Where Is Dense Irregular Connective Tissue Found – The nucleus is offset to one side by the fat drop Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Insulates against heat loss Supports and protects organs Location Under the skin Around the kidneys Behind the eyeballs, in the abdomen and chest Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
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Where Is Dense Irregular Connective Tissue Found
Description – network of reticular fibers in loose ground substance Function – forms a soft, internal skeleton (stroma) – supports other cell types Location – lymphoid organs Lymph nodes, bone marrow, and spleen Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Unit 6: Tissue Structure And Functions
Dense irregular connective tissue Dense regular connective tissue Elastic connective tissue Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Description Mostly irregularly arranged collagen fibers Some elastic fibers and fibroblasts Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Function Withstands tension Provides structural strength Location Dermis of the skin Submucosa of the digestive tract Fibrous capsules of joints and organs Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Description Mainly parallel collagen fibers Fibroblasts and some elastic fibers Poorly vascularized Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Dense Irregular Connective Tissue Is Found In
Function Attaches muscle to bone Attaches bone to bone Withstands large loads in one direction Location Tendons and ligaments Aponeuroses Fascia around muscles Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Description Predominantly elastic fibers Function – Allows for rebound after stretch Location In arterial walls, certain ligaments, and surrounding bronchial tubes Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Cartilage Stiff, flexible tissue Contains no blood vessels or nerves Matrix contains up to 80% water Cell type – chondrocyte Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Invisible collagen fibers (hyaline = vitreous) Chodroblasts form the matrix Chondrocytes are in the gaps Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Reticular Dermis. Human Skin Stock Image
Costal cartilages Nasal, tracheal, and larynx cartilages Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Provides great flexibility Location Supports the outer ear Epiglottis Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
The matrix is similar to, but less rigid than, hyaline cartilage. Thick collagen fibers predominate Function Tensile strength and ability to absorb compressive shock Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Calcified matrix containing many collagen fibers Osteoblasts – secrete collagen fibers and matrix Osteocytes – mature bone cells in crevices Well vascularized Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Dense Connective Tissue
Provides leverage and attachment for muscles Stores calcium and other minerals Stores fat Brain is the site for blood cell formation Location Bones Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Blood tissue Atypical connective tissue Develops from mesenchyme Consists of cells surrounded by a nonliving matrix Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Red and white blood cells in fluid matrix Function Transport of respiratory gases, nutrients, and waste Location in blood vessels Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
In order to operate this website, we record user data and share it with processors. To use this website, you must agree to our Privacy Policy, including our Cookie Policy. As its name suggests, one of the main functions of connective tissue is to connect tissues and organs. Unlike epithelial tissue, which is composed of cells that are tightly packed with little or no extracellular space, connective tissue cells are dispersed throughout the matrix. The matrix usually includes large amounts of extracellular material produced by the connective tissue cells embedded within it. The matrix plays an important role in the functioning of these tissues. The main component of the matrix is ground substance, which is often crossed by protein fibers. This ground substance is usually liquid, but it can also be mineralized and solid, as in bones. Connective tissue comes in a wide variety of forms, but generally has three characteristic components: cells, large amounts of amorphous ground substance, and protein fibers. The amount and structure of each component correlates with tissue function, from the hard ground substance in bones that supports the body to the inclusion of specialized cells; such as a phagocytic cell that engulfs pathogens and also rids tissue of cellular debris.
Dense Irregular Tissue Stock Photos
Connective tissue performs many functions in the body, but the main one is to support and connect other tissues; from the connective tissue sheath that surrounds muscle cells, to the tendons that attach muscles to bones, and to the skeleton that supports body positions. Protection is another important function of connective tissue in the form of fibrous capsules and bones that protect delicate organs and of course the skeletal system. Specialized connective tissue cells protect the body from microorganisms entering the body. Transport of fluid, nutrients, waste, and chemical messengers is accomplished by specialized liquid connective tissues such as blood and lymph. Fat cells store excess energy in the form of fat and contribute to thermal insulation of the body.
