connective tissue

connective tissue links, separates, supports, embeds, and protects the body's cells, tissues, and organs, and imparts varying degrees of fluidity, elasticity, or rigidity. There are many types. All contain non-cellular fibres together with the living cells which manufacture them and a matrix which ranges from near-liquid to solid. There are fibres of collagen in all types and also of elastin in many. Loose areolar tissue is the least solid, with gelatinous material among its fibres. Fatty (adipose) tissue has lipid-containing cells in a network of collagenous fibres. Fibrous connective tissue forms a framework among muscle fibres, and among nerve fibres, as well as sheaths for whole muscles and whole nerves; it also forms membranes such as the thin sheets of fascia which separate whole tissue layers from their neighbours, and stronger capsules for individual organs and ligaments which support joints. Elastic fibres in the lungs are crucial for the mechanics of breathing, and in the major arteries for their rhythmic expansion and recoil. Tendons (‘sinews’) are strong, resilient straps of collagenous and elastic fibres which connect a muscle to a bony attachment. Cartilage is a rigid connective tissue; it encircles the windpipe and stiffens the nostrils to keep the airway open, keeps the ears from flapping, and covers the ends of bones in the joints. Finally, bone is obviously the most rigid in the category, with mineral deposits laid down in a collagen fibre framework.

Sheila Jennett