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145 Cards in this Set
- Front
- Back
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tissue
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an aggregation of similar cells or types of cells that are adapted to perform one or more functions
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organ
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composed of tissues and cells that are adapted to perform one or more functions
as part of a differentiated structure or system |
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integument functions
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protection
sensation thermoregulation immunologic function vitamin D production |
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integumentarysystem
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integument (skin, cutis) and its derivatives integument = epidermis and dermis
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derivatives of epidermis
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hair, sebaceous glands, sweat (sudoriferous) glands, nails,
and mammary glands |
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hypodermis
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subcutaneous fascia (superficial fascia)
hypodermis is not part of the integument |
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epidermis
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keratinized stratified squamousepithelium
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dermis
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loose and dense connective tissue
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dermatoglyphics
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fingerprint identification-
integument grooves and ridges each person genetically unique |
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thickest epidermis
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located in the hairless palms of the hands and soles of the feet
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stratum basale (stratum germinativum)
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single cell layer
adjacent to basal lamina cuboidalto low columnar cells stem cells (mitoticallyactive) extensive cell junctions desmosomes hemidesmosomes |
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stratum spinosum (prickle cell layer)
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several cell layers thick
cuboidal to squamous cells mitotically inactive cytoplasmic processes (spines) desmosomes (nodes of Bizzozero) |
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stratum granulosum
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one to three cell layers thick
squamouscells retain nuclei keratohyalingranules |
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stratum corneum (with deep stratum lucidum in thick skin)
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variable thickness of layer
squamouscells anucleate keratinized cells |
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papillary layer (dermis)
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loose connective tissue
more cellular thin collagen fibers (I, III) finer elastic fibers |
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reticular layer (dermis)
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dense connective tissue
less cellular thick collagen fibers (I) coarser elastic fibers |
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wound healing
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stratum basaleramps up mitosis
migration of proliferating cells exfoliation of dead keratinocytesfrees scab (blood clot) |
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Langer’s lines
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collagen and elastic fibers oriented in parallel lines
surgical incisions parallel to Langer’s lines heal faster |
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keratinocytes
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keratinizationis the process by which keratins
are assembled into keratin filaments or tonofilaments (classified as intermediate filaments) which are then bundled into tonofibrils as keratinocytes differentiate and move outward keratinization includes keratohyalin granules releasing intermediate filament-associated proteins like filaggrin to aggregate keratin filaments into tonofibrils, thus converting granular cells into keratinized cells water barrier formed by lamellar bodies which contain pro-barrier lipids, lipid processing enzymes, and proteases which are secreted by exocytosisinto intercellular space between stratum granulosum and stratum corneum cell junctions undergo proteolyticdegradation in a pH dependent manner to exfoliate (desquamate) dead keratinocytes |
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nodes of Bizzozero
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in keratinocytes' cell junctions
arrows indicate cytoplasmic processes that are connected by desmosomes |
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melanocytes
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neural crest derived and migrate to stratum basale
number similar across humans produce and distribute melanin to keratinocytes integument pigmentation determined by melanin content of keratinocytes production of melanin granules |
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basal cell carcinoma
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stratum basale
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squamous cell carcinoma
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stratum cornuem and stratum granulosum
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malignant melanoma
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melanocytes migrate through statrum spinosum
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ABCD rule
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asymmetrical shape of lesion
border of lesion is irregular color variations diameter greater than 6 mm |
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Langerhan’s cells
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antigen-presenting cells
originate in bone marrow and migrate to stratum spinosum indented nucleus rod-shaped Birbeck granules |
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Merkel’s cells
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located in stratum basale
most abundant in fingertips contain dense-cored neurosecretory granules synapse with pseudounipolar neurons function in tactile sensation |
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free nerve endings
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pain
temperature tactile |
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Pacinian corpuscle
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deep pressure
vibration found in reticular layer, deep connective tissue, below dermis |
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Meissner’s corpuscle
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tactile, more superior
found in papillary layer |
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Merkel’s cell
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tactile
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Corpuscles
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Connective tissue encapsulated
nerve endings |
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Ruffini’s corpuscle
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tactile
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list level of hair (epidermal derivatives)
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M = medulla
Cx= cortex (contains cuboidal cells) Cu = cuticle (squamous cells) IRS = internal root sheath ERS = external root sheath GM = glassy membrane CT = connective tissue HP = hair papilla enclosed by hair bulb |
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sebaceous glands
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holocrine secretion of sebum
