Notes on connective tissues

Connective tissues are one kind of animal tissue and are responsible for the interconnections between the organs and another part of the body. They are present in the liquid matrix in the body. Small fine fibres are combined to form the connective tissues. There are mainly three kinds of connective tissues. Let us learn more about the connective tissues. 

Definition 

Connective tissues are creating links between the other tissues and organs. It consists of an adequate amount of liquid, many kinds of cells and a fibrous extracellular matrix material. 

When the organs are covered with the connective tissues, they are known as stroma. Tissues have variability with respect to the quantity of elements and structures of organs. 

Then, there are some specialised kinds of tissues, such as bones, cartilage, fat, etc. 

In other words, connective tissues are formed by the framework that is responsible for the connections, and it consists of liquid content and fibres. The functionality, type and site of tissues creates variations in the components of the tissues. 

Connective tissues fibers 

Mainly, there are three kinds of extracellular fibers, which are mentioned below:

Collagenous or collagen fibers are present in abundance. There is a network of micro fibrils which form the collagen fibers. However, the protein type is different according to the micro fibrils. Collagen fibers consist of low elasticity, still they have high strength. 

Elastic fibers are yellow in appearance. They are formed by the combination of micro fibrils and matrix both. There is protein present in the matrix which supports the flexibility and is known as elastin. After stretching they reach their original position if force applied is eliminated. 

Reticular fibers are present in the individual cells, and they are not very flexible and string in nature as compared to collagen fibers. They have the combination of collagen and glycoproteins. They are very thin in nature. 

All types of fibers are embedded in the gel-like matrix known as ground substance. Apart from that, there are many types of cells exist in different kinds of connective tissue. 

Types of Connective Tissue

There are mainly three kinds of connective tissue groups. 

Loose Connective Tissue: These kinds of tissues are present throughout the body and provide strength and flexibility. Nerves, muscles, and blood capillaries consist of this kind of connective tissue. A subcutaneous sheet under the skin in combination with adipose tissues which attach them to muscles. 

In this, fibres and cells both are organised in loose manner with the semi-fluid matrix. They act as the filling and reservoir for salt and aqueous content substance between the many organs. 

Areolar Tissue: This kind of tissues are present beneath the skin and provide support to the epithelial tissues. They are made up of unorganised fibres, fibroblasts, last cells and macrophages. It also gives strength to the organs inside the abdominal cavity, and also fills the gaps. 

Adipose Tissue: They are present beneath the skin and also act as the storage for fat. It is also considered as the shock absorber and maintains the optimum temperature of the body during the winter season. 

Additionally, white adipose tissue provides protection to the kidneys and also present at the backside of the eyes, blubber of whales, etc. Brown adipose tissue is present in the infants, polar bears and penguins and animals who are living in cold areas. It has the capacity to generate more energy as it consists of more mitochondria. Hence, it emits metabolic heat. 

Dense Connective Tissue: This has tightly packed fibroblast cells and fibres. The primary function of it is to provide support and transfer the mechanical forces. However, they are less elastic than the loose connective tissues. They are further divided into two categories: 

Dense regular tissue: In this the fibres are organised in regular form. Due to parallel arrangement of fibres the tissues have great strength and resistance. Tendons and ligaments are the types of dense regular tissues. Tendons are responsible for the attachment of bones to skeletal muscles. On the contrary, ligaments are responsible for the attachment between two bones. 

Dense irregular tissue: In the body, there are many disoriented and organised fibres. They consists uniform strength due to irregularities. They are found beneath the skin. 

Specialised Connective Tissue

Apart from these tissues, some are for regulation and maintenance of correct posture and provide support to internal organs, for instance, bones and cartilage. Some of them are mentioned below: 

Cartilage: It is found during the embryonic stage and supports the skeleton. They are replaced by the bones during adulthood. 

Bones: It is the hardest connective tissue and supports the shape and posture of the body. It provides protection to the internal organs. They are made-up of calcium, phosphorus, collagen fibres etc. 

Blood: It is the combination of various cells such as red blood cells (RBCs), white blood cells (WBCs) and platelets. RBCs consist of haemoglobin through which oxygen. WBCs develop the antibodies and protect the body from the foreign particles and platelets in the blood support the blood clotting process. 

Lymph: They are responsible for the transport of fat through blood. It is a white colour liquid matrix. 

Conclusion

Therefore, connective tissues are present throughout the body of animals and responsible for various functions. Apart from types of connective tissue, there are some specialised kinds of connective tissues, such as blood, lymph, bones, and cartilage. Small fine fibres are combined to form the connective tissues.