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Lumen definition biology5/28/2023 ![]() This type of tissue is used extensively throughout the body for fastening down the skin, membranes, blood vessels and nerves as well as binding muscles and other tissues together. This slide shows a thin section of loose connective tissue (sometimes called areolar tissue). layer) Lab-2 05ģ - Simple columnar epithelium & 2 - Goblet cell Peristaltic contraction of these two muscle layers keeps food moving through the digestive tract. The muscularis externa is divided into an outer longitudinal muscle layer with cells that run along the axis of the intestine and an inner, circular muscle layer whose fibers encircle the organ. Beneath a thin, outer covering of the intestine called the serosa is a thick layer of smooth muscle cells called the muscularis externa. During routine histological preparation, the mucus is lost, leaving a clear or lightly stained cytoplasm. Interspersed among these columnar cells are goblet cells that secrete mucus into the lumen of the intestine. The lining of these villi is a tissue layer called the mucosa, which is made up of simple columnar epithelial cells. ![]() Projecting into the intestinal lumen (space) are numerous finger-like projections called villi, which function to slow the passage of food and increase the surface area for the absorption of nutrients. This slide is a cross section from the small intestine. In subsequent units of the Zoo Lab website, you will be introduced to the diversity of animal life that results from the interaction of all of these key components. Organs are combined to form organ systems (e.g., the circulatory system, nervous system, skeletal system, muscular system, excretory system, reproductive system, etc.) that function as an integrated unit called an organism. Tissues rarely work alone but instead, they are grouped into organs. In terms of understanding the workings of the multicellular animal body, however, you should realize that tissues are but one of many connected levels of biological organization. In the following pages of this lab unit, you will have an opportunity to examine a few (of the many) types of animal tissue. The tissue is composed of nerve cells (neurons), each of which is made up of a cell body and cell processes that carry impulses toward (dendrites) or away from (axons) the cell body. Nervous tissue is specialized for the reception of stimuli and conduction of nerve impulses. Cardiac (heart) muscle is striated like skeletal muscle, but each cell contains only one nucleus. ![]() Skeletal, or striated muscle, which is associated with voluntary contractions, contains cylindrical cells with many nuclei per cell arranged in bundles.Smooth muscle (designed for slow, sustained, involuntary contractions) is made up of spindle-shaped cells with one nucleus per cell.Muscle tissue is specialized for contraction. Examples of connective tissue would include bone, cartilage, tendons, ligaments, loose connective tissue, adipose (fat) tissue, and even blood (although some authorities would classify blood as a vascular tissue). Thus, what distinguishes the different connective tissues is the type of matrix. Despite their diversity, all connective tissues are comprised of living cells embedded in a non-living cellular matrix consisting of extracellular fibers or some type of ground substance. Connective tissue performs such diverse functions as binding, support, protection, insulation and transport. ![]()
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