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Vertebrate Histology Exam 2

front 1 Chapter 3: Connective Tissue	back 1
front 2 Functions of connective tissue	back 2 Support: Binds, anchors and supports (structurally and functionally) cells, tissues, and organs Glue that holds everything together Defense: Can act as physical barrier Transport: Cells, fluid, and other substances between tissues of the body Storage: E.g. calcium or fat Repair: Scar formation
front 3 Connective tissue	back 3 Develops from mesenchyme (mesoderm; embryonic connective tissue) Consists of cells and extracellular matrix (ECM) ECM consists of Extracellular fluid (ECF) Ground substance (gel-like matrix supporting fibers & cells and allows for diffusion of ECF) Protein fibers (collagen, reticular, elastic)
front 4 Classification of connective tissue	back 4 Based on amount, type, arrangement, and abundance of cells, fibers, and ground substance Loose: loose, irregular arrangement of fibers in matrix and abundant cells Dense: thicker more densely packed fibers with fewer cells and less ground substance Irregular: random orientation of fibers Regular: parallel orientation of fibers

front 5 Classification of connective tissue	back 5 Embryonic connective tissue Mesenchyme Mucus connective tissue Connective tissue proper Loose connective tissue Dense connective tissue (regular and irregular) Specialized connective tissue Cartilage Bone Adipose tissue Hematopoietic tissue (blood, bone marrow, lymphatic tissue)
front 6 Connective Tissue Components	back 6 Cells Extracellular matrix (ECM) Extracellular fluid (ECF) Ground Substance Fibers
front 7 Cells of connective tissue	back 7 Permanent / resident cells Fibroblasts Special names: chondroblasts, chondrocytes & osteoblasts, osteocytes Adipose cells Cells with pigmented granules Migratory cells Macrophages Mast cells Plasma cells Other leukocytes
front 8 Cells of connective tissue	back 8

front 9 Resident cells: Fibroblasts	back 9 Fibroblasts: fusiform-shaped, synthesize fibers and ground substance (proteins and carbohydrates) Elongated cell with cytoplasmic projections Ovoid nucleus (typically all that is visible with H & E) Cartilage = chondroblasts & chondrocytes Bone = osteoblasts & osteocytes
front 10 Resident cells: Adipose cells	back 10 Single cells or groups of cells When major cell type, connective tissue is called adipose tissue store fat (insulation, protection, energy source) Narrow rim of cytoplasm Flattened off-center nucleus Large empty space (dissolved fat)
front 11 Migratory cells: Macrophages	back 11 Phagocytic cells Ingest bacteria, dead cells, cell debris, and foreign material Antigen presentation Found in loose connective tissue Round with irregular borders Special names: Kupfer cells in liver; osteoclasts in bone; microglia in central nervous system
front 12 Migratory cells: Mast cells	back 12 Found near blood vessels in connective tissue of skin, digestive organs, and respiratory organs Spherical with fine dark-staining (purple) granules that induce inflammatory responses Small central, spherical nucleus Synthesize and release heparin and histamine during allergic reactions (anaphylactic reactions & shock)

front 13 Migratory cells: Plasma cells	back 13 Lymphocytes that have migrated into connective tissue of respiratory and digestive tracts Small cell Off-center nucleus with radial clumps of chromatin Synthesize and secrete humoral antibodies Primary cell type during chronic inflammation
front 14 Migratory cells: Other Leukocytes (white blood cells)	back 14 Migrate into connective tissue to produce immune response (defense) Lymphocytes: spherical cell with dense purple nucleus; antibodies and cytotoxic reactions Eosinophils: bilobed nucleus, large pink/red granules in cytoplasm; parasitic infections and allergic reactions Neutrophils: multilobed nucleus, non-staining granules; destroy bacteria
front 15 Connective Tissue Components	back 15 Cells Extracellular matrix (ECM) Extracellular fluid (ECF) Ground Substance Fibers
front 16 Extracellular matrix: ECF	back 16 Fluid component that is similar to plasma Circulates throughout the ground substance Transporting nutrients, oxygen, signaling molecules, carbon dioxide, waste, and blood-borne materials to/from cells Originates from blood in capillaries and returns to blood through capillaries and lymphatic vessels

