Derm anatomy Flashcards
Where is thick skin found on the body?
Palms of hands, bottoms of feet, fingers, toes
Stratum corneum
Most superficial layer (20-30 cell layers thick in thick skin). All keratinocytes in this layer are dead. Layer deep to stratum is the stratum lucidum (thick skin only) or stratum granulosum
Layers of epidermis that are dead
Stratum corneum, stratum lucidum, and stratum granulosum (beginning to die)
Stratum lucidum
Thick skin only! 5-10 cell layers thick, SF: s. Corneum; D: s. Granulosum. Keratinocytes are dead in this layer
Stratum granulosum
5-10 cell layers thick. Keratinocytes are beginning to die. SF: s. Lucidum (thick skin only) or s. Corneum; D: s. Spinosum
Stratum spinosum
10-20 cell layers thick. Cells are alive but beginning to produce precursor protein for cell death in more superficial layers. SF: s. Granulosum; D: s. Basale
Stratum basale
Deepest later of the epidermis; 1-2 cell layers thick; site of cell division for SF layers of epidermis; contains melanocytes and Merkel cells. SF: s. Spinosum; D: basement membrane (separates epidermis from dermis)
Melanocyte
Present in stratum basale layer of epidermis. Produce pigment that determine skin color
Merkel Cell
Oval shaped mechanoreceptors that specialize in light/fine touch stimuli. Present in stratum basale layer of epidermis.
Layers of epidermis
(Stratum) corneum (10-20 layers thick for thick skin, less otherwise), lucidum (thick skin only, 5-10 cell layers), granulosum (5-10 layers), spinosum (10-20 cell layers), basale (1-2 cell layers). All layers are composed of stratified squamous epithelial tissue.
Papillary layer
Most superficial dermis layer. Made up of areolar connective tissue and is highly vascularized. Plays a role in temperature control with dilation/constriction of papillary loops. Papilla increase surface area with epidermis and contain meissner’s corpuscles and nociceptors. SF: basement membrane; D: d. Reticulum
Meissner’s Corpuscle
Nerve ending present in dermal papilla. Transmit sensations of fine, discriminative touch and vibration.
Dermis reticulum
Made of up dense, fibrous, irregular connective tissue; well vascularized; contains nocireceptors. SF: d. Papilla; D: adipose layer/subcutaneous layer of the hypodermis
Nociceptor
Free nerve endings that initiate sensation of pain. Present in d. Reticulum and d. Papilar (entire dermis).
Types of sweat glands
Eccrine and Merocrine
Merocrine/eccrine glands
Abundant throughout the entire body. Produces watery sweat and excretes it into tubules that connect to s. Corneum. Stimulated by sympathetic nervous system and is involved in temperature regulation (evaporative cooling).
Layers of Dermis
Papillary, reticulum.
Hypodermis
Made up of adipose/subcutaneous connective tissue. Contains pacinian corpuscles
Pacinian corpuscles
Mechanoreceptors found in hypodermis. Deep touch, pressure, vibrations.
Types of mechanoreceptors
Pacinian corpuscles, meissner’s corpuscles, Merkel’s disks, and Ruffini’s corpuscles
Apocrine gland
Produce a fluid that is secreted onto the superficial stratum lucidum. Contains proteins and lipids that are broken down by bacteria and creates body odor. Found only in axillary and anogenital region.
Hair follicle
Contains shaft, bulb, and root. Connected to arrector pili muscle (autonomic control). Next to sebaceous gland Not present in thick skin.
Sebaceous gland
Surrounds hair follicle shafts in the dermis. Produces lubricating oil (sebum) into the hair follicles to lubricate the skin and hair and kill certain types of bacteria.
Components of the integumentary system
Skin, subcutaneous tissue, appendages
What are the appendages of the integumentary system?
Sweat glands, sebaceous/oil glands, hair, hair follicles, nails
what proportion of the body’s total body mass is skin?
8%
Follow the skin regions from most deep to superficial
reticular dermis, papillary dermis, stratum basale, stratum spinosum, stratum granulosum, stratum lucidum*, stratum corneum.
