Short answers, pulled from the story.
Connective tissue is biological tissue found between other tissues throughout the body, holding structures together, providing mechanical cushioning, and allowing oxygen and nutrients to diffuse from capillaries to cells. It is one of the four primary types of animal tissue, alongside epithelial, muscle, and nervous tissue. Its functions vary widely depending on which type of cells and fibers are present.
Johannes Peter Müller introduced the term connective tissue, or Bindegewebe in German, in 1830. The tissue had already been recognized as a distinct class in the eighteenth century, but Müller gave it the formal name that remains in use today.
Most connective tissues consist of collagen and elastic fibers, ground substance, and cells. Ground substance is a clear, colorless, viscous fluid containing glycosaminoglycans and proteoglycans. Together the fibers and ground substance form the extracellular matrix.
Type I collagen makes up approximately twenty-five percent of the total protein content of the mammalian body. It is present in many forms of connective tissue, including tendons, ligaments, skin, the cornea, cartilage, bone, and blood vessels.
Yes, blood is classified as a specialized fluid connective tissue. It contains no fiber, which distinguishes it from most other connective tissue types, but it develops from the same embryonic origins and is categorized within the broader connective tissue family. Lymph is similarly classified as a fluid connective tissue.
Connective tissue disorders include the congenital diseases Marfan syndrome and Ehlers-Danlos Syndrome, the autoimmune conditions systemic lupus erythematosus and mixed connective tissue disease, and scurvy, which results from vitamin C deficiency that impairs collagen synthesis. Fibromuscular dysplasia, myxomatous degeneration, and connective tissue neoplasms such as hemangiopericytoma are also recognized disorders of this tissue type.