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WHERE AM I? Online Anatomy Module 1 INTRO & TERMS CELL EPITHELIUM CONNECTIVE TISSUE MUSCLE NERVOUS SYSTEM AXIAL SKELETON APPENDICULAR SKELETON MUSCLES EMBRYOLOGY SOFT CONNECTIVE TISSUES The ‘soft’ distinction being made here is between cartilage and bone as firm connective tissues and the softer ones, such as fatty tissue, ligament, dermis of skin, etc. Articular cartilage Dermis Marrow Hypodermis Bone Joint capsule Ligament & Periosteum Tendon Text reading in Marieb is pp. 79-82 Muscle SMALL-GUT CONNECTIVE TISSUE ROLES VILLI covered with simple columnar epithelium on a core of very loose-textured CT Extensive area of fairly loosetextured CT holding the lining to the muscle of the wall Another layer of connective tissue outside and assisting the muscle by carrying vessels, nerves, and just holding things together GUT VILLUS transport Simple Columnar Epithelium absorbing ENTEROCYTES mucus-secreting GOBLET CELLS BASAL LAMINA { VILLUS CORE of: loose connective tissue C T cells lymphatic capillary capillaries CONNECTIVE TISSUE ROLES I Connect/Support Transport/Nourish EPITHELIUM } Connective tissue VESSEL The connective tissue under an epithelium is termed the LAMINA PROPRIA (adjacent layer). Where it is more intermingled with epithelial cells, as in a gland, it becomes the STROMA. THE CELL: Some basics IV Cells do not operate in isolation. They have surroundings and attachments - to other cells and materials outside them Surface specializations of the plasmalemma to interact with tube content Cell-cell attachments more specializations of the plasmalemma or ‘cell membrane’ Attachments to materials outside the cell in the EXTRACELLULAR MATRIX THE CELL: Some basics V The cells shown here form a single layer. It holds this form in part by the cells’ fastening at the base to a sticky porous membrane named a BASAL LAMINA or a BASEMENT MEMBRANE Basement membrane Basement membrane itself attaches to connective tssue below it THE CELL: Some basics VI Cell are soft and squishy. Think jellyfish - it needs water to support it. To holds us together & for life on land and the ability to move and manipulate things, we need a strong , in place rigid, extracellular matrix. Cells of the soft connective tissues , cartilage, and bone make materials that interact outside the cells to provide strength and support via EXTRA-CELLULAR MATRIX (ECM) CONNECTIVE TISSUE MATERIALS Cells of the soft connective tissues make materials that interact outside the cells to provide strength and support One very special product is the basement membrane to support epithelial cells The bulk of the connective-tissue matrix comprises: bound water, meaning that it does not slosh as you move molecules to bind the water and hold other components together long fibers to give strength and elasticity to the tissue other sticky molecules - glycoproteins - to hold the fibers in place CONNECTIVE TISSUE MATERIALS: Details bound water molecules to bind the water - PROTEOGLYCANS long fibers - COLLAGEN (strength) & ELASTIC other sticky molecules - GLYCOPROTEINS MORE CONNECTIVE TISSUE ROLES While the matrix properties allow the tissue to support & connect , other things are going on. The matrix offers an ideal place for microorganisms to grow, so that connective tissues have a range of defensive cells and are a battle-ground of great medical significance The matrix stores a number of useful materials, including ones to help control defensive reactions and adjacent tissues. And a special cell - the fat cell/ adipocyte - stores fats/lipids for energy & growth Connective tissue readily repair themselves & react to damage to other tissues CONNECTIVE TISSUE ROLES Connect/Support Transport/Nourish Defend Storage Control EPITHELIUM } Connective tissue VESSEL Repair CONNECTIVE