CHAPTER 3 Cells and Tissues – Connective Tissues
Body Tissues Connective Tissue as its name suggests, this tissue connects body parts. Locations: found everywhere in the body. It is the most abundant and widely distributed of the tissue types. Functions: primarily involved in protecting, supporting, and binding together other body tissues.
Body Tissues Common Characteristics of Connective Tissue Variations in blood supply: most connective tissues are well vascularized. Exceptions: Tendons and ligaments have poor blood supply Cartilages are avascular - Consequently, all these structures heal very slowly when injured.
Body Tissues Common Characteristics of Connective Tissue, continued Extracellular Matrix: connective tissues are made up of many different types of cells plus varying amounts of a nonliving substance found outside the cells, called the extracellular matrix.
Body Tissues Extracellular Matrix - - Produced by connective tissue cells, then secreted to their exterior Two main elements: - Ground substance: composed mostly of water plus adhesion proteins and large charged polysaccharide molecules - Fibers: collagen fibers, elastic fibers, and reticular fibers
Body Tissues Types of Connective Tissue - Bone - Cartilage - Dense connective tissue - Loose connective tissue - Blood - - their major differences are specific cell types, fiber types, and the number of fibers in the matrix they are listed here from hardest (most rigid) to softest (most fluid)
Body Tissues Bone sometimes called osseous tissue Structure: - composed of osteocytes (bone cells) sitting in cavities called lacunae (“pits”) - the pits are surrounded by layers of a very hard matrix that contains calcium salts and large numbers of collagen fibers -
Body Tissues Bone
Body Tissues Bone, continued Function: - due to its rocklike hardness, bone has an exceptional ability to protect and support other body organs
Body Tissues Cartilage Structure: -less hard and more flexible than bone -major cell type is chondrocytes (cartilage cells) Found in only a few places in the body -most abundant type is hyaline cartilage
Body Tissues Cartilage, continued Hyaline cartilage has abundant collagen fibers hidden by a rubbery matrix with a glassy (hyalin = glass), blue-white appearance. Functions: forms the supporting structures of the larynx (voice box), attaches ribs to the breastbone, covers the ends of many bones where they form joints.
Body Tissues Hyaline cartilage
Body Tissues Fibrocartilage – highly compressible, forms cushionlike disks between the vertebrae of the spinal column Elastic cartilage – found in structures with elasticity (the external ear)
Body Tissues Fibrocartilage
Body Tissues Dense Connective Tissue aka, dense fibrous tissue Structure: collagen fibers are the main matrix element - crowded between the collagen fibers are rows of fibroblasts (fiber-forming cells) Dense connective tissue forms strong, ropelike, structures such as tendons and ligaments
Body Tissues Dense connective tissue, continued Functions: Tendons – attach muscles to bones Ligaments – attach bones to bones at joints. They are more stretchy and contain more elastic fibers that do tendons Dense connective tissue also makes up the lower layers of the skin, where it is arranged in
Body Tissues Dense connective tissue
Body Tissues Loose connective tissue Structure: - softer and have more cells and fewer fibers than other connective tissues (except blood) Areolar Tissue – most widely distributed connective tissue in the body
Body Tissues Areolar Tissue Functions: - cushions and protects the body organs it wraps. - helps hold internal organs together and in there proper positions
Body Tissues Areolar tissue
Body Tissue Adipose Tissue, aka fat Structure: - basically an areolar tissue in which adipose (fat) cells predominate Forms the subcutaneous tissue beneath the skin. Functions: Insulates the body and protects it from bumps and extremes of both heat and cold.
Body Tissues Adipose tissues, continued - protects some organs individually—the kidneys are surrounded by a capsule of fat, and adipose tissue cushions the eyeballs in their sockets
Body Tissues Adipose tissue
Body Tissues Reticular Connective Tissue Structure: - consists of a delicate network of interwoven reticular fibers associated with reticular cells, which resemble fibroblasts Functions: - Forms the stroma: the internal framework of an organ
Body Tissues Reticular connective tissue
Body Tissues Blood, aka vascular tissue Structure: - considered a connective tissue because it consists of blood cells surrounded by a nonliving fluid matrix called blood plasma. - the “fibers” of blood are soluble protein molecules that become visible only during blood clotting
Body Tissues Blood, continued Functions: blood is the transport vehicle for the cardiovascular system, carrying nutrients, wastes, respiratory gases, and many other substances throughout the body.
Body Tissue Blood