Overview and Types of Connective Tissue
As their name suggests, connective tissues serve to both support and link the many organs and tissues found throughout the body. They are located in vast quantities all throughout the body, Their genesis may be traced back to the mesoderm(embryo). A few cells that are located in the interfacial network of collagen or elastin protein fibres that are produced by the cells make up connective tissue. These protein fibres are called collagen or elastin. In addition, the cells exude a watery gel composed of polysaccharides, which, when combined with the fibres, form the matrix or ground material.
It is the fibres that are responsible for the elasticity, suppleness, and sturdiness of the connective tissues. The kind of intercellular material that is present determines not only the function of connective tissues but also the types of connective tissues that are present. There are three different types of connective tissue fibres:
- Collagen (or) gelatin,
- Elastic(or)elastin, and
- Reticular (or) glandular fibres.
Collagen Fibres (or) Gelatin
- They consist of collagen the most common kind and are composed of the protein collagen, which is fibrous. Collagen fibres have a high tensile strength in addition to their flexibility (similar to steel).
- Location-Tendons, ligaments, dermis, eye, cartilage, bone, capillaries, gastrointestinal tract, and intervertebral disc are the locations.
Elastic (or) Elastin fibres
- The elastic fibres come together to create a network that is capable of being stretched out just like a ribbon. They are constructed of elastin, which is a protein. As soon as the force is withdrawn, they go back to having their normal form and dimensions.
- Location-Extracellular matrix.
Reticulate fibres (or) Glandular
- Collagen and glycoproteins are the building blocks of reticulated fibres. They are very slender and come together to create a delicate network. They link connective tissues to the tissues around them.
- Location: in the liver, the bone marrow, and other lymphatic organs.
The numerous varieties of connective tissues each have their own unique population of cells of varying sorts. They produce a variety of matrices and fibres in their secretions. Adipocytes and fibroblasts are examples of stationary cell types, while macrophages, mast cells, monocytes, and lymphocytes are examples of migratory cell types.
Fibroblasts are cells that are prevalent in growing tissues and are essential to the healing process after an injury. They have the form of a spindle and may be found in the spaces between collagen fibres. They produce tropocollagen as well as a number of other chemicals that are located in the matrix.
Macrophages are also referred to as scavenger cells in other contexts. Phagocytosis is the process by which they eliminate germs and other antigens as they pass through connective tissues and clean up waste.
Types of Connective Tissue
- Slack connective tissue (or) Loose Connective tissue
- Thick connective tissue (or) Dense Connective Tissue
- Specifically Designed connective tissue (or) specialized connective tissue.
Slack Connective Tissue (or) Loose Connective Tissue
There are areas in the body that need support as well as suppleness, and these areas contain loose connective tissues. The blood arteries, nerves, and muscles in the body are all surrounded by a layer of loose connective tissue. They, together with adipose tissues, make up the subcutaneous layer that lies under the skin and is responsible for linking tendons and other organs to the skin. Within the semi-fluid matrix, the fibre and cells are only weakly organised into patterns. They serve as a shock absorber, as well as storage for salts and fluids, and may be found as a filler in the spaces between numerous organs.
Areolar Tissue: It may be found just under the surface of the skin and provides support to the epithelium. It is made up of fibroblasts, mast cells, and macrophages, all of which are dispersed in a haphazard manner. It does things like fill the gap between the muscle fibres, wrap over blood and lymph veins, and provide support for the organs that are found in the abdominal cavity.
Adipose Tissue: These tissues may be found beneath the skin and are responsible for storing fat. It helps the body regulate its temperature and works as a shock absorber in settings when the temperature is lower.
In addition to the kidneys, white adipose tissues may be found in the back of an eye, in the hunch of camels, in the blubber of whales, and in other locations.
Brown adipose tissue is something that may be found in babies as well as polar bears, penguins, and other creatures that live in colder climates. In comparison to the other fat, it has a greater number of mitochondria and may produce 20 times the amount of heat. It generates heat via metabolic processes.
It is composed of reticular fibres and is known as reticular connective tissue. It provides structural assistance to organs including the liver, lymph nodes, and spleen from the inside out.
