Connective Tissue: What It Is, Characteristics And Types
Recent research estimates that the human body is made up of 30 billion cell bodies, divided by their capabilities into different functionalities. 80% of all these cells are red blood cells, as they report the unimaginable number of 5 million erythrocytes for every cubic millimeter of blood of an adult person. After them are platelets (4.9%), hematopoietic cells of the bone marrow (2.5%), lymphocytes (1.6%) and other vascular bodies.
Curiously, epithelial cells and those that make up organs are the minority of the total cell bodies, since the epidermis only represents 0.5% of the total. Adipocytes, muscle cells, neurons, hepatocytes and other cellular conglomerates are the immense minority within our body. In any case, they perform a series of essential functions in the survival of the individual and species over time.
With these data, we wanted to reflect a little of the immense cellular and tissue diversity that the human body contains. So that all these structures have three-dimensional coherence and aggregation, some type of fabric is necessary that acts as a bridge and support In the following lines, we tell you everything about connective tissue.
Connective tissue, also known as connective tissue (CT), is a term that encompasses different cellular groupings (in addition to the matrix and its fluids), whose common functionality is to connect, support and help maintain the physical integrity of the different tissues of the body
Connective tissue is an “umbrella” term, since it encompasses a large number of tissue groups. In any case, all of them have 3 basic characteristics:
Types of connective tissue
All connective tissues have these characteristics, but beyond them, variety takes precedence over generality. Next, we present the types of connective tissue, according to their functionality and degree of specificity.
The connective tissue itself (or connective tissue itself) is that with a more general function and a lower degree of development. It is divided into two variants: loose and dense.
1.1. Loose connective tissue
It is the most common type of connective tissue in vertebrates. It is responsible for keeping organs in place and fixing the skin to the underlying tissues
In this category are, for example, mucosal, reticular and mesenchymal connective tissue. Loose connective tissues usually have a network-like tissue organization, a fluid matrix and a functionality characterized by the protection of weak organs and structures.
1.2. dense connective tissue
Unlike the previous case, dense connective tissue type is characterized by having a high content of fibers in its matrix, which are usually type I collagen. Among these collagen fibers are fibroblasts, the cells that produce collagen on their own. through various metabolic pathways. Due to its solid state and high cohesion, this fabric is ideal for forming part of ligaments and tendons, for example.
At the same time, Dense connective tissue is subclassified into two variants: regular and irregular In the first, the collagen fibers are arranged in parallel, while in the second, the collagen is found in disorganized arrangements.
2. Specialized connective tissues
From here, we move away from the “usual” connective tissues, diffuse and mostly undifferentiated, to enter a much more organized and known terrain. Let’s go there.
2.1. adipose tissue
It is a tissue of mesenchymal origin, made up of a cellular association responsible for storing lipids: adipocytes These cells represent 95% of the total adipose tissue and their function is to store energy in the form of triglycerides.
Within adipose tissue, two types can be differentiated. Brown and white. White adipose tissue (unilocular) is the majority in mammals, and is responsible for storing fat in a semi-liquid state in the form of a large drop.
On the other hand, brown fat stores lipid content in different droplets (multilocular) and contains a high number of mitochondria in each adipocyte. While the white tissue is responsible for storing fat in the long term, the brown tissue burns it at times when it is necessary to produce heat.
2.2. Woven bone
Normally, human beings have the perception of bone tissue as immovable, strong and permanent over time. Although bone tissue is hard (due to the hydroxyapatite crystals that make up its matrix), it is also synthesized and resorbed at variable rates, depending on the needs of the body at any given time. 99% of calcium is stored in the bones, and when it is necessary to use it and it is not present in the diet, part of the bone tissue has to be destroyed to recover it.
Depending on its nature, bone tissue can be dense or spongy Various cell bodies are found in both, such as osteoclasts, osteoblasts, osteocytes and osteoprogenitor cells. Unfortunately, the more time passes in the individual’s life, the more the matrix is broken and the less is generated. It is no coincidence that up to 80% of the population (especially women) show signs of osteoporosis by the age of 80.
23. Blood tissue
Although it may not seem like it, blood is also a type of specialized connective tissue, because at the end of the day it is putting different organs in contact with each other, through a series of fibers, matrix (the plasma) and cell bodies. Platelets, white blood cells and erythrocytes navigate through the blood vessels, all of them with different and complementary functionalities. Platelets are responsible for clotting blood in the event of injury and maintaining internal homeostasis, lymphocytes respond to endogenous and exogenous threats, and erythrocytes transport oxygen to each and every tissue.
Although it is a different type of tissue, this group can also include hematopoietic tissue, the precursor of the blood cells already mentioned. This is mainly found in the red bone marrow, the synthesis center for erythrocytes and white blood cells.
The cartilaginous tissue is a type of elastic, avascular (without blood vessels), specialized connective tissue made up almost entirely of matrix and scattered chondrocytes
Cartilage is essential for the movement and locomotion of living beings, as it covers the joints, joins the ribs with the sternum and, in addition, serves as a support point and covering for the trachea, bronchi, external ear and the nasal septum.
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2.5. lymphatic tissue
In this section something similar happens to what was mentioned in blood tissue: It is not a solid tissue organization, but it also contains fibers, cells and matrix, so it falls within the definition of “connective tissue”; even if it is in a highly specialized modality.
Lymphatic tissue is the travel highway (along with blood) for lymphocytes, macrophages and plasma cells. Therefore, its functionality is eminently immunological.
Summary
As you may have seen, connective tissue goes far beyond those diffuse layers that are located holding the skin or protecting the organs and keeping them in place in the abdominal cavity. Much more specific concepts are also included here, such as fat, blood, lymph, cartilage and even bones.
All these tissues have 3 characteristics in common: they contain fibers, matrix and cells embedded in it. Depending on the dominant cell type and its primary function, connective tissue can be analyzed into many different categories and dimensions.
