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The Integumentary System

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Presentation on theme: "The Integumentary System"— Presentation transcript:

1 The Integumentary System
Chapter 4

2 Overview of the Integumentary System
Guiding Question: What are the components of the integumentary system? Cells and tissues associated with the skin.

3 Overview of the Integumentary System
Not just a covering for the body Largest organ Blood vessels, connective tissue structures, glands, hair, nails, nerves, skin Plays a large role in homeostasis Has inherent and adaptive characteristics Calluses Darken in sun Elasticity Sensitive to moisture Inherent = characteristics determined by genes BUT adaptive = flexibility designed into the genetics of the cells.

4 The Integumentary System
Guiding Questions: 1.) What embryonic layers form the integumentary system? 2.) Describe the development of the integumentary system. 3.) What are some various causes of hair loss?

5 Development of the Integumentary System
Ectoderm & mesoderm in origin Skin is a complex structure Many things can go wrong in its development Let’s make a timeline!

6 4 weeks: Simple ectoderm epithelium over mesenchyme
outermost layer of skin form a simple squamous tissue that becomes stratified as the embryo develops from the ectoderm

7 4-5 weeks Deeper parts of skin begin to form from mesoderm (dermis, hypodermis)

8 8-9 wks: mesenchyme begins to mature and fibroblasts form, and dents occur in the upper squamous layer form lanugo.

9 10 weeks: ridges form between the outer and inner layers of skin—so don’t separate when rubbed
11 weeks: small nails at the tips of fingers & toes, followed by development of special blood vessels in the layers of skin Angiogenic factors stimulate the production of these vessels

10 20 weeks: Glandular structures form
Inward growths of the outermost squamous cell layer Will eventually produce oils and sweat 25 weeks: Pigmentation

11 About 26 weeks: melanoblasts mature into melanocytes (build pigments)
nervous tissue structures develop Mesenchyme: embryonic connective tissue composed of star-shaped cells in the gel-like matrix or extracellular material. Fibroblasts: secretes collagen fibers that strengthen the delicate tissue ***Have students create a timeline of skin development. One color card has the # of weeks and a second color card has the development that occurs. They match & put in order. May not need to show this slide…Or have them do a human timeline…

12 Skin Structure

13 Skin Structure Guiding ?’s:
What are the three major layers of the skin? Describe the basic characteristics of the three major layers of the skin (recommend a chart)

14 Skin: Structure – 3 layers
1. Epidermis: Epithelial Superficial & thinnest cells are very tightly packed New cells produced here 2. Dermis: Connective Deep to epidermis & thick Primarily connective tissue loosely packed cells 3. Subcutaneous/Hypodermis (adipose tissue) Deep to the skin/dermis Layer of insulation

15 Diagrammatic vs. Histological view

16 Epidermis Outermost: Stratum corneum Stratum Granulosum
Dry, dead, keratin filled (waterproof, tough) Stratum Granulosum Waterproof Contains granules of keratin Stratum Spinosum “Prickly” layer Contains Langerhans cells (fight infections)

17 Stratum germinativum / basale
Cells undergoing mitosis, move up and horizontally Contains malpighian layer or “Pigment layer” with melanosomes Forms epidermal ridges


19 Stratum corneum: Dead squamous cells Stratum lucidum: (only in thick skin); oils from lysosome disintegration Stratum granulosum: Granules with lipids and keratin – forms waterproof layer Stratum Spinosum: cuboidal cells, desmosomes hold together >> spiny Stratum Germinativum/ Basale: dividing columnar cells

20 Epidermis Specialized cells within epidermis: Melanocytes
Melanin: pigment, inc. w/sun (protection) Keratinocytes Keratin: tough, waterproof material Abrasion resistance for cells Langerhans cells Immune response against microbes invading the skin

21 Second layer of the skin
Dermis Second layer of the skin

22 Dermis Collagen, elastin fibers– scattered

23 Dermal Connective tissue
Dense, irregular connective tissue Loose, connective tissue = areolar connective tissue Binds blood vessels, membranes, muscles, nerves, and skin to other structures Contains extensive meshwork of protein fibers (fibroblasts) Involved primarily in body growth Connective tissue maintenance Wound healing

24 Dermal-epidermal junction
Dermal papillae: parallel rows of peg-like projections Unique to each individual; akin to fingerprints

25 Subcutaneous Layer Third layer of the skin

26 Subcutaneous layer Third, innermost layer of the skin
Thickness, composition vary throughout body Composed of loosely-arranged elastic fibers that anchor the skin to the fascia Sheet of fibrous connective tissue Covers muscles, skull bones, some organs Large amount of adipose (fat) cells Large network of blood vessels, capillaries, lymphatic vessels

27 Skin Appendages Glands Nerves Nails Hair

28 Glands 3 Types: Ceruminous Sebaceous Sweat/sudoriferous

29 Ceruminous Produce cerumen (waxy secretion), an apocrine secretion (ear wax) Found lining ear canal

30 Sebaceous Holocrine glands (secrete whole dead cells)
Produce, store abundance of fat, which burst and die, releasing sebum

