2General Characteristics most abundant and widely distributed of all the tissue typesbinds structures, provides support and protection, serves as frameworks, fills spaces, stores fat, produces blood cells, protects against infection, and helps repair tissue damagefarther apart than epithelial cells
3General Characteristics—cont. variations in blood supplymost are well vascularizedtendons and ligaments have a poor blood supplycartilages are avascularhave an abundance of extracellular matrixproduced by the connective tissue and then secreted to the exteriorcould be liquid, semisolid or gel-like, or very hardvarious types and amounts of fibers are deposited in the matrix
4Major Cell Types in Connective Tissue Fibroblastsmost common type of fixed cell in connective tissuelarge, star-shapedproduce fibers by secreting proteins into the extracellular matrixproduce three types of fibers: collagenous fibers, elastic fibers, and reticular fibersBefore 1st bullet—Connective tissue contain a variety of cell types. Some are called fixed cells b/c they reside in the tissue for an extended period of time (fibroblasts and mast cells). Some are called wandering cells b/c they move through and appear in the tissues temporarily, usually in response to injury or infection (macrophages).
5Major Cell Types in Connective Tissue Macrophageswandering cells that originate as white blood cellsspecialized to carry on phagocytosiscan move about and function as scavenger and defensive cells that clear foreign particles from tissuesAfter 1st bullet—almost as numerous as fibroblasts in some connective tissuesAfter 2nd bullet—process by which a cell engulfs and digests solidsPic—shows several macrophages starting to engulf a cell
6Major Cell Types in Connective Tissue Mast cellslarge and widely distributedusually located near blood vesselsrelease heparin, which prevents blood clotting, and histamine, which promotes some of the reactions associated with inflammation and allergiesAfter 1st bullet—fixed cell
7Connective Tissue Fibers Collageneous fibersthick threads of the protein collagenflexible, but only slightly elasticgreat tensile strengthimportant parts of ligaments (which connect bone to bone) and tendons (which connect muscles to bone)Before 1st bullet—Remember these are secreted by fibroblast cells.After 3rd bullet—they resist considerable forceAfter 4th bullet—b/c of their tensile strength, they are found in body parts that hold structures togetherBonus Question: Why are collagenous fibers called white fibers? (found in dense connective tissue and such tissue appears white)
8Connective Tissue Fibers Elastic fiberscomposed of the protein elastinthin fibers that branch forming complex networksweaker than collageneous fibers but can stretch easily and resume original length and shapecommon in body parts that are frequently stretched, like the vocal cordsReticular fibersvery thin collagenous fibershighly branched and form delicate supporting networksfound in a variety of tissues, including the spleenBonus Question: Why are they called yellow fibers? (tissues supplied with them appear yellowish)Read blue box on page 100.See Table 5.4 on page 100 for Review
9Loose Connective Tissue also called areolar tissuesoft, pliable tissue that cushions and protects the body organs it wrapsconsidered a connective tissue “glue”lies beneath most layers of epithelium, where its many blood vessels nourish nearby epithelial cellsWhen a body region is inflamed, the areolar tissue in the area soaks up the excess fluid like a sponge. The area swells and becomes puffy, a condition called edema.Before 1st bullet—There are six types of connective tissue: loose connective tissue, adipose tissue, dense connective tissue, cartilage, bone, and blood.After 3rd bullet—binds the skin to the underlying organs and fills spaces between musclesAfter pictures—What are fibroblast cells? (cells that produce fibers) collagenous fibers are the thick threads of protein collagen; the elastic fibers are the thin, branching fibers that are made of elastinSee Figure 5.13 on page 101.
10Adipose Tissue also called fat specialized form of loose connective tissue that develop when certain cells store fat in droplets within their cytoplasm and enlargelies beneath the skin where it insulates and stores energycushions joints and some organsRead under Adipose Tissue on page 101.About pictures—Adipose tissue cells contain large fat droplets that push the nuclei close to the cell membranes.See Figure 5.14 on page 101.
11Dense Connective Tissue also called dense fibrous tissuehas collagen fibers as its main matrix elementscrowded between the collagen fibers are rows of fibroblasts that manufacture the fibersform strong, ropelike structures such as tendons and ligamentsblood supply is lowalso makes up thelower layers of skin(dermis)After 4th bullet—enables tissue to withstand pulling forcesAfter 4th bullet—where they bind bone to bone or muscle to boneAfter 6th bullet—tissue repair is slowSee Figure 5.15 on page 102.
12Cartilages less hard and more flexible than bone only found in a few places in the bodyseveral types in the bodyhyaline cartilage—most widespread; attaches ribs to breastbone, and covers the ends of bones where joints are formedelastic cartilage—found where a structure with elasticity is desired, such as the external earfibrocartilage—very tough tissue; forms the cushionlike disks between the vertebrae of the spinal column; shock absorberSee Figures 5.16 on page 102 and Figures 5.17 and 5.18 on page 103.Read box on page 103.
13Bone most rigid connective tissue sometimes called osseous tissue composed of bone cells sitting in cavities called lacunae and surrounded by layers of a very hard matrixhas an exceptional ability to protect and support other body organsSee Figure 5.19 on page 104.
14Bloodconsidered a connective tissue because it consists of blood cells, surrounded by a nonliving, fluid matrix called blood plasma“fibers” of blood are soluble protein molecules that become visible only during blood clottingtransport vehicle for the cardiovascular systemSee Figure 5.20 on page 105.See Table 5.5 on page 105.Have students complete questions 1-4 on page 102 and 1-3 on page 105.
15Muscle Tissue contract in response to specific stimuli muscle fibers shorten during contractionthree types of muscle tissue: skeletal, smooth, cardiacAfter 3rd bullet—About 40% of the body is skeletal muscle, and almost another is smooth or cardiac muscle.
16Skeletal Muscle found in muscles that attach to bones form the flesh of the bodycan be controlled voluntarilypull on bones or skin when they contract which results in gross body movements or changes in facial expressionscells are long, cylindrical and multinucleate with obvious striationsSee Figure 5.21 on page 107.
17Smooth Muscle Tissue no striations are visible individual cells have a single nucleus and are spindle shapedfound in the walls of hollow organs such as the stomach, bladder, uterus and blood vesselsWhen smooth muscle contracts, the cavity of an organ alternately constricts and dilates so that substances are propelled through the organ along a specific pathway.contracts more slowly than the other two musclesinvoluntary movementSee Figure 5.22 on page 107.
18Cardiac Muscle Tissue found only in the heart As it contracts, the heart acts as a pump and propels blood through the blood vessels.has striations like skeletal muscle, but cardiac cells are uninucleate and fit together tightly at junctions called intercalated disksunder involuntary controlSee Figure 5.23 on page 108.
19Nervous Tissue cells are called neurons All neurons receive and conduct electrochemical impulses from one part of the body to another.have a unique structure—drawn out cytoplasm into long extensionsmake up the structures of the nervous systemSee Figure 5.24 on page 109.See Table 5.6 on page 108.Read “Types of Membranes” on page 109—defining the four types of membranes.