Integument Flashcards
The functions of this include barrier for protection, sensation and excretion, thermoregulation, and synthesis of Vitamin D3.
Integument
What is the integument composed of?
Epidermis (epithelial layer – ectoderm)
Dermis (CT layer – mesoderm)
Deep to the dermis lies the ________, a loose CT layer that binds the skin to underlying tissues and corresponds to the superficial fascia.
Hypodermis
The epidermis is made of what epithelial cell type?
Stratified squamous keratinized epithelium
***Composed of keratinocytes
These are irregular projections at epidermal-dermal junction. They interdigitate with epidermal ridges to strengthen adhesion.
Dermal papillae
Fingerprints, palms, and soles are (THICK/THIN) skin.
Thick (five layers)
Glands, hair follicles, and most of the body is (THICK/THIN) skin.
Thin (four layers)
The epidermis consists of 4-5 layers which are…
Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale
The epidermis has 4-5 layers consisting of what different types of cells?
Keratinocytes
Melanocytes
Merkel cells
Langerhans cells
This is the predominant cell type of the epidermis. It produces keratins (85 percent of cells) and participate in the epidermal water barrier. Will produce ‘cornified’ cells, full of keratin.
Keratinocytes
This layer of the epidermis has a single-layer of keratinocytes with stem cells interspersed. It is mitotically active, and made of cuboidal/low columnar cells. Contains melanin.
Stratum basale
The Stratum basale is bound apically by ________ and basally by _________.
Desmosomes
Hemidesmosomes
This is the thickest layer of the epidermis. It has polyhedral cells with central nuclei and spiny processes. Keratin filaments assemble here into microscopically visible bundles called tonofibrils.
Stratum spinosum
***Tonofibrils associated with desmosomes, resulting in a spiny appearance. Called “prickle layer”
This layer of the epidermis consists of three to fiver layers of flattened cells. It is filled with keratohyaline granules and lamellar granules (small ovoid structures containing lipids and glycolipids).
Stratum Granulosum
***Lamellar granules undergo exocytosis and release lipids, creating an impermeable layer that protects against water loss
In the Stratum Granulosum, the keratohyaline granules are composed of…
Tonofibrils + Filaggrin (bundling protein)
In this layer of the epidermis, there is 15-20 layers of squamous, keratinized cells filled with filamentous keratins. Cells are anucleate and coated by an extracellular layer of lipids.
Stratum Corneum
In the Stratum Corneum, fully keratinized ‘cornified’ cells called ________ are continuously shed as desmosomes break down.
Squames
This epidermal layer is found ONLY in thick skin. It is a thin, translucent layer of flattened eosinophilic keratinocytes held together by desmosomes. Nuclei and organelles have been lost and the cytoplasm is almost exclusively keratin filaments.
Stratum Lucidum
These cells produce melanin and transfer it to keratinocytes. They are neural crest-derived and scattered along the Stratum Basale.
Melanocytes
This is a pigment protein that protects nuclei form UV radiation.
Melanin
In an ________-________ unit, one melanocyte maintains an association with a specific number of keratinocytes (1:10).
Epidermal-melanin
What are the steps in melanin production?
Tyrosinase converts Tyrosine into DOPA, DOPA is then polymerized into Melanin
Melanin production reactions occur in membrane-bound organelles called __________. As melanin increases these organelles, they are converted into _________. These are then transferred to keratinocytes where they give the “pigment donation”.
Premelanosomes
Melanosomes
The cells are APCs that provide defense against pathogens (developed from monocyte precursor). Identifiable in Stratum Spinosum, and appear as pale cytoplasm with long processes.
Langerhans cells
Explain epidermal differentiation and replacement.
Epidermal cell replacements is initiated by the division of stem cells in the Stratum Basale. New cells undergo divisions and move upward as they differentiate into keratinized cells. Eventually lost by skin exfoliation.
The Dermal-Epidermal Junction consists of an uneven boundary with finger-like _______ ______ that project into the dermis. These are complemented by epidermal protrusions called _______ _______. Increased in size/number at sites of mechanical stress.
Dermal papillae
Epidermal ridges
***Attached by hemidesmosomes and focal adhesions
This layer of the dermis consists of loose CT immediately beneath the epidermis. It has vasculature and nerve endings.
