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Dermatology
Anatomy and Pathophysiology
Built from Dermatology, 5th Edition
What’s inside
8 sections · 115 slides
Skin structure and function
Disease reveals what healthy skin normally does — five patient stories open this topic.
- How this topic is organized
- Skin has six jobs
- Five patient stories open this topic
- What the vignettes teach
- Skin is one of three body barriers
- Scientists now try to breach the skin barrier on purpose
- Disease rarely has just one cause
- A disease can reveal a function no one expected
- Three layers, one organ
- Regional variation in skin structure
- Dermal thickness varies by body site
- Palms and soles carry a thick protective surface
- Palm skin shows the same thick, compact layer
- Four resident cell types live in the epidermis
- The four layers of the epidermis
- Keratinocytes: the epidermis workhorse
- 50 um
- Keratinocytes speed up when the skin is under attack
- Melanocytes make the skin's UV shield
- Langerhans cells sample the environment for threats
- Merkel cells: the least understood epidermal cell
- The dermis supports the epidermis from below
- Five resident cell types complete the dermis
- Inflammation changes which cells fill the dermis
- The basement membrane joins epidermis to dermis
- The real job of skin: protecting DNA
- Skin's requirements, learned from its failures
- Selected requirements and failings of skin
Immunologic protection
Innate and adaptive immunity, shown through infection, autoimmunity and cancer.
- Two arms of immune protection
- How a skin immune response begins
- Skin keeps its own resident immune memory
- Infection tests every layer of skin defense
- Chronic warts (verrucae vulgares)
- How a wart forms and why some persist
- Treatment options for persistent warts
- Fungal infection also tests the stratum corneum barrier
- HIV shows what happens when cellular immunity fails
- Shingles along the trigeminal nerve in an immunocompromised patient
- Hansen disease (leprosy): most people clear it
- The tuberculoid-to-lepromatous spectrum
- What Hansen disease teaches about sensation
- Autoimmunity: the immune system attacks its own host
- Pemphigus vulgaris: cells lose their grip on each other
- Pemphigus vulgaris compared with bullous pemphigoid
- Pemphigus vulgaris vs bullous pemphigoid
- Paraneoplastic pemphigus can also attack the lungs
- Common autoimmune skin diseases
- The immune system also watches for cancer
- How cancer cells switch the immune system off
- Melanoma: a visible test of immune surveillance
- Under the microscope, host response predicts outcome
Maintaining a barrier
Keeping fluid in and microbes, chemicals, and UV radiation out.
- What the barrier has to hold back
- Toxic epidermal necrolysis: the epidermis detaches
- Toxic epidermal necrolysis: the barrier fails completely
- Consequences of losing the barrier in TEN
- There is no specific cure for TEN
- A defective barrier lets a topical drug cause systemic toxicity
- A defective barrier lets chemicals through
- How the stratum corneum limits UV damage
- Oculocutaneous albinism shows melanin's protective value
Repairing injury
Wound healing, its failures, and the DNA-repair disease that shows why UV matters.
- Injury comes in several forms
- Some wounds fail to heal on schedule
- Keloids: healing that overshoots
- Xeroderma pigmentosum: when DNA repair fails
Circulation
Two circulatory systems keep the skin fed, cooled, and connected to the immune system.
- Two circulatory systems serve the skin
- Two kinds of blood vessels in skin
- Lymphatic vessels carry cells back to the immune system
- Blocked arteries kill the tissue downstream
- Vasculitis: inflammation targets the vessel wall itself
- Vasculitis can progress to skin ulceration
- Occlusive vasculopathy: clots block flow without inflammation
- Venous insufficiency: the most common vascular skin problem
- Blocked lymphatics cause chronic swelling
Communication
Nerves, hormones, cytokines, and traveling cells all carry messages through skin.
- Three ways skin sends and receives messages
- Skin is wired with an intricate nerve network
- What skin nerves actually control
- Botulinum toxin works by silencing local nerves
- Touch shapes early development, not just sensation
- Itch: common, distressing, and structurally unexplained
- Postherpetic neuralgia: pain that outlasts the rash
- Hyperhidrosis: a nerve problem, not a gland problem
- Losing sensation leaves skin unprotected from trauma
- Vitamin D: a hormone the skin manufactures
- Adrenal hormones swing skin disease both ways
- Cytokines: the skin's local chemical messengers
- Understanding cytokines changed how psoriasis is treated
- Dendritic cells physically carry information out of the skin
Regulating temperature
Skin works as both radiator and insulator to hold core temperature near 37C.
- Two tools keep core temperature near 37C
- millions
- Cooling the body needs nerves, vessels and glands together
- No sweat glands, no cooling: a lethal example
- Heat is also used as a therapy
- Cold injury: two different mechanisms
- Cryosurgery turns cold injury into a treatment
Interpersonal communication
Skin conveys beauty, attention, and self-identity — and its loss causes real distress.
- Skin is a canvas for identity, not just biology
- Chronic skin disease has a measurable quality-of-life cost
- Skin can be deliberately modified to express identity
- What counts as an 'unattractive' appearance varies by culture
- Vitiligo: an autoimmune loss of pigment
- Pigmentary disorders are more visible on darker skin
- Pigmentation loss carries added risk where it is stigmatized
- Hair distribution: two opposite kinds of concern
- Scarring alopecia matters even though it is less common
- Fat distribution: mostly a psychologic concern
- Therapy side effects also reveal structure and function
- Key takeaways
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- Dermatology, 5th Edition (2-Volume Set)