Introduction to Sports Science Epithelial Tissue Epithelial Tissue: or epithelium is the lining, covering, and glandular tissue of the body. Glandular epithelium forms various glands in the body. Covering and lining epithelium covers all free body surfaces. Function Protection (protects against bacterial and chemical damage; cilia lining the respiratory tract) absorption (lines some digestive system organs such as stomach and small intestine) filtration (kidneys absorb and filter) secretion (produces such substances as perspiration, oil, digestive enzymes, and mucus) Special characteristics Epithelial cells fit closely together to form continuous sheets. Membranes always have one free (unattached) surface or edge. The lower surface of an epithelium rests on a basement membrane, a structureless material secreted by the cell. no blood supply of their own (avascular) depend on diffusion from capillaries well-nourished- ability to regenerate themselves. Classification Each epithelium is given two names. The first indicates the relative number of cell layers it has. Simple epithelium (one layer of cells) stratified epithelium (more than one cell layer). Classification The second describes the shape: squamous cells- flattened like fish scales (squam = scale) cuboidal cells- are cube-shaped like dice columnar cells- shaped like columns Simple squamous Simple squamous Simple cuboidal Simple cuboidal Simple columnar Simple columnar Pseudostratified columnar Pseudostratified columnar Stratified squamous Stratified squamous Transitional Connective Tissues Characteristics: variations in blood supply- most well vascularized. exceptions- tendons and ligaments have poor blood supply, and cartilages are avascular. (This is why all of these structures heal more slowly when injured). Extracellular matrix: Connective tissues are made up of many different types of cells plus nonliving substance found outside of the cells. Extracellular Matrix Makes connective tissues so different! Matrix is produced by the connective tissue cells and secreted to their exterior. Depending on the connective tissue type, the matrix may be liquid, semisolid or gel-like, or very hard. able to bear weight, withstand stretching, or even abrasion. Various types and amounts of fibers are deposited in and form a part of the matrix material. They include: Collagen (white) fibers Elastic (yellow) fibers Reticular (fine collagen) fibers. Fibers made by the connective tissue and secreted. Types of Connective Tissues (All connective tissues consist of living cells surrounded by a matrix) Differences reflect fiber type and number of fibers in the matrix. From most rigid to softest BONE CARTILAGE DENSE CONNECTIVE TISSUE LOOSE CONNECTIVE TISSUE BLOOD BONE composed of bone cells sitting in cavities called lacunae (lah-ku’ ne) and surrounded by layers of a very hard matrix. The matrix contains calcium salts in addition to larger numbers of collagen fibers. Ability to protect and support other body organs. Skull protects the brain. CARTILAGE Less hard and more flexible than bone. Found in a few places in the body. In hyaline cartilage, which is found in the voice box, attaches the ribs to the breastbone and covers the ends of bones where they form joints. DENSE CONNECTIVE Has collagen fibers as its TISSUE main matrix element. fibroblast (fiber-forming cells) manufacture these fibers. Form strong rope-like structures such as tendons and ligaments. also makes up lower layers of the skin (dermis), arranged in sheets. Tendons Attach skeletal muscle to bones. Ligaments connect bones to bones at joints. more stretchy contain more elastic fibers than tendons. LOOSE CONNECTIVE TISSUE Softer and have more cells fewer fibers than any other connective tissue type except blood. 3 Subclasses of LCT 1.) Areolar tissue soft, cushions and protects body organs it wrap. packing tissue and connective “glue”. 2. Adipose Tissue: Common name- FAT. insulates the body and protects it from extremes of both heat and cold. (subcutaneous tissue beneath the skin) protects some individual organs- kidneys surrounded by capsules of fat, and cushions the eye sockets. fat “deposits” - such as hips and breast, where fat is stored and available for fuel if needed. 3. Reticular Connective tissue: consists of a delicate network of interwoven reticular fibers associated with reticular cells, which resemble fibroblasts. Forms the stroma or internal supporting framework. supports free blood cellssuch as in the lymph nodes, the spleen, and bone marrow. BLOOD Vascular tissue consists of blood cells, surrounding by nonliving, fluid matrix called blood plasma. “fibers” are soluble protein molecules visible only during blood clotting transport vehicle for the cardiovascular system: carries nutrients, wastes, respiratory gases, and other substances throughout the body. Muscle Tissue highly specialized to contract or shorten, to produce movement. Muscle fibers: muscle cells are elongated to provide a long axis for contraction. 3 types of muscle tissue Skeletal Muscle: voluntarily Cardiac Muscle: involuntary control Smooth: involuntary Skeletal Muscle: controlled voluntarily ( or consciously). contractions pull on bones or skin. results of action is gross body movement or change in our facial expression. cells are long, cylindrical, and multinucleate; they are obvious striations (stripes). Cardiac Muscle: involuntary control found only in the HEART striations, but uninucleate, branching cells that fit tightly together (like clasped fingers) at junctions called intercalate disks. Ions can pass freely from cell to cell Smooth Muscle: involuntary No striations are visible. individual cells have a single nucleus and are spindleshaped (pointed at each end). in walls of hollow organsstomach, bladder, uterus, and blood vessels. wavelike motion that keeps food moving through the small intestine.