front 17 Edema	back 17 increased ECF and/or cells in any tissue type—common in epithelial & connective tissues
front 18 Connective Tissue Components	back 18 Cells Extracellular matrix (ECM) Extracellular fluid (ECF) Ground Substance Fibers
front 19 Extracellular matrix: Ground substance	back 19 Amorphous, transparent extracellular matrix Semifluid gel with high water content to allow diffusion of nutrients—due to ECF perfusion May be mineralized (bone, cartilage) Resistance to compression Supports, surrounds, and binds all connective tissue cells and fibers Composed of glycosaminoglycans, proteoglycans, and adhesive glycoproteins (fibronectin, integrins, and laminin)
front 20 Extracellular matrix: Ground substance	back 20 Gel quality of ground substance slows down flow rate of ECF Allows for more time for diffusion of oxygen, electrolytes, nutrients, and metabolites between cells and blood vessels Slows down movement of large molecules and pathogens

front 21 Connective Tissue Components	back 21 Cells Extracellular matrix (ECM) Extracellular fluid (ECF) Ground Substance Fibers
front 22 Fibers of connective tissue	back 22 Amount and arrangement of 3 fiber types depend on function of tissues and organs where they are found Collagen Reticular Elastic All fiber types produced by fibroblasts Proteins with long peptide chains
front 23 Fibers: Collagen fibers	back 23 Tough, thick, non-branching fibers Most abundant fiber type in connective tissue Numerous subtypes of collagen fibers Stain with eosin (pink) Flexible and strong
front 24 Skin scar (keloid formation):	back 24 increased abundance of collagen fibers replacing normal tissue structures

front 25 Fibers: Reticular fibers	back 25 Mainly type III collagen Delicate, thin, netlike framework of branching fibers Do not form bundles Only visible with silver stain (brown to black) Liver, lymph nodes, spleen, hemopoietic organs, where blood/lymph filtered Support capillaries, nerves, muscle cells
front 26 Fibers: Elastic fibers	back 26 Thin, small branching fibers Allow stretch (up to 150% resting length)—recoil without deformation Less tensile strength than collagen Often interwoven among collagen fibers Composed of proteins Microfibrils and elastin Lungs, bladder, skin, aorta, and pulmonary trunk are examples where elastic fibers are prominent
front 27 Connective tissue types	back 27
front 28 Embryonic connective tissue	back 28 Mesenchyme (top panels) and mucus connective tissue (bottom panels) Loose and irregular Ground substance is semifluid to jellylike Numerous fibroblasts (lots of projections) Fine collagen or reticular fibers

front 29 Loose (areolar) connective tissue	back 29 More prevalent than dense connective tissue Loose, irregular fiber arrangement Cell density > Fiber density Large amount of intercellular space Main constituents: Collagen fibers Fibroblasts Adipose cells Mast cells Macrophages
front 30 Loose connective tissue	back 30
front 31 Loose connective tissue	back 31
front 32 Dense connective tissue	back 32 Thicker and more densely packed collagen fibers vs. loose connective tissue Fewer cell types Fiber density > Cell density Minimal intercellular space Less ground substance

front 33 Dense irregular connective tissue	back 33 Random and irregular orientation of collagen fibers, interlaced with a few elastic and/or reticular fibers Fibroblast is main cell type (occasional macrophages and mast cells) Dermis of skin, capsules of organs, and areas needing strong support Provides tensile strength and support in many directions Resists stretching and tearing
front 34 Dense irregular connective tissue	back 34
front 35 Dense irregular connective tissue	back 35
front 36 Dense irregular connective tissue	back 36 Hypertrophic scars and keloids

front 37 Dense regular connective tissue	back 37 Densely packed collagen fibers with a parallel arrangement and very little ECM Some ligaments have densely packed, parallel elastic fibers Fibroblasts main cell type and line up between fiber bundles Tendons and ligaments Provide great tensile strength in a single direction
front 38 Dense regular connective tissue: longitudinal section	back 38
front 39 Dense regular connective tissue: longitudinal section	back 39
front 40 White adipose (unilocular) tissue	back 40 Lipid storage Large cells Fat is single droplet of triglycerides Wide distribution Energy source Insulation Cushions organs Highly vascular

