Connective Tissue

1. Connective Tissue • Forms metabolic and structural connections between tissues • Found everywhere in the body and represents most abundant tissue by weight. • Examples: Blood, tendons, fat, cartilage, bone • Some systems are almost exclusively composed of connective tissue • Skeletal, integumentary • Is vascularized • Loose & Adipose = good supply, Dense = poorly supplied • Form and function may vary • Form: can be flexible, rigid, semisolid, liquid • Function: reserve for energy, protective sheath, framework of structural support, transport medium, promote healing, control foreign invaders

2. Connective Tissue Components • 3 major components of connective tissue: • Extracellular fibers, Ground substance, Cells • _______________ ________ = Extracellular fibers + Ground substance • Matrix surrounds and separates the cells, providing important structural and nutritional support to them, allowing them to be farther apart than epithelial cells. • 1. Extracellular fibers • Collagenous, Reticular, Elastic • 2. Ground substance • Liquid, solid, or gel • 3. Cells • Fixed cells • Fibroblasts, Adipocytes (fat cells), Reticular cells • Wandering cells • Mast cells, Leukocytes (white blood cells), Macrophages (fixed and wandering)

4. Connective Tissue Components: Ground Substance • An amorphous, homogenous material that ranges from ______ to _____ to _______. • Composed of glycoproteins called __________________ (GAGs) • hyaluronic acid • Help to orient fiber formation in connective tissue. • Is medium through which cells exchange nutrients and waste with the _________________. • Acts as shock absorbing cushion and helps to protect the delicate cells that it surrounds. • Serves as obstacle for invading microorganisms.

5. Fibers of Connective Tissue • Collagenous: • Most common fiber found in the body • Strong, thick bands organized into bundles, composed of ____________ (structural protein). • Resist ___________ forces, so they are found in tendons and ligaments that are continuously being pulled and stretched. • wavy appearance when not stretched • Sometimes called white fibers • Density and arrangement can vary depending on tissue function. • Loose around organs to dense within tendons.

6. Fibers of Connective Tissue • Reticular: • Composed of collagen, but are not thick • Thin, delicate, ____________ into complicated networks. • Form support around highly ____________ organs • endocrine glands, lymph nodes, spleen, bone marrow, liver • Found around blood vessels, nerves, muscle fibers, capillaries • Elastic: • Composed primarily of protein ________. • Are branched and form networks • Can stretch and contract. • Found in tissues that stretch: vocal cords, lungs, skin, blood vessel walls. • May be referred to as yellow fibers.

7. Major Cell Types of Connective Tissue • Fixed Cells: • Remain in the connective tissue • Produce and maintain the __________ • Fibroblast: • secrete fibers and ground substance of the matrix • Can reproduce and are metabolically active. • Name is based on _________. • Chondroblast (cartilage), osteoblast (bone), etc. • As the cells mature and the matrix is formed, cells become less active and suffix is changed to –_______. • Chondrocyte, osteocyte, fibrocyte • Can revert back to blast if more matrix is needed.

8. Major Cell Types of Connective Tissue • Fixed cells continued. • Adipose cells/Adipocytes: • Found throughout connective tissue • Resemble fibroblasts early on, but as they age they become filled with lipid and swell. • __________ gets pushed to the side • Adipocytes clustered together form _________ tissue. • found all over, but is prominent under the skin, behind the eyes, around the kidneys, and in the abdomen • Reticular Cells: • Flat, star-shaped cells that form net-like connections with other cells • Manufacture reticular fibers. • Found in tissues of the immune system: lymph nodes, spleen, bone marrow

9. Major Cell Types of Connective Tissue • Wandering Cells: • Move in and out of connective tissue as needed. • Help _______ and _________ the tissue • Leukoctyes: (white blood cells) • Found in blood, move into connective tissue during periods of infection/inflammation. • Squeeze through the simple squamous epithelium of blood vessels (diapedesis) • Important in immune function- engulf and digest invaders or produce antibodies against them • Mast cells • Carry histamine and heparin granules which initiate inflammatory response when released into tissue • Usually found near blood vessels

10. Major Cell Types of Connective Tissue • Wandering cells continued.. • Macrophages: • ___________ scavengers that may be either fixed or transient in connective tissue. • Engulfmicrobes, dead cells and debris that are digested by the macrophage’s lysosomes • drawn to sites of infection where they engulf invaders • Given different names depending on locations • Kupffer cells in liver, microglial cells in brain

