Connective tissue is a "grab bag" category of diverse tissue types. Functions include binding and supporting. Types include bone, cartilage, fibrous connective tissue, blood, and adipose (fat) tissue. If you took away everything in the body except the connective tissue, you’d still be able to see the basic form of the body.
Adipose tissue Figure 1 or body fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat. Fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts. Its main role is to store energy in the form of lipids, although it also cushions and insulates the body. Far from hormonally inert, adipose tissue has in recent years been recognized as a major endocrine organ, as it produces hormones such as leptin, estrogen, resistin, and the cytokine TNFα. Moreover, adipose tissue can affect other organ systems of the body and may lead to disease. The two types of adipose tissue are white adipose tissue (WAT) and brown adipose tissue (BAT). Adipose tissue is found in specific locations, which are referred to as adipose depots.
Cartilage Figure 2 is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes, and the intervertebral discs. Cartilage is composed of specialized cells called chondroblasts that produce a large amount of extracellular matrix composed of Type II collagen fibers (except fibrocartilage which also contains type I collagen), abundant ground substance rich in proteoglycan, and elastin fibers. Cartilage is classified in three types: elastic cartilage, hyaline cartilage, and fibrocartilage, which differ in the relative amounts of these three main components. Unlike other connective tissues, cartilage does not contain blood vessels.
Bone tissue is a type of dense connective tissue. Bones come in a variety of shapes and have a complex internal and external structure, are lightweight yet strong and hard, and serve multiple functions. One of the types of tissue that makes up bone is the mineralized osseous tissue, also called bone tissue, that gives it rigidity and a coral-like three-dimensional internal structure. The primary tissue of bone, osseous tissue, is a relatively hard and lightweight composite material, formed mostly of calcium phosphate in the chemical arrangement termed calcium hydroxylapatite (this is the osseous tissue that gives bones their rigidity). It has relatively high compressive strength, but poor tensile strength and very low shear stress strength.
This means bone resists pushing forces well, but not pulling or torsional forces. The hard outer layer of bones is composed of compact bone tissue, so-called due to its minimal gaps and spaces. Its porosity is 5-30%. This tissue gives bones their smooth, white, and solid appearance, and accounts for 80% of the total bone mass of an adult skeleton. Filling the interior of the bone is the trabecular bone tissue (an open cell porous network also called cancellous or spongy bone), which is composed of a network of rod and plate-like elements that make the overall organ lighter and allow room for blood vessels and marrow.
Blood is considered a specialized form of connective tissue, given its origin in the bones and the presence of potential molecular fibers in the form of fibrinogen. Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. In vertebrates, it is composed of blood cells suspended in a liquid called blood plasma. Plasma, which constitutes 55% of blood fluid, is mostly water (92% by volume), and contains dissipated proteins, glucose, mineral ions, hormones, carbon dioxide (plasma being the main medium for excretory product transportation), and blood cells themselves.
The lymphatic system Figure 3 is a part of the circulatory system, comprising a network of conduits called lymphatic vessels that carry a clear fluid called lymph unidirectionally towards the heart. The lymph system is not a closed system. The circulatory system processes an average of 20 liters of blood per day through capillary filtration which removes plasma while leaving the blood cells. Roughly 17 liters per day of that gets reabsorbed directly into the blood vessels. The primary function of the lymph system is to provide an accessory route for these excess three liters per day to get returned to the blood. The lymphoid tissue is primarily involved in immune responses and consists of lymphocytes and other white blood cells enmeshed in connective tissue through which the lymph passes. Regions of the lymphoid tissue that are densely packed with lymphocytes are known as lymphoid follicles.