Human Organ Systems Test 1, Lectures 1-3

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Human Organ Systems Test 1, Lectures 1-3
2013-01-18 00:11:27
Medical Physiology nEpithelial Tissue nConnective

Carver College of Medicine
Show Answers:

  1. Main functions of epithelial cells (5)
    • Protection
    • Absorption
    • Secretion/excretion
    • Sensation
    • Contractility
  2. Basal lamina
    • Specialized extracellular matrix which anchors cells to underlying connective tissue
    • Synthesized by epithelia
    • Has two layers
  3. Layers of basal lamina
    • Lamina densa, which contains fine fibrils
    • Lamina lucida, which is the electron lucent layer next to the basal cell surface and the lamina densa
  4. Functions of basal lamina
    • Structure and organization (attachment of epithelium to connective tissue and organization of the basal membrane)
    • Filtering (acts as a barrier regulating exchange between epithelium and connective tissue)
    • Regulation (binds growth factors that regulat cell proliferation, differentiation, and metabolism)
    • Migration (orients movement of epithelial cells)
  5. Main components of basal lamina (4)
    • Type IV Collagen
    • Laminins
    • Entactin (nidogen)
    • Perlecan
  6. What is the name of an autoimmune disease in which the patient has damage to basal laminae and epithelial cells?
    Goodpasture's syndrome, in which patients synthesize antibodies that bind to type IV collagen, resulting in progressive renal failure and pulmonary hemorrhage
  7. Epithelial cell shapes can be easily determined by examining the:
    Cell nucleus, which parallels the shape of the cell
  8. Blood vessels penetrate the epithelium (T/F)?
    False. They penetrate the supportive, underlying connective tissue
  9. Lamina propria
    The connective tissue which lies beneath epithelial cells and the basal lamina. Blood vessels penetrate this tissue.
  10. Type IV collagen
    Trimeric molecules with rodlike and globular domains that form a 2D network, making up most of the basal lamina
  11. Laminins
    Multiadhesive proteins that form a fibrous 2D network with type IV collagen, providing attachment sites for epithelial cells
  12. Entactin (nidogen)
    A rodlike molecule that crosslinks type IV collagen and laminin and helps incorporate other components into the basal lamina
  13. Perlecan
    A large, multidomain heparan sulfate proteoglycan that binds to and crosslinks many components of the basal lamina and cell surface proteins
  14. Basement membrane
    • Two basal laminae attached to one another as seen in the kidney glomeruli or
    • The basal lamina of the epithelial cells attached to the reticular lamina of connective tissue cells
    • It is not synonymous with basal lamina, as it is thicker
  15. Anchoring fibrils
    Type VII collagen fibrils embedded in a heparan sulfate gel that anchor the basal lamina to the underlying connective tissue
  16. What type of junction anchors the basal membrane of epithelial cells to the basal lamina?
  17. What are the transmembrane receptors involved in hemidesmosomes?
    • Integrins, such as alpha-6-beta-4
    • They link the basal lamina outside the cell to the keratin-based intermediate filament cytoskeleton inside the cell
  18. Types of adhering junctions (2)
    • Zonulae adherens
    • Desmosomes
  19. Types of impermeable junctions (1)
    Zonulae occludentes (aka tight junctions)
  20. Types of communicating junctions (1)
    Gap junctions (aka intercytoplasmic junctions)
  21. Zonula versus macula
    Zonula means belt-like and macula means spot-like
  22. Zonulae occludentes
    • Aka tight junctions
    • Found at the most apical portion of the lateral surface of epithelial cells
    • Prevents macromolecules and some water/ions from diffusing across sheets of epithelial cells
  23. Cholera
    • Caused by vibrio cholerae (and other enteric bacteria)
    • Toxins produced by these bacteria alter the tight junction permeability barrier of intestinal epithelia by changing the composition or activity of tight junctions
    • Massive loss of ions and water into the GI tract occurs, leading to diarrhea and potentially lethal dehydration
  24. Zonulae adherens
    • Aka adherens junctions
    • Located near the apical surface, just below tight junctions
    • Associated with actin/myosin belt that functions as a tension cable to control cell shape