11. Types of Connective Tissue • Connective Tissue Proper: • Loose Connective Tissue- supports structures that it surrounds • Areolar, Adipose, Reticular • Dense Connective Tissue- highly fibrous (collagen); little vascularization, ground substance, or cells; reinforces and binds structures • Dense regular, Dense irregular, Elastic • Specialized Connective Tissue: • Cartilage • Hyaline, Elastic, Fibrocartilage • Bone • Compact, Cancellous • Blood

12. Loose Connective Tissue: Areolar • Most common type of connective tissue • Surrounds every organ, connects skin to muscle, envelops blood vessels, nerves, and lymph nodes • Acts to support and cushion organs and other delicate structures. • Predominant cell is ____________. • Has “_______” spaces that are filled with fluid and viscous ground substance • GS- Hyaluronic acid • Nutrients and wastes easily move in and out of bloodstream; foreign invaders get trapped • Hyaluronidase allows WBCs to pass through easily • Filling of open spaces during trauma is called __________

13. Loose Connective Tissue: Adipose • Commonly known as ________ • Found beneath skin, between muscles, behind eyeballs, on heart surface, around joints, in bone marrow, in abdomen • Energy storage, insulator, shock absorber • Highly vascularized areolar tissue in which adipocytes predominate • Cells __________/__________ based on amount of lipid being stored in them. • May be classified as: • White: • Found throughout body • Adipocytes change from resembling fibroblasts to filling with lipid • Brown: • Found in _________ and ____________ animals • Site of heat production, temperature regulation

14. Loose Connective Tissue: Reticular • Framework for spleen, liver, lymph nodes, bone marrow • Called _________ • Contains only one type of fiber: ___________ • Many fibroblasts

15. Dense Connective Tissue: Regular • Makes up tendons and ligaments, fascia • Tightly packed,__________ collagen fibers • Little vascularization, slow to heal • Little ground substance • Fibroblasts line the collagen bundles • Resists strong pulling forces in _____ direction.

16. Dense Connective Tissue: Irregular • Found in dermis, organ capsules • Forms tough capsule of joints. • Collagen fibers in thicker bundles than those in denseregular connective tissue. • Sheets of collagen in ___________ directions. • Single sheet that can withstand pulling force from _______ different directions.

17. Dense Connective Tissue: Elastic • Found in areas of the body that require ___________: • Stomach, large airways, artery walls, bladder, between vertebrae • Beneath transitional epithelium in urinary tract • High concentration of elastic fibers (more than collagen) that are extremely flexible.

18. Specialized Connective Tissue: Cartilage • More rigid than dense connective tissue, more flexible than bone. • Prevents bones from rubbing against each other. • Does not contain nerves or blood vessels. • Receives nutrition from ________________. • Cells are chondrocytes, matrix is a gel of chondroitin sulfate, hyaluronic acid, and chondronectin plus fluid. • Fluid gives nutrients to the chondrocytes, which live in pockets called _______ • Fluid allows cartilage to be resilient and withstand compression • 3 types of cartilage: • Hyaline cartilage, Elastic Cartilage, Fibrocartilage

19. Specialized Connective Tissue: Types of Cartilage • Hyaline Cartilage • Most common type of cartilage found in body. • Found as ____________ cartilage at end of long bones and joints and connects ribs to the sternum. • Nose, trachea, larynx • Most rigid type of cartilage. • Closely packed collagen fibers that make it tough but more flexible than bone. • Elastic Cartilage • Similar to hyaline cartilage but contains _________ fibers • Give it flexibility, ability to bend • Found in pinnae, ear canal, epiglottis

20. Specialized Connective Tissue: Types of Cartilage • Fibrocartilage • Found between vertebrae, in pelvis, and in knee joint • Thick bundles of collagen, but few chondrocytes • Thicker bundles than hyaline, matrix less firm • Able to handle compression, absorbs ______

21. Specialized Connective Tissue: Bone • Also called osseous connective tissue • Hardest and most rigid type of connective tissue • Forms animal’s frame, protects organs, calcium reserve, fat storage, blood cell production • Is well vascularized • Structure • Matrix – collagen fibers and calcium salts • ____________- tiny channels through matrix that allows osteocytes to communicate • _________- chambers where osteocytes reside • Blood Supply- __________ canals (channels in bone that carry blood supply and nerves) • Cells- Osteoclasts and osteoblasts • Remodel bone as needed

23. Specialized Connective Tissue: Blood • Most atypical type of connective tissue. • Carries nutrients and gases through the body • Matrix: _______ (plasma) • Fibers: few and only visible in a _____ • Cells: • Erythrocytes (______ blood cells) • Leukocytes (________ blood cells) • Thrombocytes (________)