Skeletal Flashcards
What does the skeletal system compose of?
Bone and cartilage
What is the skeletal system divided into?
The axial and A
appendicular skeleton
What is included in the axial skeleton?
The skull, vertebrae, sacrum ribs and sternum
What is included in the appendicular skeleton?
Bones of upper and lower limbs including the scapula and clavicle
What are the functions of bones?
Enables movement Protection of vital organs Structural support Storage of minerals Haematopoiesis (blood cell formation)
What is the structure of bone?
It has a collagen fibre framework in mucopolysaccharide semisolid gel
What is bone hardened by?
Precipitation of calcium phosphate crystals (hydroxyapatite)
What is the difference between cartilage and bone?
Bone is calcified
What three components make up bone?
Osteoblasts, osteocytes and osteoclasts
What is the head of the bone called?
Epiphysis
What section of bone sits just below the epiphysis?
Metaphysis
What is the main function of metaphysis?
Region of growth in childhood
where does the blood enter the bone
Nutrient foramen
What is the middle section of bone called?
Diaphysis
What cells can be found in the diaphysis?
Fibroblasts, mesenchymal cells
What function do mesenchymal cells have?
Differentiating into osteoblasts, chondrocytes
WHat tissue surronds the shaft of compact bone?
Periosteum
What are the two major kinds of bone?
Trabecular and Coritcal
What is trabecular bone?
Spongy and porous
Gives supporting strength to the ends of weight bearing bone
What is coritcal bone?
Bone on the outside, forms the shaft of the long bone, provides stiffness and strength
How are trabeculae bones formed?
Along the lines of stress
What two types of canals carry blood to the bone?
Haversian and Volkman’s canals
What do Haversian canals do?
Cary blood along the long axis of the bone
What do Volkman’s canals do?
Carry blood perpendicularly
What is trabecular bone home to?
Haemopoiesis, formation of blood cellular components
What is the composition of bone?
Mostly protein fibres- collagen
Crystallised mineral salts, hydroxyapatite
Water
ossified calcium phosphate
What is an osteoblast?
bone forming cell, cover the surface of bone forming an osseous matrix in which it becomes enclosed as an osteocyte
What is an osteoclast?
osteophage; a large, multinucleated cell derived from haematopoietic cells response to mechanical stresses and physiological demands they resorb bone matrix by demineralization
What is an osteocyte?
– bone cell – trapped, “retired” osteoblasts. Mature bone cells - embedded in lacunae, relatively inactive. Maintain bone matrix through cell-to-cell communication (via projections in canaliculi) and influence bone remodelling. Mechanosensing
What is an osteoprogenitor?
Stem cell population, gives rise to osteoblasts (but also other cells)
Where do osteoblasts originate from?
Osteoprogenitor cells
What happens when osteoblasts become stimulated?
Will deposit collage as an organic matrix then hydroxyapatite
What happens to osteoblasts that become entombed in stimulation?
Mature into osteocytes
What does osteoclasts do?
Form a “sealing zone” on bone, regulated by hormones
What do osteocyte communicate by
Communicate via finger-like projections in canaliculi
What are canaliculi?
microscopic canals between the lacunae of ossified bone
What are lacunae?
a cavities or depressions, especially in bone
What is hypertrophy?
Too much bone formation
What is atrophy?
Too much bone resorption
Why is it important to maintain an equilibrium of bone formation and resorption?
To stop developing diseases such like hypertrophy and atrophy
What controls the activity of osteoclasts?
Calcitonin, decreases blood calcium levels
What controls the activity of osteoclasts?
Parathyroid hormone
What are the steps in trabecular bone remodelling?
Quiescence,
resorption by osteoclasts,
surface exposed osteoprogenitors adn differentiate into osteoblasts,
osteoblasts lay down new bone
What are the steps in cortical bone remodelling>
Osteoclasts form a cutting cone at the resorption front
At the closing cone, osteoblasts line the osteoid
What is Wolff’s law?
Bone adapts to the load under which it is placed
When bones from in a fetus, where does the cartilage model come from?
Chondroblasts
When the cartilage model is developed in fetuses, what process does it go under?