    • Actin filaments arise from a terminal web, a meshwork of actin, intermediate filaments and spectin in the apical region of the cell
    • Provides the primary adhesive junctions between adjacent cells in an epithelium by linking actin filaments between adjacent cells
    • Uses cell adhesion molecules (CAMs) and cadherins (E-cadherins)
  25. Maculae adherens
    • Aka desmosomes
    • Button-like points of attachment between adjacent epithelial cells via attachment plaques
    • Attach internal to the cell via tonofilaments, which are intermediate filaments composed of cytokeratins that insert into attachment plaques or make hairpin turns and return to the cytoplasm
    • Provide tight adhesion between adjacent epithelial cells by linking tonofilaments from cell to cell
  26. Pemphigus vulgaris
    • An autoimmune disorger in which patients synthesize antibodies that bind to desmosomal cadherins and disrupt desmosomes and cell-cell adhesion
    • Results in blistering skin
  27. Intercytoplasmic junctions
    • Aka gap junctions
    • Present in epithelia but also abundant in nearly all tissues except for skeletal muscle
    • Allows communication between cells by permitting passage of small molecules and ions
    • Made up of connexons, which are hydrophilic channels made up of connexin proteins
  28. Microvilli
    • Fx: Increase cell surface area for absorption
    • Actin microbilaments are in the center of each microvillus and are anchored in the terminal web
    • The outer surface has a thick coat of glycoproteins, called the glycocalyx (appears as a "brush or striated border")
  29. Stereocilia
    • Fx: Increase cell surface area for absorption (as in the epididymis) or sense fluid motion or fluid pressure (as in the inner ear hair cells)
    • Like long, branched microvilli
  30. Cilia and Flagella
    • Fx: Movement (flagella) and removal of foreign particles, bacteria and mucus from the lungs or exterior of nose (cilia)
    • Made of microtubules in a 9 + 2 arrangement that insert into basal bodies
  31. Basal bodies
    • Electron-dense structures at the apical pole of epithelial cells
    • Allow for attachment of microtubules
    • Structurally analogous to centrioles
  32. Non-motile primary cilia
    • Elongated structures that do not move on their own but can bend upon external pressures (such as fluid flow)
    • Nearly all differentiated cells of adult tissues, including most epithelial cells, fibroblasts, chondrocytes, osteocytes, smooth muscle cells, skeletal and cardiac muscle, photoreceptor cells, hippocampal neurons, etc. have a primary cilium
    • Made of microtubules in a 9 + 0 arrangement and insert into basal bodies
  33. Polycistic Kidney Disease and non-motile primary cilia
    • Polycystis are disrupted in polycystic kidney disease and result in inability to sense fluid flow
    • These polycystins form a fluid-sensing mechanism that control the diameter of renal tubules
  34. Types of covering epithelia based upon layers (3)
    • Simple
    • Stratified
    • Pseudostratified (all cells contact the basal lamina, but not all cells reach the free surface)
  35. Types of covering epithelia based upon shape (3)
    • Squamous
    • Cuboidal
    • Columnar
    • (These classifications are determined by the most superficial layer)
  36. Simple squamous epithelium (distribution and function)
    • Distribution: Inner surface of tympanic membrane, part of nephrons (Bowman's capsule and loop of Henle), lungs, testes, the smallest excretory ducts of many glands, mesothelium lining serous cavities, mesenchymal epithelium lining cavities in connective tissue, and endothelium lining the walls of blood and lymph vessels
    • Fx: Exchange, barrier, lubrication
  37. Simple cuboidal epithelium (distribution and function)
    • Distribution: Small ducts of exocrine glands, choroid plexus (in ventricles of brain which secrete or absorb CSF), free surface of the ovary, thyroid follicles, inner surface of the lens capsule, retinal pigment epithelium, and kidney tubules
    • Fx: Absorption, conduit (channel), barrier, secretion
  38. Simple columnar epithelium (distribution and function)
    • Distribution: Digestive tract, excretory ducts of glands, gallbladder
    • Ciliated simple columnar epithelium: Uterus and oviducts, small bronchi of the lung, paranasal sinuses, central canal of spinal cord
