onto skin surface – Secrete sweat composed of 99% water and 1% other chemicals include electrolytes, metabolites, and waste products  Integumentary Structures Derived from Epidermis: Exocrine Glands of the Skin Sweat glands Merocrine sweat glands (continued) – Major function of thermoregulation regulation of body temperature by fluid evaporation – Provide a means for loss of water and electrolytes – Secretions diluting harmful chemicals – Secretions with antibacterial activity – Produce secretions by exocytosis  Integumentary Structures Derived from Epidermis: Exocrine Glands of the Skin Sweat glands Apocrine sweat glands – Coiled tubular glands – Discharge their secretions into hair follicles – Produce secretions by exocytosis – Found in axillae, around nipples, in pubic and anal region – Produce viscous cloudy secretions contain proteins and lipids produce odor when acted on by bacteria – Start producing secretions during puberty  Integumentary Structures Derived from Epidermis: Exocrine Glands of the Skin Sebaceous glands – Produce oily secretion called sebum acts as a lubricant for skin and hair has bactericidal properties discharged into a hair follicle – Holocrine glands – Secretion stimulated by hormones, especially androgens – Activated during puberty  Integumentary Structures Derived from Epidermis: Exocrine Glands of the Skin Other integumentary glands Ceruminous glands – Modified apocrine sweat glands – Located only in the external acoustic meatus – Secretions form waterproof earwax, cerumen help trap foreign material help lubricate acoustic meatus and eardrum Mammary glands – Modified apocrine sweat glands of the breast – Only function in pregnant and lactating females – Produce milk  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Sweat pore Sweat gland duct Exocrine Glands of Hair follicle the Skin Sebaceous gland (Figure Merocrine sweat gland 6.10a) Arrector pili muscle Apocrine sweat gland (a) Functions of the Integument—Protection and More: Epidermis Functions Protection – Acts as a physical barrier – Protects body from physical injury and trauma – Protects from chemicals, toxins, microbes, temperature extremes – Protects deeper tissue from solar radiation Functions of the Integument—Protection and More: Epidermis Functions Prevention of water loss – Helps prevent unnecessary water loss – Water unable to exit skin unless secreted by sweat glands – Dehydration a danger with severe burns – Water resistant, not waterproof some interstitial fluid penetrating through epidermis to air release of water vapor from sweat glands when not sweating termed transpiration Functions of the Integument—Protection and More: Epidermis Functions Metabolic regulation Other forms of metabolic regulation – Skin able to convert some compounds to slightly different forms – UV rays stimulating melanocytes to produce melanin Functions of the Integument—Protection and More: Epidermis Functions Secretion and absorption Secretion – Waste products secreted onto skin surface during sweating urea, salts, water amounts able to be adjusted plays a role in electrolyte homeostasis – Sebum of sebaceous glands lubricating skin surface and hair Functions of the Integument—Protection and More: Epidermis Functions Secretion and absorption Absorption – Can absorb certain chemicals and drugs – Other materials blocked, so termed selectively permeable – Some oil soluble drugs delivered by adhesive patch termed transdermal administration – Drugs absorbed into blood vessels of dermis – Get continual slow absorption of drug over a long period Functions of the Integument—Protection and More: Epidermis Functions Immune function Dendritic cells – Within stratum spinosum in epidermis – Initiate immune response against pathogens – Attack cancer cells – Also present in the dermis Functions of the Integument—Protection and More: Dermis Functions Temperature regulation – Body temperature influenced by capillaries and sweat glands here – Blood vessel dilation and sweating when body too warm – Blood vessel constriction when body too cold Functions of the Integument—Protection and More: Dermis Functions Sensory Reception – Detectors mostly in dermis – Detect heat, cold, touch, pressure, and vibration Also some shared functions with epidermis – E.g., secretion and absorption and immune function  Repair and Regeneration of the Integumentary System Response to repetitive mechanical stress – Mitosis stimulated in stratum basale – Thickening of the epidermis – Provides more protection e.g., thickened soles after walking barefoot  Repair and Regeneration of the Integumentary System Response to damaged tissues – Regeneration replacement of damaged cells with same cell type restores organ function – Fibrosis gap filled with scar tissue composed primarily of collagen produced by fibroblasts functional activities not restored if organ too damaged or cells lack ability to divide  Repair and Regeneration of the Integumentary System Stages of wound healing 1) Cut blood vessels bleed into wound. 2) Blood clot forms and leukocytes clean wound. – clot a temporary barrier for pathogens 3) Blood vessels regrow and granulation tissue forms. – vascular connective tissue that initially forms in wound 4) Epithelium regenerates and connective tissue fibrosis occurs.  Repair and Regeneration of the Integumentary System Wound healing – Not rapid – Longer for wider and deeper surfaces – With severe damage less likely to return to original condition hair follicles, exocrine glands, nerves, and arrector pili muscle cells not repaired  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Wound Blood clot Epidermis Dermis Macrophages Fibroblast Neutrophils Leukocyte Stages in 1 Cut blood vessels bleed into the wound. 2 Blood clot forms, and leukocytes clean wound. Wound Blood clot Scab Healing (Figure 6.12) Granulation tissue Regenerated epidermis Macrophages Scar tissue Regrowth of (fibrosis) blood vessel Fibroblast Fibroblast 3 Blood vessels regrow, and granulation tissue forms. 4 Epithelium regenerates, and connective tissue fibrosis occurs.