Bone & Skeleton Flashcards
What are the 6 functions of bones?
1) Protect soft parts
2) Support body
3) Fat Storage
4) Site of hematopoiesis
5) System of levers for movement
6) Mineral homeostasis
What are the 4 different cells of bones
1) Osteogenic/ osteoprogenitor cells
2) Osteoblasts
3) Osteocytes
4) Osteoclasts
Describe the role of osteogenic/ osteoprogenitor cells
Stem cells that differentiate into
Describe the function of osteoblasts
Osteoblasts synthesise and secrete new bone
Describe the function of osteocytes
Osteocytes are bone maintaining cells
Describe the function of osteoclasts
Osteoclasts are bone reabsorbing cells
What are lamellae?
Layers of bone - can help with age determination
What is an osteon?
A structural unit of compact bone
Describe the structure and function of the osteon
Function as pressure-resistant columns.
Collagen fibres spiral in each lamella
Angle of spiral is opposite in adjacent lamellae. This resists compression and twisting forces.
What does axial mean (with reference to the skeleton)
Central column (spine and vertebrae)
What does appendicular mean (with reference to the skeleton)
To do with the limbs (arms and legs)
What is endochondral ossification
Bone development from hyaline cartilage
What is intramembranous ossification?
Bone development from fibrous membranes.
What is the medullary cavity?
Hollow space in the centre of a bone’s shaft that stores bone marrow and allows blood vessels to deliver blood throughout the bone.
What are the 5 different shapes of bone?
1) Long
2) Short
3) Flat
4) Sesamoid
5) Irregular
Describe the structure of a long bone (different vertical layers)
Proximal Epiphysis
Metaphysis (growth plate)
Shaft/ diaphysis
Metaphysis (growth plate)
Disal Epiphysis
(Remember Eat My Donuts Mr Eagle)
Do long bones have a medullary cavity?
Are long bones compact and spongy?
Yes
Yes
Describe the structure of short bones
About as long as wide. Can be different shapes (e.g., cylindrical, cubic)
1) Do short bones have a medullary cavity?
2) Are short bones compact and spongy?
1) No
2) Yes
Describe the structure of flat bones
Thin, flat and wide.
Compact bone surrounding spongy bone or air sinus.
Describe the location and formation of sesamoid bones
Found under tendons, close to joints
Formation is sensitive to biomechanical forces.
Describe irregular bones
Odd shapes. Jutting processes - sticking out bits to increase surface area for muscle attachment.
Describe the 2 types of membrane found in bones - include layers, their function and location.
Periosteum - covers the outside of bone. Contains 2 layers (cellular and fibrous) Osteogenic (produces new bone). Site of sensory nerves, blood and lymphatics.
Endosteum. lines inside surface (medullary cavity). Single layer. Osteogenic and osteolytic to stop bone being too dense.
How are bones well vascularised?
Arteries enter via nutrient foramen (holes in the surface), passing through the subchondral bone to supply the calcified part of cartilage.
What is bone remodelling?
The continuous deposition and reabsorption of bone Influenced by hormones and forces (Wolff’s law - bone adapts to load).
What hormones are influential in bone remodelling?
PTH and Calcitonin.
What is ossification?
The process of bone formation. Can be either intramembranous or mesenchymal
What are mesenchymal cells/ tissue?
Multipotent stem cells that differentiate into osteoblasts, osteocytes etc.
What happens to the mesenchymal tissue in intramembranous ossification.
Mesenchymal tissue is converted to bone to form the flat bones of the skull and clavical.
What happens to the mesenchymal tissue in endochondral ossification.
Mesenchymal tissue transforms into cartilage, then is replaced by bone. Forms the remainder of the axial skeleton and long bones.
