Integumentary System Physiology and Pathophysiology PDF

Integumentary System Physiology and Pathophysiology of Diseases 1 Primary Physiological Processes and Functions 2  PROTECTION: The Body’s first line of Defense Barrier function...

Integumentary System Physiology and Pathophysiology of Diseases 1 Primary Physiological Processes and Functions 2  PROTECTION: The Body’s first line of Defense Barrier function The skin acts as a physical barrier, preventing the entry of pathogens, harmful chemicals, and excessive UV radiation The stratum corneum, the outermost layer of the epidermis, is composed of tightly packed, keratinized cells forming a tough, waterproof barrier. Mucous membranes in orifices provide additional protection. Melanin, produced by melanocytes, absorbs UV radiation, protecting underlying tissues from damage. Primary importance: Prevents infection, dehydration, and skin cancer. 3 PROTECTION: The Body’s first line of Defense 4  PROTECTION: The Body’s first line of Defense Chemical barrier The skin secretes substances that inhibit microbial growth and protect against chemical damage. Sebaceous glands secrete sebum, an oily substance with antimicrobial properties. Sweat glands secrete sweat, which contains antimicrobial peptides and lactic acid. The slightly acidic pH of the skin inhibits bacterial growth. Primary importance: Prevents infection and protects against chemical irritants. 5 PROTECTION: The Body’s first line of Defense Acne formation 6  PROTECTION: The Body’s first line of Defense Biological barrier The skin houses immune cells that defend against pathogens. Langerhans cells (dendritic cells) in the epidermis act as antigen- presenting cells, initiating immune responses. Other immune cells, such as macrophages and lymphocytes, reside in the dermis and contribute to immune defense. Primary importance: Provides a crucial component of the innate immune system, preventing infection and initiating adaptive immune responses. 7 PROTECTION: The Body’s first line of Defense 8  THERMOREGULATION: Maintaining Body Temperature Vasoconstriction and Vasodilation Blood vessels in the dermis constrict (vasoconstriction) to conserve heat or dilate (vasodilation) to release heat. In cold conditions, sympathetic nervous system stimulation causes vasoconstriction, reducing blood flow to the skin and minimizing heat loss. In warm conditions, vasodilation increases blood flow to the skin, facilitating heat dissipation. Primary importance: Maintains core body temperature within a narrow range. 9 THERMOREGULATION: Maintaining Body Temperature 10  THERMOREGULATION: Maintaining Body Temperature Sweating Sweat glands secrete sweat, which evaporates and cools the skin. Sweat is produced by sudoriferous glands. As sweat evaporates from the skin surface, it absorbs heat, cooling the body. The rate of sweating is regulated by the hypothalamus in response to changes in core body temperature. Primary importance: Effective mechanism for heat dissipation, particularly in hot and humid environments. 11 THERMOREGULATION: Maintaining Body Temperature 12  THERMOREGULATION: Maintaining Body Temperature Insulation The subcutaneous layer (hypodermis) provides insulation against heat loss. The hypodermis contains adipose tissue, which acts as an insulator, reducing heat loss from the body. The thickness of the hypodermis varies depending on body location and individual factors. Primary importance: Minimizes heat loss in cold environments. 13 THERMOREGULATION: Maintaining Body Temperature 14  EXCRETION & SECRETION: Waste Removal and Protection Sweat Gland Secretion Sweat glands, particularly eccrine glands, secrete sweat onto the skin surface. This process is regulated by the autonomic nervous system, responding to factors such as temperature, humidity, and physical activity. The composition of sweat varies depending on factors such as temperature and hydration status. Primary importance: Excretes small amounts of metabolic wastes, helping to regulate body fluid balance. 15  EXCRETION & SECRETION: Waste Removal and Protection Sweat Gland Secretion Sweat is a clear, odorless fluid produced by sweat glands (sudoriferous glands) in the skin. The excretion of waste products through sweat helps maintain homeostasis by regulating body temperature and fluid balance. It also plays a minor role in detoxification, as some toxins and metabolites can be eliminated through the skin. 16  EXCRETION & SECRETION: Waste Removal and Protection Sebum Secretion Sebaceous glands secrete sebum, an oily substance that lubricates and protects the skin. Sebum is secreted by sebaceous glands and released onto the skin surface. It lubricates the skin and hair, preventing dryness and cracking. Sebum also has antimicrobial properties. Primary importance: Maintains skin hydration and protects against microbial invasion. 