They are the most abundant and widely distributed tissues in animals. All connective tissues, apart from blood cells, secrete collagen or elastin (fibrous proteins that provide structural support, flexibility, and elasticity.) Connective tissues are called so because of their special function of linking and supporting other tissues in the body. There are three different types of connective tissues: Loose connective tissue, dense connective tissue, and specialised connective tissue.
The main function of blood is to transport gases, food, waste materials and hormones in the body.
Therefore, blood has a fluid Matrix present in it which is called Plasma.
The plasma contains the red blood cells, the white blood cells and blood platelets.
The RBC have hemoglobin pigment which carries oxygen to tissues.
White blood cells fight diseases and platelets are involved in clotting of blood when injured.
The plasma also contains proteins and hormones in it.
Lymph is a colourless fluid that carries white blood cells throughout the human body in lymphatic vessels. There are lymphoid organs present in the body that produce lymph and together form the lymphatic system. Some of them are lymph nodes and tonsils.
Lymph is similar to blood except for a few differences:
- It contains only white blood cells.
- It contains less amount of blood proteins, calcium and phosphorous but more glucose.
- It flows in one direction only.
- Lymph moves in the body through its normal function unlike blood which is pumped by the heart.
- Constituents of Lymph:
Lymph Plasma – Lymph Plasma carries infection-fighting proteins along with other substances such as water, calcium and phosphorous.
Lymph Corpuscles – Lymph Corpuscles comprises white blood cells. Red blood cells and platelets are not present in lymph.
Functions of Lymph:
- It carries oxygen and minerals to the cells in the body and carries back carbon dioxide and waste materials back into the blood.
- It keeps the body cells moist.
- It maintains the volume of the blood.
- It helps in eliminating harmful bacteria and virus from the body and hence is responsible for the immunity of human beings.
- It absorbs fats from the intestine and transports them throughout the body.
- Bones form a framework of the body over which the muscles are wrapped together.
- The bone tissue is strong and inflexible in nature.
- Therefore, the bone cells are present in a rigid matrix which is formed from calcium and phosphorus.
- The bones comprises of microscopic tubes called Haversian Canals.
- They are contained in osteons, rough cylindrical structures present along the axis of the bone.
- They allow the blood vessels, lymphatic vessels, and nerve fibres to travel through them.
- These canals have concentric channels called Lamellae around them.
- The Haversian canals communicate with bone cells through connections called Canaliculi.
- Cartilage is present over the joints of the bones and provides them with a smooth structure.
- For Example in the nose tip and ear pinna, trachea, larynx.
- They contain solid matrix made of protein and sugar. They have homogenous matrix.
- It provides support and flexibility to various parts of our body.
- A ligament connects two bones together.
- It has an elasticity which facilitates the connection.
- The cells of ligaments have a little matrix.
- The tendons tissues are responsible for connecting bones and muscles together.
- They have limited flexibility but very great strength.
- This tissue acts as a filter in between the spaces present inside the organs of the body.
- It helps in repairing other tissues as well.
- It is found in the skin and bone marrow.
Components of the Areolar Connective Tissue
- Fat Cells (Adipocytes) – They are responsible for secretion of lipids.
- Fibroblasts – They are the present in the highest amount in areolar tissues. They are responsible for secretion of fibres.
- Mast Cells – They release histamine that plays role in allergic reactions
- Macrophages – They eat any germs or infectious cells in the body
- Plasma Cells – They produce antibodies
- Collagen Fibres – They provide tensile strength to the tissue
- Elastin Fibres – They provide elasticity to the tissue
- Ground Substance – It is a fluid matrix that holds cells and fibres of the tissue
- Fats are stored in our body in the adipose tissues.
- They are found below the skin and between the organs of the body.
- Provides cushioning to the organs.