sebum is lipid product plus cell debris after apoptosis |
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pilosebaceouscanal
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sebum secretion into duct system
that begins with pilosebaceouscanal correlation between sebum amount and acne |
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eccrine sweat glands
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widely distributed in integument
coiled tubular gland three cell types merocrinesecretion innervationis sympathetic cholinergic (ACh) sweat and antibacterial glycoprotein granules narrow lumen |
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apocrine sweat glands
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primarily axilla, anus, and external genitalia
associated with hair follicles coiled tubular gland one cell type merocrinesecretion innervationis sympathetic adrenergic (NE) protein-rich product can be stored in lumen wide lumen |
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clear cells
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columnar shape
produce sweat increased mitochondria and glycogen increased surface area of PM adjacent to intercellular canaliculi make up fluid part of sweat |
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dark cells
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pyramidal shape
antibacterial glycoprotein granules increased RER and Golgi adjacent to lumen |
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myoepithelialcells
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contraction assists secretion
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nail matrix
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epidermal germinativezone
keratinized cells of nail contain hard keratin and do not desquamate |
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eponychium
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cuticle
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hyponychium
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thick epidermis
that secures free edge of nail |
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lines of Blaschko
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named after investigator who first reported a common set of patterns in patients with dermatological disorders in 1901
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Cartilage - general characteristics
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Specialized CT: resist loading without permanent deformation
Dynamic tissue: responds to strain Avascular(no blood/lymph), no innervation-reliance on diffusion to nourish tissue Chondrocytesin lacunaesurrounded by ECM |
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Perichondrium
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Layer of dense CT surrounding cartilage
-type I collagen, fibroblasts, vasculature Inner layer has chondrogenic (stem) cells Present in elastic& some hyaline cartilage |
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Perichondritis
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inflammation of the perichondrium, often from trauma or infection from piercings. May result in fibrosis, causing deformed appearance (e.g., cauliflower ear)
auricular perichondritis and cauliflower ear |
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Which three cells would you see in growing cartilage?
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chondrogenic cell
chondrocytes chondroblast |
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Chondrogenic cells
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Stem cells: give rise to cartilage cell lineage
Arise from multipotent mesenchymal cells that also give rise to bone cell progenitors Small, flattened cells within the perichondrium |
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Chondroblasts (immature chondrocytes)
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Growth: secrete ECM on cartilage surface
Derived from chondrogenic cells Present in growingcartilage near perichondrium |
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Chondrocytes
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Large; centrally-located in growing cartilage
Predominant cell type in adult cartilage Growth & maintenance: -secrete/digest ECM components -mechanosensitive (regulate ECM synthesis) -mitotic rER (LM: basophilia) Golgi (LM: pale regions) |
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Isogenous groups
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clusters of recently
divided chondrocytes |
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Chondrogenesis
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1. Mesenchymal (chondrogenic) cells migrate,
proliferate, and aggregate –avascular; Sox9 2. Differentiation into chondroblasts 3. Chondroblasts secrete ECM, tissue expands 4. Differentiation into chondrocytes, expansion continues via mitosis & ECM secretion (forms isogeneous groups) |
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Appositional growth (cartilage)
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growth on a surface
Chondroblasts arise from chondrogenic cells and synthesize ECM Deposition on existing cartilage surface Cells remain fairly stationary (tissue expands away from them) |
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Interstitial growth
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growth from within
Chondrocytes divide and secrete ECM -isogenous groups Deposition within existing cartilage Chondrocytes are “pushed” apart as tissue expands Cartilage shape is achieved by differential interstitial and appositional growth (ex. shape of ear cartilage) |
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Why is cartilage thickness limited?
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No vasculature = reliance on diffusionfrom neighboring tissues
Cartilage thickness is limited because tissue cannot grow beyond its ability to diffuse material across ECM |
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Chondrodysostosis
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malformation of bone from a cartilage precursor
Madelung-type chondrodysostosis |
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Chondrodysplasia
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faulty development of cartilage (e.g., achondroplasia)
achondroplasia dwarfism |
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Composition of (hyaline) cartilage
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~5% Cells
~95% ECM -water, collagen, ground substance Composition changes with age: -fewer PGs, less hydrated, decreased thickness |
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Fibers
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resist tension, type I, II, and II collagen
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type II collagen fibrils
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ALLtypes of cartilage
more resistant to compression |
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type I collagen fibers
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fibrocartilage ONLY
more resistant to tension |
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Ground substance
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resist compression, resilience, mechanosensory
PGs, PG aggregates multiadhesive glycoproteins |
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PGs, PG aggregates
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all types of cartilage
part of GS |
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multiadhesive glycoproteins
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all types of cartilage
part of GS |
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Type II fibrils and PG aggregates (mostly aggrecan) in ECM -
State characteristics |
are integrated-resists tension AND compression; regulates movement through tissue
PGs highly sulfated and with hyaluronic acid (non sulfated) |
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How are PGs oriented and what is the relevance of their orientation?
