The Skeletal System Flashcards
What are the 5 functions of the skeletal system?
1) Support the body’s structure
2) Protects internal organs
3) Leverage for movement
4) Stores Calcium
5) Produces blood cells
What are the 2 bone functions?
1) Hard, yet brittle
2) Strong, yet flexible
What compound is responsible for the bone’s function of hard, yet brittle?
HYDROXYAPATITE (inorganic) - this compound contains mineral salt deposits (calcium carbonate and calcium phosphate)
What compound is responsible for the bone’s function of strong, yet flexible?
OSTEOID (Organic) - this compound contains collagen and protein complexes
What are the 4 types of cells contained in bones?
1) Osteogenic stem cells
2) Osteoblasts
3) Osteoclasts
4) Osteocytes (mature bone cells)
What are osteogenic stem cells?
Contained in the epistem and peristem. Responsible for new bone growth.
What are osteoblasts?
They secrete osteoids to become osteocytes. They deposit minerals.
What are osteoclasts?
They remove minerals from bones and release into the circulation. Important for bone remodelling.
What are the osteocytes?
Mature bone cells that are found in the lacunae (nests) of bones and they maintain the matrix
What percentage do cells make up out of the whole bone mass?
2%
What are the 2 difference types of tissue which make up bones and what is their role?
1) Compact Bone (around the outside) - needs to be able to resist stresses
2) Cancellous Bone (inside) - needs to be able to be light so you can move around
What are the 2 components of compact bone?
1) Osteons (functional unit)
2) Lamellae (rings of flat sheets around the osteons)
What are the 3 types of lamellae?
Concentric - around osteons
Interstitial - between the osteons
Circumferential - around all the osteons
What is the importance for the osteons to be positioned in the same direction?
It will increase unidirectional strength
What are the 2 components of cancelleous bone?
1) Trabeculae (tissue elements)
2) Bone marrow (contained within the spaces between the trabeculae)
What are the 2 types of bone marrow?
1) Red bone marrow (aka myeloid tissue) = (located in the spaces at the heads of long bones) produces red blood cells
2) Yellow bone marrow (aka fatty tissue) = can no longer produce red blood cells
Who has more red bone marrow in the heads of their long bones?
Children as they require more RBC’s to grow.
What are the advantages are disadvantages of yellow bone marrow?
Advantage = in severe anaemia - the yellow bone marrow can convert back to red in order to produce RBC's Disadvantage = Pieces of fatty tissue can break off and cause an embolism
What are the 2 names given to bone formation?
Either: Ossification or osteogenesis
What are the 2 types of bone formation and where so they occur?
1) INTRA-MEMBRANEOUS OSSIFCATION (in clavicles and flat bones)
2) ENDO-CHONDRIAL CLASSIFCATION (in cartlidge)
What occurs in INTRAMEMBRANEOUS OSSIFICATION?
1) MESENCHYMAL CELLS secrete osteoid.
2) They differentiate into osteoblasts and then become osteocytes (mature cells).
3) Calcium deposits (calcification)
4) Blood vessels grow in the area to supply O2 and nutrients.
5) Bone remodelling occurs - to form compact bone.
When does bone modelling occur?
All throughout life the bones will deposit calcium into the circulation and reabsorb it again.
What occurs in Endochondrial classification?
1) Cartlidge model is laid down.
2) The outer cell differentiate into osteoblasts and forms a thin layer of bone.
3) The cells in the shaft (diaphysis) differentiate into osteoblasts (forming the: primary ossification centre).
4) Osteoclasts will erode away the osteoblasts forming bone marrow cavities.
5) Cells at the ends of the cartlidge model (epiphyses) will differentiate into osteoblasts (forming the: secondary ossification centre).
6) When the epiphyses are completely occified = forms the Epiphysgeal Plate.
How do bones grow after endochondrial classifcation?
1) Cartlidge models will continue to be placed down on epiphsgeal plate.
2) Endochondrial classification repeats.
3) Cells in the shaft (diaphysis) will differentiate into osteoblasts.
What does the continuation of endochondrial classification rely on?
As long as cartlidge growth is faster than osteoblast activity, the bones will continue to grow!
When does bone growth stop?
At puberty.
1) As sex and thyroid hormones will increase. This causes the osteoblast activity to increase at a rate higher than cartlidge growth.
2) Therefore, bone growth stops.
3) No more cartlidge is laid down on the epiphsgeal plate. 4) The epiphsgeal plate will narrow and errode away.
Why do fractures occur?
1) Excessive load
2) Sudden Impact
3) Unusual direction
How are different types of fractures classified?
Type: 1) Compound (in contact with the outside world) & 2) Simple
and
Nature: Spiral, Transverse, Comminuted, Linear, Oblique, Greenstick
Which fracture is the worst?
Comminuted - as it results in 2 types of bones
Which fracture is most common in children?
Greenstick
What are the steps that are involved in bone formation?
1) When a bone has been fractured, blood vessels are torn.
2) Bleeding will show that a HEAMATOMA has formed.
3) 5 things will invade the area in order to form aSOFT CALLUS: 1) Osteogenic stem cells 2) osteoblasts 3) fibroblasts 4) macrophages 5) cappilaries
4) A HARD CALLUS will be formed when calcium phosphate and calcium carbonate deposit
5) Osteoclasts will remodel the bone and the hard callus is removed.
What can be seen on an X-ray?
Soft Callus
What factors promote healing?
1) Good blood supply
2) Free from infection
What occurs to encourage the bone healing process?
1) Alignment
2) Immobilisation (using cast or pins)
What things discourage bone healing?
1) Poor blood supply
2) Infection (either won’t heal or painful)
3) Tissue fragments between bones so can’t heal together
4) Poor alignment (either won’t heal or shortened limb - will need to rebrake and realign)
5) Too much mobility
6) Age
7) Medication
8) Malnutrition
9) Systemic infection
What is a ‘joint’?
Where 2 bones meet
What are the 2 ways to classify a joint and what are they each concerned with?
1) Functional Classification - How much movement occurs in that joint
2) Structural Classification - What is contained in that joint
What are the 3 ways to functionally classify a joint?
1) Synarthrosis = Little or no movement
2) Ampharthrosis = Slightly moveable
3) Diarthrosis = Freely moveable
What are the 3 ways to structurally classify a joint?
1) Cartilaginous = cartilage makes the joint in between the 2 bones
2) Fibrous = collegen fibres makes the joint in beween the 2 bones
3) Synovial = bones are seperated by a synovial cavity containing synovial fluid
What are the 2 problems that are associated with Synovial joints?
1) Inflammation of the synovial cavity = arthritis
2) Easily dislocated
What are the components of the synovial joint?
Synovial cavity containing synovial fluid, lined by synovial membrane.
Lining the bones is = articular cartlidge
Around the synovial membrane is = articualar capsule
What are the 6 different Synovial joint:
1) Ball and Socket
2) Pivot
3) Sliding
4) Ellipsoid
5) Saddle
6) Hinge
What are the 6 different movements of the Synovial Joints:
Flexion and extension Abduction and adduction Circumduction Rotation Pronation and suprination Dorsiflexion and Plantar Flexion
