Bones Diseases and the Cytokines who love them: The Unedited version of the Guide Entry: Bone Diseases to your right
Created | Updated Jan 28, 2002
Today I just handed in a 5000 word MSc paper about Metabolic Bone Diseases, so I assume I'm an expert on it. I also handed in a piece of paper containing 10 haiku's about bone cell biology, just in case the grader got bored. Here's an example:
What's Paget's disease?
It's like, bone remodeling
by a Circus Clown
If I don't get a First Class Honors for that, then I'm in the wrong course!
Anyway, here's the low down on bones and the diseases they cause:
Bones are formed in three ways. 1) At birth. Cartilage turns into bone. 2) At post-birth. You're born. You're a baby. You're surrounded by all these adults saying, "eat you're greens, or you'll never get big and strong!" You're ignorant of the fact that bones mostly require calcium, phosphorus, and Vitamin D to form, all of which are NOT in your greens. But you eat your greens anyway, you get big and strong - so strong you don't have to share your toys with the other children or wash behind your ears. In this time, your infant bones are gone and you have adult bones. This is the process of "modeling." 3) Remodeling. This is maintanance. Picture yourself on a highway in Nevada, surrounded by desert, and you're on your Harley-Davidson. All the sudden, your front tire hits a pot hole and you have road rash. While you're in the hospital, recovering from your wounds, you scream at the highway department to repair the highway. Being lazy (insert colorful metaphore here), the workers do not replace the entire highway but rather dig up a bit of the pot hole, refill it with new pavement, and go down to the roadhouse for lots of beer and listen to Bruce Springsteen music. Much of the same is going on in your body as you recover from the motorcycle accident. The bones are fractured and they recruit cells (workers) to fix the problem. The first set are the osteoclasts. Think of them as demolition men, cells that degrade bone. The second set are the osteoblasts. Osteoblasts reform bone. The final set are the osteocytes. Osteocytes are retired osteoblasts, much like the old men who sit on their porches by the street and yell at everybody, saying what kinds of bums they are. The osteocytes help recruite osteoclasts and osteoblasts to do useful work. The process of Osteocytes recruiting cells, Osteoclasts removing damaged bone, and Osteoblasts filling in new bone like pavement is REMODELING.
What in the name of dyslexic marsupials does this have to do with bone disease? Many bone diseases have to do with the remodeling process going wrong. This can happen in many way. With LOADS and LOADS of regulatory molecules governing remodeling, it isn't surprising that just one going wrong could have disasterous results. Because I'm writing an entry, not a book, I'll go over three disease types very quickly:
1) Osteoporosis. This is what you're grandmother might have. What happens is that she stopped making estrogen, a sex hormone that regulates many activities, including bone remodeling. Think of estrogen as the important guy in the yellow hard hat who tells the demolition men that although blowing up an entire building might be fun, they are only supposed to dig up a sidewalk. When estrogen, the guy in the yellow hard hat, is gone, the osteoclasts go beserk, digging up bone left and right. The osteoblasts, who are supposed to repair the bones the osteoclasts dig up, can't keep up. The net result is decreased bone density. So, when your grandma falls down, she is going to break her hip.
2) Osteopetrosis. You know how Superman has "Bizzaro Superman", who is like Superman only his opposite? Ostopetrosis is Bizzaro Osteoporosis. In this case, the Osteoclasts are on strike and don't degrade any bone. The Osteoblasts, who are bored, decided to build new bone anyway. This results in increased bone density. In this case, "More is NOT better," and several problems may result, including deformity and joint problems.
3) Paget's disease. Now our worker cells are on Speed. They are working at an accelerated rate, so fast that they get sloppy. Instead of blowing up an ancient building and replacing it with a nice looking Hotel, they are blowing up ancient buildings and replacing them with cardboard boxes. In more technical terms, remodeled bones are no longer highly structured. Instead, they are weak and brittle. This is a bad thing. If you go up and read my Haiku, this is what I mean by remodeling by circus clowns.
That's it for now. If you were bored enough to read this entry, I hope it has been enlightening. 8-)
What's Paget's disease?
It's like, bone remodeling
by a Circus Clown
If I don't get a First Class Honors for that, then I'm in the wrong course!
Anyway, here's the low down on bones and the diseases they cause:
Bones are formed in three ways. 1) At birth. Cartilage turns into bone. 2) At post-birth. You're born. You're a baby. You're surrounded by all these adults saying, "eat you're greens, or you'll never get big and strong!" You're ignorant of the fact that bones mostly require calcium, phosphorus, and Vitamin D to form, all of which are NOT in your greens. But you eat your greens anyway, you get big and strong - so strong you don't have to share your toys with the other children or wash behind your ears. In this time, your infant bones are gone and you have adult bones. This is the process of "modeling." 3) Remodeling. This is maintanance. Picture yourself on a highway in Nevada, surrounded by desert, and you're on your Harley-Davidson. All the sudden, your front tire hits a pot hole and you have road rash. While you're in the hospital, recovering from your wounds, you scream at the highway department to repair the highway. Being lazy (insert colorful metaphore here), the workers do not replace the entire highway but rather dig up a bit of the pot hole, refill it with new pavement, and go down to the roadhouse for lots of beer and listen to Bruce Springsteen music. Much of the same is going on in your body as you recover from the motorcycle accident. The bones are fractured and they recruit cells (workers) to fix the problem. The first set are the osteoclasts. Think of them as demolition men, cells that degrade bone. The second set are the osteoblasts. Osteoblasts reform bone. The final set are the osteocytes. Osteocytes are retired osteoblasts, much like the old men who sit on their porches by the street and yell at everybody, saying what kinds of bums they are. The osteocytes help recruite osteoclasts and osteoblasts to do useful work. The process of Osteocytes recruiting cells, Osteoclasts removing damaged bone, and Osteoblasts filling in new bone like pavement is REMODELING.
What in the name of dyslexic marsupials does this have to do with bone disease? Many bone diseases have to do with the remodeling process going wrong. This can happen in many way. With LOADS and LOADS of regulatory molecules governing remodeling, it isn't surprising that just one going wrong could have disasterous results. Because I'm writing an entry, not a book, I'll go over three disease types very quickly:
1) Osteoporosis. This is what you're grandmother might have. What happens is that she stopped making estrogen, a sex hormone that regulates many activities, including bone remodeling. Think of estrogen as the important guy in the yellow hard hat who tells the demolition men that although blowing up an entire building might be fun, they are only supposed to dig up a sidewalk. When estrogen, the guy in the yellow hard hat, is gone, the osteoclasts go beserk, digging up bone left and right. The osteoblasts, who are supposed to repair the bones the osteoclasts dig up, can't keep up. The net result is decreased bone density. So, when your grandma falls down, she is going to break her hip.
2) Osteopetrosis. You know how Superman has "Bizzaro Superman", who is like Superman only his opposite? Ostopetrosis is Bizzaro Osteoporosis. In this case, the Osteoclasts are on strike and don't degrade any bone. The Osteoblasts, who are bored, decided to build new bone anyway. This results in increased bone density. In this case, "More is NOT better," and several problems may result, including deformity and joint problems.
3) Paget's disease. Now our worker cells are on Speed. They are working at an accelerated rate, so fast that they get sloppy. Instead of blowing up an ancient building and replacing it with a nice looking Hotel, they are blowing up ancient buildings and replacing them with cardboard boxes. In more technical terms, remodeled bones are no longer highly structured. Instead, they are weak and brittle. This is a bad thing. If you go up and read my Haiku, this is what I mean by remodeling by circus clowns.
That's it for now. If you were bored enough to read this entry, I hope it has been enlightening. 8-)