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Oriented in vertical line that branch out like a Y towards the lumen
Orientation of type II collagen fibrils resists shearing near surface Orientation of PGs resists compression of the tissue |
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Multiadhesive glycoproteins (in cartilage ECM)
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E.g., fibronectin, chondronectin
Integrin, actin cytoskeleton Help bind cells to ECM Mechanosensory role -aid in regulation of ECM synthesis in response to tissue strain |
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Capsular matrix
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around chondrocytes
-verybasophilic (GAGs) |
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Territorial matrix:
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-near chondrocytes, isog. groups
-basophilic |
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Interterritorial matrix
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-away from chondrocytes
-light staining (more collagen) |
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Regional differences in ECM staining
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-GAG (basic stain) & collagen concentrations (acidic)
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Describe bone repair
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Limited ability to repair damage: avascular, poor chondrocyte mobility
If repair occurs, it is initiated at the perichondrium Typically, damage results in scar tissue deposition, bone formation, or degeneration(e.g., osteoarthritis) |
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Hyaline Cartilage
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Found in:
Synovial joints Costal cartilages Nose Larynx Trachea, bronchi Embryonic skeleton Growth plate Function: Structural support -resists compression articular cartilage and growth plates lack periochondrium only interstitial growth |
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Elastic Cartilage
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Found in:
Pinna of external ear External auditory meatus Auditory tube Larynx Function: Structural support -elasticity, resist compression Like hyaline cartilage, but with dense network of elastic fibers in the ECM that make it more elastic Always has a perichondrium(w/ elastic fibers) Exhibits appositional growth because of periochondrium |
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Fibrocartilage
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Found in:
Articular discs & labra Intervertebral discs Pubic symphysis Tendon/ligament insertions Menisci Function: Structural support -resist compression & tension Type I collagen in ECM No perichondrium chondrocytes: rounder, often in isogenous groups -basophilic matrix around cells (GAG’s) Looks like dense CT |
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Bone characteristics
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General Characteristics:Specialized CT (rigid; mineralized ECM)Dynamic tissue: responds to strainHighly vascular; innervated
Functions:-structural support-store minerals (e.g., 99% of Ca) -house hematopoietic tissue |
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Calcified bone looks like what in TEM
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Surrounding cell is electron dense
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Periosteum
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Layer of dense CT surrounding bone except at articular surfaces; vascular
Inner layer has osteoprogenitor (stem) cells |
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Perforating fibers
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in periosteum
Tendons & ligaments attach to bone via the periosteum Perforating fibers (or Sharpey’s fibers): -type I collagen fibers of the periosteum embedded firmlyin bone |
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Avulsion fractures
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in perforating fibers
rip periosteum from bone so bone is also torn |
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Endosteum
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Monolayer of cells covering the surfaceof the medullary cavity
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Bone cell types (list and define role)
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Osteoprogenitor cell (stem)
Osteoblast(synthesize) Bone-lining cell (line) Osteocyte(maintain) Osteoclast(resorb) |
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Osteoprogenitor Cells
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Stem cells that give rise to osteoblasts
-arise from multipotent mesenchymal cells that also give rise to chondrogenic cells Reside on bone surfaces periosteum, endosteum, or lining central canals (neurovascular channels) |
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Osteoblasts
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Synthesize& mineralizebone ECM: polarized; extensive rER, Golgi
Reside on bone surfaces periosteum, endosteum, or lining central canals (neurovascular channels) Arise from osteoprogenitor cells; give rise to bone-lining cells/osteocytes |
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Bone-Lining Cells/quiescent osteoblasts
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flattened cell, condensed nucleus
Occupy bone surfaces where no formation/resorption is occurring Reside on bone surfaces periosteum, endosteum, or lining central canals (neurovascular channels) |
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Osteocytes
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Former osteoblasts surrounded by bone ECM
Reside in lacunae: amitotic; no interstitial growth Signal other bone cells to form/resorb bone (little rER, Golgi) -mechanosensitive(adaptation to stress); calcium homeostasis |
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Which bone cells communicate via gap junctions?