31 Specialized Structures of the Dermis
Sebaceous Glands Secrete oil (sebum) for hair/skin Ducts open into hair follicles Accumulated sebum enlarges ducts>>white heads Darkened sebum>>black head

32 Specialized Structures of Dermis
Sudoriferous/Sweat Glands Eccrine Glands Widespread Watery Fluid Separate pore Apocrine Glands Armpits/Genitals Thick/milky fluid Secrete into hair follicle

33 Sweat Aprocrine Eccrine
Odorous, sweat-like material in armpits, navel, groin region, areolae Inactive until puberty Contain pheromones Broken down by bacteria, creating odor Eccrine Skin of armpits, foreheads, palms, soles Mostly secrete water, w/ salts, organic compounds, and wastes (like urea) Microbes feed on these as well, producing odors


35 Dermis Specialized structures:
Hair follicle: cells of the epidermis extend into the dermis forming a small tube Hair bulb: base of the follicle Hair papilla: cluster of cells (live); nourished by BV’s Root: part of hair hidden in follicle Shaft: visible part of hair

36 Nerves Sensory receptors Free nerve endings/Nociceptor
Communicate information from environment to the body Found in all skin layers Mostly in innermost regions, fascia Free nerve endings/Nociceptor Pain-sensing structures Found throughout inner part of epidermis Detect chemicals associated with tissue damage and bleeding


38 Encapsulated receptors
Merkel cells Sensitive to gentle physical sensation Found in stratum germinativum Abundant in fingertips

39 Meissner’s (tactile) corpuscles
Elongated, club-shaped pile of connective tissue Upper region of dermis (in dermal papilla) Respond to touch

40 Pacinian (lamellated) corpuscle
Look like onions Deeper parts of hypodermis Hard pressure, vibrations

41 Ruffini receptors Pressure, constant touch

42 Krause end bulbs Sensitive touch receptors
Found mostly in mucous membrane of mouth


44 Nails Merely a keratin secretion Nail root Lies beneath skin-nail fold
Grow back as long as nail root and skin-nail fold are not severely damaged Grow 1/8 in per month

45 Hair Modified stratum corneum
Grows from an individual follicle buried in subcutaneous layer



48 Dermis Specialized Structures (continued)
Arrector pili: tiny, smooth muscle attached to base of dermal papillae & side of hair follicle Contracts: pulls on both simultaneously>>goose bumps


50 Functions of the Integumentary System

51 Guiding Questions What are the major roles of the integumentary system? What are “commensals”? How does heat regulation in the skin work? How does sensation in the skin work? Briefly describe the three classifications of burns

52 Roles of the Integumentary System
Protection Heat regulation Sensation Waste excretion

53 Protection The skin protects from: Chemical Damage
Can break down connections between cells Can disintegrate cells Sweat dilutes & neutralizes Cerumen and sebum are oily barriers Repels water Repels dangerous chemicals that are dissolved in water Prevents water from escaping the body through the skin.

54 Protection The skin protects from: Mechanical Damage
Any type of force that can compress, erode, stretch or tear the skin. Loose connective tissue = flexibility Shedding stratum corneum = reduce erosion Calluses, adipose tissue and reticular fibers = shock absorption to minimize compression damage

55 Protection The skin protects from Microorganism damage
Produce destructive secretions in sebum / sweat Kept in check by chemicals that benefit commensals— ”good” bacteria and yeast that reduce the chance that harmful bacteria will survive on the skin. Shedding of stratum corneum removes microorganisms

56 Heat Regulation The body’s ability to maintain a constant internal temperature (98.6F) Blood vessels contract / expand Evaporation of the sweat from the surface Adipose tissue is a natural “blanket”

57 Sensation Sensation: received stimuli from the environment which is interpreted in a way that the brain can comprehend Done by sensory nerves in the skin Cold, heat, injury, pressure, stretching, touch Transducers: nerve cells that convert various environmental messages into body signals.

58 Waste Excretion & More Eccrine sweat glands Other functions
Removes urea, organic chemicals, and excess salts Not as efficient as the Excretory System Other functions Vitamin D production when exposed to sunlight Predictor of a person’s health

59 Burns Skin loses ability to maintain homeostasis locally and for the whole body Sun, cooking, acids, bases, corrosive chemicals, electricity, fires, and steam rooms Damage the skin differently Severity of burn is based on the extent of the skin damage.

60 First Degree Burns Reddening, swelling Superficial damage Steam, sun

61 First Degree Burn

62 Second Degree Burns Damage to Strata spinosum & basale
Blisters, reddening, swelling and fluid build up under the epidermis

63 Second Degree Burn

64 Third Degree Burns Entire epidermis affected, could be missing so stratum basale not available Damage to dermis: nerve cell loss Pain registers b/c histamine from immune system is released in response to the damage. Susceptible to dehydration, loss of body heat, and infection

65 Third Degree Burn

66 4th degree? Skin entirely damaged; bone, muscle underlying skin damaged as well. (Too graphic to show)

67 Pathology of the Integumentary System
Guiding Questions: What are the three major categories of disease in the integumentary system? What are the various types of degenerative skin disorders? Genetic skin disorders? Infectious skin disorders?