All connective tissue arises from the mesodermal layer of the embryo (see Figure 4.3). The first connective tissue to develop in the embryo is mesenchyme, the stem cell line from which all connective tissue is later derived. Clusters of mesenchymal cells are scattered throughout adult tissues and supply the cells needed for replacement and repair after connective tissue injury. A second type of embryonic connective tissue is formed in the umbilical cord, called mucous connective tissue or Wharton’s jelly. After birth, this tissue is gone, leaving only scattered mesenchymal cells throughout the body.
The three broad categories of connective tissue are classified by the properties of their parent material and the types of fibers found in the matrix (Table 4.1). Proper connective tissue includes loose connective tissue and dense connective tissue. Both tissues have different cell types and protein fibers suspended in a viscous ground. Dense connective tissue is reinforced by bundles of fibers that provide tensile strength, flexibility and protection. In loose connective tissue, the fibers are loosely arranged, leaving large spaces between them. Supportive connective tissue—bones and cartilage—gives structure and strength to the body and protects soft tissues. These tissues are characterized by a few distinct cell types and densely packed fibers in a matrix. In bone, the matrix is rigid and described as calcified due to deposited calcium salts. In fluid connective tissue, in other words, lymph and blood, various specialized cells circulate in a watery fluid containing salts, nutrients, and dissolved proteins.
Fibroblasts are present in all connective tissues (Figure 4.12). Fibrocytes, adipocytes, and mesenchymal cells are fixed cells, meaning they remain in the connective tissue. Other cells move in and out of connective tissue in response to chemical signals. Macrophages, mast cells, lymphocytes, plasma cells, and phagocytic cells are found in connective tissue, but are actually part of the immune system that protects the body.
Solved Explore Dense Connective Tissue. Histology Slides
4.12. image. Appropriate connective tissue Fibroblasts produce this fibrous tissue. Connective tissue includes fixed cell fibrocytes, adipocytes, and mesenchymal cells. LM × 400. (Micrograph courtesy of University of Michigan Medical School Regents © 2012)
The most common cell in connective tissue is fibroblasts. Polysaccharides and proteins secreted by fibroblasts combine with extracellular fluids to form a viscous ground substance that forms the extracellular matrix with embedded fibrous proteins. As you might expect, the fibrocyte, a less active form of fibroblast, is the second most abundant cell type in connective tissue.
Adipocytes are cells that store lipids as droplets that fill most of the cytoplasm. There are two main types of adipocytes: white and brown. Brown adipocytes store lipids in the same number of droplets and have high metabolic activity. In contrast, white fat adipocytes store lipids as one large droplet and are metabolically less active. Their effectiveness in storing large amounts of fat is seen in obese people. The number and type of adipocytes depends on the tissue and location and varies among individuals in the population.
A mesenchymal cell is a multipotent stem cell of an adult. These cells can differentiate into any type of connective tissue cells needed to repair and heal damaged tissue.
Dense Irregular Connective Tissue
A macrophage cell is a large cell derived from a monocyte, a type of blood cell that enters the connective tissue matrix from blood vessels. Macrophage cells are an essential part of the immune system, which is the body’s defense against potential pathogens and degraded host cells. When stimulated, macrophages release cytokines, small proteins that act as chemical messengers. Cytokines attract other cells of the immune system to infected sites and stimulate their activity. Roaming or free macrophages move rapidly with amoeboid motility, engulfing infectious agents and cellular debris. In contrast, fixed macrophages are permanent residents of their tissues.
Mast cells located in connective tissue contain many cytoplasmic granules. These granules contain the chemical signals histamine and heparin. When mast cells are irritated or damaged, they release histamine, an inflammatory mediator that causes vasodilation and increased blood flow to the site of injury or infection, and the itching, swelling, and redness you recognize as an allergic reaction. Like blood cells, mast cells are derived from
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