    • Fx: Absorption and secretion
    • Side note--often found with goblet cells, which secrete fluids and are unciliated
  39. Stratified squamous epithelium (types, distribution, and function)
    • Non-keratinized stratified squamous epithelium: Moist surfaces, lining wet cavities (mouth, vagina, female urethra, anus, esophagus, part of epiglottis, part of conjuctiva adn conrea in the eye)
    • Keratinized stratified squamous epithelium: Skin and hard palate
    • Fx: Barrier, protection
  40. Stratified cuboidal epithelium (distribution and function)
    • Rare
    • Distribution: Excretory ducts of sweat glands, developing ovarian follicles, anorectal junction
    • Fx: Barrier, conduit
  41. Stratified columnar epithelium (distribution and function)
    • Relatively rare
    • Distribution: Fornix of conjunctiva, cavernous part of urethra, anal mucous membrane, pharynx, epiglottis, large excretory ducts of some glands
    • Ciliated stratified columnar epithelium: Nasal surface of the soft palate, larynx, fetal esophagus
    • Fx: Barrier, conduit
  42. Pseudostratified columnar epithelium (distribution and function)
    • Distribution: Large excretory ducts of the parotid and other glands, male urethra
    • Ciliated pseudostratified columnar epithelium: Greater part of mucous membrane of respiratory passages (trachea, bronchi, nasal cavity), pharyngoauditory tube, part of typmanic cavity, lacrimal sac, and excretory passages of the male reproductive system
    • Fx: Secretion, absorption, conduit
  43. Transitional epithelium (definition, distribution, and function)
    • Definition: Epithelial cells that vary in appearance because they are subject to great mechanical changes due to contraction and distention
    • Distribution: Urinary bladder, ureters, and upper part of urethra
    • Fx: Barrier, distensible property
  44. Metaplasia
    • A reversible event where one differentiated cell type is replaced with another mature differentiated cell type
    • Usually an adaptation to cellular stress (NOT cancer)
    • Examples: Barrett's esophagus, airway epithelial metaplasia (replacement of ciliated pseudostratified columnar cells with stratified squamous cells in response to cigarette smoke), and cervical erosion (non-keratinized stratified squamous epithelium is replaced by glandular columnar epithelium, caused by trauma, infections, and chemicals)
  45. Size classifications of glandular epithelium (2)
    • Unicellular (only goblet cells)
    • Multicellular
  46. Goblet cells
    Unicellular glands (aka mucous cell) that secrete mucin, a protein-polysaccharide that forms a lubricating solution
  47. Mode of secretion classifications of glandular epithelium
    • Exocrine glands: Secrete into ductal system, retain connections with surface epithelium from which they were derived, discharge product at an external or internal surface
    • Endocrine glands: Secrete into vascular system, do not retain connections with surface epithelium of origin, do not have ducts
  48. Secretory product classifications of glandular epithelium (3) and examples
    • Serous: Parotid gland and pancreas
    • Mucous: Goblet cells and mucous salivary gland
    • Mixed: Submandibular and sublingual salivary glands
  49. Alveoli
    Spherical structures that adjacent serous cells form within serous glands
  50. Zymogen granules
    Contain digestive enzymes and are found in serous cells; separate from secretory granules
  51. Mechanism of secretion classifications of glandular epithelium (3)
    • Merocrine
    • Apocrine
    • Holocrine
  52. Merocrine
    • Secretory granule fuses with plasma membrane by exocytosis without accompanying loss of cytoplasm
    • Salivary glands and pancreas
  53. Apocrine
    • Secretory granule plus apical cytoplasm is lost
    • Mammary glands and sweat glands
  54. Holocrine
    • Entire cell becomes secretory product and is shed
    • Uncommon
    • Sebaceous gland (cells that produce sebum which are found on skin and near hair follicles)
  55. Glandular morphology classifications of glandular epithelium
    • Duct system: Simple (one) or compound (branching)
    • Secretory units: Tubular, coiled tubular, branched tubular, acinar, branched acinar, tubuluacinar
    • *You will need to learn these from the notes*
  56. Carcinoma
