C o m p o n en ts o f co n n ectiv e tissu e • Figure 3.23
Connective tissue consists of various cells, fibers, and other
substances (ground substance).
Fibroblasts
(Fl-bro-blasts) are large flat cells that move
and secrete fibers and ground substance.
Macrophages
(MAK-ro-faj-es) develop from white blood cells
They eat bacteria and cell debris by phagocytosis
Elastic fibers
are stretchable but strong fibers made of proteins
elastin, and fibrillin. They are found in skin, blood
vessels, and lung tissue.
Reticular fibers
(re-TIK-u-lar) are made of collagen and glycoproteins. They
provide support in blood vessel walls and form branching networks
around various cells (fat, smooth muscle, nerve).
Collagen fibers
(KOL-a-jen) are strong, flexible bundles of the protein
collagen, the most abundant protein in your body.
Mast cells
are abundant along blood vessels. They
produce histamine, which dilates small
blood vessels during inflammation and
kill bacteria.
Adipocytes
D f
They are found below the skin and
around organs (heart, kidney).
Ground substance
is the stuff between cells and fibers. It is made of water and
organic molecules (hyaluronic acid, chondroitin sulfate,
glucosamine). It supports cells and fibers, binds them
together, and provides a medium for exchanging substances
between blood and cells.
Eosinophils
(e-o-SIN-o-filz) are white blood
cells that migrate to sites of
parasitic infection and allergic
responses.
Neutrophils
(NOO-tro-filz) are white
blood cells that migrate to
sites of infection.
Plasma cells
are small cells that develop
from a white blood cell. They
secrete antibodies that
attack and neutralize foreign
substances.
Connective Tissue Protects and
Supports the Body and Its Organs
Connective tissue is one of the most abundant tissues in
your body. It has various forms and performs the following
functions:
Binds together, supports, and strengthens other tissues
Protects and insulates internal organs
Divides structures into compartments
Transports materials throughout the body
Stores energy (in fat tissues and cells)
Protects the body by destroying invading microorganisms
and eliminating cellular debris
Connective tissue consists of two major components, cells
and the extracellular matrix (
). The cells in-
clude fibroblasts, macrophages, plasma cells, mast cells, and
adipocytes, as well as some white blood cells (neutrophils,
eosinophils) (Figure 3.24). The extracellular matrix in-
cludes various fibers—for example, collagen, elastic fibers,
and ground substance made up of water and various organic
76 CHAPTER 3
Cells and Tissues
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