Facts about Bones
Bone: a living dynamic tissue
In the living body, bones are very much alive. They have their own nerves and blood vessels and are made of living cells which help them to grow and to repair themselves. As well, proteins, minerals and vitamins make up the bone.
Babies are born with about 300 soft bones (mostly made of cartilage). During childhood and adolescence, the cartilage grows and is slowly replaced by 'hard' bone. Some of these bones later fuse together, so that the adult skeleton has 206 hard bones.
The major functions of bones are:
- to provide structural support for the body
- to provide protection of vital organs
- to provide an environment for marrow (where blood cells are produced)
- to act as a storage area for minerals (such as calcium)
Bones are made of two types of tissue:
- Hard outer layer called cortical (compact) bone, which is very strong, dense and tough.
- Spongy inner layer called trabecular (cancellous) bone, which is lighter and less dense than compact bone but still very strong.
العظم: نسيج حي وحيوي
في جسم الإنسان، تُعتبر العظام من الأنسجة الحية والحيوية، فهي تتمتع بأعصاب وأوعية دموية خاصة بها وهي تتألف من خلايا حية تساعدها على النمو وعلى ترميم ذاتها. كما أنّ العظام تتألف من بروتينات ومعادن وفيتامينات.
يتمتّع حديثو الولادة بحوالى 300 عظمة طرية (مكوّنة معظمها من الغضروف). خلال فترة الطفولة والمراهقة، ينمو الغضروف ويُستبدل تدريجياً بعظام "صلبة". في ما بعد، تندمج بعض هذه العظام ببعضها البعض حتى يصبح عدد عظام جسم الراشدين 206.
أبرز وظائف العظم هي
• دعم بنيوي للجسم
حماية الأعضاء الحيوية.
• تغليف النخاع العظمي حيث يتم إنتاج الخلايا الدموية.
• هو بمثابة منطقة تخزين للأملاح المعدنية كالكلسيوم.
تتألف العظام من نوعين من الأنسجة:
طبقة خارجية صلبة تُسّمى العظم القشري (المكتنز)، وتكون قوية وكثيفةً وصلبةً--
طبقة داخلية ليّنة تُسّمى العظم التربيقي (الإسفنجي) تكون أخف وأقل كثافة من العظم المكتنز ومع ذلك تكون قوية جداً-
What is peak bone mass?
By around the age of twenty or twenty-five, the growth process of bones is completed and a person's 'peak bone mass' is normally reached. Peak bone mass is the maximum bone mass achieved in life. The age at which peak bone mass is achieved varies between different parts of the skeleton and different populations. A person's peak bone mass is determined largely by genetic factors, but other factors such as nutrition, physical activity and disease also influence bone development. In youth, optimising peak bone mass as much as possible is important in reducing the risk of osteoporosis later in life.
As we get older we are no longer able to replace bone tissue as quickly as we lose it – in a process called 'bone remodeling'. In women the rate of bone tissue loss increases significantly after menopause, when estrogen production stops and bones no longer benefit from its protective effect. Men also suffer from loss of bone tissue, but the rate of loss is much slower than in women. Lifestyle factors (see prevention) can play a role in helping to reduce age-related bone loss that contributes to osteoporosis risk.