    A tumor of epithelial cell origin
  57. Adenocarcinoma
    A tumor derived from glandular epithelial tissue
  58. Major constituent of connective tissue
    Extracellular matrix
  59. Broad components of ECM (2)
    Protein fibers and ground substance
  60. Collagens that form fibrils
    Types I, II, and III
  61. Fibril-associated collagens
    Types IX, XII, and XIV
  62. Collagens that form anchoring fibrils
    Type VII
  63. Collagens that form networks
    Type IV collagen in basal laminae
  64. Type I collagen
    • Fx: Resistance to tension
    • Densely-packed thick fibers and bundles with variable diameters
    • Most abundant form, found in dense and loose CT, skin, tendons, fibrous cartilage, organ capsules, bones, cornea, dentin
    • Made by fibroblasts and specialized CT cells such as osteoblasts, odontoblasts, and chondroblasts
  65. Type II collagen
    • Fx: Resistance to intermittent pressure
    • Usually found with many fibril-associated proteins and lots of ground substance, giving it a shock-absorbing property
    • Does not form thick fibers--only very thin fibrils
    • Found in hyaline and elastic carilages and vitreous body (intervertebral discs)
    • Made by chondroblasts
  66. Type III collagen
    • Fx: Structural maintenance in expansible organs
    • Forms reticular fibers, which are loosely-packed thin fibrils with uniform diameters
    • Found in smooth muscle, arteries, uterus and in networkds around cells in spleen, lymph nodes, bone marrow, liver, kidney, and endocrine glands
    • Made by fibroblasts, smooth muscle cells, reticular cells, Schwann cells, and hepatocytes
  67. Visual differences of types I, II, and III collagens
    • Type I: Strongly birefringent (transmits light unequally in different directions) yellow or red fibers, nonargyrophilic (not capable of binding silver salts)
    • Type II: Visible only with picro-Sirius stain and polarization microscopy
    • Type III: Weakly birefringent greenish fibers, argyrophilic (does bind silver salts because more sugars are associated with these loosely-packed reticular fibers)
    • Under EM: Fibrils have a striabed appearance due to lacunae and overlapping regions
  68. Type VII collagen
    Anchors skin epidermal basal lamina to connective tissue
  69. Ehlers-Danlos type IV disease
    Deficiency of type III collagen (reticular fibers) characterized by ruptures in arteries (often aorta) and intestines
  70. Ehlers-Danlos type VI disease
    Defects in processing type I collagen and causes hyperextensible skin but increases chance of eyeball rupture
  71. Ehlers-Danlos type VII
    Patients have double-jointedness
  72. Synthesis of collagen
    • Pro-a-chains are made first
    • Procollagen is assembled in the ER
    • Proline and lysine residues are hydroxylated in the ER
    • Procollagen is packaged into secretory vesicles in the Golgi and secreted
    • Procollagen peptidases cleave procollagen into insoluble tropocollagen, which polymerizes in an overlapping pattern to form collagen fibrils
  73. Scruvy
    • Caused by a deficiency of vitamin C, which is a cofactor for the hydroxylation of proline and lysine residues
    • Bone growth, wound and fracture healing, and stability of adult organs may be affected, in addition to periodontal bleeding and ulceration
  74. Elastic fibers
    • Found in almost all connective tissue, but is enriched in places that must stretch and relax (skin, tendons, heart, blood vessels, fascia of anterior abdominal wall)
    • Made by fibroblasts and smooth muscle cells
  75. Components of elastic fibers (2)
    • Microfibrils: Elastic scaffold consisting of fibrillin and associated glycoproteins
    • Elastin: A non-glycosylated protein that forms amorphous deposits
  76. Development of elastic fibers
    • 1) Oxytalan fibers: Lattice of fibrillin without elastin
    • 2) Elaunin fibers: Elastin protein is deposited and surrounds oxytalan fibers
    • 3) Elastic fibers: Blob of elastin surrounded by tubular microfibrils
  77. Marfan syndrome
    • Mutations in the fibrillin gene result in defective elastic fibers
    • Tissues rich in elastic fibers (such as large arteries) suffer a lack of resistance and patients often suffer ruptures in the aorta
  78. Ground substance main components (2)
    Glycosaminoglycans (GAGs) and glycoproteins
  79. Glycosaminoglycans
    • Linear (non-branching) polysaccharides
