A&P I Exam 2 - Bone 3 (Bone Formation)
promotes intestinal absorption of calcium
What does calcitriol (vitamin D) do?
Yes
Can bones still thicken and are they capable of repair even after the epiphyseal growth plates have closed?
bone stores 99% of the body's calcium; this reserve is used to regulate the level of calcium in the blood
Describe calcium reservoir.
a process whereby cartilage is replaced by bone forms both compact and spongy bone
Describe endochondral ossification (simplified).
it produces spongy bone this bone may subsequently be remodeled to form compact bone
Describe intra-membranous ossification (simplified).
1. occurs 6-8 hours after injury formation of a fracture hematoma as a result of blood vessels breaking in the periosteum and in osteons 2. takes a few weeks, as many as six months formation of a callus: phagocytes remove cellular debris and fibroblasts deposit collagen to form a fibro-cartilaginous callus which is followed by osteoblasts forming a bony callus of spongy bone 3. takes several months and is called remodeling spongy bone is replaced by compact bone the fracture line disappears, but evidence of the break remains
Describe the steps in the fracture and repair process and when they occur.
-if too much tissue is formed, the bones become abnormally thick and heavy (acromegaly) -excessive loss of calcium weakens the bones, as occurs in osteoporosis -they may also become too "soft", as seen in the bone diseases rickets and osteomalacia
Describe why there must be a balance between osteoclasts and osteoblasts.
stress patterns experienced during the remodeling
Remodeling alters the bone shape for better support based on what?
demands placed on it by new or heavy loads
Remodeling provides for strengthening of bone tissue to meet what?
injured bone tissue
Remodeling removes (blank) bone and replaces it with new (blank).
intra-membranous ossification
This type of ossification is used in forming the flat bones of the skull, mandible, and clavicle.
synaptic transmission, muscle contraction, blood clotting
What activities is calcium required for?
1. intra-membranous ossification 2. endochondral ossification
What are the methods of which osteogenesis occurs?
1. formation of bone in an embryo 2. growth of bones until adulthood 3. remodeling of bone 4. repair of fractures
What are the situations that bone formation occurs?
1. development of cartilage model: mesenchymal cells develop into chrondroblasts, which form the cartilage model 2. growth of the cartilage model: growth occurs by cell division of chondrocytes 3. development of primary ossification center: in this region of the diaphysis, bone tissue replaced most of the cartilage 4. development of the medullary (marrow) cavity: bone breakdown by osteoclasts forms the medullary cavity 5. development of secondary ossification centers: these occur in the epiphyses of the bone 6. formation of articular cartilage and epiphyseal plate: both structures consist of hyaline cartilage
What are the steps for endochondral ossification?
1. development of ossification center: osteoblasts secrete organic extracellular matrix 2. calcification: calcium and other mineral salts are deposited and extracellular matrix calcifies (hardens) 3. formation of trabeculae: extracellular matrix develops into trabeculae that fuse to form spongy bone 4. development of the periosteum: mesenchyme at the periphery of the bone develops into the periosteum
What are the steps for intra-membranous ossification?
release of calcium from the bone matrix retention of calcium by the kidneys
What are the two main ways that blood calcium can be increased?
bone resorption bone deposition
What does bone remodeling involve?
parathyroid hormone
What does the following: promotes resorption of bone matrix prevents loss of calcium in the urine promotes vitamin D (calcitriol) formation
negative feedback
What feedback system is used for the regulation of blood calcium concentration?
any break in a bone
What is a fracture?
osteogenesis
What is another name for ossification?
osteoblasts
What is involved in bone deposition - osteoclasts or osteoblasts?
osteoclasts
What is involved in bone resorption - osteoclasts or osteoblasts?
new bone
What is more resistant to fracture: new or old bone?
the process of forming new bone
What is ossification?
calcitonin
What is produced by parafollicular cells of the thyroid gland and lowers blood calcium levels by inhibiting bone resorption?
bone deposition
What is the addition of minerals and collagen fibers to bone by osteoblasts?
bone remodeling
What is the ongoing replacement of old bone tissue by new bone tissue?
bone resorption
What is the removal of minerals and collagen fibers from bone by osteoclasts?
endochondral ossification
What method of ossification is the method used in the formation of most bones, especially long bones; involves the replacement of cartilage by bone; and has one primary and two secondary centers of growth?
intra-membranous ossification
What ossification process does this describe: bone forms from mesenchymal cells that develop within a membrane - without going through a cartilage stage. Has many ossification centers.
bone remodeling
What supports calcium homeostasis in terms of bone?
vitamin A
What vitamin stimulates activity of osteoblasts?
vitamin A vitamin C vitamin D vitamins K B12
What vitamins are needed for normal bone metabolism?
vitamins K and B12
What vitamins are needed for snythesis of bone proteins?
about the 6th week of embryonic development
When does the methods of osteogenesis occur?
18-21 years of age
When is ossification contributing to bone length usually complete by?
intra-membranous
Which type of osteogenesis is more simpler - intra-membranous ossification or endochondral ossification?
vitamin D
what vitamin is essential to healthy bones because it promotes the absorption of calcium from foods int he gastrointestinal tract into the blood?
vitamin C
what vitamin is needed for synthesis of collagen irt bone metabolism?