skeletal system Flashcards
Describe the difference between spongy and compact bone
- Spongy bone is made up of trabeculae. Trabeculae has holes and arches that contain bone marrow, allowing haematopoiesis to take place. It is found in the inner layer of flat and irregular bones, contributing to shock absorption. There are no osteons within spongy bone.
- Compact bone is the outer layer of long bones, it is dense and solid providing strength and protection. Compact bone has osteons.
What are the main functions of the bone?
- Protection
- Support
- Movement
- Mineral storage
- Blood cell formation
- Hormone storage
- Hormone production
- Triglyceride (fat) storage in bone cavities
What is haematopoiesis?
- Formation of blood cellular components
What are the three sections/ layer of bone
- Proximal epiphysis
- Diaphysis
- Distal epiphysis
What is the periosteum
- Thin layer of connective tissue that covers outer surface of bones, on all places except joints. It has a rich nerve supply.
- It has two layers: Fibrous & osteogenic
- Sharpey’s fibres connect periosteum to the bone.
What is an endosteum?
- Lining of cavities and canals that pass through compact bone. Release endosteal cells
What are endosteal cells?
- They are bone lining cells that communicate with osteocytes.
What are canaliculi?
- Is found in compact bone, they are hairlike canals that connect lacunae to each other and central canal.
Compact bone microstructure: How is canaliculi formed?
- Osteoblasts secrete bone matrix
- They maintain close contact to each other and other bone cells.
- Mature osteocytes develop as bone matrix calcifies
- Then a very fine web of canaliculi is formed.
What are synovial joints?
- Freely moveable joints
- It has synovial fluid, which is produced in the synovial membrane. It is made up of hyloronich acid and lubricate. It lubricates articular cartilage.
What are the accessory structures of synovial joints, describe them.
- Bursae= fluid filled sacs allowing tendon and articulating cartilage to roll against each other without creating friction.
- Fat pads= contain fat cells, act as a cushion. Have a rich blood supply.
- Ligaments= Fibrous structure attaching bone to bone. They help to maintain the integrity of a structure.
- Menisci= made of fibrocartilage. They are two wedge shaped pieces of fibrocartilage that act as a shock absorber between the tibia and femur.
- Tendon= Attach muscle to bone. Tendon sheath wraps around the tendon and are fluid filled.
What are the main divisions of the skeleton?
Axial skeleton: bones of the head and trunk of a vertebrate.
Appendicular skeleton: bones of the shoulder girdle, the upper limbs, the pelvic girdle, and the lower limbs.
What are classifications of bones by shape?
- Long= Bones longer than they are wide e.g., femur, humerus
- Short= Bones as wide as they are long e.g., carpal bones
- Flat= Bones like plates e.g., scapula, sternum
- Irregular= e.g., vertebrae, inner ear
- Sesamoid= Are embedded in tendon e.g., patella, psiform
What are the types of endosteal cells/ bone lining cells?
Osteoblasts= Builder cells. They produce calcium binding proteins and lay down collagen fibres.
Osteoclasts= Remodelling cells. Release enzymes/ acids from ruffled edge to break down the bone.
* These both work together to remodel the bones.
Osteocytes= Sitter cells. Sit in bone and monitor the stress and strains of the bone. Help/ coordinate remodelling of bone.
Endosteal cells (bone lining cells)=
Squamous cells that communicate with osteocytes.