    • All GAGs are in proteoglycans except for hyaluronic acid
  80. Proteoglycan
    Made up of glycosaminoglycans and a protein core
  81. Dermatan sulfate
    A GAG associated with type I collagen; found in the dermis, tendons, ligaments, and fibrocartilage
  82. Chondroitin sulfate
    A GAG associated with type II collagen; found in hyaline and elastic cartilage
  83. Heparan sulfate
    A GAG associated with types III and IV collagens; found in reticular fibers and basal laminae
  84. Keratan sulfate
    A GAG found in cartilage
  85. Functions of glycosaminoglycans
    • Structural: Bind together protein fibers of ECM and anchor cells to ECM
    • Hydration: Bind lots of cations (usually sodium) and water
  86. Glycoproteins
    • Protein-sugar macromolecules composed primarily of proteins (whereas proteoglycans are primarily carbohydrate)
    • Examples: Fibronectin (cell adhesion and migration), chondronectin (holds chondrocytes to collagen), and laminin (binds epithelia to basal lamina)
  87. Indigenous connective tissue cells
    • Are generated in the connective tissue and produce the ground substance of the tissue
    • Includes primitive mesenchymal cells, fibroblasts and fibrocytes, and adipose cells
  88. Immigrant connective tissue cells
    • Cells that migrate into connective tissue. Their main functions are immunological and defense (phagocytosis, cytokine production, antigen presentation, and allergic reactions)
    • Includes mast cells, neutrophils, monocytes, macrophages, lymphocytes, plasma cells, and eosinophils.
  89. Primitive mesenchymal cell (origin and function)
    • Arise from embryonic mesenchyme (mesoderm) which is plentiful in the fetus. These multipotent undifferentiated CT cells then decrease in numbers until persisting as single cells along small blood vessels in the adult.
    • Fx: Produce more indigenous CT cells
  90. Fibroblast (origin and function)
    • Arise from primitive mesenchymal cells
    • Fx: Make and secrete the fibers and ground substance of CT ECM (collagen, elastin, GAGs and PGs, and adhesive glycoproteins)
    • Also play a role in wound healing by repairing the area by making protein fibers and ground substance
  91. Adipose cell (origin and function)
    • Arise from primitive mesenchymal cell
    • Fx: Store neutral triglycerides. These triglycerides remain in the cell for an average of 4 days. "Brown" fat cells (multilocular cells) are important for heat production in babies and hibernating animals. Human adults have only unilocular tissue cells.
  92. Hypertrophic obesity
    Excessive fat accumulation in unilocular tissue cells that become abnormally large
  93. Hyperplastic obesity
    Excessive fat accumulation in which adipocyte number increases
  94. Mast cell (origin and function)
    • Arise from hematopoietic stem cells in the bone marrow
    • Fx: Begin the inflammatory response, which is important for beginning allergic reactions. Also recruits eosinophils. Secretes granules containing heparin (anti-coagulant), histamine (increases permeability of vascular endothelial cells), and proteolytic enzymes, which can cause itching and edema.
  95. Polymorphonuclear leukocyte (origin and function)
    • Aka neutrophils
    • Arise from bone marrow and respond to chemotactic factors to migrate via bloodstream
    • Fx: Rapid defense system, phagocytosis following recognition by complement or IgG. Cells are committed to die after phagocytosis because they are unable to synthesize more granules (lysosomes) or membrane receptors.
  96. Monocyte (origin and function)
    • Arise from bone marrow and respond to chemotactic factors to migrate via bloodstream
    • Fx: Provide a population of potential macrophages to CT
  97. Macrophage (origin and function)
    • Arise from monocytes
    • Fx: Defend the body by ingesting and killing bacteria and fungi which have been coated by IgG or serum complement, ingest wastes such as dead cells and foreign particles, and store wastes in residual bodies
    • In addition, they can further mature to give rise to specialized macrophages for specific tissues, such as osteoclasts (bone), Langerhans cells (skin), and dendritic cells (lymph nodes)
  98. Lymphocyte (origin and function)
    • Arise from bone marrow or lymphatic nodules in CT. They are motile and migrate through endothelia and epithelia.
