7 Bone Flashcards
Different types of bone
Long e.g.) humerus
Short e.g.) trapezoid, calcaneus
Flat bone e.g.) sternum, ilium, occipital, ribs
Irregular bone e.g.) vertebrae, sacrum
Sesamoid bone e.g.) patella
Function of long bones
Supports the weight of the body and facilitate movement
Function of short bones
Provide stability and some movement
Function of flat bones
Protects internal organs
Provide large areas of attachment for muscles
Function of irregular bones
-Protect internal organs
e.g.) protects spinal cord, organs in pelvic cavity
-Provide important anchor points for muscle groups
Structure of Sesamoid bones
Small, round bones found in the tendons of hands, knees, and feet
Function of Sesamoid bone
Protect tendons from stress and damage from repeated ‘wear and tear’
Where are the long bones mostly located in
Appendicular skeleton
Osteomyelitis
Infection within bone
Osteosarcoma
A cancer originating from bone forming cells
How many bones does the skeleton have
206
Name the bones of the axial and appendicular skeleton
Axial: Head, vertebrae, ribs (80)
Appendicular: Shoulder girdle, upper limbs, pelvic girdle, lower limb (126)
Functions of bone
-Mechanical (protect delicate organs, provide framework)
-Synthetic (Haemopoiesis)
-Metabolic (mineral/fat storage, acid-base homeostasis)
Describe the difference between Cancellous and Compact bone
Cancellous:
-trabeculae (combines strength with lightness)
-spaces are filled with by bone marrow
Compact:
-forms external surfaces of bones
-80% of skeletal mass
Describe endochondral ossification
Formation of long bones from hyaline cartilage
-continued lengthening is by ossification at epiphyseal plates
-e.g.) appositional growth (at edges)
Describe intramembranous ossification
Condensations of mesenchymal tissues from flat bone
-cancellous bone
-e.g.) interstitial growth (in the middle)
How do bones undergo remodelling
Osteoclast: bone reabsorption
Osteoblast: remaking bones
-RANK L (initiated remodelling)
-osteoprotegerin (turns off remodelling)
Composition of bone in terms of its cells & extracellular components
Bone marrow
-red marrow (haemopoiesis)
-yellow marrow (energy source)
-BV
-Nerves
Difference between Cancellous bone and Compact bone
Cancellous bone:
-composed of trabeculae
-no nerves, lymphatic/blood vessels
Compact bone:
-composed of osteons
-Haversian canal, Volkmann’s canal
How is Cancellous bone converted to Compact bone
- MSC convert into osteoblast
- Osteoblast lays down osteoid that is mineralised
- Osteoblasts are trapped = Osteocytes
- Repeat of 1~3
- Central MSC converts into blood/lymphatic vessels, nerves
Importance of Vitamin D in normal bone stability
Produces calcitriol (calcium absorption)
-either absorbed from gut or synthesised in the skin
Two steps involved in bone-remodelling
- Osteoclasts make a wide tunnel in the bone (cutting cone)
- Osteoblasts make a smaller tunnel of compact bone (closing cone)
Why do the main force lines go through the cortical/compact bone
Lamella (structure in compact bone) are thought to be able to slip relative to each other to resist fracture
Factors affecting bone stability
-activity of osteocytes (osteoid recycling)
-activity of osteoblasts (bone deposition)
-activity of osteoclasts (bone resorption)
-nutrients (vitamin D3, C, K, B12)
Importance of Vitamin C in bone stability
Synthesis of collagen
Function of osteoid
Undergoes calcification and mineralisation to form lamellae or layers in the bone matrix
Importance of Vitamin K and B12 in bone stability
Synthesis of bone proteins
Importance of Vitamin D3 in bone stability
Produces calcitriol (calcium absorption)
-either absorbed in gut/synthesised in skin
Constituents of bone marrow
Haemopoietic cells
-myeloid
-lymphoid lineages
Marrow adipose tissue
Supportive stromal cells
In what parts of an adult body can bone marrows be found
Ribs
Vertebrae
Sternum
Bones of the pelvis
Functions of the bone marrow
-Used to treat severe diseases e.g.) leukaemia
-Bone marrow stem cells can be transformed into functional neural cells and can potentially be used to treat inflammatory bowel disease
Constituents of blood and its classification
Loose connective tissue
-Formed elements (i.e. blood cells, platelets)
-Liquid phase (plasma)
3 major groups of blood vessels
- Arteries and arterioles
- Capillaries
- Vein and venules
Key arteries in the body
Aorta
Brachiocephalic trunk (supplying head, neck, upper limb)
Carotid arteries (head, neck)
Subclavian arteries (upper limbs)
Iliac arteries (lower limb)
Pulmonary arteries
Conducting arteries
The key, large arteries in the body that transport blood away from the heart towards the distributing arteries (medium sized arteries)
Which artery contain deoxygenated blood
Pulmonary artery
Which veins contain oxygenated blood
Pulmonary veins
Umbilical vein
Constituents of the medulla region of long bones
Adipose tissue (contains stem cells that can become cartilage, fat, bone cells)
What are the different types of vein
-Pulmonary veins (carry oxy. blood from lung to LA)
-Systemic veins (return oxygen-depleted blood from the rest of body to RA)
-Superficial veins (surface of the skin)
-Deep veins (located near a corresponding artery with the same name) e.g.) femoral artery and vein
Function of collateral blood vessels
Provide protection for tissues that may become compromised
-alternative path for arterial blood flow
When are collateral blood vessels formed
-Chronic diseases
e.g.) ischaemia, atherosclerosis
-Produced during development (e.g. brain and joints)
Describe Vasculogenesis
Formation of new blood vessels from angioblast precursors (bone marrow)
e.g.) embryo development, new cancers, endometriosis
Describe Angiogenesis
Formation of new blood cells from existing blood vessels
e.g.) fetal development, collateral arteries, postnatal lung dev.
Two types of Vasculogenesis
Production of single vessel (VEGF, generates primary plexus, which folds into a primary vessel)
- Sprouting: Angiogenesis
-FGF
-Pericytes convert into SMC
-slow - Division of primary vessel: Intussusception
-Twinned vessels from primary vessel
-Multiple GF
-Quick
-Explains neurovascular bundles
Function of pericyte
-Prevents endothelial cell proliferation
-Maintains tight capillaries
e.g.) blood, brain barrier, in the retina
Features of pericyte
-Immature ‘smooth muscle-cell like’ cell
-Found inside the basal lamina
-Key component of capillaries
-Contractile properties
-Nerve cell communication
-Able to differentiate into endothelial cell, SMC, fibroblast
During human development, when does the sesamoid bone first appear
Post-natal period
Where is the osteoprogenitor cell found
Periosteum under the connective tissue layer
(some on the endosteum)
Function of canaliculi
Movement of nutrients
Ossification centre in the diaphysis
Primary ossification centre
Ossification centre in the epiphyses
Secondary ossification centre
What separates the ossification centres
Epiphyseal plates (growth plates)
