Lecture 6 Flashcards
Define connective tissue and give examples.
Supports the body by holding parts together, transporting substances (blood) and protecting the body from foreign invaders. e.g. bones, tendons, ligaments, cartilage.
What are the 2 extracellular components of bone, what percentage does each component take up and what properties do they provide to the bone.
Organic component - 33% of the matrix, made up of collagen proteins, and proteoglycans. This provides the bone with the ability to resist tension. If this component of bone is removed, bone beams brittle.
Inorganic component - 67% of the matrix, made up of minerals salts (hydroxyapatite), provides hardness and allows for bones to support us. (resists compression) If this component of the matrix is removed, bone becomes flexible.
What is remodelling and what cells carries out this process.
Remodelling is the constant building and breaking of the bones extracellular matrix.
Osteoblasts - build the ECM
Osteocytes - Mature Osteoblasts that are stuck within the bone structure. Osteocytes communicate to the Osteoblasts and Osteoclasts and keep the continuous process of remodelling going.
Osteoclasts - Breaking down the ECM.
Describe the structure and features of the compact bone at a gross level.
- Seems impenetrable from the outside
- Holes located at the extremities which allow for blood flow supply in order for cells to get nutrients to survive and stay health (osteocytes).
List the structures of the compact bone at a microscopic level.
- Osteons - Lengthwise units that make up the compact bone
Lamella - tubes of ECM with collagen fibres aligned to resist forces.
Lamellae - Rings of Lamella that form the osteon.
List the structures that make up the Osteon and their functions.
- Made up of multiple rings of lamella running down the shaft
- Central Canal - contains blood vessels which allows blood to flow and diffuse to areas of the cell that need nutrients (osteocytes) and nerves which are used to signal.
- Lacunae - Lakes where osteocytes are located.
- Canaliculi - Channels that penetrate through lamella and allow for blood flow (to provide nutrients to the Osteocytes) and allow for communication by the Osteocytes.
What does the Central Canal of the Osteon do?
Contains blood vessels which allow for blood to flow though and diffuse to areas and provide nutrients to cells.
What is the Lacunae?
Lake containing an Osteocyte.
What are lamellae and what is their function?
Lamellae tubes of collagen fibres and several vertically running rings of them make up an Osteon, and provide resist forces.
What are Canaliculi and what is their function?
Canaliculi are channels that run through the lamellae, and allow for blood flow so nutrients can be delivered to Osteocytes to keep them healthy. They also serve as communication pathways for the Osteocytes.
What is the periosteum?
An outer layer of connective tissue with no inorganic component, that holds the Osteoblasts, which are then released into the blood vessels when needed for remodelling.
Explain the structure of cancellous bones and their lamella.
Lamellae on the cancellous bone are struts, which are exposed and filled with marrow, these struts are called Trabeculae and the lacunae reside on these. These Trabeculae are exposed to the vessels and so get fed directly.
What does the concentration of trabeculae at a point of a bone depend on?
The amount of stress in that given area.