    • Fx: Immunologic (T cells initiate cell-mediated immune response and B cells divide and produce plasma cells). Both have receptor sites for antigens on the surface membrane
  99. Plasma cell (origin and function)
    • Arise from B lymphocytes in CT
    • Fx: Synthesize and secrete large amounts of a specific immunoglobulin (up to 2000 mol/sec)
  100. Eosinophil (origin and function)
    • Arise from bone marrow via bloodstream
    • Fx: Participate in response to allergies and certain parasitic infections
  101. Types of connective tissue proper
    • Loose
    • Dense irregular
    • Dense regular
  102. Loose (areolar) ordinary CT
    • Many cells and ground substance
    • Made up of an irregular arrangement of collagen fibrils and elastic fibers
    • Fx: Flexibility
    • Found in mesentary, next to epithelium, and around blood vessels and glands
  103. Dense irregular CT
    • Few cells and ground substance
    • Made up of a non-parallel, rough-lattice arrangement of collagen fibers and a random arrangement of elastic fibers
    • Fx: Resist stress
    • Found in dermis, organ capsules, periosteum, and perichondrium
  104. Dense regular CT
    • Few cells and ground substance
    • Made up of a parallel arrangement of collagen fibers and varying amounts of elastic fibers
    • Fx: Resist stress
    • Found in tendons and ligamens, and in the cornea of the eye (GAG matrix and no elastin)
  105. Types of cartilage
    Hyaline, elastic, fibrous
  106. Hyaline cartilage
    • Made up of many type II collagen fibrils in a homogenous mixture
    • Fx: Cusion forces, form temporary skeleton
    • Found in articulations, the temporary skeleton, ventral ends of ribs, larynx, trachea, and bronchi
  107. Elastic cartilage
    • Made up of many type II collagen fibrils and numerous branched elastic fibers
    • Many chonbroblasts
    • Fx: Flexible skeleton
    • Found in the auricle of the ear, the external auditory meatus, the auditory tube, epiglottis, and parts of the larynx
  108. Fibrous cartilage
    • Made up of type I collagen fibers (resembling dense connective tissue), resulting in a little matrix that is acidophilic (collagen has many + charges)
    • Few cells and proteoglycans
    • Fx: Stability
    • Found in tendon attachments and linings, intervertebral discs, and the pubic symphysis
  109. Cartilage ECM
    Made of collagen, proteoglycan aggregates (GAGs that are hydrated gels attached to proteins), and glycoproteins (adhesive proteins that bind cells and ECM such as integrins)
  110. Chondroblasts
    • Free, untrapped cells in the ECM of cartilage that secrete matrix and fibers
    • These cells persist int he perichondrium and undergo mitosis
  111. Chondrocytes
    • Cells that are trapped in lacunae of cartilage and are surrounded by matrix
    • They bind to the collagen in the ECM via chondronectin
    • Have mitotic potential during growth but are limited in adult
  112. Chondronectin
    An adhesion molecule (glycoprotein) which binds chondrocytes to collagen in the ECM of cartilage
  113. Growth of cartilage
    • Interstitial (inside the cartilage tissue) growth occurs only in the young and results in isogenic populations of cells in cell nests
    • Appositional growth is from the outside inwards from the chondrogenic layer of perichondrium
    • Somatomedin C and other growth factors promote cartilage synthesis
  114. Somatomedin C
    A growth factor made by the liver which stimulate cartilage production
  115. Layers of perichondrium (2)
    • An outside, fibrous layer (where fibroblasts secrete type I collagen)
    • An inside, chondrogenic layer (where appositional growth occurs via chondroblasts)
  116. Regeneration of cartilage
    Typically does not occur due to low metabolic rate. Tissue is avascular and receives nutrients from matrix. Does occur more easily in children
  117. Intervertebral disc composition
    • Annulus fibrosis: Fibrocartilage surronded by external layer of dense connective tissue
    • Nucleus pulposis (aka hyaline plate): Gel-like, contains hyaluronic acid and type II collagen
  118. Key characteristics of bone versus cartilage
    • Dense collagen matrix
    • Mineralized matrix
    • Repairable
    • Remodeling
  119. Compact (cortical) bone location
    Found on the surfaces of all bones
  120. Spongy (cancellous) bone
    Found in the interior of bones. Has a honeycomb appearance, which reduces bone weight while still providing support. Marrow is found within spaces.