68 Disorders Degenerative Genetic Infectious
Progressive deterioration of tissue, environmental or physical stress Genetic Mutations Infectious Microorganisms that damage tissues and organs

69 Degenerative Skin Disorders
Solar lentigene People in their 30s w/ overexposure Dermatitis Cosmetics Facial cleansers Toners Can accelerate skin aging

70 Degenerative Skin Disorders
Skin Cancer Underlying genetic component—precancerous genes If damaged, genes cause abnormal divisions of cells Sun exposure Irregularly shaped black or brown spots that can develop into open sores Injury deep in the skin Discolored blisters or sores


72 Degenerative Skin Disorders
Moles: flat squamous cell tumors Skin tags: soft knobby tumors that grow out of skin Seborrheic keratosis: Black to brown growth on face or body that creates a greasy, rough appearance to the skin Sebaceous hyperplasia: caused by oil glands, small yellow bumps with an opening in the middle Syringomas: sweat-gland duct tumor, small lumps on the cheeks and eyelids Lipomas: fat cell tumor, don’t cause problems normally


74 Genetic Skin Disorders
Acne: stimulated by hormonal changes that cause and increase in sebum around the hair follicles. Furuncle or boil: a buildup of dead cells and blood components caused by the inflammation of hair follicles. Cysts or nodules: a sack-like structure filled with a fluid or semi-solid Bacteria that feed on the acne pimple produce chemicals that aggravate acne

75 Genetic Skin Disorders
Psoriasis Increased amt of skin cell production Causes a build up of thick scales on skin. Unsightly, inflamed, painful, swollen Birthmarks Port wine: begins at birth and grows, can bleed Spider veins: central blood vessel with smaller vessels branching from it Strawberry hemangiomas: enlarged blood vessels

76 Genetic Skin Disorders
Vitiligo Michael Jackson White spots—hypopigmentation Reduced melanocytes Albinism No melanin production in the eyes, hair or skin Melasma Brown patches on both sides of the face Symmetrical Does not completely disappear

77 Infectious Skin Disorders
Staphylococcus aureus (bacteria) destructive secretions that erodes and inflame the skin Impetigo, SSSS, folliculitis Candida albicans (fungus) Yeast in digestive system and female reproductive tract infect skin when immune system is compromised Degrade tissue and cause inflammation

78 Infectious Skin Disorders
More fungal infections = dermatophytes Eat keratin-rich materials: hair, nails, and outer layers of epidermis Itching, hair loss, deformation of nails Ringworm (aka tinea) Contracted from furry pets Spread from one person to another through contact via clothes and skin Related to athlete’s foot or jock itch

79 Infectious Skin Disorders
Warts (virus) 60 types HPV (human papilloma virus) Incurable Removal procedure Protists Exotic tropical diseases that are spread by insect bites. Can cause severe bodily damage if spread to internal organs

80 Infectious Skin Disorders
Arthropods Insects with exoskeletons, segmented bodies, jointed limbs Follicle mite—undetected until inflammation of eyelash follicle occurs Lice—blood sucking insects that irritate skin and spread infection as they feed

81 Aging of the Integumentary System
Guiding Questions What are “intrinsic” factors? How can they affect the skin’s aging? What kinds of extrinsic factors can affect skin aging? How does lifestyle accelerate skin aging?

82 Aging Extrinsic Intrinsic Also external aging
Environmental factors: disease, pollution, sun Intrinsic Natural maturation Also internal aging Accelerated by stress—pathology of other organ systems or environmental interactions

83 Aging Characteristics of skin aging Loss of head hair
Graying and whitening of hair Excessive growth of body and facial hair Wrinkling Drying of the skin due to diminished oil secretion Skin sagging due to muscle atrophy Regular irritation due to microbial population changes on the skin

84 Aging Impossible to stop Natural decline of cells
Can be slowed by living in a mild environment Elastin is naturally degraded by the dermis and subcutaneous layers Makes the skin less flexible, thinner, more brittle Decrease in blood flow slows cell division in basale & causes thinning of the epidermis More difficult to repair skin damage People with vascular diseases exhibit premature aging

85 Aging Decrease in melanocytes, nerves Susceptible to DNA damage
More susceptible to environmental damage Older skin can’t protect from UV and has difficulty registering injury. Susceptible to DNA damage Oxidizing chemicals and sunlight Cause cancers and tumors

86 Aging How to slow… Diet, reducing exposure to UV, avoiding skin irritation, not smoking, protecting from air pollutants Smoking reduces blood flow to skin Can’t heal Decreases ability to maintain body’s temp Skin needling Promotes growth and swelling in wrinkled depression areas Makes skin smooth for a while Take care of skin at a young age…difficult to reverse skin aging once the damage is done

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