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Osteoprogenitor cells, osteoblasts, osteocytes, bone-lining cells (but not osteoclasts)
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canaliculi
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junctionsSmall, fluid-filled channels in bone called canaliculiconnect cytoplasmic processes of osteocytes to bone cells on bone surfaces
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Osteoclasts
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Large, multinucleated, polarized cells that resorb ECM
-lysosomes, rER, Golgi, transport vesicles Depressions formed via resorption = resorption bays Arise frommonocyte precursor(mononuclear phagocyte system) |
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Organic (bone ECM)
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resists tension
Primarily type I collagen with little ground substance |
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Inorganic (mineralized; bone ECM)
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resists compression
Hydroxyapatitecrystals arranged along the collagen fibers |
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Osteoid
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Organic matrix is not immediately mineralized
-observed as lighter-staining |
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Reasons why mineralization would slow down?
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low vitamin D, low calcium, renal failure
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osteocalcin and alkaline phosphatase
blood tests –what do they tell you about bone? |
osteocalcin only tells you about organic matrix does not imply that bone is mineralized
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Runx2
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Osteoblast differentiation from osteoprogenitor or bone-lining cells
(Runx2-text calls it “Cbfa1”) |
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Osteocalcin
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calcium binding proteins in organic matrix, secrete during osteoblast formation
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alkaline phosphatase
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Osteoblastsmineralizethe matrix
-secrete matrix vesicles containing alkaline phosphatasethat catalyzes hydroxyapatite crystallization from extracellular minerals |
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RANKL
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Osteoclast precursors travel in blood to exposed bone surface,
fuse & differentiate intoosteoclasts -induced by RANKL |
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clear zone
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seal that contains lytic secretions
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basolateral region
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region where digested material is exocytosed
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ruffled border
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folds that increase surface area for resorption
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mineral matrix is degraded during osteoclast formation by?
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proton pumps
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organic matrix is degraded during osteoclast formation by?
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lysosomal enzymes
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How does OPG affect osteoclast formation?
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Osteocytes/blastssecrete RANKLthat promotes osteoclastogenesis and OPG that inhibits it
Bone diseases treated with OPG to inhibit RANKL |
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How does inflammation affect bone resorption?
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Stromal cells in bone marrow promote osteoclastogenesis with cytokines and RANKL
T lymphocytes can promote osteoclasto-genesis with RANKL during inflammatory response |
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Remodeling
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coupled action of osteoblasts & osteoclasts to replace bone (resorption followed by formation)
Repairsdamage Adaptsbone to stress Hormonally and mechanically regulated |
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What would signal a bone turnover disease? Give examples of diseases
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Elevated osteocalcin and alkaline phosphatase serum levels indicative of bone turnover diseases
osteo-porosis, Paget’s disease, cancer, hyperparathyroidism |
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Osteopenia/osteoporosis
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greater resorptionthan formation
-decreased bone mass -increased bone weakness |
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Osteosclerosis/osteopetrosis
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greater formation than resorption
-increased bone mass -ultimately increases bone fragility |
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Calcitonin
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Released from thyroid gland(C-cells) and targets osteoclasts
Decreases blood calcium levels by inhibiting bone resorption |
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Parathyroid hormone (PTH)
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Released from parathyroid glandand targets osteoblasts, which secrete RANKL
Increases blood calcium levels by promoting bone resorption |
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Hyperparathyroidism:
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bone loss and kidney stones
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Estrogen
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Released from gonadsand targets osteoblasts
Maintains bone mass(by inhibiting osteoblast apoptosis and promoting osteoclast precursor apoptosis) |
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Compact bone(
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also: cortical, dense)
-forms outer bone cortex |
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Trabecular bone
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also: cancellous, spongy)
-forms meshwork interior of bone trabeculae oriented toward stress lines |
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Woven bone (immature bone)
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Initial bone formed during development & early fracture repair
Laid down rapidly (irregular collagen bundles, highly mineralized) = weak Replaced by lamellar bone Found in many bone pathologies (e.g., Paget’s disease, bone tumors) |
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Lamellar bone (mature bone)
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Always formed on existing calcified surface
Organized into lamellae (sheets of mineralized ECM); stronger Adult bone is lamellar (exception: alveolar bone around teeth) |
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Osteons (Haversian Systems)
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Osteon: concentric lamellae around a neurovascular canal
Formed during bone remodeling |
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Central Canals (Haversian Canals)
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Central canal: centrally-located canal in osteons
Contains neurovasculatureand is lined by bone cells |
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Perforating (Volkmann’s) Canals
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Perforating canals: connect central canals with periosteum & endosteum
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Bone Blood Supply describe
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Blood vessels in marrow & periosteum anastomose via blood vessels in the central and perforating canals –“inside-out” blood flow
diffusion with caniliculi |
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Cement Lines (Reversal Lines)
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Cement line: site where resorption stopped and formation began
Abundant in pathologies involving bone remodeling (e.g., Paget’s disease) Bones often fractures along cement lines |
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Parietal mesoderm (lateral plate)
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pelvis, shoulder, limbs, sternum
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Somites, somitomeres (paraxial mesoderm)
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post. cranium, vertebrae, ribs
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Neural crest
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mandible, ant. cranium
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Hypoxia affects bone osteogenesis in what manner?