front 41 White adipose (unilocular) tissue	back 41
front 42 Brown adipose (multilocular) tissue	back 42 Metabolism Smaller cells Fat is multiple small droplets Heat supply Dominate adipose tissue in hibernating animals and infants In adults—adrenal glands and vessels in neck or in wasting disease
front 43 Cartilage	back 43 Tensile strength Structural support for soft tissues Flexibility without distortion Resists compression
front 44 Cartilage has typical connective tissue components	back 44 Cells Extracellular matrix ECF + Ground Substance Fibers Collagen often obscured by viscosity of ground substance

front 45 Cartilage	back 45 Cells Chondrocytes and chondroblasts (generate ECM)—cartilage fibroblasts Extracellular matrix (ECM) (>95% tissue volume) Fibers = collagen (individual fibers not visible) Ground substance = hyaluronic acid & glycoproteins Nonvascular: nutrients must diffuse through ECM
front 46 Cartilage cells	back 46 Mesenchyme cells (during development) Differentiate into chondroblasts Also form fibroblasts of perichondrium Chondroblasts Divide via mitosis forming isogenous groups and synthesize ECM Chondrocytes Mature chondroblasts surrounded by ECM and located in lacunae Maintain ECM
front 47 Perichondrium	back 47 Found surrounding hyaline and elastic cartilages only Peripheral layer of vascularized dense irregular connective tissue Outer fibrous layer = collagen and fibroblasts Inner cellular layer = chondrogenic cells that form chondroblasts
front 48 Cartilage matrix	back 48 Produced and maintained by chondrocytes and chondroblasts Appears glassy Collagen fibers provide firmness and resilience Semi rigid (shock absorber)—soft and pliable Chondronectin links cells to fibers in matrix Obscured by ground substance Ground substance associated with fibers Sulfated glycosaminoglycans Hyaluronic acid High water content

front 49 Cartilage matrix staining regions	back 49 Ground substance is basophilic but does not stain homogenously --> glycoproteins concentration Capsular/ pericellular matrix: ring of more densely stained matrix around the chondrocyte Territorial matrix: surrounds the isogenous group Interterritorial matrix: outer region that occupies spaces between isogenous groups
front 50 Cartilage matrix, cells, and perichondrium	back 50
front 51 Types of cartilage are distinguished based on amount and types of fibers	back 51
front 52 Hyaline cartilage	back 52 Most common with glassy ECM Embryos Skeletal model for most bones Adults Articular surfaces (joints), end of ribs, nose, larynx, trachea, bronchi Firm structural and flexible support

front 53 Hyaline cartilage and perichondrium: trachea	back 53
front 54 Osteoarthritis: Erosion of Joint Hyaline Cartilage	back 54
front 55 Elastic cartilage	back 55 Similar in appearance to hyaline cartilage Matrix has numerous branching elastic fibers in matrix in addition to hyaline cartilage components Has perichondrium Highly flexible Structural support Matrix NEVER calcifies! External ear, walls of auditory tube, epiglottis, and larynx
front 56 Elastic cartilage (epiglottis)	back 56

front 57 Fibrocartilage	back 57 Large amounts of dense irregular bundles of coarse collagen in ECM Alternating layers of cartilage matrix and collagen bundles Fibers oriented in direction of stress Intervertebral disks, symphysis pubis, and certain joints Tensile strength, bear weight, resist stretch or compression No perichondrium
front 58 Fibrocartilage (intervertebral disk)	back 58
front 59 Chondrogenesis	back 59 Interstitial growth Mitosis of chondrocytes within matrix Addition of matrix surrounding new cells Increase cartilage size from within
front 60 Chondrogenesis	back 60 Appositional growth At periphery of cartilage Chondroblasts differentiate from perichondrium New matrix deposited next to existing cartilage Increase cartilage width

front 61 Bone	back 61 Calcified due to mineral deposition in matrix Collagen fibers and calcium dominate matrix Can bear more weight than cartilage Rigid skeleton Attachments for muscles and organs Protects organs Hemopoeisis (blood cell formation) Storage of calcium, phosphate, and other minerals
front 62 Bone	back 62 ECM continually renewed or remodeled Mineral needs of body Mechanical stress Bone thinning (age or disease) Fracture healing Blood calcium regulation Parathyroid hormone: increases blood calcium by promoting bone resorption (activate osteoclasts) Calcitonin: decreases blood calcium by inhibiting bone resorption (inhibit osteoclasts; activate osteocytes
front 63 Bone formation (ossification)	back 63 Endochondral ossification Cartilage model Bones that bear weight Intramembranous ossification No cartilage model Flat bones
front 64 Endochondral ossification	back 64 Way most bones develop Temporary hyaline cartilage model precedes bone formation As cartilage model grows and development progresses Calcification begins Chondrocytes die due to lack of nutrients