Dense Connective Tissue(or) Thick connective tissue
Fibroblasts cells and fibres are packed very closely together in the thick connective tissue. Their primary purpose is to both sustain and transfer the forces that are applied mechanically. They have a degree of rigidity that is greater than that of loose connective tissue. In accordance with the direction in which the collagen fibres are oriented, we may divide them into 2 groups, which are as follows:
Dense regular Tissue
The orientation of the fibres is uniform in the thick connective tissue that is otherwise regular. The collagen fibres may be found in the spaces between the bundles of fibres that run in parallel to one another. Because of the arrangement’s regularity, the material’s tensile strength is increased, and it resists stretching in the same direction as the fibres are oriented. Tissues such as tendons and ligaments are examples of thick, regular tissue.
Properties of ligaments and tendons
Tendons attach skeletal muscles to bones, while ligaments tie bones to one other. The connection between two bones is made by ligaments.
Dense irregular tissues
This kind of dense tissue is characterised by the presence of numerous fibres, including collagen, that is orientated in an erratic or random pattern. Because of the disorganised organisation, the strength is distributed evenly in all directions. A network consisting of fibres may sometimes seem like a mesh. The dermis layer of the skin is where you will find this sort of tissue.
Specialized Connective Tissue
In addition to these, there are other supporting connective tissues, such as cartilage and bone, that assist in the maintenance of normal posture and provide support for the body’s internal organs.
Blood and lymph are both examples of fluids connective tissues that travel throughout the body and contribute to the contact and communication that takes place between all of the organs.
Cartilage: Cartilage is a kind of fibrocartilage that is made up of collagenous fibres that are packed very densely together and are suspended in chondrin, which is a rubbery gelatinous fluid. Cartilage makes up the bones of sharks as well as the skeletons of embryonic humans. In mature humans, cartilage serves as a flexible support system for a number of different structures, along with the nasal, throat, and ears.
There are three distinct forms of cartilage, each of which exhibits a distinct set of properties.
Hyaline cartilage: It is by far the most prevalent form of cartilage, and it may be found in places like the trachea, the ribs, and the nose. Hyaline cartilage is characterised by its pliability and elasticity, in addition to being encased in a thick membrane known as perichondrium.
Fibrocartilage: It is the most durable kind of cartilage, which is due to its composition of hyaline and thick collagen fibres. It is rigid and robust, and it may be found in places such as between the vertebrae, in various joints, and in the heart valves. Fibrocartilage does not even have perichondrium.
Elastic cartilage: It is by far the most flexible form of cartilage and is characterised by the presence of elastic fibres. It may be discovered in areas of the body like the ear and the larynx (voice box).
Bones: It is the connective tissue that is the densest and most rigid, and it aids in the preservation of the body’s form and posture while also shielding the body’s vital organs. They have a high concentration of calcium and collagen fibres that provide strength.
Osteoblasts are cells that are known by this term and are necessary for the creation of bone cells. They may be found in the lacunae and are responsible for the matrix’s secretion. The cytosolic expansion of osteocytes forms what is known as canaliculi, which are very small channels. . The communication that takes place between the osteocytes and the capillaries is helped along by these channels. There are 2 primary kinds of bone tissue, which are referred to as compact and sponge-like respectively
- Spongy bone: Bone with a sponge-like consistency Bone with a sponge-like consistency is found in the core, which is surrounded by compact bone. The spindle-shaped unit that may be seen in compact bone is known as an osteon. Osteocytes may be found scattered throughout the lamellae, which are the concentric layers of the matrix that make up each osteon. Haversian canals are channels in the central nervous system that capillaries and neurons travel through. Lamellae may be found all the way along Haversian canals.
It is sometimes referred to as cancellous bone and derives its name from the spongy look of the bone. In this kind of bone tissue, the huge voids, also known as vascular cavities, contain blood vessels as well as bone marrow. The production of compact bone surrounds spongy bone, which is the first kind of bone to form throughout the process of bone development.
- Compact bone: The firm and thick tissue that makes up the outermost, more brittle layer of the bone is called compact bone, and it also goes by the name cortical bone. There are narrow passageways inside the tissue that is for blood capillaries and nerves.
