Include tissues such as bone, fat, and blood.
Very different in appearance and function.
Found everywhere in the body, it is the most
abundant and widely distributed of the tissue
Well vascularized (except tendons, ligaments,
All connective tissue have three basic
Three basic components
Extracellular protein fibers
A fluid known as the ground substance
The extracellular fibers and ground
substance constitute the matrix that
surrounds the cell. The extracellular
matrix typically accounts for most of the
volume of connective tissue.
Funtions of Connective Tissue
Establishing a structural framework for the
Transporting fluids and dissolved materials
throughout the body.
Protecting delicate organs.
Supporting, surrounding, and
interconnecting other tissue types.
Storing energy reserves.
Defending the body from invading
Classification of Connective
Connective tissue proper
Fluid connective tissue
Supporting connective tissue
Connective Tissue Proper
Connective tissue with many types of cells and
extracellular fibers in a syrupy ground substance.
Differ in number of cell types they contain and the
relative properties and proportions of fibers and
Divided into two categories based on the relative
number of fibers, cells, and ground substance.
Loose connective tissue
Dense connective tissue
Adipose tissue and tendons help comprise
connective tissue proper.
Connective Tissue Proper:
Fibroblasts – most abundant permanent
resident, they are the only cell that are
always present in every connective tissue
Macrophages – engulf pathogens or
damaged cells that enter the tissue.
Mesenchymal Cells – stem cells that
respond to local injury by producing
daughter cells that become fibroblasts,
macrophages or other type of connective
Melanocytes – synthesize and store the
brown pigment melanin.
Mast Cells – small, mobile, found near blood
cells and contain histamine and heparin
which are released after injury or infection.
Lymphocytes – migrate throughout the
body, may develop into plasma cells.
Microphages – phagocytic blood cells.
Connective Tissue Fibers
Collagen Fibers – long, straight, and unbranched.
Most common fibers in connective tissue proper.
Flexible and stronger than steel when pulled from
either end. Tendons and ligaments are made of
Reticular Fibers – thinner than collagen fibers and
form a branching interwoven framework that is
tough, flexible and can withstand forces applied
from many different directions.
Elastic Fibers – contain the protein elastin, fibers
are branched and wavy. After stretching they will
return to their original length. Relatively rare but
have important functions.
Loose Connective Tissue
Also known as areolar tissue.
Is the “Packing Material” of the body.
It fills space between organs, provides
cushioning, supports epithelia, blood
vessels and nerves, as well as providing a
route for the diffusion of materials.
The least specialized connective tissue in
the body, has an open framework, can
distort without damage.
Two types of loose connective tissue.
Adipose tissue provides padding, cushions
shock, acts as an insulator, serves as
packing or filler around structures.
Common under the skin of the groin,
buttock, sides, and breasts. Fills in the bony
sockets behind the eye, surrounds the
kidney, and dominates extensive areas of
loose connective tissue in the pericardial
and abdominal cavities.
Found in organs such as the spleen
Creates a three dimensional network,
stroma, that supports the functional
cells of these organs.
This fibrous framework is also found in
lymph nodes and bone marrow.
Dense Connective Tissue
Often called collagenous tissues because
collagen fibers are the dominant type.
Two types of dense connective tissue in the
Dense regular – collagenous fibers are arranged
parallel to each other, packed tightly, and
aligned with forces applied to the tissue.
Dense irregular – form an interwoven framework
and do not show any consistent pattern. These
tissues provide strength and support to areas
open to stresses from many directions.
Fluid Connective Tissue
Distinctive population of cells.
Suspended in a watery matrix that
contains dissolved proteins.
Two fluid connective tissues
Contains blood cells and fragments known
collectively as formed elements.
Red blood cells (erythrocyte) make up
almost half the volume of blood.
Plasma, the watery ground substance,
contains white blood cells and leukocytes.
Also contains platelets that function in the
clotting response that seals breaks in the
Forms as interstitial fluid and enters small
passageways, lymphatics, that return it to
the cardiovascular system.
Cells of the immune system monitor the
composition of lymph and respond to signs
of injury and infection.
99% of the cells in lymph are lymphocytes
(the rest are macr & microphages).
Supporting Connective Tissue
Less diverse cell population than
connective tissue proper and a matrix
that contains tightly packed fibers.
Two types of supporting connective
The matrix of cartilage is gel like whose
characteristics vary depending on the
predominant fiber type.
Cartilage cells are known as chondrocytes
and they are the only cells found in the
Avascular – all nutrient and waste product
exchange must occur by diffusion through
Cartilage grows by two mechanisms:
Three major types of cartilage:
Hyaline Cartilage – most common type.
Elastic Cartilage – extremely resilient and
Fibrocartilage – little ground substance,
dominated by collagen fibers.
Location – between tips of ribs and
bones of sternum; covering one
surfaces at synovial joints; supporting
larynx, trachea, and bronchi; forming
part of nasal septum.
Functions – provides stiff but
somewhat flexible support; reduces
friction between bony surfaces.
Location – tip of nose; epiglottis.
Function – provides support but
tolerates distortion without damage
and returns to original shape.
Location – pads within knee joints;
between pubic bones of pelvis;
Function – resists compression;
prevents bone-to-bone contact; limits
The matrix of bone is said to be calcified
because it contains mineral deposits,
primarily calcium salts. This is what gives
bone its rigidity.
Ground substance is very small. One third of
the bone matrix is made of collagen fibers.
The minerals are organized around the
collagen fibers resulting in a strong, flexible
combination resistant to shattering.
Can compete with the best steel reinforced