front 65 Endochondral ossification	back 65 Inner perichondrial cells form thin collar of bone around middle of bone shaft Now called a periosteum Osteoblasts secrete osteoid matrix that later calcifies Once surrounded cells called osteocytes (located in lacunae)
front 66 Endochondral ossification	back 66 Osteocytes form cell-cell connections through channels called canaliculi Link to blood vessels here as well Osteoprogenitor cells are also found on inner bone surface (endosteum) Bone gradually replaces cartilage
front 67 Endochondral ossification	back 67
front 68 Intramembranous ossification	back 68 Mesenchyme cells differentiate directly into osteoblasts—no cartilage precursor Osteoblasts produce osteoid matrix which calcifies Form and produce network of spongy bone Thin rods, plates, and spines of bone matrix called trabeculae Osteoblasts change to osteocytes located in lacunae and connected by canaliculi Mandible, maxilla, clavicles, and flat bones of skull

front 69 Bone cells	back 69 Osteoprogenitor (osteogenic) cells Osteoblasts Osteocytes Osteoclasts
front 70 Osteoprogenitor (osteogenic) cells	back 70 Undifferentiated stem cells derived from mesenchyme Inner layer of periosteum and entire endosteum Continuous source of osteoblasts
front 71 Osteoblasts	back 71 Found on surfaces of bone Synthesize, secrete, and deposit osteoid matrix Calcify bone matrix by releasing vesicles of hydroxyapatite crystals Apposed next to growing bone
front 72 Osteocytes	back 72 Mature osteoblasts trapped in lacunae Smaller than osteoblasts Branched with extensions in canaliculi Form gap junctions with neighboring cells Exchange of nutrients

front 73 Osteoclasts	back 73 Large, multinucleated cells Bone macrophages Where resorption, remodeling, and repair are occurring
front 74 Bone matrix	back 74 Hard, no diffusion of nutrients Highly vascularized Resists tension and compression Mostly collagen fibers Other components Sulfated glycosaminoglycans Hyaluronic acid Osteocalcin and osteopontin Hydroxyapatite crystals (calcium phosphate)
front 75 Bone types	back 75 Compact bone Cancellous (spongy) bone Look the same under microscope when stained with H & E! Therefore, we use dried sections for compact bone in lab.
front 76 Compact bone	back 76 Collagen fibers arrange in thin layers of bone called lamellae Each lamellae is parallel to adjacent ones Form concentric circles around blood vessels Outer circumferential lamellae Just interior to periosteum Inner circumferential lamellae Surround bone marrow cavity (endosteum) Concentric lamellae Surround canals with blood vessels and nerves Form unit called osteon (Haversian canal system)

front 77 Compact bone	back 77 Lacunae with osteocytes and canaliculi are found between lamellae of osteon Volkmann’s perforating canals cross concentric lamellae and connect adjacent osteons
front 78 Compact bone	back 78
front 79 Compact bone	back 79
front 80 Cancellous (spongy) bone	back 80 Resembles developing bone during intramembranous ossification Calcified matrix forms interconnecting trabeculae (spicules) with numerous connected marrow cavities Usually sandwiched between layers of compact bone

front 81 Cancellous (spongy) bone	back 81
front 82 Osteogenesis Imperfecta (OI)	back 82 Genetically inherited mutation of Collagen Type I genes Not only causing brittle bones but also other connective tissue defects OI decreases bone thickness due to slow bone formation, reduced # trabeculae, thinner trabeculae, & increased bone resorption
front 83 Overview of Blood	back 83 Fluid connective tissue (ECM = ECF + Ground Substance) Functions Transport nutrients and oxygen to cells Transport carbon dioxide and waste away from cells Transport of hormones and other regulatory substances to/from cells Maintenance of homeostasis (buffer, coagulation, thermoregulation) Transport of antibodies and immune cells
front 84 Components of blood	back 84 Cells (45% volume)—formed elements Erythrocytes: red blood cells Leukocytes: white blood cells Thrombocytes: platelets Plasma (55% volume) Liquid extracellular matrix (ECF + Ground Substance) Mostly water No fibers Gives fluid properties to blood

