162
UNIT ONE
within the hollow parts of certain bones. Blood is described
in chapter 14.
Red blood cells are the only type of blood cells that func-
tion entirely in the blood vessels. In contrast, white blood
cells typically migrate from the blood through capillary walls
to connective tissues, where they carry on their major activi-
ties. The white blood cells usually reside in the connective
tissues until they die.
Table 5.7
lists the characteristics of the
connective tissues.
PRACTICE
18
Describe the general characteristics of cartilage.
19
Explain why injured bone heals more rapidly than does injured
cartilage.
20
What are the major components of blood?
to the membranes of nearby cells. As a result, materials can
move rapidly between blood vessels and bone cells. Thus,
despite its inert appearance, bone is an active tissue. Injured
bone heals much more rapidly than does injured cartilage.
(The microscopic structure of bone is described in more
detail in chapter 7, p. 195.)
Blood
Blood,
another type of connective tissue, is composed of
cells suspended in a fl
uid extracellular matrix called
plasma.
These cells include
red blood cells, white blood cells,
and cel-
lular fragments called
platelets
(f
g. 5.27)
. Red blood cells
transport gases; white blood cells F
ght infection; and plate-
lets are involved in blood clotting. Most blood cells form
in special tissues (hematopoietic tissues) in red marrow
TABLE
5.7
|
Connective Tissues
Type
Description
Function
Location
Areolar connective tissue
Cells in F
uid-gel matrix
Binds organs, holds tissue F
uids
Beneath the skin, between muscles, beneath epithelial
tissues
Adipose tissue
Cells in F
uid-gel matrix
Protects, insulates, and stores fat
Beneath the skin, around the kidneys, behind the eyeballs,
on the surface of the heart
Reticular connective tissue
Cells in F
uid-gel matrix
Supports
Walls of liver, spleen, and lymphatic organs
Dense regular connective
tissue
Cells in F
uid-gel matrix
Binds body parts
Tendons, ligaments
Dense irregular connective
tissue
Cells in F
uid-gel matrix
Sustains tissue tension
Dermis
Elastic connective tissue
Cells in F
uid-gel matrix
Provides elastic quality
Connecting parts of the spinal column, in walls of arteries
and airways
Hyaline cartilage
Cells in solid-gel matrix
Supports, protects, provides framework
Ends of bones, nose, and rings in walls of respiratory passages
Elastic cartilage
Cells in solid-gel matrix
Supports, protects, provides F
exible
framework
±ramework of external ear and part of larynx
±ibrocartilage
Cells in solid-gel matrix
Supports, protects, absorbs shock
Between bony parts of spinal column, parts of pelvic
girdle, and knee
Bone
Cells in solid matrix
Supports, protects, provides framework
Bones of skeleton, middle ear
Blood
Cells and platelets in
F
uid matrix
Transports gases, defends against
disease, clotting
Throughout the body in a closed system of blood vessels
and heart chambers
Red blood
cells
Plasma
(extracellular
matrix of blood)
Platelets
White blood
cell
(a)
(b)
FIGURE 5.27
Blood tissue consists of red blood cells, white blood cells, and platelets suspended in a F
uid extracellular
matrix (1,000×).
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