Connective Tissues They hold us all together Connective

Connective Tissues They hold us all together

Connective Tissue n n n Hold things together Provide support and protection Serve as frameworks Fill spaces Produce blood cells and prevent infection Help repair tissue damage Further apart than epithelial cells Have much matrix (intercellular fluid) between them Have good blood supply Can be rigid or flexible Can usually reproduce

Fluid semisolid Matrix n n Fibers Ground Substance: varies from fluid to solid n . solid

Major Cell Types Resident Cells: Stable numbers including Fibroblasts and Mast Cells n Wandering Cells: Can move in/out of bloodstream by ameboid movement. Include white blood cells. n

Resident Cells Fibroblasts: Large, usually star shaped fiber producing cells. Secrete protein into matrix, VOILA! Instant fiber. n Mast Cells: Large, widely distributed, near blood vessels generally, release heparin (prevents blood clots) and Histamine (promotes inflammation reactions/allergies) n

Fibroblasts

Mast Cells

Wandering Cells n Macropohages: Do phagocytosis, scavenge/defend by clearing foreign particles

Macrophage

Connective Tissue Fibers Collegenous Fibers n Elastic Fibers n Reticular Fibers n

Collagenous Fibers Thick threads made from the protein collagen n Fibers in long, parallel bundles n Flexible, though not overly elastic n Have great tensile strength n Tissue containing a lot of this: dense connective tissue (or white fibers) n Present in tendons n

Collagenous Fibers ELASTIC MEMBRANES COLLAGENOUS FIBERS Aorta Rat, Helly's fluid, Mallory's stain (A), Mallory-azan stain (B), 162 x.

Elastic Fibers Made from protein Elastin. n Fibers are branched, form complex networks n Stretchy n Called yellow fibers n In vocal cords n

Elastic Fibers

Reticular Fibers Very thin collagenous fibers n Highly branched, form delicate supporting networks n Found in a variety of tissues n

Reticular Fibers

Loose Fibrous Connective Tissue Forms thin, delicate membranes throughout body n Mostly fibroblasts, separated by matrix loaded with collagenous, elastic fibers n Glues skin down, fills space between muscle n It’s beneath most epithelium, highly vascularized n

Loose Fibrous Connective Tissue

Adipose Tissue FAT n Cells store fat droplets in their cytoplasm, enlarge n Beneath skin, in spaces between muscle, behind eyeballs, in certain abdominal membranes, on the heart, around joints n Stores energy, insulates, cushions organs, joints, n

Adipose Tissue

Dense Fibrous Connective Tissue n n n Closely packed, thick, collagenous fibers and a fine network of elastic fibers Few cells, mostly fibroblasts Strong, dense, good tensile strength Common in ligaments and tendons In the white of the eyeball, deeper skin layers Poor vascularization; slow healing

Dense Fibrous Connective Tissue

Connective Tissue Summary

Cartilage n n n Is partly rigid, partly flexible It provides support, frameworks, attachments, serves as template for developing bones Much intercellular material composed of collagenous fibers embedded in a gel-like ground substance Chondrocytes (cartilage cells) are in small lacunae (small chambers), surrounded by matrix Perichondrium (fibrous connective tissue) encloses cartilagenous structure. It contains blood vessels

Cartilage Types distinguished by type of intracellular matrix Hyaline Cartilage: n Elastic Cartilage n Fibrocartilage n

Hyaline Cartilage: Most common n Has fine collagenous fibers in matrix n Looks like white plastic n Found on ends of bones in joints, soft part of nose, rings in respiratory passages n Important in bone formation n

Hyaline Cartilage

Elastic Cartilage Has dense network of elastic fibers n More flexible than hyaline n Provides framework for ears(external) and parts of larynx n

Elastic Cartilage

Fibrocartilage Tough n Contains many collagenous fibers n Shock absorber for structures subjected to pressure n Found in intervertebral disks, knees, pelvic girdle n

Fibrocartilage

Bone n n n Most rigid of connective tissues Mineral salts between cells Matrix contains collagen Supports, protects body structures Houses marrow (where blood cells form) Stores calcium, phosphate Matrix is deposited in layers called lamellae around osteonic canals Osteocytes in lacunae An osteon is osteocytes and matrix wrapped around an osteonic canal Osteons contain blood vessels Canaliculi are small tubes through which osteocyte cytoplasm extends

Bone

Blood Transport n Matrix=plasma n Red blood cells n White blood cells n Platelets n Blood cells float in plasma, formed in bone marrow n

S m e a r � Blood N e u t r o p h i l s ( g r e e n ) � M o n o c y t e ( b l u e ) � N o t i c e t h e h o r s e s h o e

Muscle Tissue Contract: Muscle fibers shorten n Skeletal n Smooth n Cardiac n

Skeletal Muscle Attach to bones n Conscious control: Voluntary n Long, threadlike cells n Have light/dark bands called striations n Has many nuclei n

Skeletal Muscle

Cardiac Muscle Only in heart n Striated, joined end to end n Branched, interconnected n One nucleus/cell n At ends, where cells join: Intercalated disk n involuntary n

Cardiac Muscle

Smooth Muscle Lack striations n Shorter/spindle shaped n One centrally located nucleus n In walls of hollow internal organs n involuntary n

Smooth Muscle

Nervous Tissues Found in brain, spinal cord, peripheral nerves n Sensitive to change n Transmit nerve impulses along nerve fibers (cellular extensions) to other nerves, muscles, glands. n Coordination, regulation, integration n Contain Neuroglial cells n

Neuroglial Cells Support, bind components of nervous system n Carry on phagocytosis n Supply nutrients: connect to blood vessels n

Nervous Tissues

Neuroglial Cells