CHAPTER 5 - INTRODUCTION TO THE SKELETAL SYSTEM
What is in central canal?
contains blood vessels and nerves
Before 6 weeks of development, the skeleton is _________
hyaline cartilage
What is flat bone? Give examples
thin small bone Cranial bones Sternum Ribs Scapula
What happens during phase 2?
- Blood vessels grow around the edges of the cartilage - Perichondrium converts into periosteum - Formation of bone collar: thin layer of compact bone around the shaft of cartilage
What is a process?
bumpy projection
What happens during phase 7?
- Decrease in rate of epiphyseal cartilage enlargement - Increase if rate of osteoblast activity - Epiphyseal closure: epiphyseal cartilage gets narrower and narrower, eventually disappears - Articular cartilage forms
What happens during phase 6?
- Epiphyses filled with spongy bone - CYTES WANT TO GO SIDE TO SIDE - Formation of epiphyseal cartilage • Between epiphysis and diaphysis • Within metaphysis
What happens during phase 3?
- Increased blood supply - Primary ossification center • Cartilaginous matrix is replaced by spongy bone produced by osteoblasts
What happens during phase 5?
- Secondary ossification • Migration of capillaries and osteoblasts into epiphyses centers • Varies from: bone to bone, individual to individual
What happens during phase 4?
- Shaft filled with spongy bone - Osteoclasts create medullary cavity - Cartilage of metaphysis invaded by osteoblasts: production of bone columns - Further growth: increase in length, increased diameter
What are the first steps of endochondral ossification?
1-4: initiation of ossification in developing bone
Collagen fibers make up how much of the bone matrix?
1/3
What is the normal homeostasis level of blood/calcium?
100mg/100ml
Bone cells only contribute to how much of the bone mass?
2%
Calcium phosphate makes up how much of the bones mass?
2/3
What are the last steps of endochondral ossification?
5-7: increasing length of developing bone
What vitamins are essential in bone remodeling?
A C D
What is the skeletal system made up of?
Bones (osseous tissue) Connective Tissue (cartilages, ligaments)
What is a short bone? Give examples
Box like in appearance Carpals Tarsals
What are essential nutrients in bone remodeling?
Calcium Phosphorus Magnesium Sodium
________ is a type of dense connective tissue that is often found in joints to reduce friction. _________ is a type of fibrous connective tissue which attaches a bone to another bone.
Cartilage; ligament
What is found inside of an osteon?
Central canal Canaculi Osteocytes Lacunae Lamallae
What happens during phase 1?
Chondrocytes near the center of the diaphysis increase in size Chondrocytes die and disintegrate due to lack of nutrients Formation of cavities within the cartilage
What are factors that affect bone remodeling?
Diet Body resources: hormones
What is canaliculi?
Hairlike canals that connect lacunae to each other and the central canal
What is a pneumatized bone? Give an example
Have little air pockets, ethmoid bone
What does calcium phosphate eventually convert into?
Hydroapatite crystals
What are osteoprogenitor cells?
Mesenchymal stem cells that divide to produce osteoblasts
Where is bone added to during endochondral ossification?
Metaphysis
What are the cells are in charge of bone resorption?
Osteoclasts
What is the compact bone consisted of?
Osteons
What happens when the calcium is too low in the blood?
Parathyroid gland releases PTH Stimulates calcium release from bones (resorption) Stimulates calcium uptake in the kidneys Increases calcium uptake in the intestines Blood calcium level rises
The outside lining of bone that helps it attach to fascia and circulatory components is the
Periosteum
What is the correct order of events for bone remodeling?
Resting > Resorption > Reversal > Matrix deposition > Mineralization
What is the function of an osteoblast?
Secrete osteoid and build bone
What is the structure of the bone?
Supporting connective tissue Specialized cells
What happens when calcium is too high in the blood?
