How are bones vascular....i mean how and where are vessels present in bone? And why are not cartilages vascular?
Answers
Explanation:
Both bone and cartilage contain living cells that require an influx of nutrients and an outflux of waste material in order to survive, this is known as perfusion.
In bone, perfusion is provided to bone cells (osteocytes) and nerves by blood vessels that permeate the bone. Blood vessels are required because bone is a thick structure. The individual cells are buried deep into an impermeable, calcified matrix. Without nearby blood vessels, nutrient-filled fluid cannot permeate deep into bone tissue to provide effective perfusion to living cells.
In cartilage, there are no blood vessels or nerves. Instead, cartilage cells (chondrocytes) exchange nutrients and waste through diffusion with surrounding “ground substance”.
This is possible because, unlike bone, cartilage is a thin structure composed of chondrocytes which secrete an extra-cellular matrix. This matrix (ground substance) is a permeable, gelatinous fluid full of elastic collagen fibers and proteoglycans (suggary proteins) that give cartilage its form and function.
Again, blood vessels directly feeding cartilage is unnecessary due to the thinness and permeability of ground substance. Nutrients from nearby blood vessels and joint space fluid can seep through the ground substance and diffuse into living chondrocytes.