17  EXCRETION & SECRETION: Waste Removal and Protection Sebum Secretion Sebum is composed primarily of triglycerides, free fatty acids, wax esters, squalene, and cholesterol. The antimicrobial properties of sebum help reduce the risk of skin infections by inhibiting the growth of harmful bacteria and fungi. This is particularly important in areas of the skin that are prone to moisture and friction, where infections are more likely to occur. 18  EXCRETION & SECRETION: Waste Removal and Protection Vitamin D Synthesis The skin synthesizes vitamin D when exposed to ultraviolet (UV) radiation. Primary importance: Vitamin D plays a vital role in immune function by modulating both innate and adaptive immune responses, exerting anti-inflammatory effects, and providing protection against infections and autoimmune diseases. 19 EXCRETION & SECRETION: Waste Removal and Protection 20  SENSORY RECEPTION: Touch, Temperature, and Pain Sensory Receptors Specialized nerve endings in the skin detect various stimuli, including touch, pressure, temperature, and pain. Different types of sensory receptors respond to specific stimuli. Meissner's corpuscles detect light touch, Pacinian corpuscles detect deep pressure, and free nerve endings detect pain and temperature. Primary importance: Provides information about the external environment and helps protect the body from harm. 21 EXCRETION & SECRETION: Waste Removal and Protection 22  SENSORY RECEPTION: Touch, Temperature, and Pain Sensory Transduction and Pain Perception The conversion of sensory stimuli into electrical signals that are transmitted to the brain. Sensory receptors convert stimuli into electrical signals, which are then transmitted along sensory neurons to the spinal cord and brain. Free nerve endings in the skin detect painful stimuli. Painful stimuli activate free nerve endings, which transmit signals to the spinal cord and brain. The brain interprets these signals as pain. Primary importance: Allows the brain to interpret sensory information and respond appropriately. Alerts the body to potential harm and triggers protective responses. 23 SENSORY TRANSDUCTION: Touch, Temperature, and Pain 24  Wound Healing and Repair Inflammation The body's initial response to tissue injury, characterized by redness, swelling, heat, and pain. Primary importance: Prevents the spread of infection, removes debris, and prepares the tissue for repair. 25 SENSORY RECEPTION: Touch, Temperature, and Pain 26  Wound Healing and Repair Cell Proliferation and Migration New cells are produced and migrate to the site of injury to repair the damaged tissue. Epithelial cells migrate across the wound surface, closing the gap. Fibroblasts produce collagen fibers, forming a scar tissue. Primary importance: Restores the integrity of the skin and protects the underlying tissues. 27  Wound Healing and Repair Remodeling and Scar Formation The scar tissue is remodeled, and the wound is healed. Collagen fibers are reorganized, and the scar tissue matures. The wound may remain slightly discolored or raised. Primary importance: Completes the healing process, although the scar tissue may not have the same properties as the original tissue. 28 SENSORY RECEPTION: Touch, Temperature, and Pain 29  Representative Diseases and Disorders of the Integumentary System Birthmarks Ringworm Eczema 30  Representative Diseases and Disorders of the Integumentary System Ringworm Infections 31  Representative Diseases and Disorders of the Integumentary System Ringworm Infections Tinea pedis -caused by Trichophyton rubrum and Epidermophyton floccosum - Athlete’s foot Tinea unguium - caused by Trichophyton rubrum, Trichophyton mentagrophytes, and Epidermophyton floccosum - Onychomycosis Tinea corporis - caused by Trichophyton rubrum - Ringworm - caused by Epidermophyton floccosum ***Removal of infected skin, followed by topical application of antifungal antibiotics (Miconazole, Clotrimazole), is the Tinea capitis first course of treatment. - Scalp ringworm - caused by Trichophyton tonsurans Tinea cruris - Jock itch 32  Representative Diseases and Disorders of the Integumentary System Frostbite 33  Representative Diseases and Disorders of the Integumentary System Psoriasis Psoriasis is believed to be an autoimmune disorder in which the immune system attacks a person’s own tissues, leading to the rapid overproduction of skin cells. Attacks are often triggered by trauma, infection, hormonal changes, stress, and some drugs (beta-blockers, lithium, antimalarial drugs such as (hydroxy)chloroquine, interferons, imiquimod, and terbinafine. Targeted oncology drugs). When severe, psoriasis may be disfiguring. Management includes application of topical steroids and systemic management with Methotrexate. 34 35  Representative Diseases and Disorders of the Integumentary System Vitiligo Alopecia areata 36  Representative Diseases and Disorders of the Integumentary System Impetigo Erysipelas Swollen patches in the skin caused by the bacterium Streptococcus pyogenes Affects all age groups, patients with erysipelas suffer from a fiery red, advancing erythema, especially on the face and lower limbs. Aka Pyoderma Drug of choice: Penicillin G Topical treatment with mupirocin is adequate for single Alternatives: Clarithromycin, lesions or small areas of involvement. Systemic Azithromycin antibiotics (e.g., cephalexin, erythromycin, dicloxacillin) are indicated for extensive cases. 