The subcutaneous adipose layer is not technically part of the skin
What are the tissue types in the epithelium vs dermis
stratified sq. epithelium in the epidermis, connective tissue in dermis
cell types in the epithelium
Keratinocytes (90%), Melanocytes (10-25% of cells in basal layer), Langerhans cells, Merkel cells
What proteins are produced by cells in the epidermis
Keratin (fibrous), Filaggrin (water retention)
How many rows of cells are present in the stratum basale
1 single row of stem cells (rapid division)
Source of keratinocytes in epithelium and lifespan
Cell division in s. basale followed by migration superficially before being sloughed off at the s. corneum. The cells are largely dead upon reaching the s. granulosum. It takes 25-24 days to migrate to s. corneum
What epidermal layer are langerhans cells found in?
s. spinosum
What do the granules in the s. granulosum contain and what is this layer’s function?
- Lipid-rich secretion 2. filaggrin. These act as a water sealant (lipids) and also retain water inside the dying keratinocytes (filaggrin)
What kind of skin has a s. lucidum
thick only
Functions of the s. corneum
dead, flat, keratinized membranous sacs account for 3/4 of the epidermal thickness and continuously slough off. They provide protection from abrasion and penetration, give the skin its waterproof property, and act as a barrier against biological/chemical/physical assaults
Bullous pemphigoid
Autoimmune blistering disease typically affecting older patients. autoantibodies bind to antigens directly beneath the s. basale. Presentation involves tense bullae on an erythematous base
Pemphigus Vulgaris
Autoimmune disease typicall affecting yound adults. autoantibodies bind antigens in intercellular spaces, causing decreased adhesions between cells (skin breaks off)
Psoriasis
epidermal turnover is increased. Not enough time (25-45 days) for differentiation. Presents with scale (secondary lesion)
Atopic dermatitis
Caused by mutations in filaggrin (water retention protein in keratinocytes). May be associated with other atopic diseases such as asthma
Melanocyte nevi
(Moles), benign collections of melanocytes
Melanoma
Malignancy of melanocytes
Basal cell Carcinoma
proliferation of basal keratinocytes. Presents with pearly, erythematous papules/plaques with rolled borders and telangectasias in photodistributed areas.
Tissue contents of Dermis
connective tissue, blood vessels, lymph vessels, nerves. All supply skin, sweat glands, and hair follicles
Layers of dermis from most deep to superficial
Reticular, papillary
Functions of the papillary dermis
Mechanical anchorage of epidermis, metabolic support of epidermis
Contents of dermal papillae
Capillary loops, meissner’s corpusle, pacinian corpuscle, Free nerve endings
Name the receptors present in all skin layers and what they detect
Merkel Cells (light/fine touch), Pacinian corp (pressure/vibration), meissner’s corp (light touch), free nerve endings (pain)
Fibers present in areolar connective tissues of papillary dermis
Elastic and collagen fibers
Function of reticular dermis
thick collagen fibers provide strength and reiliency
Cells present in the dermis
Fibroplasts (fiber production), Macrophages, some mast cells/WBCs
Factors that can influence Fibroblast activity
Steroid hormones, dietary content, mechanical stresses. Vitamin C deficiency impairs collagen formation
Keloid
Abnormal scars resulting from uncontrolled synthesis and excessive deposition of collagen (fibroblasts!) at sites of prior injury and wound repair. results in a prominent scar that extends beyond the wound. Genetics play a role
Hypertrophied scar
prominent/raised scar that is localized to the wound (compare to keloid)
Mast cells
Defensive cells; contain granules of histamine (and other chemicals) that activate inflammation. Filopodia extend outward from membrane. They are numerous around blood vessels.
types of inflammatory response
localized (urticaria) or generalized (anaphylactic shock)
Friction ridges
dermal papillary ridges push up on the epidermis to create epidermal ridges.
Cleavage lines
tension lines of collagen fibers arranged in bundles. Healing is more rapid when incisions are made parallel to cleavage lines
pigments that contribute to skin color
Melanin (dark skin), Carotene (yellow/orange; palms/soles), hemoglobin (pink)
Hypodermis contents
loose connective tissue, adipose component
Function of hypodermis
thermal insulation, shock absorber, metabolic energy store
Lipoma
benign tumor of fat. Mobile, slow growing, painless (unless angiolipoma). Most common soft tissue tumor of adulthood. Multiple lipomas suggest presence of rare autosomal dominant syndromes
Erythema nodosum
inflammation of hypodermis. Could be from infection reaction, medication, or Autoimmune disease
2 types of sweat glands
Eccrine (merocrine); thermoregualtion, Apocrine; BO
Where are different types of swear glands found?
