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?