Difference Between Loose and Dense Connective Tissue

Main Difference – Loose vs Dense Connective Tissue

Loose and dense connective tissues are the two types of connective tissue in the human body. Connective tissue fills the surfaces between the other types of tissues in the body. It provides both metabolic and structural support to the other tissues. Connective tissue is made up of cells and their extracellular matrix. The extracellular matrix consists of protein fibers and polysaccharides. The main difference between loose connective tissue and dense connective tissue is that loose connective tissue consists of protein fibers packed with spaces whereas dense connective tissue consists of tightly packed protein fibers. The three types of loose connective tissue are areolar, adipose, and reticular tissues. The three types of dense connective tissue are dense regular, dense irregular, and elastic tissues. Reticular, collagen, and elastin are the three types of protein fibers that specifically occur in the connective tissue.   

Key Areas Covered

1. What is Loose Connective Tissue
      – Definition, Characteristics, Function
2. What is Dense Connective Tissue
      – Definition, Characteristics, Function
3. What are the Similarities Between Loose and Dense Connective Tissue
      – Outline of Common Features
4. What is the Difference Between Loose and Dense Connective Tissue
      – Comparison of Key Differences

Key Terms: Adipose, Areolar, Collagen, Dense Connective Tissue, Dense Irregular, Dense Regular, Elastin, Loose Connective Tissue, Reticular

What is Loose Connective Tissue

Loose connective tissue is a type of connective tissue with loosely arranged collagen fibers. However, it consists of many cells. Loose connective tissue is the most common type of connective tissue in vertebrates and it holds the organs in place and attaches the epithelial tissue to the underlying tissues. It mainly surrounds the blood vessels and nerves. Fibroblasts are widely dispersed in the loose connective tissue, secreting protein fibers and proteoglycans to the extracellular matrix. The loose connective tissue is classified based on the type of protein fibers in the extracellular matrix and the weave of the fibers.

Figure 1: Loose Connective Tissue

The three types of loose connective tissue are areolar, adipose, and reticular connective tissue. The most abundant types of loose connective tissue are areolar and adipose. They occur in places where vessels, nerves, and ducts pass through the tissues. The most characteristic feature of areolar and adipose tissues is their elasticity. This allows accommodating the stretch that occurs in vessels and other organs during the movements of the body. Areolar and adipose connective tissues also absorb the shocks to protect the internal body tissues. The reticular connective tissue forms the framework around organs, glands, and the lymph nodes. The location and the function of each type of loose connective tissue are described in table 1.

Loose Connective Tissue Location and Function

What is Dense Connective Tissue

The dense connective tissue is the type of connective tissue in which the main matrix component is the protein fibers. That means dense connective tissue consists of numerous protein fibers in the matrix. The main fiber component of the dense connective tissue is the collagen fibers. Since the dense connective tissue is resistant to stretch, it provides strength to organs and tissues. The bands called tendons and capsules in the joints are formed by dense connective tissue. Tendons are another structure produced by dense connective tissue to connect muscles to bones. Muscles are covered by layers of dense connective tissue. The dermis contains the largest single mass of dense connective tissue. The dense connective tissue is classified based on the weave of the collagen fibers in the tissue. The dense regular and irregular connective tissue are shown in figure 2.

Figure 2: Dense Connective Tissue

The three types of dense connective tissue are regular, irregular, and elastic tissue. The dense regular connective tissue contains parallelly arranged collagen fibers in a single direction. It forms structures like tendons in which the forces are directed in a single direction. The dense irregular connective tissue contains collagen fibers that run in all directions. This tissue can withstand multidirectional forces and it is found in large connective tissue sheets. Both dense regular and dense irregular connective tissue are inelastic. The dense elastic tissue is the only type of dense connective tissue that is elastic and it is mainly composed of elastin fibers. Therefore, the dense elastic tissue is yellow in color while other dense connective tissues are white in color. The dense elastic tissue occurs in the organs that exhibit continuous expansions and contractions such as lung tissue and blood vessels. 

Similarities Between Loose and Dense Connective Tissue

• Loose connective tissue and dense connective tissue are the two types of connective tissues in the body.
• Both loose and dense connective tissues are made up of cells and extracellular matrix.
• Both loose and dense connective tissues provide structural support and connect various types of tissues in the body.

Difference Between Loose and Dense Connective Tissue

Definition

Loose Connective Tissue: Loose connective tissue is a type of connective tissue that surrounds blood vessels, nerves, and organs, holding the epithelium and organs in place.

Dense Connective Tissue: Dense connective tissue is a type of connective tissue that contains numerous collagen fibers and provides a strong connection between the tissues that mainly form the structural parts of the body.

Number of Cells

Loose Connective Tissue: Loose connective tissue consists of many cells.

Dense Connective Tissue: Dense connective tissue consists of a fewer cells.

Fibroblasts/Fibrocytes

Loose Connective Tissue: The loose connective tissue mainly contains fibroblasts.

Dense Connective Tissue: The dense connective tissue mainly contains fibrocytes.

Fibers

Loose Connective Tissue: Loose connective tissue consists of loosely arranged fibers.

Dense Connective Tissue: Dense connective tissue consists of numerous, thick fibers.

Types

Loose Connective Tissue: The three types of loose connective tissue are areolar, adipose, and reticular tissue.

Dense Connective Tissue: The three types of dense connective tissue are dense regular, dense irregular, and elastic tissue.

Function

Loose Connective Tissue: The major function of the loose connective tissue is to serve as a supporting matrix for the blood vessels, lymphatic vessels, nerves, muscle fibers, organs, and the skin.

Dense Connective Tissue: Dense connective tissue produces tendon and ligaments by forming strong, rope-like structures.

Conclusion

Loose and dense connective tissues are the two types of connective tissues that are found in animals. Connective tissue mainly provides structural support to the soft organs. It also helps to supply nutrients and oxygen to the epithelial tissue. Loose connective tissue contains loosely-arranged fibers whereas dense connective tissue contains heavily-arranged fibers. Therefore, the main difference between loose and dense connective tissue is the density of fibers in the extracellular matrix in each type of connective tissue.

Reference:

1.“Loose Connective Tissues.” Loosects, Available here. Accessed 10 Sept. 2017.
2.“Loose Connective Tissue Types, Location, and Function.” Quizlet, Available here. Accessed 10 Sept. 2017.
3. “Dense Connective Tissue.” Histology of Connective Tissues – 4 Available here. Accessed 10 Sept. 2017.

Image Courtesy:

 1. “Anatomy and physiology of animals loose connective tissue” By The original uploader was Sunshineconnelly at English Wikibooks – Transferred from en.wikibooks to Commons by Adrignola using CommonsHelper. (CC BY 2.5) via Commons Wikimedia
2. “411 Reg Dense-Irregular Dense” By OpenStax College – Anatomy & Physiology, Connexions Web site.  Jun 19, 2013 ( CC BY 3.0) via Commons Wikimedia