Chapter 4
Tissue: The Living Fabric
129
4
As noted, all classes of connective tissue consist of living cells
surrounded by a matrix. Teir major differences reflect cell
type, and types and relative amounts of fibers, as summarized
in ±able 4.1.
As mentioned earlier, mature connective tissues arise from
a common embryonic tissue, called
mesenchyme
(meh
9
zin-
kīm). Mesenchyme has a fluid ground substance containing fine
sparse fibers and star-shaped
mesenchymal cells
. It arises dur-
ing the early weeks of embryonic development and eventually
differentiates (specializes) into all other connective tissue cells.
However, some mesenchymal cells remain and provide a source
of new cells in mature connective tissues.
Figure 4.8
illustrates the connective tissues that we describe
in the next sections. Study this figure as you read along.
selective appetites. For example, those of the spleen primarily
dispose of aging red blood cells, but they will not turn down
other “delicacies” that come their way.
Check Your Understanding
11.
What are four functions of connective tissue?
12.
What are the three types of fibers found in connective
tissues?
For answers, see Appendix H.
Types of Connective Tissue
Describe the types of connective tissue found in the body,
and indicate their characteristic functions.
Table 4.1
Comparison of Classes of Connective Tissues
 
 
COMPONENTS
 
TISSUE CLASS
AND EXAMPLE
SUBCLASSES
CELLS
MATRIX
GENERAL FEATURES
Connective Tissue
Proper
Dense regular
connective tissue
1. Loose connective tissue
Areolar
Adipose
Reticular
2. Dense connective tissue
Regular
Irregular
Elastic
Fibroblasts
Fibrocytes
Defense cells
Adipocytes
Gel-like ground substance
All three fiber types:
collagen, reticular, elastic
Six different types; vary in
density and types of fibers
Functions as a binding tissue
Resists mechanical stress,
particulary tension
Provides reservoir for water
and salts
Nutrient (fat) storage
Cartilage
Hyaline cartilage
1. Hyaline cartilage
2. Elastic cartilage
3. Fibrocartilage
Chondroblasts
found
in growing
cartilage
Chondrocytes
Gel-like ground substance
Fibers: collagen, elastic fibers
in some
Resists compression because
of the large amounts of
water held in the matrix
Functions to cushion and
support body structures
Bone Tissue
Compact bone
1. Compact bone
2. Spongy bone
Osteoblasts
Osteocytes
Gel-like ground substance
calcified with inorganic salts
Fibers: collagen
Hard tissue that resists both
compression and tension
Functions in support
Blood
See Chapter 17 for details
on blood cell formation and
differentiation.
Erythrocytes
(RBC)
Leukocytes
(WBC)
Platelets
Plasma
No fibers
A fluid tissue
Functions to carry O
2
, CO
2
,
nutrients, wastes, and other
substances (hormones, for
example)
previous page 163 Human Anatomy and Physiology (9th ed ) 2012 read online next page 165 Human Anatomy and Physiology (9th ed ) 2012 read online Home Toggle text on/off