37 Representative Diseases Decubitus ulcers and Disorders of the Integumentary System Acne Representative Diseases and Disorders of the Integumentary System Acne 39 Representative Diseases and Disorders of the Integumentary System Rubeola Hard Measles Caused by a virus (Measles virus) contracted through the respiratory tract Manifest as maculopapular erythematous rash Resolves in 2-3 weeks; no treatment; prevented by vaccination Rubella German Measles Usually mild viral disease (due to Rubella virus) contracted through the respiratory tract; may be dangerous if contracted during pregnancy because the virus can cross the placenta and damage the fetus ; nonblanching rash, faint, pink, maculopapular rash – scarlatiniform eruption (sandpaper-like texture) 40  Representative Diseases and Disorders of the Integumentary System Chickenpox Shingles 41  Representative Diseases and Disorders of the Integumentary System Both are caused by Varicella-Zoster Virus Treated with antiviral drugs Acyclovir and its derivatives (Famciclovir, Penciclovir, and Valacyclovir) Chickenpox Shingles Aka Varicella Aka Zoster The hallmark of varicella is the simultaneous caused by the chickenpox virus after presence of different stages of the rash. childhood infection; can recur when The vesicles are delicate and are often the dormant virus is activated by described as appearing as “dewdrops on rose petals.” trauma, stress, or another illness 42  Representative Diseases and Disorders of the Integumentary System Cold sores Genital herpes HSV-1 is also known as human herpes virus 1, or HHV-1, and causes most infections above the waist; 80% are due to HSV-1, and 20% are due to HSV-2. HSV-2 causes most infections below the waist; 80% are due to HSV-2, and 20% are due to HSV-1. Usually resolve within 2 weeks Drug of choice: Acyclovir 43  Representative Diseases and Disorders of the Integumentary System Diaper rash Oral thrush Both infections are classified as cutaneous candidiasis caused by the fungus Candida albicans, which is a part of the body’s normal microbiota. Topical medications - Nystatin and Miconazole Systemic - Ketoconazole 44  Representative Diseases and Disorders of the Integumentary System Lyme disease Lyme disease is caused by Borrelia burgdorferi, a bacterial spirochete. This picture shows the large classic “bull’s eye” (erythema chronicum migrans) lesions on the posterior area of upper arm following a tick bite. Oral doxycycline, amoxicillin, or cefuroxime can be given to a patient bitten by a tick from an area that is endemic for Lyme disease. Patients with certain neurologic or cardiac forms of illness may require intravenous treatment with ceftriaxone or penicillin. To prevent tick bites, avoid tick habitats, wear appropriate clothing (long-sleeved garments and long pants) when outdoors, and use insect repellants. Because it can take several hours for the bacteria to infect a person, prompt removal of attached ticks can prevent infections. 45  Widespread rashes that are usually accompanied by systemic symptoms of Exanthems - fever, malaise (body ache), and headache. 46 Manifestations of Childhood Exanthems 47  Papules, Plaques, and Patches HYPOPIGMENTED PLAQUES SERPIGINOUS or ANNULAR PLAQUES Tinea versicolor Lyme disease ERYTHEMATOUS PLAQUES SMOOTH PAPULES Candidiasis Erythema nodosum Tinea Molluscum contagiosum Erythrasma Condyloma lata Cellulitis Erysipelas VERRUCOUS PAPULES Subcutaneous necrotizing infections Verrucae (warts, genital warts) Blastomycosis 48  Diseases that result in Vesicular, Bullous, and Purulent Lesions Vesicular and Bullous Lesions Purulent Lesions Herpes simplex skin lesions Acne vulgaris Varicella (Chickenpox) Folliculitis Herpes zoster Furunculosis Hand, foot, and mouth disease Carbuncles Herpangina Herpetic whitlow Bullous impetigo Gonococcemia Vaccinia (Cowpox) 49  Petechial, Hemorrhagic, Ulcerative, and Necrotic Lesions Petechiae Hemorrhagic lesions pinpoint, flat, round lesions caused by intradermal or flat, irregularly shaped lesions larger than petechiae, and are also submucosal hemorrhage caused by intradermal or submucosal hemorrhage Ulcer Necrotic lesions a localized excavation of the skin surface and are result when cells in the skin die and are destroyed by the produced by sloughing of inflammatory necrotic tissue progressive degradative action of various enzymes 50  Petechial, Hemorrhagic, Ulcerative, and Necrotic Lesions Diseases that cause Petechial & Diseases that cause Ulcerative & Hemorrhagic Lesions Necrotic Lesions Endocarditis Impetigo Meningococcemia Ecthyma Gonoccocemia Primary syphilis Rocky Mountain spotted fever Burn or Wound infections Ecthyma gangreonosum Gas gangrene Herpes simplex skin lesions 51