Transcript Photo Album
Tissues “The Building Blocks of Organs” What is a tissue? A tissue is a grouping of cells where all the cells have similar structure and function. What are the Four Major Tissue Types… - epithelial - connective - neural (=nervous) - -muscle “Every Concert Needs Music” Epithelial Tissue… What is epithelial tissue? …a sheet of cells that covers a body surface or lines a body cavity. Epithelial Tissue examples • lines body cavities open to the exterior (e.g., digestive and respiratory tracts) • moist membranes found in closed ventral body cavity Figure 4.9b In the next set of slides you will see blue rectangles that cover up important vocabulary. Try to figure out the correct vocabulary term. Then when you hit the space bar the blue rectangle will disappear and uncover the answer. What is this structure? A GLAND Connective Tissue… What are two distinguishing features of connective tissue? …cells are spaced apart from each other and are separated by a “matrix.” …has an extra-cellular “matrix” composed of ground substance and fibers (elastin or collagen). Functions of Connective Tissue What are six functions of connective tissue? • • • • • • Binding (ex: holds skin onto body) Support (ex: bone, cartilage, ligaments) Protection (ex: skull, ribs, pelvis) Cushioning (ex: fat around internal organs) Thermal insulation (ex: fat below skin) Transport of materials (ex: blood, lymph) Fibers What are two types of fibers found in the matrix of connective tissue – and what are their properties? • Collagen – – tough, thick fibers; provide high tensile strength (“ropes”) • Elastin – – long, thin fibers; allow for stretch (“rubber bands”) How can you tell that this is connective tissue? Cells are far apart and there are fibers and ground substance. A stretched preparation of loose (areolar) connective tissue. The pink fibers of different thicknesses are collagenous (or white) fibers. The dark, thin, more tortuous fibers are elastic (or yellow) fibers. Most of the nuclei belong to fibroblasts. Fat cells -- note nucleus and rim of cytoplasm pushed to one side by the accumulation of fat. In the center of the picture, in the space bounded by the four large fat cells, there is a small, round cross-section of a capillary with a dark, shrunken red blood cell inside. WOW…how cool! Tendon (dense, regular c.t.), cut longitudinally. The thick collagen fibers (pink) are lined up parallel to each other. Fibroblasts (cells) are squeezed between the fibers and therefore also line up in parallel rows. Note that there are no striations so this is NOT skeletal muscle even though it resembles it. Dense regular connective tissue – tendons and ligaments Dense irregular conn. tiss. with fibers running in all directions. The fibers are mainly collagen, but there is a small amount of thinner elastic fibers (not visible). Found in the joint capsules that enclose joints. Connective Tissue: Cartilage • Hyaline cartilage – barely visible network of collagen fibers – has chondrocytes (cartilage cells) – Supports, reinforces, cushions, and resists compression • • • • ex: costal (rib) cartilage ex: embryonic skeleton ex: articular cartilge at ends of long bones ex: nose, trachea (“windpipe”), and larynx (“voicebox”) Hyaline cartilage (greenish matrix), There are some collagen and elastin fibers in the cartilage matrix, but they are invisible. Cartilage cells = chondrocytes. Close-up of two chondrocytes. The matrix appears very smooth, clear, and glassy (or "hyaline"). Notice the reddish elastin fibers in the matrix. Fibrocartilage, with collagen fibers in the matrix. They look "cotton-y", unlike the sharply defined elastic fibers seen before. Connective Tissue: Bone Describe the properties and functions of bone tissue. – Hard, calcium phosphate matrix with collagen fibers – Osteocytes = bone cells – Supports, protects, and provides levers for muscular action – Stores calcium, minerals, and fat – Marrow inside bones is the site of blood production. Section of bone. In the center of each “spaghetti” is a “canal” that carries blood vessels and a nerve. Therefore, bone is a well “vascularized” tissue, meaning that it has a rich blood supply. (By contrast, cartilage and epithelial tissue are “avascular.”) Higher magnification of bone. Black smudges are the osteocyters (bone cells). Notice the canaliculi (red arrows) that radiate outward from the central canal. This is how oxygen and nutrients get to the bone cells from the blood vessels inside the central canal. Even higher magnification of bone. Nervous Tissue What are the functions of nervous tissue? •Functions •respond to stimuli •communicate with other cells •transmit impulses Muscle Tissue What are the functions of muscle tissue? •Functions •contract •move bones •pump blood •move substances through internal organs •ex: urinary bladder, uterus, blood vessels, digestive tract What type of muscle tissue is this? Skeletal muscle