Papillary layer
This layer of the dermis consists of dense irregular CT with coarse elastic fibers. Form regular lines of tension, called Langer’s lines.
Reticular layer
***Deep to Papillar layer
This is a rich, nutritive capillary network located between the Papillary and Reticular layers.
Subpapillary plexus
This lies near the dermis-subcutaneous layer interface.
Deep plexus
This is the loose CT that binds the skin loosely to the subjacent organs. It has adipocytes that vary in number and size based on body regions/nutritional state.
Hypodermis (Subcutaneous Fascia)
The ________ has extensive vasculature that promotes rapid uptake of insulin or drugs injected into this tissue.
Hypodermis
These are epithelial tactile cells that function as low-threshold mechanoreceptors essential for sensing gentle touch. They are abundant in highly sensitive skin (fingertips, hair follicles).
Merkel cells
These cells resemble surrounding keratinocytes but lack melanosomes. They also contain small, Golgi-derived granules concentrated near the basolateral surface.
Merkel cells
This type of cancer is rare, aggressive and difficult to treat. 40 times less common than malignant melanoma, but 2x the mortality rate.
Merkel cell carcinoma (MCC)
These are located in the papillary dermis and extend into lower epidermal layers. Respond primarily to high and low temperatures, pain, and itching. May also function as tactile receptors.
Free nerve endings
These are encapsulated receptors responsive to light-touch or low-frequency stimuli. They are perpendicular to the epidermis in the dermal papillae. Numerous in the fingertips, palms, and soles.
Meissner’s Corpuscles
These are large, encapsulated oval structures found deep in the reticular dermis and hypodermic. They are specialized for sensing coarse touch, pressure (sustained touch), and vibration.
Lamellated (Pacinian) Corpuscles
T/F. Lamellated (Pacinian) Corpuscles are also found in the CT of visceral organs and the wall of the rectum and urinary bladder (produce pressure sensations when distorted).
True
This type of gland has secretion delivered via membrane-bound vesicles and undergo exocytosis.
Merocrine gland (eccrine)
This type of gland has secretion that accumulates within the cell. Apoptosis occurs and the secretion and cell debris is released.
Holocrine gland
This type of gland has release of the apical portion of the cell, surrounded by cytoplasm within a plasma membrane.
Apocrine gland
These glands have several per follicle and are abundant on the face and scalp. They produce a lipid mixture of sebum via holocrine secretion.
Sebaceous glands
Sebaceous glands have a waxy mix of ________ and ________ that lubricates and softens skin as well as waterproofs the skin. The ________ produced by the gland is released into the hair follicle.
Triglycerides
Cholesterol
Sebum
These are simple, coiled glands found extensively throughout skin. The duct is stratified cuboidal and myoepithelial cells facilitate expulsion of secretions.
Eccrine sweat glands
Eccrine sweat glands provide temperature regulation via cooling. Evaporation of _______ from sweat on body surface.
Water
***Sweat components – Water, salt, ammonia, uric acid, and mucinogen granules
The are large-lumen, tubular glands. The duct is stratified cuboidal and myoepithelial cells facilitate expulsion of secretions.
Apocrine sweat glands
Apocrine sweat glands use merocrine secretion (protein, carbohydrate, and ammonia-rich secretion). The secretions are odorless until mixed with bacteria. Becomes functional at ________.
Puberty
Hair follicle has a terminal dilation called a ______ _____. The dermal papilla inserts into this structure and provides nutrients via capillaries.
Hair bulb
Keratinocytes form the hair matrix. They are continuous with the epidermis and divide and differentiate, which is what causes…
Hair growth
This is near the Arrector Pili muscles insertion and contains epidermal stem cells.
Follicular bulge
This is a small bundle of smooth muscle that extends from the midpoint of the hair root to the papillary layer (dermis). It’s what causes “goose bumps” – contracting muscles distort attached dermis.
Arrector pili muscle
Nails are highly keratinized cells on a bed of epidermis (nail bed). The nail _______ is the most proximal region, covers the nail matrix.
Root
The nail _______ consists of stem cells that divide and form keratinocytes. The nail plate remains attached to the nail bed but is pushed forward by continuous growth.
Matrix
This is the crescent-shaped white area near the nail matrix.
Lunula
This is the extension of skin covering the nail root.
Cuticle