Major Tissue Classification
Blood is one of the most unobvious types of human tissue. Unlike other biological tissues, blood is a fluid structure, a subspecies of connective tissue. Like all other types of connective tissue, blood has no specific function or is not responsible for a specific organ; instead, it creates interconnections between different organismal systems and plays a predominantly supporting role (LT, 2020).
Gross and Histological Features Characteristic
Blood, skeletal bone tissue, fatty tissue, and cartilage are examples of connective tissues. Like all connective tissues in living organisms, blood consists of cells, intercellular substances, and fibers, the latter of which form the extracellular matrix. The basic substance is a liquid colloidal solution containing glycoproteins and proteins responsible for the tissue’s adhesive properties (LT, 2020).
Subcellular Characteristics That Distinguish Blood
Fibers are represented by three different structures, namely collagen, elastic fibers, and reticular fibers, each with specific functions. The composition and structure of cells for each type of connective tissue are different variables; for blood, the primary cells are the form elements represented by red blood cells, platelets, and leukocytes.
Another difference between blood and other examples of connective tissue is the fluid medium: blood cells are not fixed in space but can move freely throughout the body, unlike, for example, bone cells. It is worth specifying that red blood cells also differ from other connective tissue cells by not having a nucleus and other organelles that allow division when maturing.
Functional Specialization Resulting From Subcellular Features
The unique physical form of blood allows this type of tissue to migrate freely throughout the body, providing organs and tissues with the necessary amount of oxygen. Red blood cells, which contain hemoglobin molecules that bind oxygen, are responsible for this function. Under normal conditions, hemoglobin is transported through the blood vessels with the help of red blood cells and provides gas exchange. This is why red blood cells do not have many organelles, since they need to hold more hemoglobin to promote efficient metabolism in the body.
Medical Conditions Arising From Abnormal Organelle Structure
However, the presence of hemoglobin simultaneously makes the blood tissue vulnerable, as mutational changes lead to sickle cell anemia (MCS, 2022). In this condition, hemoglobin loses its usual structure, affecting oxygen transport efficiency. However, the multiplicity of cells that form the blood can also become a threat. Leukemia is a cancerous abnormal blood condition in which predominantly white blood cells become abnormal and spread through the bloodstream, causing metastases.
References
LT. (2020). Characteristics of connective tissue. LibreTexts Medicine. Web.
MCS. (2022). Sickle cell anemia. Mayo Clinic. Web.