TISSUE COMPONENTS Synthetic cells signals for structural macromolecules, e.g. for building fibers collagen elastic Defensive cells Cells lie in, attach to, & are supported by the EXTRACELLULAR MATRIX (ECM) of fibers & ‘ground substances’ DEFENSIVE CONNECTIVE TISSUE CELLS The matrix offers an ideal place for microorganisms to grow (food, warmth) so connective tissues have a range of defensive cells, and are a battle-ground of great medical significance MACROPHAGE (MF) eats dead & bad stuff; coordinates defense PLASMA CELL (from B Lymphocyte) makes & secretes antibodies (Igs) MAST CELL triggers defensive reaction/ inflammation (degranulates) MACROPHAGE (MF) lysosomes PLASMA CELL MAST CELL Golgi much GER Cartwheel nucleus [Peripheral clumps of heterochromatin] Big granules MACROPHAGE Mf POD Macrophage can: attach to fibers; release & crawl around; extend projections - podia; recognize bad things; wrap its podia around them; eat the stuff (phagocytosis); digest it with lysosomes MACROPHAGE MF Collagen fiber FOCAL ADHESION - attachment lysosome -POD Actin monomers & filaments in controlled flux for crawling, podia-extension, & phagocytosis MACROPHAGE /MF receptors Pathway for phagocytosis & lysosomal digestion lysosome POD Membrane scavenger receptors to recognize targets CONTEXT FOR MAST CELL ACTIONS Invader EPITHELIUM } CT VESSEL Defensive white blood cells & chemicals in vessel need to get out to counteract the invader MAST CELL Triggered by invader Releases granules Granule agents act on vessels & white blood cells to encourage exit MAST CELL MAST-CELL ACTIVATION IgE antibody molecules Fce Receptor for a region of the Ig molecule Invader IgE binding triggers degranulation IgE binding triggers degranulation MAST-CELL ACTIONS I Granules contain many agents (& proteoglycans), e.g. HISTAMINE to increase permeability & loosen wall MAST CELL CHEMOKINES to attract leukocytes out into CT of Vessel MAST-CELL ACTIONS II Heparin & proteoglycans influence signaling MAST CELL Chemokine receptors White blood cell Vessel Defensive blood chemicals, e.g., Complement CONNECTIVE-TISSUE CELLS: TWO MORE TYPES MACROPHAGE (MF) lysosomes PLASMA CELL MAST CELL Fibroblast is an elongated cell amidst the fibers etc it has made Golgi much GER Cartwheel nucleus [Peripheral clumps of heterochromatin] ADIPOCYTE FIBROBLAST Big granules Adipocyte/ fat cell grows to be very large, with a thin shell of cytoplasm around a huge fat droplet fat droplet COLLAGEN - Molecule to Fiber Collagen I trimer Three intertwined helices Last of the spinning. Hereafter, strength comes from cross-linking & glueing “Glueing” & control of fibril & fiber width are done by high-# collagens, glycoproteins, and proteoglycans Assembly of trimers end-to-end, side-by-side, but staggered to build a cross-banded fibril Further glueing of fibrils to make a FIBER CONNECTIVE TISSUES ROLES CELLS EC MATRIX WORKING CONTEXTS TYPES CONNECTIVE-TISSUE CELLS FIBROBLAST MACROPHAGE (MF) lysosomes PLASMA CELL MAST CELL Golgi much GER Cartwheel nucleus [Peripheral clumps of heterochromatin] ADIPOCYTE One huge fat droplet Big granules ROLES OF CONNECTIVE-TISSUE CELLS FIBROBLAST makes ECM; destroys ECM MACROPHAGE (MF) eats dead & bad stuff; coordinates defense PLASMA CELL (from B Lymphocyte) makes & secretes antibodies (Igs) MAST CELL triggers defensive reaction/ inflammation (degranulates) ADIPOCYTE stores & releases ‘energy’ (& brown adipocytes can make heat) ROLES OF CONNECTIVE-TISSUE CELLS FIBROBLAST MACROPHAGE (MF) PLASMA CELL) MAST CELL ADIPOCYTE CONNECTIVE TISSUE COMPONENTS: Cells & ECM Fibroblast Osteoblast Chondroblast synthetic Macrophage Plasma cell Lymphocyte Mast cell defensive Fat cell or Adipocyte storage Structural & other ECM molecules What are these? CONNECTIVE TISSUE COMPONENTS: Cells & ECM Collagen Fibroblast synthetic