front 85 Blood Cell Types: Appearance	back 85
front 86 Blood Cell Types: General Features	back 86
front 87 Erythrocytes	back 87 Enucleated and devoid of typical organelles Bind oxygen and carbon dioxide Biconcave disk to maximize surface area for gas exchange 120 day lifespan Stain uniformly with eosin (hemoglobin
front 88 Erythrocytes and platelets	back 88

front 89 Erythrocytes: sickle cell anemia	back 89
front 90 Leukocytes	back 90 Granulocytes: cells containing specific granules Neutrophils Eosinophils Basophils Agranulocytes: cells without specific granules Lymphocytes Monocytes Function outside of blood vessels (defense)
front 91 Neutrophils	back 91 Most numerous white blood cell (60-70%) 2-3 day lifespan Phagocytic 10-12 µm diameter No characteristic cytoplasmic staining Multilobed nucleus
front 92 Eosinophils	back 92 Same size as neutrophils 10 day lifespan Bilobed nucleus 2-4% of leukocytes Allergic reactions, parasitic infections, chronic inflammation

front 93 Eosinophillia in epithelial tissue during parasitic infections or allergic reactions	back 93
front 94 Basophils	back 94 Rare (< 1%) Same size as neutrophils Short life span Numerous, large, purple granules Lobed nucleus Vascular disturbances associated with hypersensitivity and anaphylaxis
front 95 Lymphocytes	back 95 Most common agranulocyte (20-30% leukocytes) Variable lifespan Immunocompetent cells In transit from one lymphatic tissue to another About size of erythrocyte Intensely purple stained, indented nucleus (may also be round) Thin, pale blue rim of cytoplasm
front 96 Lymphocytes: Leukemia	back 96

front 97 Monocytes	back 97 Largest white blood cell (18 µm diameter) 3-8% of leukocytes Differentiate in body tissues to macrophages Only in blood 3 days Indented nucleus (round to horseshoe shape)—kidney bean shape common Abundant pale blue cytoplasm Act as antigen presenting cells
front 98 Thrombocytes: platelets	back 98 Platelets derived from large polyploid cell (megakaryocyte) Small bits of cytoplasm from peripheral area of megakaryocyte break off ~2-3 µm 10 day life span Important for hemostasis (clotting and blood vessel repair)
front 99 Human blood smear	back 99
front 100 Formation of blood cells	back 100 Hemopoiesis (hematopoiesis) includes erythropoiesis, leukopoiesis, and thrombopoiesis Blood cells are continuously produced and destroyed Formed in red bone marrow and lymphatic tissue of adults Yellow bone marrow no longer supports hematopoiesis because marrow is full of fat Monophyletic theory of hemopoiesis: blood cells derived from a common stem cell

front 101 Formation of blood cells	back 101 Cell #1: Pluripotential hemopoietic stem cell in red bone marrow is common stem cell Cell #2 (one of the following): Pluripotential myeloid stem cells Erythrocytes, granulocytes, monocytes, megakaryocytes Pluripotential lymphoid stem cells Lymphocytes Stem cells undergo numerous divisions and differentiations before mature blood cells are formed
front 102 Formation of blood cells	back 102
front 103 Red bone marrow: reticular connective tissue	back 103
front 104 Erythropoiesis	back 104 1.Pluripotential hemopoietic stem cell 2.Pluripotential myeloid stem cell 3.Proerythroblast 4.Basophilic erythroblast 5.Polychromatophilic erythroblast 6.Normoblast 7.Reticulocyte 8.Mature erythrocyte