Fluid Connective Tissue
It may come as a surprise to learn that blood is classified as a form of connective tissue. Blood, like other forms of connective tissue, originates from the mesoderm, which is the intermediate germ layer seen in growing embryos. In addition to providing the body’s other organ systems with the nutrients they need, blood is also responsible for delivering signal molecules from one cell to the next throughout the body. Blood consists of plasma, red blood corpuscles, white blood corpuscles, and platelets, all of which are floating in the plasma. Plasma is an important structural component of blood.
The bulk of the fluid connective tissue is comprised of the blood and lymphatic system.
Characteristics of the Structural Components
- The tissue in question has a liquid matrix. In the matrices, there are many different kinds of organic components in the colloid form. These materials make up the matrix.
- Function: The primary purpose of the vascular system is to keep blood flowing throughout the inside of the organism and to provide the body with resistance to illness. This tissue may be broken down into two categories: blood and lymph.
- Blood: Blood is a form of alkaline, somewhat salty, red-coloured, liquid connective tissue that is characterised by its alkaline pH and red colour. Blood is able to participate in the body’s internal circulation by travelling via the arteries, veins, and capillaries. The fluid that circulates throughout our body and carries substances from one location to another is called blood. The heart, the blood, as well as the blood vessels are all parts of the blood circulation that are essential to its functioning.
- Lymph: Some of the smaller capillaries in the body are responsible for collecting the fluid contents that are stored in the gaps between the various tissues. These very tiny vessels will eventually be combined to make much bigger ones. The lymphatic system is the name given to the network of vessels that make up the lymphatic system. These tubes are lymphatic veins, and the liquid within them is lymph. In the area of the shoulder in the human body, the major lymph arteries drain into the vein. The term “lymphocyte” refers to a specific kind of cell that may be found in the lymph. The lymphatic system contains a fluid that is somewhat alkaline, clear, and yellow in colour. It is more of a protective fluid as it comprises a bunch of granulocytes and it destroys all the remote body since it is so far away.
Connective Tissue Disorder
- Gene mutations or defective genes that are passed down from parents may both be to blame for connective tissue illnesses. Example-The condition known as Marfan syndrome is brought on by faulty genes that produce the protein fibrillin-1. The condition causes the body to become very emaciated and stretched out.
- Autoimmune connective tissue disorders are the other subtype of this condition. An autoimmunity illness is a sickness that manifests itself when the immune system of the body starts to attack healthy tissues inside the organism rather than targeting foreign objects as its primary target. Example-Scleroderma is distinguished by the progressive thickening and hardness of the connective tissue throughout the body. It may be local, in which case it would just affect a certain section of the skin, or it could be systemic, in which case it would harm the essential organs
Frequently Asked Questions
Question 1: Which kind of connective tissue is referred to as fluids connective tissue?
Blood is a fluid that makes up the body. Plasma is the fluid matrix of blood, in which red blood corpuscles (Erythrocytes), Leucocytes, and platelets are suspended for transport through the circulatory system.
Question 2: What does the name “connective tissue” mean?
As their name suggests, connective tissues serve to both support and link the many vital organs found throughout the body.
Question 3: Which three different forms of connective tissue are there?
- Slack connective tissue(or)Loose Connective Tissue
- Connective tissue that is either very thick or particularly dense
- Connective tissue that has been specially designed for a particular purpose or specialised connective tissue.
Question 4: Which connective tissues do not include collagen?
The connective tissue seen in loose connective tissue is extremely cellular and abundant in proteoglycans, although it has a lower collagen fibre content.
Question 5: Which kind of connective tissue is the most resistant?
The connective tissue that is the toughest is bone. It supports the body and offers the organs within the body some kind of protection. The inflexible extracellular matrix of bone is composed almost entirely of collagen fibres that are immersed in a mineralization ground material that comprises hydroxyapatite, which is a kind of calcium phosphate.
Question 6: Where can connective tissue be observed in the body?
They are most often found in the flexible cartilages, yellow ligaments, lungs, and epidermis of the body. Huge blood vessel walls also contain them. The numerous forms of connective tissue are the consequence of distinct variants in the cellular and polypeptide fibre combinations as well as the configurations of these components.
Question 7: What are the different roles that connective tissue plays?
- Connecting and maintaining are two of the primary roles that connective tissue plays in the body.
- Preserving leftover fuel.
- Carrying materials throughout the inside of the body.
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