Thyroid gland releases calcitonin Stimulates calcium deposition in the bones Reduces kidney uptake Blood calcium level declines to set point
What is an irregular bone? Give examples
Weird shape Vertebrae Hip bones Temporal Sphenoid Some facial bones
What is a fissure?
a long, deep sulcus
what is a turbercle?
a small, rounded projection
What is the fascia?
a thin sheath of fibrous tissue enclosing a muscle or other organ
When does the secondary ossification center develop?
after birth
What is osteogenesis?
bone formation
What is solid matrix?
calcium salts around calcium fibers that are hard
What is another name for spongy bone?
cancellous or trabecular bone
What are chondrocytes?
cartilage cells
Stem cells differentiate into what during ossification?
chondroblasts
What forms the cartilaginous bone model?
chondroblasts
What is a foramen?
circular hole or passageway
What are the two types of osseous tissue?
compact bone and spongy bone
What is another name for compact bone?
cortical bone
What is calcification?
deposition of calcium salts
What is the inner lining of the bone called?
endosteum
What is the epiphysis of a long bone? What does it contain?
ends of bone MAINLY SPONGY BONE consists of red marrow
Where is hyaline cartilage found?
ends of bones, nose or ears
In an adult, the epiphysis is separated from the diaphysis by the:
epiphyseal line
Where is the secondary bone centers located?
epiphysis
When does endochondral ossification begin and end?
fetal stage until about age 20
What is a sesamoid bone? Give an example
found in joints Patella
What is an osteoblast?
immature bone cell
How is spongy bone arranged?
in parallel struts, trabeculae, thats what makes the bones lightweight
What is intramembranous ossification? What is it derived from?
involved in the development of clavicle, mandible, skull and face mesenchyme during embryonic periodxf
Where is cartilage found?
joints rib cage ear nose throat
What is a long bone? Give examples
long, have epiphysis, diaphysis, and metaphysis Femur Tibira Fibula Radius Clavicle MetaC MetaT Phalanges Humerus
What are osteocytes?
mature bone cells they release calcium ions position salts in the surrounding matrix
What does the endosteum line?
medullary cavity
What is reversal?
mononuclear cells soothing cut bone
What is resting?
no modeling
When does intramembranous ossification occur?
occurs during embryonic period and into the fetal period
How thick is the endosteum?
one cell thick
What is bone remodeling?
ongoing replacement of old bone tissue by new bone tissue
What is a canal/meatus?
opening a bone that is elongated into a tunnel-like passage through the bone
What is matrix deposition?
osteoblasts released into the fluid matrix
What is the function of an osteoclast?
osteoclasts are involved in bone reabsorption (breaking down bone)
What is resoprtion?
osteoclasts eat away at the bone
The functional unit of bone is known as:
osteon
What is the outer lining of the bone called?
periosteum
What is ossification?
process of bone formation
What is the function of the periosteum?
protection attaches to the fascia attachment site for circulatory and nervous supply
What is the function of an osteocyte?
provide nutrients and keep tissue alive
What osteolysis?
removing bone tissue
What is endochondral ossification?
replacement of cartilage by bone in limbs, vertebrae and hips
What is lamellae?
rings around the central canal, sites of lacunae
What is a tuberosity?
rough projection
What is a condyle?
rounded articular projection
What is the diaphysis? What does it contain
shaft of a long bone the medullary cavity which contains yellow/red marrow
What is a fossa?
shallow depression
What is lacunae?
small cavities that contain osteocytes
What is a sutural bone or wormion?
small flat bones, not everybody has, found in between sutures
What is a facet?
smooth, nearly flat articular surface
What are the functions of the skeletal system?
support, protection, movement, storage of minerals, blood cell formation
What is the primary difference in growth from primary to secondary bone centers?
the timing before birth the bone growth occurs at the primary ossification center after birth bone growth occurs at the secondary ossification center
What is mineralization?
trapping of osteoblasts and subsequent change into osteocytes
What are osteoclasts?
very big cells with multiple nuclei release calcium ions
What is the metaphysis?
where diaphysis and epiphysis meet