  121. Osteon
    A central canal and the concentric osseous lamellae encircling it, occurring in compact bone. Also called the Haversian system, it is necessary for blood, lymph, and nerve supply.
  122. Layers of periosteum
    Fibrous outer layer and osteogenic inner layer
  123. Endosteum
    The inner lining of bone surfaces made up of osteogenic cells and small amounts of collagen
  124. Development of osteoprogenitor cells
    Stem cells --> Mesenchymal cells --> Osteoprogenitor cells
  125. Osteoblasts
    • Non-mitotic cells that arise from osteoprogenitor cells
    • Secrete bone constituents (collagen and matrix)
  126. Osteocytes
    Non-mitotic cells that are trapped in lacunae which are necessary for survival. They form cell-cell contact via gap junctions
  127. Bone is not vascularized but does contain nerves (T/F)
    False. Bone is both vascularized and does contain nerves
  128. Canaliculi (in compact bone)
    Canals between adjacent lacunae that contain osteocyte processes
  129. Cement line (in compact bone)
    A 1-2um thick matrix with adhesion molecules but no collagen
  130. Volkmann's canals
    Connect parallel Haversion canals
  131. Patterns of lamellae (3)
    • Interstitial: Between osteons
    • Concentric: In osteons
    • Circumferential lamellae: At outer and inner bone surfaces
  132. Trabeculae
    Branching connections that are found in spongy bone. They must be about .2mm in order to maintain weight
  133. Location of spongy bone
    All immature bone and interiors of mature bones
  134. Blood supply patterns to long bones
    • Diaphyseal: Supply to the shaft of the long bone from the nutrient artery
    • Epiphyseal-metaphyseal: Supply to the ends of long bones which have distinct supply to the epiphysis and metaphysis
  135. Major components of organic bone matrix
    Collagen (type I mostly), binding proteins, glycoproteins, and growth factors
  136. Major components of inorganic bone matrix
    Hydroxyapatite needles, amorphous CaPO4, and minerals, which are stored in bone
  137. Hydroxyapatite crystals
    Give bone its hardness. Are found in needle-like shapes, with an interior surface and a hydration shell, which facilitates ion exchange between the crystals and body fluids
  138. Osteoclasts
    Multinucleated cells derived from the fusion of multiple monocytes which cause bone resorption at the ruffled border
  139. Bone resorption mechanism
    Oteoclasts release hydrolytic enzymes from lysosoes to remove organic matter and H+ to dissolve minerals and activate the enzymes by creating an acidic environment
  140. Osteopetrosis
    Dense bone caused by a genetic disease. Osteoclasts do not have ruffled borders and cannot resorb enough bone
  141. Wolff's law
    Use and disuse of bone are directly related to their internal architecture by opposite effects (ex: bed rest leads to bone loss and activity leads to bone deposition)
  142. Osteoporosis
    • Decreased bone density caused by an imbalance of bone resorption and deposition (age related, diet deficiencies, endocrine, drug related)
    • Major sites: Vertebrae, femoral necks, and wrists
  143. Hormones which cause increased bone matrix
    • Calcitonin: Inhibits osteoclast resorption
    • Estrogens: Decrease rate of bone turnover
    • Androgens: Increase bone density
    • Growth hormone: Increases bone deposition
  144. Hormones which cause decreased bone matrix
    • Parathyroid hormone: Cause a calcium shift from the matrix to extracellular fluid (hypercalcemia)
    • Thyroxine: Stimulates osteoclast resorption
  145. Epiphyseal disk
    • Aka growth plate
    • The plate of cartilage which separates diaphyseal and epiphyseal bone during growth
    • Has zones of inactivity, proliferation, hypertrophy, and calcification
  146. Metaphpysis
    A region of bone on the diaphyseal side of the epiphyseal disk which is characterized by ossification at the edge of the cartilage and by resorption of bone on its interior surfaces towards the diaphysis
  147. Immature bone
    • Has more cells than mature bone
    • Is non-lamellar, has more heterogeneous ECM, and collagen is disorganized
  148. Mature bone
    Lamellar bone in which collagen is oriented in the same plane (but is perpendicular in the next lamella)
  149. Diaphysis
    Aka the shaft, the primary center of ossification in a long bone