1. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Lecture 26 Connective tissues

2. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Connective tissues bind and support other tissues –Characterized by Sparse population of cells scattered through an extracellular matrix Cells synthesize matrix – a web of fibers embedded in a liquid, jelly, or solid

3. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Connective Tissue  Most abundant and widely distributed of primary tissues  Four main classes  Connective tissue proper  Cartilage  Bone  Blood

4. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Major Functions of Connective Tissue  Binding and support  Protecting  Insulating  Storing reserve fuel  Transporting substances (blood)

5. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Characteristics of Connective Tissue  Three characteristics make connective tissues different from other primary tissues  Have mesenchyme (an embryonic tissue) as their common tissue of origin  Have varying degrees of vascularity (blood vessels)  Have extracellular matrix  Connective tissue not composed mainly of cells  Largely nonliving extracellular matrix separates cells  So can bear weight, withstand tension, endure abuse

6. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings MATRIX Matrix in Biology: the material between animal or plant cells or the material in the inner membrane of a mitochondrion Extracellular Matrix : any material part of a tissue that is not part of any cell Germinal matrix: an embryonic brain tissue

7. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Structural Elements of Connective Tissue  Three elements  Ground substance  Fibers  Cells  Composition and arrangement varies in different connective tissues

8. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Ground Substance  Unstructured material that fills space between cells  Medium through which solutes diffuse between blood capillaries and cells  Components  Interstitial fluid  Cell adhesion proteins ("glue" for attachment)  Proteoglycans  Protein core + large polysaccharides (chrondroitin sulfate and hyaluronic acid)  Trap water in varying amounts, affecting viscosity of ground substance

9. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Ground Substance: Proteoglycan Structure Figure 4.7

10. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Connective Tissue Fibers  Three types of fibers provide support  Collagen  Strongest and most abundant type  Tough; provides high tensile strength  Elastic fibers  Networks of long, thin, elastin fibers that allow for stretch and recoil  Reticular  Short, fine, highly branched collagenous fibers (different chemistry and form than collagen fibers)  Branch, forming networks that offer more "give"

11. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Collagen Polypeptide chain

12. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings EXTRACELLULAR FLUID Microfilaments Collagen fiber Connecting glycoprotein Integrin Plasma membrane Glycoprotein complex with long polysaccharide CYTOPLASM

13. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Cells  "Blast" cells  Immature form; mitotically active; secrete ground substance and fibers  Fibroblasts in connective tissue proper  Chondroblasts in cartilage  Osteoblasts in bone  Hematopoietic stem cells in bone marrow  "Cyte" cells  Mature form; maintain matrix  Chondrocytes in cartilage  Osteocytes in bone

14. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Other Cell Types in Connective Tissues  Fat cells  Store nutrients  White blood cells  Neutrophils, eosinophils, lymphocytes  Tissue response to injury  Mast cells  Initiate local inflammatory response against foreign microorganisms they detect  Macrophages  Phagocytic cells that "eat" dead cells, microorganisms; function in immune system

15. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Extracellular matrix Ground substance Fibers Collagen fiber Elastic fiber Reticular fiber Capillary Neutrophil Mast cell Fat cell Lymphocyte Fibroblast Macrophage Cell types Figure 4.7 Areolar connective tissue: A prototype (model) connective tissue.

16. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Types of Connective Tissues: Connective Tissue Proper  All connective tissues except bone, cartilage and blood  Two subclasses  Loose connective tissues  Areolar  Adipose  Reticular  Dense connective tissues (also called fibrous connective tissues)  Dense regular  Dense irregular  Elastic

17. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Areolar Connective Tissue  Support and bind other tissues  Universal packing material between other tissues  Most widely distributed  Provide reservoir of water and salts  Defend against infection  Store nutrients as fat  Fibroblasts  Loose arrangement of fibers  Ground substance  When inflamed soaks up fluid  edema

18. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Connective tissue proper: loose connective tissue, areolar Description: Gel-like matrix with all three fiber types; cells: fibroblasts, macrophages, mast cells, and some white blood cells. Function: Wraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid. Location: Widely distributed under epithelia of body, e.g., forms lamina propria of mucous membranes; packages organs; surrounds capillaries. Epithelium Lamina propria Photomicrograph: Areolar connective tissue, a soft packaging tissue of the body (340x). Elastic fibers Ground substance Fibroblast nuclei Collagen fibers Figure 4.8a Connective tissues.

19. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Adipose Tissue  White fat  Similar to areolar but greater nutrient storage  Cell is adipocyte  Stores nutrients  Scanty matrix  Richly vascularized  Shock absorption, insulation, energy storage  Brown fat  Use lipid fuels to heat bloodstream not to produce ATP

20. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Connective tissue proper: loose connective tissue, adipose Description: Matrix as in areolar, but very sparse; closely packed adipocytes, or fat cells, have nucleus pushed to the side by large fat droplet. Photomicrograph: Adipose tissue from the subcutaneous layer under the skin (350x). Nucleus of adipose (fat) cell Function: Provides reserve food fuel; insulates against heat loss; supports and protects organs. Location: Under skin in subcutaneous tissue; around kidneys and eyeballs; within abdomen; in breasts. Fat droplet Adipose tissue Mammary glands Figure 4.8b Connective tissues.

21. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Adipose tissue found below the dermis in the hypodermis

22. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Reticular Connective Tissue  Resembles areolar but fibers are reticular fibers  Fibroblasts called reticular cells  Supports free blood cells in lymph nodes, the spleen, and bone marrow

23. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Connective tissue proper: loose connective tissue, reticular Description: Network of reticular fibers in a typical loose ground substance; reticular cells lie on the network. Photomicrograph: Dark-staining network of reticular connective tissue fibers forming the internal skeleton of the spleen (350x). White blood cell (lymphocyte) Location: Lymphoid organs (lymph nodes, bone marrow, and spleen). Spleen Reticular fibers Function: Fibers form a soft internal skeleton (stroma) that supports other cell types including white blood cells, mast cells, and macrophages. Figure 4.8c Connective tissues.

24. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Dense Regular Connective Tissue  Closely packed bundles of collagen fibers running parallel to direction of pull  White structures with great resistance to pulling  Fibers slightly wavy so stretch a little  Fibroblasts manufacture fibers and ground substance  Few cells  Poorly vascularized

25. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Connective tissue proper: dense connective tissue, dense regular Description: Primarily parallel collagen fibers; a few elastic fibers; major cell type is the fibroblast. Function: Attaches muscles to bones or to muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one direction. Location: Tendons, most ligaments, aponeuroses. Shoulder joint Ligament Tendon Collagen fibers Nuclei of fibroblasts Photomicrograph: Dense regular connective tissue from a tendon (430x). Figure 4.8d Connective tissues.

26. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Dense Irregular Connective Tissue  Same elements but bundles of collagen thicker and irregularly arranged  Resists tension from many directions  Dermis  Fibrous joint capsules  Fibrous coverings of some organs

27. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Connective tissue proper: dense connective tissue, dense irregular Description: Primarily irregularly arranged collagen fibers; some elastic fibers; fibroblast is the major cell type. Function: Withstands tension exerted in many directions; provides structural strength. Location: Fibrous capsules of organs and of joints; dermis of the skin; submucosa of digestive tract. Shoulder joint Fibrous joint capsule Photomicrograph: Dense irregular connective tissue from the fibrous capsule of a joint (430x). Collagen fibers Nuclei of fibroblasts Figure 4.8e Connective tissues.

28. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Elastic Connective Tissue  Some ligaments very elastic  Those connecting adjacent vertebrae  Many of larger arteries have in walls

29. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Connective tissue proper: dense connective tissue, elastic Description: Dense regular connective tissue containing a high proportion of elastic fibers. Function: Allows tissue to recoil after stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs following inspiration. Location: Walls of large arteries; within certain ligaments associated with the vertebral column; within the walls of the bronchial tubes. Photomicrograph: Elastic connective tissue in the wall of the aorta (250x). Aorta Heart Elastic fibers Figure 4.8f Connective tissues.

30. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Dense connective tissue found in the lower area of the dermis

31. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Loose connective tissue Adipose tissue Blood Fibrous connective tissue Cartilage Bone Under skin Ligament End of bone Types of connective tissue

32. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cartilage- forming cells Matrix D Cartilage (at the end of a bone) Central canal Matrix Bone- forming cells E Bone F Blood A Loose connective tissue (under the skin) Elastic fibers Collagen fiber Cell Collagen fibers Cell nucleus B Fibrous connective tissue (forming a tendon) White blood cells Red blood cell Plasma C Adipose tissue Fat droplets –Connective tissue Binds and supports other tissues Figure 13.5A–F

33. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Connective Tissue: Embryonic  Mesenchyme – embryonic connective tissue  Gel-like ground substance with fibers and star- shaped mesenchymal cells  Gives rise to all other connective tissues  Found in the embryo

34. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Table 4.1 Comparison of Classes of Connective Tissues (1 of 2)

35. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings © 2013 Pearson Education, Inc. Table 4.1 Comparison of Classes of Connective Tissues (2 of 2)

36. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Connective Tissue Figure 4.6

37. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Thank you