FIBERS Reticular Structural & other ECM molecules Fibroblasts rework the matrix that they have formed by carefully breaking it down, while synthesizing new materials to adapt to greater or otherwise changed loads Elastic BINDERS & CONTROLLERS: Sticky glycoproteins Water-binding proteoglycans Destructive enzymes Enzyme inhibitors Signaling Molecules CONNECTIVE TISSUE ‘GROUND SUBSTANCE’ Collagen FIBERS Reticular Fibroblast Structural & other ECM molecules ‘Ground substance’ is the old-fashioned name for the non-fiber extracellular part of connective tissue Elastic BINDERS & CONTROLLERS: Sticky glycoproteins Water-binding proteoglycans Destructive enzymes Enzyme inhibitors Signaling Molecules CONNECTIVE T. COMPONENTS: Reticular fibers Fibroblast synthetic Structural & other ECM molecules Collagen FIBERS Reticular Elastic Reticular fibers are a delicate version of collagen fibers, used so as to support cells, but not interfere with blood-cell interactions, e.g., in liver Reticular fibers HEPATOCYTES Endothelial cells lining vessel blood vessel blood TYPES OF CONNECTIVE TISSUE Around the body different combinations of these cells, fibers, and other ECM materials are needed The starting embryonic tissue is mesenchyme - jellylike, with a few thin fibers and unspecialized mesenchymal cells As the mesenchymal cells become fibroblasts, these can make the tissue, by fiber packing, loose or dense The fibroblasts may align the fibers parallel to make a regular tissue ,or arrange them in different orientations - an irregular tissue Elsewhere, mesenchymal cells may become fat cells making an adipose tissue The tissue requirements also vary when the tissue is somatic (in body wall or limb) rather than visceral TYPES OF CONNECTIVE TISSUE SOMATIC VISCERAL Loose irregular Loose irregular Dense irregular Dense irregular Reticular Reticular Adipose Adipose Elastic Elastic Dense regular In the beginning was Mesenchyme MESENCHYME Mesenchymal cells, mostly synthetic for signals structural macromolecules, e.g. for building fibers immature collagen Much ground substance e.g., hyaluronan (a GAG) Mesenchymal cells - precursors/ progenitors of some differentiated CT cells, e.g., fibroblasts Mesenchyme takes up & commits space to be a future connective tissue, and has modest jellylike mechanical properties of its own CONNECTIVE TISSUES: Contexts Tube Man Head modification of body wall + brain & special senses + start of two tubes Worm Woman re Al Soma - body wall & the limbs - - - Viscera tubes, modified o tubes, & accessory organs cvl - - u diaphragm SOMATIC STRUCTURES Articular cartilage Dermis Marrow Hypodermis Bone Joint capsule Ligament & Tendon Periosteum Muscle SOMATIC CONNECTIVE TISSUES: Dense regular Ligament & Tendon dense regular Muscle DENSE REGULAR CONNECTIVE TISSUE { Bundles of thick collagen I fibers { Elongated fibroblasts Looser vascular CT between the bundles DENSE REGULAR CONNECTIVE TISSUE: Tendon { Bundles of thick collagen I fibers { Elongated fibroblasts - tenocytes Looser vascular CT between the bundles endotendinuem If the tissue is in a tendon, some special names (not to be learned) are used SOMATIC CONNECTIVE TISSUES: Reticular & Adipose Marrow reticular Hypodermis adipose Muscle WHITE ADIPOSE TISSUE Capillary Adipocyte Reticular fibers Fat cell CONNECTIVE TISSUE - Mechanical functions The stringy strength of collagen allows a variety of mechanical actions Supporting - ligament Binding - ligament Restraining - ligament Directing - tendon Separating - fascia For firmer support something has to be added to the collagen to make cartilage or bone The large soft cells of adipose tissue can be confined in sheets of collagenous tissue for Padding - fat pad SOMATIC CONNECTIVE TISSUES: Dense irregular The collagen fibers are arranged in various directions for different