Ossification to create endochondral (long bones) and intramembranous (flat bones)
Where does ossification begin?
In the diaphysis
After birth, where does bone then grow from?
The epiphysis and epiphyseal plate, end of the bone
What is required for bone growth to occur at the epiphyseal plate?
The plate of cartilage
What happens at the hypertrophic zone?
swelling of chondroblasts casuses spontaneous mineralisation
To stop any further bone growth what happens?
The epiphyseal plates fuse with the cartilage causing no more bone growth
How does the body deal with fractures?
Callus formation- osteoblasts form a woven bone to bridge gap however is weak
Lamellar bone is laid down as this is stronger as the collagen is organised
What are the three types of cartilage?
Elastic, hyaline, fribrocartilage
What cells make up hyaline cartilage?
Chondrocytes
What gives hyaline cartilage its impact resistance?
The extracellular being filled with water
What gives hyaline its structure?
Proteoglycans
What is the long bone head called?
Trabecular
What is the long bone cylinders called?
Compact
How are compact bones arranged?
Cylindrically in Haversian systems
What do osteoclasts do?
Large macrophage-like cells that digest bone
What do osteoblasts do?
Lay down framework in bone formation
What is a joint?
Where two or more ones meet
What is the function of joints?
Facilitate growth and transmit forces
What are the three types of joints by movement?
Synarthroses, amphiarthroses, diarthroses
How do synarthrose joints move?
They don’t
How do amphiarthroses joints move?
Slightly movable joint in which the surfaces of bones are connected by ligaments or cartilage
How do diarthroses joints move?
A joint that can move freely in various planes
How do you classify joints by soft tissue structure?
Fibrous, cartilaginous, synovial
What are the three types of fibrous joints?
Sutures, syndesmosis and gomphosis
What are suture joints?
Joints between skull vault bones
What are syndesmosis joints?
Fibrous membrane between long bones eg radioulnar interosseous membrane
What are gomphosis joints?
Peg and socket, teeth in jaw
What are the two types of cartilaginous joints?
Primary (synchondrosis) and secondary (symphysis)
What is the layering of primary cartilaginous joint?
Bone- hyaline cartilage- bone
What is the layering of secondary cartilaginous joints?
Bone-hyaline cartilage- fibrocartilage- hyaline cartilage- bone
An example of primary cartilaginous joints
First costosternal joint
What type of cartilaginous joint do you find epiphyseal plates?
Primary
Example of secondary cartilaginous joints
Joints of the sternum, intervertebral discs and pubic symphysis
What are synovial joints?
Joints that allow friction-free movement
Example of synovial joint
Knee
What are the features of synovial joints?
Fibrous capsule with both intrinsic and extrinsic ligaments, hyaline cartilage, synovial membrane, intra-articular disc, bursae, synovial sheaths
What are intrinsic ligaments?
Ligaments that are part of the capsule
What are extrinsic ligaments?
Ligaments that are outside the capsule
What does it mean being double jointed?
The ligaments are very relaxed
What creates the frictionless surface of joints?
Hyaline cartilage
What secretes the synovial fluid that lubricates the joint?
Synovial membrane
What is synovial fluid made out of?
Hyaluronic acid and lubricin
What effect does exercise have on synovial fluid?
Decreases viscosity so lubrication improves
What are intra-articular discs?
Discs that are found in joints where there are rotatory movements
What are bursae?
Closed sacs lined with synovial membrane
An example of a bursae?
Sits anterior to the patella
What are synovial sheaths?
Specialised bursae that surround tendons where they are subject to pressure
How many planes do ball and socket joints move?
3
How many planes do hinge joints move in?
1
What factors influence stability?
Shape of the bones, strength and position of the ligaments, tone of surrounding muscles
What is osteoarthritis?
Inflammation of the joints
What causes osteoarthritis?
Degeneracy in the articular cartilage in weight bearing joints
What is rheumatoid arthritis?
Inflammation in the joints caused by an autoimmune disease
What causes rheumatoid arthritis?
Changes in synovium lead to destruction of articular cartilage