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Vascularity affects mesenchymal cells
-hypoxia→ Sox9 → chondrogenic cells |
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Presence of oxygen affects bone osteogenesis in what manner?
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Vascularity affects mesenchymal cells
-no hypoxia→ Runx2 → osteoprogenitor cells |
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Intramembraneous ossification center
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1. Mesenchymal (osteoprogenitor) cells
migrate, proliferate, and aggregate at ossification centers(vascular; Runx2) 2. Osteoprogenitor cells differentiate into osteoblastsand form bone trabeculae 3. Trabeculaeenlarge & merge via appositional growth Forms: flat bones of cranium, mandible, medial clavicle will see trabeculae (spicules) in cranium and in between cranial bone spots called fontanelles |
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Endochondral ossification center
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1.
Mesenchymal (chondrogenic) cells migrate,proliferate, and aggregate after vasculature regresses -Sox9 2. Differentiate into chondroblasts/cytesthat form a hyaline cartilagetemplate 3. A bone collar is formed around the template (near perichondrial vasculature)by intramembranous ossification 4. Osteoclastsperforate the bone collar to allow vasculatureinto the cartilageto form the primary ossification center 5. Secondary ossification centers appear at other sites of vascularization(e.g., epiphyses, some attachment sites) 6. Growth continues at the growth plate, which eventually ossifies (timing differs by bone) |
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Nutrient foramen
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associated with endochondral
Nutrient foramen remains where primary vasculature invaded the cartilage; explains the “inside-out” blood flow of bone JC 8.14 Bone diameter increases by appositional growth of boneat the periosteum Bone length increases by interstitial growthof cartilageat the growth plate |
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Growth plate: (endochondrial ossif.)
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remnant of hyaline cartilage template responsible for longitudinal bone growth
Bone is added to the diaphysis (not epiphysis) Vasculature is in the diaphysis Divided into 5 zones |
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5 zones of growth plate
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1. Zone of reserve cartilage
-standard hyaline cartilage -supplies/directs proliferation 2. Zone of proliferation -chondrocyte mitosis: isogenous groups -columns parallel to growth -secretetype II collagen, PGs 3. Zone of hypertrophy (maturation) -chondrocytes enlarge (Runx2) -secreteVEGF(for vascular invasion) 4. Zone of calcification -chondrocytes calcifyECM (Runx2) -chondrocyte apoptosis 5. Zone of ossification -ossification occurs -vasculature invades, brings osteoprogenitor cells-OP cells → osteoblasts: woven bone formed on calcified cartilage-woven bone remodeledinto lamellar bone; medullary cavity formed |
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zone of ossification (5th layer)
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ossification occurs
-vasculature invades, brings osteoprogenitor cells-OP cells → osteoblasts: woven bone formed on calcified cartilage-woven bone remodeledinto lamellar bone; medullary cavity formed |
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Zone of calcification (4th layer)
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chondrocytes calcifyECM (Runx2)
-chondrocyte apoptosis |
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zone of hypertrophy (3rd layer)
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maturation - increase oxygen levels
-chondrocytes enlarge (Runx2) -secreteVEGF(for vascular invasion) |
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Zone of proliferation (2nd layer)
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chondrocyte mitosis: isogenous groups
-columns parallel to growth -secretetype II collagen, PGs |
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Zone of reserve cartilage (1st layer)
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-standard hyaline cartilage
-supplies/directs proliferation |
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What direction is growth plate?
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Cells stay fairly stationary
-ECM expansion drives growth “upwards |
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Most common bone fracture type and describe?
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Type II - growth plate is displaced and one side of metaphyses is fractured
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Type V fracture would exhibit what pathology
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Growth plate is crushed so there is stunted growth
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Describe inflammatory stage of bone fracture
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-clot forms seal & framework for inflammatory cells & fibroblasts
-granulation tissue, type III collagen → type I collagen -fibrocartilage-like tissue forms soft callus –no vasculature |
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Describe reparative stage of bone fracture
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-hard callus of woven bone isformed by both intramembranous &
endochondral ossification –vasculature developed |
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Describe remodeling stage of bone fracture
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-woven bone replaced by lamellar bone
(bone is typically completely reconstituted) |