pulls on the tissue Dermis dense irregular Periosteum dense irregular Joint capsule dense irregular Muscle SOMATIC CONNECTIVE TISSUES: Loose irregular marks loose irregular filling in between more solid structures & allowing them freedom of movement Muscle TYPES OF CONNECTIVE TISSUE SOMATIC Loose irregular (Areolar) between more solid structures Dense irregular joint capsule, periosteum, dermis Dense regular tendon, ligament Adipose hypodermis Elastic elastic ligament (inconspicuous in man) SOMATIC CONNECTIVE TISSUES Articular cartilage (hyaline) loose irregular Dermis dense irregular Marrow reticular Hypodermis adipose Bone Joint capsule dense irregular Ligament & Tendon dense regular Muscle Periosteum dense irregular TYPES OF CONNECTIVE TISSUE VISCERAL Loose irregular Dense irregular Reticular Adipose Elastic In the beginning was Mesenchyme Tube Man Worm Woman re Al Liver processes blood drained from the GI tract - - - - cvl - - u diaphragm Visceral Connective Tissue 1 re Al Liver - - - - Reticular cvl - - u e.g., in liver, spleen, kidney diaphragm processes blood drained from the GI tract Reticular fibers HEPATOCYTES blood vessel Macrophage Endothelial cells lining vessel Reticular fibers + Macrophages = Reticular tissue TYPICAL TUBULAR ORGAN Visceral Connective Tissue 2 - Loose irregular main working tissue Epithelium inner service tissue Connective tissue lumen motility tissue Muscle loose irregular ct with vessels & nerves outer service tissue Connective tissue VISCERAL CONNECTIVE TISSUE TYPES AORTA Elastic re ESOPHAGUS Lamina propria lumen Al Loose irregular Adventitia - - - - LIVER Reticular cvl - - - diaphragm u Kidney CAPSULE Dense irregular MESENTERY Adipose TYPES OF CONNECTIVE TISSUE Loose irregular lamina propria, tunica adventitia VISCERAL Dense irregular organ capsules Reticular liver, spleen Adipose mesentery, pericardium Elastic lung, elastic arteries have collagen fibers for strength, but need much elasticity CONNECTIVE TISSUE COMPONENTS: Cells & ECM Fibroblast Osteoblast Chondroblast synthetic Collagen Structural & other molecules Macrophage Plasma cell Lymphocyte Mast cell defensive Fat cell or Adipocyte storage FIBERS Reticular Elastic BINDERS & CONTROLLERS: Sticky glycoproteins Water-binding proteoglycans Destructive enzymes Enzyme inhibitors Signaling Molecules CONNECTIVE TISSUE ROLES Connect/Support COMPARTMENTS Transport/Nourish Defend Storage LUMINAL } (EPITHELIAL) } INTERSTITIAL connective tissue VASCULAR Control nervous, paracrine (local), biochemical Repair EXTRACELLULAR MATRIX ECM What cells produce and organize outside theselves allows them to construct huge organisms, with complex repertoires of movements & behaviors, and multiple physiologies based on separate compartments Tight junctions } LUMINAL } (EPITHELIAL) } INTERSTITIAL connective tissue VASCULAR EXTRACELLULAR MATRIX ECM 2 Cells create and achieve control over their environment by synthesizing combinations of types of macromolecule which interact outside the cells Learn the requirement, not the particular molecules meeting it Over water (why you don’t slosh as you walk) Why you can swallow, wink, spit, etc Hyaluronan Large proteoglycans Mucin glycoproteins (epithelial products) Creation of barriers - Basal laminae Laminin, Collagen IV Perlecan (a heparan sulfate proteoglycan) - Connective tissue ground substance Fibronectin Tenascin Attachment & support Collagen fibrils & fibers (I & III) + associated molecules BASAL LAMINA CONSTRUCTION a sticky hedge Learn the requirement, not the particular molecules meeting it Epithelial-cell attachments to laminin Interwoven networks of LAMININ & COLLAGEN IV attached by Nidogen/Entactin Basal-lamina Proteoglycan molecules attached to the lattice , e.g., Perlecan Generally LAMININ PERLECAN ‘IN’ ending - glycoprotein ‘AN’ ending - proteoglycan Heparin - a glycosaminoglycan - is an exception EXTRACELLULAR MATRIX ECM 3 Cells create and achieve control over their environment by synthesizing combinations of types of macromolecule which interact outside the cells Elastic fibers & Elastic recovery of shape & elastic laminae storage of the work of the heart & Elastin & fibrillin respiratory muscles Resilient firmness in joint, airway, & fetal-skeletal cartilages Resilient hardness of bone Cartilage collagens II & IX aggregated proteoglycans link proteins & hyaluronan cartilage glycoproteins Collagens I & XII bone proteoglycans bone glycoproteins mineral crystals Again, learn the requirement, not the particular molecules meeting it EXTRACELLULAR MOLECULAR INTERACTIONS 1 Further assembly of the molecules to make larger & eventually ‘visible’ structures, such as fibrils Modification of the molecules, e.g., cross-linking, to make them resistant to digestion Deliberate breakdown of the molecules by the forming cells for turnover and renewal, by proteases & other enzymes Controlled breakdown, with more synthesis & assembly, provides for remodeling & adaptation of ECM, e.g., to a heavier load in tendon or cartilage Some of these enzymes, e.g. collagenase, include a zinc atom & require Ca2+ to work - hence Matrix Metalloproteinases, e.g. MMP-3 Some of these enzymes, e.g. collagenase, include a zinc atom & require Ca2+ to work - hence Matrix Metalloproteinases, e.g. MMP-3 The inhibitors of these enzymes go under the abbreviation TIMPs - Tissue Inhibitors of MMPs; & are also made by fibroblasts & other matrix-influencing cells ECM MOLECULAR INTERACTIONS - Pathology 1 Unintended degradation by enzymes released from cells, e.g., leukocytes, engaged in defensive reactions. ECM is the battleground for defenses initially targeted at microorganisms. “--itises” occur throughout the body, & are real hazards to comfort & life, e.g., endocarditis weakens & distorts heart valves & thus can kill ECM MOLECULAR INTERACTIONS - Pathology 2 Unwanted degradation by bystander inclusion in cytokine signaling pathways of defensive cells IL-1 MF IL-1 Articular chondrocytes Lymphocytes of inner joint synovium Joint cartilage cells also respond to the signal: enzymes enzyme inhibitors proteoglycans = an inappropriate response causing cartilage matrix destruction - ARTHRITIS IL-1 Interleukin-1 a typical cytokine ECM MOLECULAR INTERACTIONS - Pathology 3 Unwanted degradation by: microbes trying to colonize, e.g., using bacterial hyaluronidase to liquify ground substance metastasizing cancer cells breaking through basal laminae & connective tissues to get into the blood or lymph streams Unwanted synthesis - the formation of excess collagen, clogging organs with delicate blood-cell relations. Cytokines released by activated macrophages trigger synthesis in fibroblasts, causing cirrhosis in the liver and fibrosis in kidney, lung, marrow, etc Bad assembly - genetically defective fibrillin makes an inadequate scaffold for elastin deposition weak aorta, slack connective tissues, etc, of Marfan’s syndrome This balance is significant matrix cells Thus, loose connective tissues have less matrix materials (except for water) and more cells than dense ones, because the looser textured matrix is more favorable to the growth of microorganisms, and hence needs more defensive cells: dense tendon needs far fewer. Adipose tissue is mostly the very large fat cells. WHERE AM I? Online Anatomy Module 1 ORIENTATION You are at the End CELL EPITHELIUM Caution how you exit. BACK on your CONNECTIVE TISSUE browser is needed MUSCLE Unfortunately there is NERVOUS SYSTEM no way that you can directly reach other AXIAL SKELETON topics listed here by APPENDICULAR SKELETON clicking on them. You get there by going back MUSCLES to the Paramedical Anatomy menu EMBRYOLOGY