Chapter 3 - Connective TissueConnective tissue provides support, binds together, and protects tissues and organs of the body. Show
Connective tissue consists of three main components: cells, protein fibers, and an amorphous ground substance. Together the fibers and ground substance make up the extracellular matrix. Whereas the other tissue types (epithelium, muscle, and nervous tissue) are largely made up of cells, the extracellular matrix is the major component of most connective tissue. This chapter will focus on the basic types of connective tissue, while subsequent chapters examine the specialized connective tissues (cartilage, bone, and blood). Connective Tissue FibersThe three types of connective tissue fibers are:
Different stains can be used to visualize each type of fiber. (collagen and elastic fibers) H&E/Azan/Verhoeff (reticular fibers) Silver (reticular fibers) Silver CONNECTIVE TISSUEConnective tissue is classified based on the characteristics of its cellular and extracellular components. The main criteria are the type of cells, arrangement and type of fibers, and composition of the extracellular matrix. Loose Connective TissueLoose (areolar) connective tissue has a sparse, irregular network of collagen and elastic fibers suspended within a relatively large amount of ground substance. Dense Regular Connective TissueDense regular connective tissue is composed of type I collagen fibers oriented in the same direction. It provides tensile strength in one direction. Dense Irregular Connective TissueDense irregular connective tissue contains type I collagen fibers woven in multiple directions. It provides tensile strength in multiple directions. Embryonic Connective TissueEmbryonic connective tissue is formed during the development of the embryo. Mesenchyme develops into the various connective tissues of the body. Mucoid connective tissue is a gelatinous substance found in the umbilical cord. CONNECTIVE TISSUE CELLSConnective tissue cells are usually divided into two types:
FIXED CELLSFixed cells are normal components of connective tissue. FibroblastsFibroblasts produce and maintain the extracellular matrix. They are the most common cell type in connective tissue. AdipocytesThere are two types of adipose tissue:
White adipocytes are specialized for the synthesis and storage of triglycerides. White fat also functions as a cushion for organs and to insulate the body. Brown adipocytes are specialized to generate heat. Newborns have a higher proportion of brown fat (5% of body weight) than adults, which gradually decreases with age. MacrophagesMacrophages are phagocytic cells that engulf and digest microbes, cellular debris, and foreign substances. Monocytes develop in bone marrow, circulate in the bloodstream, and migrate into connective tissue, where they differentiate into macrophages. Mast CellsMast cells release molecules that dilate blood vessels and recruit more immune cells to a site of mast cell activation. Progenitor mast cells (agranular) develop in bone marrow, circulate in the bloodstream, and migrate into connective tissue, where they proliferate and differentiate into mature mast cells (granular). Special stains are required to identify mast cells in connective tissue. TRANSIENT CELLSTransient cells are leukocytes (white blood cells) that circulate in the bloodstream and migrate into connective tissue at sites of an immune response. These include neutrophils, eosinophils, basophils, lymphocytes, and monocytes. These cells are discussed in more detail in the chapter on Peripheral Blood. Plasma CellsPlasma cells are mature B lymphocytes that produce large quantities of antibodies. They are abundant wherever antigens may enter the body, such as the gastrointestinal tract and the respiratory system. EosinophilsEosinophils are involved in many inflammatory processes, including parasitic infections, allergic diseases, and asthma. What are the major components of connective tissue?Basic components of connective tissues and extracellular matrix: elastin, fibrillin, fibulins, fibrinogen, fibronectin, laminin, tenascins and thrombospondins.
What are the three main components of connective tissue quizlet?Share three basic components: (1) specialized cells, (2) extracellular protein fibers and (3) a fluid known as ground substance.
What are the 3 types of connective tissues and what do each do?Loose connective tissue holds organs in place and attaches epithelial tissue to other underlying tissues. Dense connective tissue helps attach muscles to bones and link bones together at joints. Specialized connective tissue encompasses a number of different tissues with specialized cells and unique ground substances.
What are the 3 common characteristics of all connective tissue?Structural Elements of Connective Tissue
Connective tissues come in a vast variety of forms, yet they typically have in common three characteristic components: cells, large amounts of amorphous ground substance, and protein fibers.
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