front 105 Development of granulocytes: part of leukopoiesis	back 105 1.Pluripotential hemopoietic stem cell 2.Pluripotential myeloid stem cell 3.Myeloblast 4.Promyelocyte 5.Myelocyte (one of the following): 1.Eosinophilic myelocyte --> Eosinophil 2.Basophilic myelocyte --> Basophil 3.Neutrophilic myelocyte --> Neutrophil
front 106 Development of monocytes: part of leukopoiesis	back 106 1.Pluripotential hemopoietic stem cell 2.Pluripotential myeloid stem cell 3.Monoblast 4.Promonocyte 5.Monocyte leaves blood à Macrophage in connective tissue
front 107 Development of lymphocytes: part of leukopoiesis	back 107 1.Pluripotential hemopoietic stem cell 2.Pluripotential lymphoid stem cell 3.Lymphoblast 4.Prolymphocyte 5.Large lymphocyte 1.T lymphocyte 2.B lymphocyte leaves blood à Plasma cell in connective tissue
front 108 Thrombopoiesis	back 108 1.Pluripotential hemopoietic stem cell 2.Pluripotential myeloid stem cell 3.Megakaryoblasts 4.Megakaryocytes 5.Platelets

front 109 Muscle	back 109
front 110 Muscle types	back 110 Cells are oriented differently in three muscle types.
front 111 Functions of muscle tissue	back 111 Movement of body and parts of the body Skeletal muscle Change size and shape of internal organs Cardiac muscle Smooth muscle
front 112 Features of all muscle tissue	back 112 Aggregates of specialized, elongated cells arranged for mechanical work Myofilaments are the contractile proteins (clustered into myofibrils) Thin filaments: actin Thick filaments: myosin II Special terms for cellular structures Cytoplasm = sarcoplasm sER = sarcoplasmic reticulum Plasma membrane = sarcolemma Muscle cell = muscle fiber (NOT same as CT extracellular fiber)

front 113 Striated vs. smooth muscle	back 113 Striated have stripes that are visible under the light microscope due to the arrangement of myofilaments (sarcomere) Skeletal muscle Cardiac muscle Smooth has no stripes because myofilaments are not arranged into sarcomeres
front 114 Skeletal muscle	back 114 Elongated, cylindrical cells with multiple nuclei located at periphery of fiber Myofibrils extend length of fiber in a regular arrangement Cytoplasm stains intensely with eosin (pink/red)
front 115 Skeletal muscle- longitudinal section	back 115
front 116 skeletal muscle-cross section	back 116

front 117 Skeletal muscle striations	back 117
front 118 Skeletal muscle organization: connective tissue sheaths	back 118 Connective tissue (CT) surrounds individual fibers and bundles of fibers (blood and nerve supply) Endomysium: reticular fiber layer around individual fibers (cells) Perimysium: thicker layer of dense irregular CT surrounding groups of fibers (fascicles) Epimysium: sheath of dense irregular CT surrounding all fascicles in the muscle
front 119 Skeletal muscle: myofilaments & sarcomere	back 119 Each muscle cell is filled longitudinally with repeating arrays of myofilaments called myofibrils Striations A band = dark band I band = light band (bisected by Z disc) Sarcomere = Z disc to Z disc
front 120 Duchenne’s Muscular Dystrophy	back 120 Skeletal muscle fibers degenerate and undergo necrosis Increased fibrosis in endomysium & perimysium (thicker collagen bundles) Leads to progressive muscle weakness See also Clinical Considerations 6-1

front 121 Skeletal muscle: motor innervation	back 121 Motor neurons branch to synapse with individual muscle fibers Synapse called neuromuscular junction (myoneural junction) or motor end plate
front 122 Cardiac muscle	back 122 Same arrangement of myofilaments as skeletal muscle Striated (sarcomeres) Intercalated disks: attachment sites between cells (gap junctions) Fibers are variable in length Single, centralized nucleus Branched fibers Spontaneous contractions
front 123 Cardiac muscle	back 123
front 124 Cardiac muscle	back 124

front 125 Cardiac muscle- longitudinal section	back 125
front 126 cardiac muscle- cross section	back 126
front 127 Myocardial Infarction: Heart Attack	back 127
front 128 smooth muscle	back 128 Bundles or sheets of elongated, fusiform cells with finely tapered ends Connected by gap junctions Cytoplasm stains evenly with eosin Single nucleus in center of cell No regular arrangement of actin and myosin (nonstriated) Walls of hollow organs and blood vessels

front 129 Smooth muscle	back 129
front 130 Smooth muscle- longitudinal section	back 130
front 131 smooth muscle- cross section	back 131