Eccrine (abundant on palms, soles, forehead), Apocrine (axilla, perianal region, areolae, and periumbilical skin)
Contents and purpose of sweat
99% H2O, evaporative cooling, sexual scent? (apocrine)
Other types of apocrine glands
Ceruminous glands (ear wax), mammary gland
functions of hair
Defense (alert to insect presence), protection (physical trauma, heat loss, sunlight
Which part of the hair follicle is necessary for hair growth?
hair bulb
Cycles of hair growth
Anagen/growing phase, Catagen/involuting phase: hair growth ceases and follicle shrinks, telogen/resting phase: inferior segment of the follicle is absent, exogen/shedding phase
Acne Vulgaris
disorder of Pilo Seb unit. Caused by 4 things: 1. abnormal keratinization plugs the hair follicle.
2. propionibacterium acnes in the hair follicle. Causes inflammation
3. Hormones (androgens)
4. sebaceous gland activity (increased in presence of androgens)
Structure of a nail
Free edge, nail body, lunula, eponychium (cuticle), nail root (contains proliferating nail matrix)
Parts of a nail
Nail plate: keratin, nail bed: specialized skin (same 4 layers of epiderm), eponychium (cuticle): thickened skin surrounding nail
Vascular supply of the skin
Direct cutaneous system (capillary loops in papillae), musculocutaneous system, fasciocutaneous system
Innervation of the skin
somatic and autonomic components (sensory and thermoregulatory properties)
Age-related skin changes
chronological, environmental (photo-ageing)
Protective barriers the skin provides
Chemical (acidic secretions and defensins), physical (keratin and glycolipids block water and water-soluble substances, melanin protects agains UV rad), Biological (langerhans cells, macrophages
How does the skin aid in temp regulation
Elevated Temperature: dermal vessel dilation, increased eccrine gland activity
Decreased Temperature: dermal vessel constriction
Describe the sensory properties of skin
Temperature, touch, and pain
Accessory skin functions
Metabolic functions (Vit D and collagenase), Blood reservoir (5%), Excretion (sweat), social communication
Cardinal signs of inflammation
Rubor (red), Calor (heat), Tumor (swelling), dolor (pain), functio laesa (phys function has changed)
Cell involved in short-term inflammatory resoonse
Neutrophils
Components of acute inflammation
hemodynamic changes, neutrophil involvement, chemical mediators
Hemodynamic changes during acute inflammation
- transient vasoconstriction
- massive vasodilation mediated by histamine, bradykinin, and prostaglandins
- increased vascular permeability
- blood flow slows due to increased viscosity, allows neutrophils to migrate
Neutrophil involvement in acute inflammation
Margination & adhesion to capillary wall, emigration out of capillary, chemotaxis toward chemical released by mast cells, phagocytosis and degranulation, intracellular killing.
Chemical mediators involved in acute inflammation
Vasoactive amines, products of the kinin system, arachidonic acid products, products of the lipoxygenase pathway, complement system, and cytokines
Possible outcomes of acute inflammation
- Resolution of damage/infection with regeneration of damaged tissue.
- Resolution with scarring
- Abscess formation
- Transition to chronic inflammation
Characteristics of chronic inflammation
prolonged duration (weeks to years). Infiltration of inflamed area with mononuclear cells (macrophages, lymphocytes, and plasma cells), tissue destruction induced by inflammatory products, repair (new vessel proliferation and fibrosis)
5 Rs of inflammation
- Recognition of injurious agent
- Recruitment of leukocytes
- Removal of agent
- Regulation of response (control)
- Resolution (repair)
Different regenerative capacities of different cell types
Labile (regenerate throughout life), Stable (low level replication), permanent (no replication and is replaced by fibrous scar tissue)
2 types of tissue repair
- primary union
- secondary union (residual scarring)
